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Title: The Young Mechanic
Author: Lukin, James
Language: English
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THE
YOUNG MECHANIC
CONTAINING
_DIRECTIONS FOR THE USE OF ALL KINDS OF TOOLS_,
AND FOR THE
_CONSTRUCTION OF STEAM ENGINES AND
MECHANICAL MODELS_,
INCLUDING
_THE ART OF TURNING IN WOOD AND METAL_.
BY THE
AUTHOR OF “THE LATHE AND ITS USES”
“THE AMATEUR MECHANIC’S WORKSHOP,” &c.
_FROM THE ENGLISH EDITION, WITH CORRECTIONS, &c._
G. P. PUTNAM’S SONS
NEW YORK
27 WEST TWENTY-THIRD ST.
LONDON
24 BEDFORD ST., STRAND
The Knickerbocker Press
1896
Entered according to Act of Congress, in the year 1871, by
G. P. PUTNAM & SONS,
in the Office of the Librarian of Congress at Washington.
INTRODUCTION TO THE AMERICAN EDITION.
In presenting the American edition of this little work to the public,
we believe we are supplying a want that has long been felt by the Young
Mechanics of this country, and many others who desire to become versed in
the practical use of tools. We know of no other book published in this
country or England, in which the method of using tools is so clearly
explained; and although written more especially for boys and beginners,
it contains much information that will be of great value to the practical
mechanic. The author is evidently thoroughly acquainted with his subject,
and understands how to communicate his ideas in a simple and concise
manner.
The first six chapters are devoted to the description of Tools for
working wood and the manner of using them, beginning with the simplest
operations, requiring but few tools, and gradually leading on to the more
difficult, giving examples of all the methods of joining and finishing
work that are in common use among good workmen, and in this connection
we would like to call attention to the small number of tools the author
requires for performing all these different operations, the idea among
amateurs and boys generally being, that if you only have tools enough you
can make anything. This is not so, and if the beginner will follow the
advice of the author, and buy a few good tools, and learn the use of them
thoroughly, and gradually add to his stock as his knowledge of their use
increases, he will find it greatly to his advantage.
The next five chapters relate to the lathe, and the art of turning.
The author follows the same plan as in the first part of the book, and
gives more practical information in these few pages than we have seen
in any other book on the subject, most of them being written apparently
for finished mechanics, and not for beginners. The Art of Turning as
an amusement, is beginning to attract considerable attention in this
country, but not so much as it deserves and would obtain, if it were
more generally known how many beautiful and useful articles can be
produced in the lathe. The expense of the necessary tools has deterred
many from attempting to learn this branch of mechanics; but we believe if
any one has the time and patience to devote to the work, they will never
have occasion to regret the money spent for this purpose.
The last four chapters contain practical instruction in model-making and
working in metal. This part of the book we would particularly recommend
to inventors who desire to make their own models, as it contains
information in regard to files, drills, and the various small tools used
on metal, and also directions for laying out work, which are invaluable
to a novice in such operations, and will save him much time and trouble.
As this book was originally published in London, where the facilities
for getting many kinds of small tools are better than in this country,
perhaps a little advice as to the best way of getting such tools as may
be required will not be out of place. In most of the large Hardware
Stores, carpenters’ tools will be found, put up in chests, at prices
varying from five to fifty dollars or more; but we should not advise the
amateur to buy any of these, as the quality of the tools is not always
reliable, and as they are usually fitted up to make as much show as
possible for the money, they contain many tools which are of very little
use. The best way is to make a list of the tools required, and select
them for yourself. The most important thing is to have the Cutting tools
of good quality. We give below the names of some of the best makers of
tools; if you purchase any of these, you may be sure of the quality.
On Saws,—HENRY DISSTON, GROVES & SON.
On Chisels and Gouges,—BUCK BROS., MOULSON BROS.
On Plane Irons,—MOULSON BROS., WM. BUTCHER.
On Files,—P. S. STUBS, GREAVES & SON, EARL & CO.
On Rules and Squares,—STANLEY RULE AND LEVEL CO.
If you live in the City, you will probably find no difficulty in
procuring some of the above makes; but if you cannot find them there are
some others that are good, and you must rely somewhat on the dealer. In
regard to the probable cost of the tools, a set such as is described on
pages 29 and 30, would cost from fifteen to twenty dollars.
Of Foot Lathes, the following are some of the makers:
N. H. BALDWIN, Laconia, N. H.
GOODNOW & WIGHTMAN, Boston, Mass.
AMERICAN TOOL CO. ” ”
G. L. CADY, Lowell, Mass.
EXETER MACHINE CO., Exeter, N. H.
JAS. STEWART’S SONS, New York.
From some of the above the amateur will probably be able to select
a Lathe to suit him in size and price. The lowest price at which a
serviceable lathe can be bought is about forty dollars this is without
tools or chucks. About fifteen dollars more would be required for
these. Lathes can be bought from this price up to hundreds of dollars,
according to the style of lathe and the number of chucks, but of course
the beginner would not need an expensive lathe, and seventy-five to one
hundred dollars would buy a lathe and tools suitable for all kinds of
small work in wood, ivory, or metal.
This volume being an exact reprint of the English edition,
it may be well to explain that the material called _Deal_ in
England is much the same as our _Pine_. The article called in
England a “Carrier,” is with us called a _dog_ (see pp. 112,
114, 115). Articles priced in English currency would cost here
now about 35 cents to the English shilling, or $7 per £ stg.
PREFACE.
Of all people in the world who must not be neglected are, first and
foremost, “Our Boys,” and, of all boys, _mechanical boys_ deserve a very
high place in our estimation. Whatever others may be, these, at any rate,
are possessed of sound heads, and willing hands. Therefore, to help these
to carry out their designs, appears to be a special duty of those who,
once mechanical boys themselves, have lived to become the progenitors of
others. In fulfilment of this very duty I have taken up the pen, and with
special reference to _young_ mechanics, but without entirely forgetting
those of maturer growth, I have thrown together a few hints upon that
absorbing question, “How to make and how to use?” In doing this, I have
endeavoured to carry out the plan of _small beginnings_, going from
the simplest and easiest to the more complicated and difficult work,
although here and there, of sheer necessity, a somewhat different order
has been observed. The workshops of King’s College School prove the
capabilities of boys to do high-class mechanical work when their efforts
are rightly directed by a master’s hand. Where the latter cannot be
obtained, guide-books must, however insufficiently, take his place; but
whether instruction in mechanical art be oral or otherwise, practice and
perseverance are the secrets of success.
“Qui studet optatam cursu contingere metam,
Multa tulit fecitque puer; sudavit et alsit.”
CONTENTS.
CHAP. PAGE
I. INTRODUCTORY, 1
II. HOW TO MAKE A CAGE, 15
III. MORTICE AND TENON JOINTING, 29
IV. HOW TO MAKE A TABLE, 49
V. DOVETAILING AND MITRING, 66
VI. REBATING, TONGUEING, AND GROOVING, 89
VII. THE YOUNG MECHANIC AT THE LATHE, 103
VIII. ON WOODS AND MATERIALS FOR TURNING, 122
IX. SHARPENING AND SETTING TOOLS, 144
X. HAND-TURNING IN WOOD, 163
XI. HARD-WOOD TURNING, 203
XII. HOW TO MAKE A STEAM-ENGINE, 226
XIII. WATT’S ENGINE, 264
XIV. HOW TO MAKE AN ENGINE, 281
XV. HARDENING AND TEMPERING TOOLS, 325
CHAPTER I.
There never was a time when a taste for practical mechanics was so
general among boys as it is now, in this year of grace 1870. There are
comparatively few homes in which evidences of this hobby are not apparent
in every odd nook and corner, in the shape of carpenter’s tools, not
always in first-rate condition, nor by any means generally in their
proper places. A saw here, a hammer there, a gimlet, bradawl, or chisel
elsewhere.
This probably results from the giant strides which have been made of
late years in mechanical enterprise, and the introduction of machinery
into every department, as a means of saving labour and facilitating the
production of the various necessaries of life.
Man is an imitative animal, and in this as in other things “the child
is father to the man;” and hence it comes to pass that the boy whose
eyes are continually resting upon machinery of one sort or another
(agricultural implements, if a villager; engines for planing, sawing,
turning, and so forth, if resident in a town) sooner or later feels an
innate desire to construct models of these gigantic mechanical labourers,
by whose incessant but unfelt toil our several daily needs are so cheaply
and plentifully supplied.
Even if the youthful mind does not always display highly-developed
inventive faculties, there is very generally manifested a desire of
personally constructing some one or more of those articles which conduce
to the gratification of a particular hobby. If the boy has a taste for
natural history, cases and cabinets will be made, for the reception
of eggs, butterflies, and insects, or to contain stuffed specimens of
animals and birds. If he has within him the elements of a sailor, his
ingenuity will be exercised upon model boats and ships. If fond of dumb
pets, rabbit hutches, dove-cots, or cages will afford him opportunities
for the exercise of his constructive powers, and thus the young mechanic
frequently lays the foundation of future eminence in that particular line
of life to which his tastes naturally lead him.
There are few boyish hobbies in which assistance has not of late
years been given by instruction books and guides of a high degree of
excellence—natural history, botany, gardening, rearing and breeding all
manner of pets—to each of these, well-written volumes have been devoted
by able and experienced writers, but mechanical and constructive art
has been somewhat neglected. Here and there, in periodical magazines,
a few pages are dedicated to the subject, but no book about practical
mechanics, written expressly for boys, has yet appeared.
The author of the present volume, himself father of four lads, _all_ of
whom in turn occasionally try their hands at this kind of work, and who
has himself for many years practised the mechanical arts of carpentry,
turning, and model-making, hopes that the hints contained herein may
prove valuable to those young friends whom he now addresses. Some of
the following chapters will be arranged for very little boys, some for
those who are older, while it is believed that other parts of the work
may not prove altogether useless to those who have dropped jacket and
knickerbockers and rejoice in the vigour of manhood. Thus the little boy,
who receives the book as a present, will find it a fast and faithful
friend as his years, and, we trust, knowledge and bodily powers increase.
“_Small boys need few tools, but much perseverance._” Let this be their
motto, as it will stand them in good stead. A pocket-knife, gimlet,
hammer, and a few nails will generally serve their purpose; but there is
one other tool, namely, a square, which is of great importance, and of
which it is well to learn the use as early as possible. A small saw and
a bradawl may also be added to the list, and likewise a chisel half an
inch wide. Thus equipped, a very youthful carpenter can do a good deal,
and, let me tell him, a good deal has been often done without even this
moderate supply of tools. It must be taken for granted that the knife and
chisel are sharp, because blunt tools make bad work, and by far the best
plan for small boys is to get some friend to sharpen them when blunt, as
the operation is not easy and requires practice. It is a very foolish
plan to try and work with a blunt knife, for the fingers are just as much
in danger; and a boy who intends to learn how to use tools must learn at
the commencement to use them with due care, so as not to damage himself.
There are small boxes of tools sold, containing generally a wooden
mallet, saw, plane, chisel, and gimlet, at about 3s. 6d. or even 5s. Such
a box is simply useless. The tools are of iron—will not take a good edge,
and are generally disposed to bend and twist. Avoid these, and buy, or
get a friend to buy, those I have named, of good quality, and be sure to
take care of them, for which purpose you may try your hand at making a
box. For this purpose, you will require some thin board (half-inch thick)
planed on both sides. (The carpenter will prepare this for you.) Let us
see how much you will need. Measure your longest tool, the chisel or
saw, if the latter is quite a small one fit to go into a little box; if
not, it can be hung on a nail, and you can make your box to contain your
knife and chisel and gimlets. I daresay if the box is 9 inches long, 4
inches wide, and 3 inches deep, it will be large enough to take these few
tools, for I have just now measured such a hammer and chisel as I have
recommended, and find them each about 9 inches in length. The top and
bottom of a box should project a little all round, so that you will want
them about an inch and a half wider and longer, which will also allow for
the thickness of the wood; for you must remember we have given the size
of the box _inside_. To make this clear, I shall here give a plan of the
bottom of the box (Fig. 1).
[Illustration: Fig. 1.]
[Illustration: Fig. 2.]
[Illustration: Fig. 3.]
It is 10½ inches long, and 5½ inches wide. The broad black line shows
where the edges of the sides and ends will come, these being half an inch
thick, so that there is a quarter of an inch all round the outside as a
border. Reckon across and you will understand this better. A quarter of
an inch outside, half an inch for the black line (equals three-quarters
of an inch), 4 inches for the _inside_ width, half an inch again for the
black line, and a quarter of an inch outside as before,—altogether making
5½ inches. Now reckon the length. A quarter-inch border, half an inch for
the black line, 9 inches inside, half inch for the second black line,
and another quarter outside—making 10½ inches. You require, therefore,
two boards 10½ inches long and 4½ wide for the top and bottom. Now the
two long sides and the ends are to be 3 inches wide to form the depth of
the box, and here you want no extra _width_, but as the _inside_ of your
box is to be 9 inches long, and the sides are usually nailed over the
ends, like Fig. 2, where I have shown them put together, you see that you
must have the _sides_ as much longer than 9 inches as will allow them to
lap over the ends; that is, half an inch at each end where I have made
them black, or altogether, one inch; so that you will want two pieces 10
inches long and 3 wide. The ends will be also 3 inches wide and 4 inches
the other way, and here no additional size is needed. Now, the usual way
to cut the sides is to get a narrow strip of board of the required width
and thickness, and long enough to make both the sides and ends, just such
a piece as Fig. 3, on which are marked the lines where it will have to be
cut across, and you will easily perceive that you require 28 inches in
length and 3 in width.
But you must understand that when you cut with a saw you waste a little
of the wood, which falls in the shape of sawdust, and so if you did not
allow for this, your box would be too small. The waste depends on the
thickness of the edge of the saw, where you will, if you examine it, see
that the teeth spread out right and left to prevent it from sticking
fast as it is used. Probably, you would waste three-eighths of an inch,
which is nearly half an inch in cutting off the pieces, so that instead
of a piece exactly 28 inches long, you must have it 28½ inches, or even a
little more.
I want you to understand all this before you set to work, even though at
first you may get a carpenter to measure and cut it for you; because most
small boys take no trouble of this kind, and consequently they are sure
to make their boxes too large or too small, and they look very bad when
done. However, as I said before, I expect my young readers to understand
what they are about, and they must set out their work carefully, or they
will never get on so as to be able to make good use of the later chapters
of this book. A carpenter’s rule is made like this (Fig. 4).
[Illustration: Fig. 4.]
Sometimes there is a brass slide, to add to its length when necessary,
and sometimes it is hinged so as to fold up again. If you want one for
your box, you can get it so made, when it will go in nicely. It is 2
feet long—1 foot on each side of the central joint. A foot is 12 inches;
the whole rule, therefore, is 24 inches. Now, you will see that each of
these inches is divided by short lines into eight equal parts, called
eighths; at the second, the line is rather longer, this being a quarter
of an inch; at the fourth, there is a still longer line, this being the
half-inch; then comes another eighth, then the three-quarters, another
eighth, and the inch is made up,—eight-eighths being equal to one whole
inch. Very likely you will find one _edge_ of the rule, or sometimes
only one _inch_, divided into smaller parts, which are sixteenths,
or half-eighths; and sometimes, but not very often, divisions still
smaller are used, which are half-sixteenths, or thirty-seconds, because
thirty-two such divisions make the complete inch. Three feet make one
yard, but carpenters always reckon by the foot and inch, and by eighths
and sixteenths of an inch. In some trades the inch is divided into a
_hundred_ parts, and work is measured up and fitted so carefully, that it
would be considered faulty if a mistake of less than a _thousandth_ of an
inch were made; but you will not yet understand how it is possible even
to _measure_ so very small a quantity. You should certainly learn and
understand how to measure with a common two-foot rule, and when you can
add one to your box of tools, do so.
Now, let us examine the tool called a square, without which the marks
could not readily be drawn as a guide for the saw, where the strip of
board is to be cut to make the sides and ends of the proposed box. Here
is a drawing of one (Fig. 5).
[Illustration: Fig. 5.]
[Illustration: Fig. 6.]
It is a handle and a blade, like a knife half opened, the one being
fixed exactly square, or at right angles with the other. The blade is
thinner than the handle, and when the latter is placed as in Fig. 6,
a line marked across the board against the edge of the blade will be,
of course, square to the side, so that when cut off, the piece will be
like the end of Fig. 6. This is not the shape which the sides of boxes
generally have when made by small boys, because they have not a square,
and do not know how to work properly. Nevertheless, if _one_ end of a
board is cut square, you might get the piece right by measuring the same
distance on each side (say 10½ inches), and drawing a line across from
point to point, as a guide for the course of the saw. But, then, as it is
absolutely necessary that the end of the board should be square to the
side, to do this you had better get a proper square at once, and learn
how to use it. You will, indeed, find this tool most necessary for all
kinds of work, and you will be quite unable to do without it, even though
you only have, besides, a knife and gimlet.
Now, if you want to cut off a piece of board with the saw, you must
_never cut out the line you have marked as a guide by the help of your
square_, because if you do, you will get the piece too short, owing to
the width of the saw-cut which I explained before. Cut, therefore, _just_
beyond it, leaving it upon the piece you are going to use for the side
of your box, or other article. At first, you will find it difficult to
saw neatly and close to the line, but you will get used to it very soon;
and if the saw does not go quite straight, you can trim the piece with
a sharp knife neatly up to the line, which you see you could not do if
you cut out that line by sawing exactly upon it. All these directions
in little matters are very important, because you will find that, by
attending to them, you will work well, and the various things you make
will look neat and trim, and be fit to show to your friends.
Now, let us go on with the box, which was laid down just to allow a
little explanation about the carpenter’s rule and square. I shall suppose
you to have cut off all the pieces quite squarely and neat, and that the
_edges_ are also square to the sides, which you must take care to insure
by keeping the blade of the saw upright when you use it. It is a good
plan to measure and mark _both_ sides of your board for this purpose, and
to mark the edges from one of these lines to the other. You will then
have guide-marks all round, and, by keeping close to these, you will be
sure to cut your work truly. It would not so much signify if the long
sides were cut a trifle _too_ long, as I shall explain presently; but the
_ends_ must be square and true to measure, 4 inches by 3 inches. You must
now proceed to nail them together. This must be done with small _brads_,
which are fine nails, and which for the present purpose may be one inch
long. If your pieces are all exact to measure, draw a pencil line across
the two side pieces, a quarter of an inch from the ends, by the help of
the square, as if you wanted to cut off a quarter of an inch at each of
those parts, and with your bradawl make two or three holes (three will
be best) along those lines. Do not make the first and last too near the
edges, or you will split the wood, and spoil the box. Now set up one of
the short pieces, and place upon it the piece which you have bored holes
in. If you have a bench with a vice, you can screw up the short piece
into it; but it will stand up very well upon the bench if you have no
vice. It is now in the position of Fig. 7, C.
[Illustration: Fig. 7.]
Hold it thus, and run the bradawl a little way into the lower piece,
through the holes already made in the upper. Drive a brad through the
middle hole first, which will hold it together, and then through the
other two holes. If you have been careful, you will find this corner
square and neat, and the wood not split in the least. Do the same with
the other short piece, and then nail on the long side that is left. The
frame of the box will now be complete.
I told you a short time ago, that it would not much signify if the
_sides_ were cut too long. The reason is this: Suppose B to be the side
half an inch too long. You would mark off 9 inches of the middle by two
lines drawn with the square as before, which would be the length of the
_inside_ of the box; you would then place the inner edges of the end
pieces against these lines, and nail them on like A, and afterwards
neatly saw off the two pieces which lap over these at each end. If the
wood is likely to split when the holes are made for the nails, or if the
workman is pressed for time, he very frequently does his work in this
way, and then cuts it off and planes it neatly. It is, however, better to
work as directed, only be sure to bore holes carefully for the nails, so
as never to split the wood.
No very special directions are needed about putting on the bottom. Leave
all round an exactly even border of a quarter of an inch, and after it
is nailed, you may neatly round off all its edges, to give it a finished
appearance.
The cover is, of course, to be attached by a pair of small hinges. Brass
hinges are the neatest, and when you buy them, ask for screws to match.
The hinges may be three-quarters of an inch long, and they will be, when
shut, about half an inch wide, which is the size you need. Lay them
(shut up) upon the edge of the back, about two inches from the ends,
and with a hard pencil cut to a fine point, or with the point of your
bradawl, make a mark at each end, as if you were measuring the length of
the hinges on the edge of the box. Between these marks you have to cut
out pieces like Fig. 8, which will be just the length of the hinges, and
deep enough to allow them, when shut up, to fit and lie even with the
top edge of the box. Open them, make holes with the bradawl, and put in
the screws. If you have not a screwdriver, you can turn them with the
end of an old knife; but you may as well get a small screwdriver, for if
you intend to do good work, you will often use screws instead of nails.
Hinges are always screwed on. Now lay the cover in place carefully, mark
its position, so that you have some sort of guide-line to direct you,
and then by laying the cover flat on the bench, and standing the (open)
box on its side, you can screw on the hinges upon the cover. Round all
the edges of the cover as you did the bottom, but keep the edges of the
_box_ square and _sharp_; and so you have now a really well-made little
tool-chest. A little brass hook and eye will do to fasten it, for a lock
is rather difficult for a small boy to put on.
[Illustration: Fig. 8.]
CHAPTER II.
The method of constructing a simple box has been given in the first
chapter, because so many other articles are made upon exactly similar
principles. The rules laid down comprise two or three essential points,
the neglect of which render the ordinary carpentry of boys so essentially
bad. Foremost of these is _the use of the square_. There is no tool of
more general use in the hands of workmen in wood and metal, and yet,
generally speaking, either none at all, or a very faulty one is added to
the collection of tools ordinarily supplied to boys. In the next place,
I have insisted upon _accuracy in measurement_. The carpenter’s rule is
not at all difficult for a young boy to understand; but even if he is not
in possession of such at his first attempts, he should always be induced
to work by measure of some kind. This causes him of necessity to exercise
his mind as well as his hands, and teaches him to consider well at
starting as to what he must allow for thickness of wood, the difference
between inside and outside measurement, and so forth; all this will
greatly conduce to his success, and consequently satisfaction in his
work, and will lessen the chances of his beginning a number of articles
and casting them aside unfinished—a propensity too common in all boys.
I shall now resume my directions in the first person, which I think
is the more easy method both for master and pupil. The next specimen
I propose, because it requires even more care than a box, but is at
the same time perfectly within a boy’s powers, is a birdcage. Of these
there are such a number of varieties that it is difficult to settle
upon the best kind to begin upon. I think, however, a wire cage will on
the whole be the easiest to construct, only you must take great care in
boring holes in the thin strips of wood, and, indeed, if you can get a
birdcage-maker’s awl besides the one you have, it will save both time
and trouble. It is not made round with a flat end, but is three-cornered
with a sharp point, so that it has three edges, and when it is carefully
used and twirled round and round by the fingers in making holes, it will
hardly ever split even very thin strips and pieces of wood. However, if
you cannot get one never mind, you must use the common bradawl according
to directions here given.
I shall suppose you now in possession of a carpenter’s rule, and that you
have carefully learned all I told you of the inches and eighths, so that
you may be able to measure and mark your work very truly. The front of
the cage is represented in Fig. 9, before the projecting roof-boards have
been put on.
[Illustration: Fig. 9.]
Here you see two upright strips at the corners, which shall be 8
inches long. These are 12 inches apart, _outside_ measure. They are ⅜
(three-eighths) of an inch square, and you must get them ready planed
from the carpenter. There will be four of them required, as they are at
the four corners of the cage; so that, as they are each 8 inches long,
you can get a strip 36 inches in length by three-eighths wide, and this
being 4 inches more than you need, will allow for waste. At the lower
part of the drawing, you see the edge of the bottom board, which projects
a little all round. As the _outside_ of the front pillars are 12 inches
apart, this board may be 13 inches long, which will allow a border of
½ an inch (half an inch), and it may be 8 inches wide. It need not be
_thicker_ than a quarter of an inch. A little above this board (say half
an inch) is another board from one pillar to another, which is to be 1¼
inches wide and three-eighths of an inch thick. As the pillars are also
three-eighths thick, and their outside edges 12 inches apart, you must
take 6/8 (six-eighths) of an inch from 12 inches to find the length of
this board.
If you look at the divisions upon your rule, you will see that
six-eighths of an inch amounts to exactly ¾ (three quarters), so that
your board must be 11 inches and _one_ quarter long. This will also be
the length of the board at the top where it falls between the pillars,
and this too must be three-eighths thick.
I shall now show you how to mark and cut this top piece into the shape
here sketched. Cut the board first of all into an oblong, and mind
that you mark it by your square, so that the _ends shall be square to
the sides_. Let it be 2½ inches wide. Here it is (Fig. 10). Measure a
length of 6 inches from either end to the middle at A, and make a mark
at that place. Draw a line, C B, one inch from the opposite side, the
whole length of the board, and mind you draw it correctly. You should
measure an inch at B, and at C, and then draw a line from one point to
the other along the edge of your rule. You must now draw two lines from
the spot you marked at A to the ends of this line (where you see the
dotted lines). In order to cut this piece, you must begin at A, not at
B or C, or else if the saw should stick you will be sure to split off a
strip right across the piece; but if it should stick when you are cutting
_from_ A, you will only split off a bit of one of the three-cornered
outside pieces, which would not signify at all.
[Illustration: Fig. 10.]
When you are sawing, be sure, as I told you before, not to cut into the
line you have marked, but saw just outside it, so that the lines will be
left upon the two sloping sides of the board. You may _cut as close to
it as you can_, but you must not destroy it, and then you can with your
knife neatly shave off the rough edges which the saw has made, until you
have pared the wood quite neatly all along the line. If you cut this line
out, you will no longer have any guide to work by. Cutting out guide
lines is a very common fault, not confined to small boys or big ones. You
will find it easy to pare this sloping side if you begin to work from
A downwards to B and C, but you cannot cut it in the other direction. A
carpenter would, of course, run his plane down the slope, and so will you
by and by; but planing is difficult, and it is better you should wait for
a time before you buy a plane; for, remember, those foolish little things
in boys’ tool-boxes are no use at all.
You had better now prepare the holes into which the wires are to be put
as you see in the drawing. You can use either iron wire or brass, but
the first is cheapest. These will have to be a quarter of an inch apart.
Both the top and bottom strips, you will remember, are 11¼ (eleven and a
quarter) inches long. Now, 11 inches will be 44 quarters, and one more
will be 45; but as the first hole must be a quarter of an inch from the
ends, you will find that 44 holes will be required. Look at your rule and
count this. You must mark all these by little dots with a pencil on one
piece, and then laying the other upon it, mark the rest exactly even with
the first. Do this with great care, or the wires will not stand upright
when the cage is finished. The space between the top and bottom pieces
will be 5¼ inches, so that if you allow the wires to enter a quarter
of an inch at the top and bottom, you will want 44 wires 5¾ inches in
length—you may say, 6 inches. You can have them all cut and straightened
for you, but if you have a pair of pliers with cutting edges, you can do
it yourself, and it is almost necessary you should get a pair, or borrow
them, if you intend to construct wire birdcages. You will want a few less
in each side of this cage, as it will not be there so wide as it is in
front. We shall presently see how many it will require.
You may put together the front of the cage at once and set it aside,
or proceed to cut out the rest of it. Generally speaking, it is the
best plan to cut out and prepare all the main parts of your work before
proceeding to fix them in their respective places; but the front of such
a cage as I am describing, being complete in itself, you may do as you
like about it. We will begin with the wires. Insert the ends one after
the other in a row in one of the pieces, laying it upon the bench, or
fixing it on its edge in a vice, but taking care not to bend them. When
one piece is thus stuck full of wires, lay it flat on its side, and put
the other piece in its place, and one by one insert into it the other
ends of the wires. A pair of pliers will help you greatly in doing this.
I daresay the two pieces of wood will not be very parallel, but will be
closer at one end than at the other. This does not matter, because you
will set it right in nailing on the upright strips or corner pillars.
This, therefore, is the next thing you must do; and you must have two
brads top and bottom, each an inch long, but as fine as you can get. Nail
to the top board first, and then place the other in position half an inch
from the bottom of the pillars. If you have no carpenter’s vice, you had
better work with the front of the cage laid down flat and near the right
hand edge of the bench or table, so that the pillar almost overlaps it.
In this position, you can bore the two holes and nail it together; but be
guarded as to splitting the pillars.
You ought now to have the front well and firmly put together and standing
square and true as in the sketch; only the bottom board, of which you see
the front edge, is not to be attended to at present.
[Illustration: Fig. 11.]
There is another way of going to work, namely, to put the whole framework
of the cage together and add the wires afterwards. In this case (the
holes having all been made beforehand as directed here) the wires are in
turn inserted at the top, and then being slightly bent are put in place
in the bottom piece—each wire being completely fixed before the next is
added. Either way may be tried, but in that given above the wires are
not bent at all, and therefore have not to be straightened. Adding them,
however, afterwards is the common practice among the cage-makers. Indeed,
it generally happens in large establishments that one set of workmen
make the woodwork, and another set add the wires—such division of labour
proving more advantageous.
[Illustration: Fig. 12.]
Attention is now to be given to the sides, of which Fig. 11 is a drawing.
Here you need not make any corner pillars. You have only to cut out the
top and bottom strips—the lower one, 1¾ inch wide, to match that in
front: the top, 1 inch wide, to match the straight part of the ends of
the upper front piece or gable, as you see in Fig. 12. You will also see
by this drawing that you must nail the side pieces _inside_ the corner
pillars, and _not upon_ them, so that the nails go in from the front of
the cage into the ends of the two side pieces which carry the wires. I
have shown by dots (Fig. 12) where the nail holes are, and they must be
carefully made, avoiding the places where the other two nails come, which
you hammered in when you fitted together the front. The side strips, A B
(Fig. 11), may be 8 inches long. Both sides of the cage are to be made
exactly alike. I have told you to make the lower side-rails 1¾ inch wide,
because they must come to the bottom of the pillars, for no half-inch
space is required at the sides between these rails and the bottom of the
cage. It is so left in the front, because a tray, or cleaning-board,
has to be slid in there. You had certainly better put together the side
pieces by means of the wires, as in Fig. 11, before you nail them in
their places.
You now require a piece of board for the back, and quarter-inch stuff
will do very well. Bought cages are made of much thinner wood, generally
mahogany, but at first it will be easier for you to use thicker boards.
If you round off the edges, they will not appear so thick. Very thin deal
will warp or bend after it is made up; and, indeed, it is quite possible
the back of this cage will do so. Get the wood, however, as dry as you
can, and the top boards, when nailed on, will probably prevent it.
To cut out this back board, you may lay down upon the piece from which
it is to be cut the whole front of the cage, and draw a pencil round it,
only, when you come to the bottom of the side pillars, you must draw a
line straight across from one to the other. Then cut _from_ the point at
the top, as you did before. Let the grain of the wood run up and down,
_not across_, the back. Nail the back thus cut to the side strips, as you
nailed on the front, and you will then only have the roof to put on, and
the bottom.
This roof may consist simply of a thin board, cut square and true, nailed
on to the two gables, and it will look much prettier if it is made to
project beyond the front. If you measure down the slope of the front or
back top-piece, you will find it 6 inches long, and a little more. Your
board should therefore be 7 or 8 inches wide, because, although the roof
pieces meet at the top, they should come down a little beyond the sides
of the cage. As the sides are 8 inches wide, cut the top 11 inches long,
which will allow it to project in front 3 inches.
If you look at the cage at the end of these directions, you will
understand this. You must slope, or _bevel_ off, the top edges of these
roof boards, to make them fit neatly together along the ridge; and as you
will paint the cage, you can glue on a narrow strip of paper, to make it
quite water-tight. The door of these cages is generally in the back. You
merely mark and cut out a square hole about 3 inches square. You then
fit a piece in, and hinge it either with wire, or (which is easier) by
sticking on a strip of calico down the edge of it, and fasten with a wire
hook. As the back is but a quarter of an inch thick, you will be able to
cut out the hole (before nailing on the back), with a sharp pocket-knife;
and again I say, don’t cut out the guide-lines—cut inside them, and then
neatly pare exactly up to them. Make the bottom 13 inches long, and 10
wide, which will allow it to project in front, and also half an inch on
each side.
[Illustration: Fig. 13.]
You have now to make the tray, to slide into the space left in the front
below the bottom front rail. This is to hold sifted sand, and is made
loose, because it requires to be taken out and cleaned every day (Fig.
13). It is merely a flat thin board (one-eighth of an inch will be quite
thick enough), with a strip nailed on, or glued on, in front, to fit the
space left for it, and other smaller strips glued on all round it, so as
to form a very shallow tray or drawer. The small strips can be glued
on flat _upon_ the top of the board, but to fasten on the front, you
must first glue on a similar strip to those round the sides, and just
such as you made the pillars of, but not quite so thick, and then glue,
or nail on with very small brads, the front piece, nailing or gluing it
to this strip. This will make it very firm, and will do well enough for
your first cage. A, Fig. 13, shows a part of the drawer, C is the front,
and D the strip it is glued to. The handle of this drawer or tray is
to be made of wire, unless you can find some little knob or other that
will do. If you succeed in making this cage, you will have learned a
good deal, because, although not really difficult, it requires care and
consideration; and if you are in a hurry, you will split the wood, or
make it crooked, or cut the pieces too short. It should be neatly painted
in oil-colour—_green_ is a favourite colour—but the top boards may be
red, and the wires should be left clean and bright, because the bird
often pecks at them. If you paint the _inside_ of the woodwork, it should
be white.
I have not here put any feeding-boxes, or seed-drawers, because glasses
are the best; but you will see two holes (Fig. 11), one inch across, in
the lower side pieces, for the bird to put its head through to get at the
seed and water. A bit of wire, forming half a hoop, supports the glasses
or trays. These ought to be cut with a centrebit—a tool you have not, and
the carpenter had better do it for you. Here is the cage complete (Fig.
14). You can do without making holes in the sides, if you put two wires
longer than the rest, and bend them, as you see at B in Fig. 13, before
putting them in place.
[Illustration: Fig. 14.]
CHAPTER III.
The previous chapters were devoted to such exceedingly simple and easy
specimens of carpentry as can be made by any boy of eleven or twelve
years of age, or even younger, who has the necessary perseverance, and
will take sufficient care in measuring and fitting. In both and all
similar cases, it is better for such to buy pieces of board already
planed, and of nearly the desired size; but I shall no longer presuppose
such necessity, but advance the young mechanic to the dignity of a plane,
and a few more of the more necessary and useful tools. The list may
therefore now comprise—
1 HAND SAW, 16 inches or so in length, a full-sized one being
almost beyond the powers of a boy.
3 FIRMER CHISELS, quarter, half, and one inch wide.
1 MALLET.—Chisel handles should never be struck with a hammer,
which splits the handles.
1 HAMMER.—This should be light. The best way is to buy a
hammer-head, and make the handle. A heavy one can be added, but
will hardly be required at first, and is useless for light work.
1 JACK PLANE, 1 SMOOTHING DO.—The jack plane is not usually
added to a boy’s tool-chest, but it is impossible to plane up a
long straight edge without it; and as these planes can be had
from 12 inches in length, I should certainly recommend one, say
12 to 15 inches.
3 GIMLETS, 3 BRADAWLS.—One of each of these should be as small
as can be obtained. Add a medium and a larger one.
1 SCREWDRIVER, 1 PINCERS, 1 CUTTING PLIERS.—Screwdriver should
be of a medium size; the pliers such as are used by bellhangers.
1 COMPASSES.—These should be light _carpenter’s_ compasses, not
such as are made of brass and steel. They are very useful.
2 GOUGES.—_Carpenter’s_ gouges, not turner’s. They will answer
for the present, in many cases, to make round holes in boards.
The centrebits and braces are expensive.
1 OIL-STONE.—There is a cheap and quick-cutting stone called
Nova Scotia which will answer the purpose well.
MORTICE-GAUGE.—The use of this will be shown presently.
1 SQUARE, 1 2-FOOT RULE, GLUE POT, and BRUSH.—These are, as
before stated, indispensable. The rule need not have a brass
slide; the square may be made entirely of wood, or with a metal
blade 6 to 9 inches in length.
The above, with the addition of a carpenter’s brace and bit, two or
three augers, about three mortice chisels, and a hatchet, would suffice
for a very large amount of good work. Indeed, it represents almost a
complete set of tools, the only additional ones that are at all likely
to be needed being a longer (trying) plane, rebate plane, and pair of
match, or tongue and groove planes. Without any of the latter, the young
carpenter will find it easy to carry out a good many light specimens of
his ingenuity.
It is much better, in general, to work with a few tools, and contrive
to make them answer all sorts of purposes, than to lay in a larger and
more expensive set at starting, for the latter are sure to be abused and
kept in bad order, because if one chisel gets blunt, another is taken up,
instead of sharpening the first; and planes and other tools are treated
in a similar manner, and a carelessness is engendered fatal to success.
It is astonishing how much may be done with few and inefficient tools,
but then the utmost patience and industry have to be exercised, much as
we see prevailing among the native workmen of India and America, who
execute the most beautiful and delicate work with tools which, in the
hands of a European, would be generally simply useless.
The next work that should be attempted by the young mechanic should be
mortice and tenon jointing, as used in constructing frames of various
kinds for doors, window-sashes, tables, and other articles of everyday
use. Perhaps one of the simplest and easiest examples will be a
towel-horse, which, at any rate, will be of use when completed.
Now, it may be at once stated, that for work of this kind especially,
but generally also for all work, it is essential to be able to square up
truly the several pieces required. This will require practice—long and
careful practice—and the beginner will meet here with his first and chief
difficulty, but he must not despair.
[Illustration: Fig. 15.]
It has been presupposed that a strong work-bench, table-plank mounted
upon trestles, or some sort of tolerably efficient and firm bench has
been obtained, or is accessible, and, in addition, a strong stool upon
which to saw, cut out mortices, and so forth. A small carpenter’s bench,
with a wooden vice, is most handy and serviceable, but is not absolutely
necessary. It will be easy to _make_ one by and by; for the present, any
available substitute must be used. The height of the proposed towel-rail
may equal the length. About 2 feet 6 inches will be a fair size, and it
may be of the simplest possible form, such as is here delineated (Fig.
15). The upright sides may be made of strips of pine, one inch wide and
three-quarters of an inch thick—the rails 1¼ wide and three eighths
of an inch thick. The feet will be considered presently. If careful
attention is given to the following directions, not only will the result
be certainly satisfactory, but the way will be paved for the workmanlike
construction of a great number of similarly useful articles.
The size of the rough material must always be greater than that
ultimately needed, to allow of the necessary waste in sawing and planing.
Pine boards, however, are usually cut of certain general widths and
thicknesses; and although we have here set down stuff of _one inch_ by
three-quarters, it may be cut from inch board, because very little will
be wasted by the plane, and the finished work will be sufficiently near
to the above measure for the intended purpose, one-sixteenth of an inch
or so being of no practical importance in the construction of such an
article as a towel-rail. Get, therefore, from the carpenter, a strip of
pine 1 inch wide and 6 feet in length, cut from a board 1 inch thick,
and also a strip for the rails (of which there will be three), 4 inches
wide and 2 feet 9 inches long, cut from a half-inch board. The rails you
are to saw yourself from the latter strip, which will give you practice
in sawing a straight course, and the _work_ is easy in half-inch stuff.
You may therefore begin by cutting these, for which purpose you will want
guide-lines dividing the strip into three of equal width. There is a very
simple way of marking these by means of a chalk line, which I will here
describe.
The width of the board I set down at 4 inches, because the rails, when
finished, will be 1¼ inches each, or, in all, 3¾ inches. As each contains
eight eighths, as already explained, 4 inches will contain thirty-two
eighths. Dividing by 3, we shall have ten eighths for each strip, or 1¼
inches, and two eighths, or a quarter of an inch, to spare for waste.
Take the compasses, therefore, and open them to 1¼ and a little over
(rather less than to the next division on the rule), and take it off at
each end of the board (Fig 16, A B).
[Illustration: Fig. 16.]
Take off, again, from this to mark the width of the next strip, and the
board will be divided with sufficient accuracy for our present purpose.
Take a piece of twine, long enough to stretch from end to end of the
plank, and something over, and tie a knot at one end. Stick a bradawl
through the string, close to this knot and into the board, as seen at C
of the same figure. Take a lump of chalk, and chalk the line from end to
end. Then strain it down the board, holding it by the left hand, so that
it is stretched from one mark to the other, where the saw-cut is to be
made. With the finger and thumb of the other hand, raise it a little in
the middle, and let it suddenly go, when it will make a perfectly clear
and straight line upon the board. Make a similar and parallel line for
the next saw-cut. In the present case, you need not mind cutting this
chalk mark out. Try and saw right down, so as to split it.
[Illustration: Fig. 17.]
You now have your strips cut out, but they require to be planed. You
might, indeed, with advantage, have planed the whole strip on both
sides before marking and cutting it, but it is equally easy to do it
afterwards. The jack plane is the one to be used for this purpose. I must
suppose it to be sharp and in good order; if not, ask some carpenter to
set it for you for the present, but I will soon tell you how to do it
for yourself. Indeed, you will have to learn how to sharpen all your
tools before you can be called a good workman. If the plane is properly
set, the cutting edge will project very slightly only from the bottom; so
that when held as in Fig. 17, and the eye directed along the sole, only a
narrow shining slip of metal will appear. If too far out, it will hitch
and make bad work; if not far enough, it will not cut at all; but the
common fault of beginners is to have it too far out, because from their
imperfect handling of this tool they often fail to make it cut, when in
the hands of a carpenter it would work well. Now, if the iron projects
too far, hold it as shown, so that you look along the sole, and give it a
tap with your wooden mallet on the upper face at A, and this is also the
way to loosen the wedge and irons for removal. By a blow at B, you can
send the cutting edge forward to cut more deeply, or in this case you may
tap the iron itself with a metal hammer, but tapping the end of the wood
is better.
To plane the edges of these strips, you ought to have a bench with a
vice, but there are ways and means to do without it, and one is so good
that I shall speak of it here, although it necessitates a somewhat abrupt
break-off in my description of the towel-rail. It is a kind of vice that
is fixed to a board which is laid upon the work-bench when required.
[Illustration: Fig. 18.]
In Fig. 18 is a drawing of one of two kinds of such vices which I will
explain. This first consists of two pieces of wood (ash will be better
than pine) about 9 inches long and 2 inches thick. They are cut in the
shape given in the drawing, and screwed to the board, not tightly, but so
as to move freely upon the screws. The board should be an inch thick to
give the screws a firm hold. You can see by the figure that the tails of
the pieces cross each other sometimes when in use. To allow of this, they
are cut like B and C, so that one can go inside the other. Now, if you
consider a little, you will understand that if we stand a strip of board
between the two, and push it forward against the insides of the tails of
these curiously-shaped blocks, it will make the opposite knobbed ends
close nearer together, and these will grip the piece of wood, and the
harder we push it forward, the more closely it will be gripped and held;
but the moment we draw back the piece, the two jaws will open to let it
go free. You can try first of all upon a thin piece, which can be shaped
by your knife, and make a model of this vice, and then if you can’t
manage to cut out such a one of thick wood, the carpenter would do it for
you, and it will be handy for many purposes. If you have nothing of this
kind, nor a vice to your bench, drive in two pins or pegs of wood, or two
nails, a little way apart, so as to allow your strip of wood to stand
upon edge between them, and drive two more a little way from these; then
one at the end to form a planing stop. A tap at the sides of these nails
will cause them to hold the strip edgewise, quite well enough to allow
you to plane it. There are other ways, and I shall describe them by and
by. In the meantime use nails, or any other plan that will answer.
[Illustration: Fig. 19.]
[Illustration: Fig. 20.]
I shall suppose, therefore, that one of the narrow strips is thus set on
edge upon your bench ready to be planed. Grasp the handle of your plane
firmly with the right hand, and lay hold of it in front of the iron with
the left. Draw it back, and then send it steadily forward, pressing it
downwards at the same time. Now the advantage of a long plane is, that
it does not descend into the hollows of the work, but rests upon the
projections, as in Fig. 19, A. A short plane would do as seen at B, and
therefore would never make a long straight edge. You have two special
points here to attend to. You have to plane a level line from end to end,
and also keep the edges square to the sides, which is by no means easy
at first. You must keep trying it with your square, as I have shown you
in Fig. 20, and not rest satisfied until the handle fits close to the
side of the strip, and the edge lies also close upon that of the strip
anywhere along its length. I daresay you will think this of no importance
in such a common thing as a pine towel-horse; but I may tell you this
is the very secret of carpenter’s work, and when you can saw and plane
truly, and work “to square,” you can make almost anything. It is true
that the strips for the rails are not of great importance in this case,
but the upright side pieces are, and if these are out of truth, the holes
cut through them for the rails, which are called mortices, will be out
of truth also, and you will see the towel-horse, when it is made, all
twisted and awry, and nothing you can do will make it stand firm or look
well. It is, in short, no use to pretend to learn carpentry unless you
at once make up your mind to succeed, and therefore you must always use
the square and try your work as you go on. All the difference between the
usual work of carpenters, and that of boys or men who do not know how to
work, consists of the squareness and good fit of what the former make.
Boys never seem to trouble themselves about such things, and so you see
their boxes and rabbit-hutches look twisted, and being badly fitted, they
soon go to pieces.
Having planed up the sides and edges of the rails as square and true
as you can, cut the other long strip in half, and square up this also,
taking care that both pieces are alike and both truly worked. If your
bench is sufficiently long to take the whole strip, plane it up before
you cut it across, and you will be sure to have the sides of your
towel-rail equal in size. You have now to make your first essay in
cutting mortices. Follow these directions, and you will not fail. I shall
not limit the description to these special mortices, but give you general
directions.
[Illustration: Fig. 21.]
Fig. 21 represents a bar of wood—the side of the towel-horse, for
instance—with a mortice cut through it at A, and others marked out at
_ab_, _cd_. Below, at B, is a gauge, of which the construction and use
will be explained presently. F shows how the feet are to be attached and
cut. They are morticed while in a “squared-up” condition, and shaped
afterwards according to fancy; sometimes they are left square, and knobs
screwed below to make two feet.
These mortices may, of course, be of any desired length or width. Those
required for the towel-rail sides will be 1¼ inch long by half an inch
wide _nearly_. The planing of the strips may have reduced them more or
less below the exact size specified, try therefore with the compasses
what the precise thickness is of the ends, and measure that thickness on
your two-foot rule. You now want to draw the lines _a t_, which I have
represented as extending the whole length of the strip, and as all the
mortices are to be alike, you may so mark them. The gauge B is of two
parts, a sliding piece, C, and a rectangular bar of wood about 9 inches
long and half an inch square. This slides stiffly through the mortice
in C, and is fixed at any part by the small wedge D. This gauge you can
easily make. It is _not_ a mortice gauge properly so called, because the
latter has two marking points instead of the one seen at _h_, and which
may be the point of a brad driven in and filed up to an edge. Loosen the
wedge slightly, and draw back the rectangular bar, or push it forward,
until you think that the space between the sliding piece and the point is
about that which is required on each side of the mortices, so that if you
set the wedge firm, and resting the sliding piece against the edge of the
board, cause the point to make a mark, and repeat this on the other side
of the same face of the wood, there will be left between the marks thus
made the exact width of the required mortice. Try it, and if not, give a
tap to the instrument, and adjust it until the space is exactly correct.
Then fix all firm, and holding it so that the little point will mark the
wood, while the head or sliding piece is against the side of the board,
run the tool from end to end, or run it along just where the mortices
are required, using both hands. You will thus make the two long lines
between which the mortices have to be cut. Now turn the wood over, and
do the same on the other side. You are now quite sure that these lines,
on opposite sides of the piece, agree exactly in position, which is the
object of using a gauge; and as you have planed up a second strip to
exactly the size of this first, you have but to repeat the process (no
measuring being necessary) upon that; and you may be satisfied that thus
far the two sides of the towel-rail will tally. You now set off with the
compasses upon one of these lines the _lengths_ of the mortices in their
proper places, and at the points thus marked, using your square for the
purpose, mark the end lines of these mortices; but when so doing, carry
the lines across, as _a b_, _c d_, and down the sides and across the
opposite side. With the square this will be easily done, the blade of it
being laid _flat_, so that its edge becomes the ruler, while the handle
becomes the guide or gauge resting against the side of the wood. At E,
Fig. 21, this position of the square is shown.
By thus carrying round all the lines, you will have the mortices marked
on both sides in exactly the same relative position, so that you can
(and must) cut them half from one side and half from the other, using
the chisel nearest to the size required, but _always of less width_ (or
length) than the mortice, because _you must never cut out the guide
lines_, but must keep within them, only carefully paring the wood at
last close to them. You will never cut mortices correctly, unless you
thus mark the position on both sides, and work as directed.
The ends of the cross rails will not have to be cut into tenons, as they
will fit as they are, only requiring to be glued into their places,
when, if you have worked carefully, the whole will look well, and will
be square and true, without twist; but if you did not plane up the sides
square, you will find the towel-rail awry and unworkmanlike. Although,
however, there is no necessity to make regular tenons in the present
case, the usual way is to do so, and to fix with wedges, as in Fig. 15.
After a mortice has been cut straight through a piece as directed, this
mortice is slightly eased, or sloped off, as seen at _a b_, which is a
section of one. The rail or tenon _c_ is put through after being brushed
with glue; and when in exact position, two wedges are glued and driven in
at each end, as seen in the drawing. After all is dry, these wedges being
firmly united to the rail, as seen at _k_, prevent it from being drawn
back or moved. Nearly all mortice and tenon joints are fixed in this way.
As I am describing this kind of work, I may as well explain the method of
marking and cutting tenons, as it will answer not only for affixing the
feet, as shown in Fig. 21, but for all similar work.
[Illustration: Fig. 22.]
In Fig. 22, I have illustrated the mode of marking out tenons, and at
D is a double tenon, which is in wide pieces often substituted for the
single, and makes an excellent joint. The longitudinal lines _e_, _f_,
_g_, _h_, are marked as before with the gauge, whether for single or
double tenons; the line _a b_, with the assistance of the square; the
cheeks, _c_ and _d_, are then cut off entirely with a fine saw, called on
this account a tenon-saw,—and care must be taken as before not to cut out
the guide lines. If, instead of the outer cheeks, the piece between them
is to be removed to make a double tenon, this must be done with mallet
and chisel, after carefully sawing down the lines _x y_; and the chisel
is to be used first on one side and then on the other, by which means
the shoulder will be cut true to the guide lines. If, however, the cut
across should curve a little downwards like _n_, it will not much matter,
so long as the _edges_ fit closely. It is nevertheless better to cut
straight across. The outer cheeks of this will be marked and cut as in
the single mortice (Fig. 22).
If a workman has to cut many mortices on pieces of the same size, he
frequently constructs a rough mortice gauge with double points, which
marks both sides of the mortice at once, like K. A fixed block at K,
the right distance from the points, _l m_, of two nails, is sufficient
when all the mortices are to be alike. There is, however, a regular
double-pointed gauge, made generally of ebony, plated with brass, and a
brass rule to which one of the points is fixed, and which is acted on by
a screw at the end, which can be turned by the thumb and finger. This
has the effect of separating or closing the two points according to the
desired width of the mortice, its distance from the side of the piece
being regulated as before by the sliding head fixed by a wedge. This is
an expensive tool, and need not be purchased. There are also, let me add,
many costly tools of various forms and uses; but let the boy’s motto (and
man’s, too, for all that) be, “_Do as well as you can without_.” You have
no idea how a little ingenuity and contrivance will save your pockets,
and that, too, without in the least tending to spoil your work. All
you require are a few of the most generally useful tools in first-rate
condition—chisels, saws, and planes, sharp and well set, and fit for work
at any moment.
With regard to uniting two pieces of wood or other material with glue,
it must be remembered that if you use this substance in a thick semifluid
state, and in quantity, its effect will be lost. Make it a rule to put on
as thin a coat as possible, and let it be not thicker than cream, so that
it will freely flow into corners, and spread evenly over the surfaces to
be united. Make the wood also _quite warm_, so that the glue shall not be
suddenly chilled, and let it be used boiling. Always heat it either in a
proper glue-pot, or at any rate, place the vessel which contains it (a
small gallipot, for instance) inside another vessel in which water can be
kept boiling.
The glue, which should be thin and transparent, being broken into small
pieces, should be put into such a vessel as suggested, and covered
with cold water, and it should be allowed to remain thus until swollen
and softened. Then bring the water in the outer vessel to the boiling
point, and do not use the glue until it is entirely dissolved and of one
uniform consistence. It should be stirred while boiling with a piece of
stick, and a brush used to lay it upon the pieces to be joined. It very
generally happens that pieces glued by boys fall apart almost directly.
This is almost entirely due to the fact that the glue is used thick and
clotty, and in too great quantity, while the wood is never made warm
as it should be. If two pieces are properly joined in this way, it is
almost impossible to separate them at the joint—the wood itself will give
way and split before the glue will yield to the strain. Carpenters use
various forms of clamps or vices to hold work together until the glue
shall be dry; but for boys by far the best plan, where any such holdfast
is needed, is to bind the parts together with twine, and then to set them
aside for twelve hours at least. It is seldom that articles once united
by glue and separated will unite firmly a second time.
CHAPTER IV.
The exercise of a boy’s mechanical tastes upon works of practical utility
is, of course, far preferable to its expenditure upon mere trifles,
made one day to be cast aside and destroyed the next; and as there is
scarcely any household that does not need its furniture repaired or added
to from time to time, I shall now give directions for the construction
of one or two articles that seem to be within fair scope of a young
mechanic’s abilities. The first is a plain, useful table, without a
drawer, and with square legs, because without a lathe the latter cannot
be made ornamental; and lathe work will occupy some future pages, since
it is necessary first to give the young mechanic a fair insight into the
principles and practice of plain carpentry and joinery.
The _very_ young mechanic, so far as my experience of him goes (and it is
rather extensive), makes his early attempt by sticking the points of four
nails into the corners of any tolerably square piece of board he can lay
hands on. His next attempt, when he has risen to the dignity of a knife
and gimlet, is to place four _wooden_ legs at the corners of a similar
board, which, if the said legs are _glued_ in (by which a wonderful mess
is always made of the structure), is considered a great feat, and worthy
of the admiring patronage of fond parents and playmates. Now, a table
does not consist of any such arrangement of pieces, although I certainly
have seen sometimes, in the cottages of the poor, a three-legged
affair of this nature, which is just nothing more than a magnified
milking-stool. We cannot content ourselves now with anything of the kind.
We shall have to work away with plane and chisel and square, and with
neat tenon and mortice joints first construct the frame upon which the
top will be placed, and then finish it _secundum artem_, the English of
which, as I am writing to boys, I shall not reveal.
The table shall be 3 feet long, 1 foot 8 inches wide, 2 feet 4 inches
high; the top board being half an inch thick when planed and fitted, for
which it will therefore be required to be three-quarters of an inch in
the rough. The legs demand attention first. Plane up strips cut from a
2-inch board, and let them be exactly 2 inches wide. These must be worked
up with the greatest possible accuracy, or it will be impossible to fit
the framework so as to make the table stand truly or bear inspection.
After four such strips have been planed up, cut a piece from a half-inch
board, or from a board that will plane to half an inch. Let this be 4
inches wide and 9 feet long, and be sure to plane this also truly, and to
make the edges square to the sides.
[Illustration: Fig. 23.]
If you have no strip that will answer of 9 feet long, you can cut two or
more instead, remembering that you will require two pieces each 18 inches
long and two of 2 feet 9 at the least, all as nearly alike in _width_ as
possible. You have now all that you will need for the framework of your
table—the top may be left till the rest is fitted. Now you may proceed
to cut the requisite mortices in the legs, which you will understand by
sketch Fig. 23, which represents one corner of the table before the top
is added. There is no more difficulty in this than in the previous work,
except perhaps that somewhat more care is requisite in squaring up the
several pieces and cutting the mortices with accuracy. Use the gauge as
before in marking the mortices, trying it until it is so fixed that it
will leave the proper width of the holes, namely, half an inch (which is
the thickness of the strips which are to form the framework). This is
upon the supposition that your gauge has but one marking point: but to
explain its use.
[Illustration: Fig. 24.]
I shall now introduce to your notice a regular mortice-gauge of two
points, which is vastly more convenient. This is represented in Fig. 24.
The main stem is grooved along its length on one side with a dovetailed
slit, that is, a groove which is wider below than above. This is
generally made in a brass plate attached to the stem of the gauge, but
sometimes in the wood itself. In this slides a slip of brass which can be
drawn back by pulling the knob A, or by turning a thumbscrew at one end,
as in the more expensive gauges. One of the marking points is fixed in
the end of this slide, the other in the wood (or metal) beyond it, at
B, and when these are allowed to be together they form but one point,
being flattened on one side, so that they will fit accurately against
each other. Thus it is easy to separate the two points at pleasure to the
exact width of the required mortice. By means of the wedged sliding piece
C, we now have merely to determine how far the edge of the mortice is to
be from _one side of the piece_. Thus, suppose that in the present case
we should prefer to have the side of the frame nearer to the outside edge
of the legs than to the inside, we can so arrange it easily; but we must
then take care to gauge all alike, either from the inside edge or the
outside. We do not, therefore, with this kind of gauge work from _both_
edges, and leave the space _between_ the lines for the width of the
mortice, but we work from _one_ edge only of the piece of wood, and mark
the mortice at once in any desired position. I need hardly repeat, that
for any particular job, a very good substitute for such gauge can be made
by driving two small nails into a strip of wood cut with a projecting
piece to serve instead of the movable head.
[Illustration: Fig. 25.]
Let us now proceed with the work in hand. One of the legs of the table,
before being worked into shape, is shown in Fig. 25; the dotted lines
show how it will be eventually sloped off below the mortices which carry
the top frame. These mortices must not now go through the legs, and
therefore you will have to be very careful to hold the chisel upright,
so as to insure the _squareness_ of the frame when put together. The
mortices being in adjacent sides, will of course meet, but it will be
advantageous to cut those which are intended to receive the two longest
strips, viz., the front and back, rather deeper than the other two.
First set off an inch from the top of the leg at the line A B. If less
than this intervenes between the top of the mortice and the end of the
leg, you will probably break the piece out and spoil your work. As the
side boards are 4 inches wide, and must come flush with the top of the
legs, you will have to cut them like C, and there will be 3 inches left
for the tenon, all of which may be left, as the wider this is the more
hold it will have on the legs into which it is to be glued. It is plain,
therefore, that the mortice will be 3 inches long and half an inch wide;
and when you have marked it to this size, take care to cut it accurately,
because if it is too small, you will break out the piece between the
mortices when you try to force in the frame pieces, and if too large,
you will scarcely get the whole to remain secure. Work therefore exactly
to gauge. It is usual to keep these side and end pieces more to the
outside of the legs than the inside, as F, where you are supposed to be
looking at the _inside_ corner; and if you look at D (which shows the
top or cross section of a leg, as if after the pieces were fitted you
had sawn off the leg close down to the mortices, exposing them to view),
you will see that by thus keeping near the outside edges you get _both_
mortices deeper than if you cut them, like E, in the middle of the sides
of the leg. Of course, the deeper these tenons are let into the legs, the
stronger their hold will be. There will now only remain to warm all the
pieces and glue them into their respective places, with the precautions
before stated as to the thinness of the glue and speed of the operation.
See that all stands square and true; if not, a tap here and there as
required will set it straight, and then let all stand till dry.
I have told you to cut the side and end pieces 18 inches and 2 feet 9
respectively, so that if the mortices are 1½ inches or so deep, your
frame will be about 1 foot 6 inches wide, and 2 feet 6 inches long. The
top, which is to overlap as usual, will be now prepared as follows.
It will not be possible to make this of a single width of board; and
nothing will more fully test the young workman’s skill, than planing the
edges of two pieces so that they shall fit accurately together. It must,
nevertheless, be attempted.
Cut two pieces of three-quarter-inch board, and plane the sides as
accurately as possible. Then set them up edgewise, either singly or
together, and plane the edges with steady, long strokes of the longest
plane you have, set fine—that is, with the cutting edge projecting but
slightly. Try each singly with the square from end to end, and then lay
them on any perfectly flat surface, as on your bench, or on a table, and
see whether the edges lie close all along. Remember, too, that they may
do so when one surface is upwards, and not when turned over, as will
occur when the edges are not square to the sides. In cutting out the
pieces, therefore,—which, when finished, are to be together 1 foot 8
inches,—you should make them 1 foot 9, so as to allow you a whole inch
to waste in planing and fitting. When both are as true as you can get
them, lay them down near together, and brush the edges with boiling hot
glue. Then immediately put them together, and rub them a few seconds one
against the other, till they seem to stick slightly. Then leave them in
their exact position, and drive a couple of nails into the bench against
the outside edges, so as to keep them together, or in any other way wedge
them tightly in position until they are quite dry. When the glue is hard
which has been squeezed out along the joint, you may run a plane all over
the united boards, and you ought hardly to see the joint, which will be
nearly as strong as any other part.
This top has now to be attached to the frame, as follows. Cut some pieces
like K in Fig. 25, and glue them here and there along the inside edges
of the frame, so that one side of them shall come quite flush with the
upper edge. To these the top has to be glued. Lay it, therefore, with its
under side upwards, upon the floor (I suppose the short pieces glued and
_dry_ on the frame), and having also glued the sides of the short pieces
which will touch the under side of the table top, turn the whole upside
down, with its legs in the air, adjusting it quickly. Its own weight will
keep it in position until dry; or, if not, it is easy to lay an odd board
or two across, and put some weights upon them. When dry, turn over your
table, and plane round the edges where necessary; and, if it does not
stand very well, trim the bottoms of the legs. Clean off glue, and rub
any rough places with sandpaper or glasscloth, filling up any accidental
holes with putty, after which it will be fit for receiving paint or
stain, if it is not considered desirable to leave it white. The corners
and edges of the top may be rounded off, to give a finished appearance.
I showed by dotted lines the usual shape of the squared legs. They are
planed off, tapering from below the frame, and this should be done after
the mortices are cut, and before fitting the parts together. The best
way to insure equal taper of all the legs, is to prick off at the bottom
of each equal widths from the corners or edges, and to run a pencil line
from the point where the taper is to begin to these marks. Then plane
exactly to the lines thus made.
[Illustration: Fig. 26.]
Let us now consider what errors of construction are most likely to occur
in working out these directions. First, it is possible that the framework
may be out of square. This may proceed from two causes. In the first
place, the side or end pieces may not be of equal length between the
legs, owing to some one or two being driven further into their mortices
than the others. To avoid this, which is not uncommon in many works of a
similar nature, it is well always to mark the length that each is to be,
irrespective of the part within the mortices, as Fig. 26, A and B. If the
space on each between the dotted lines (_carefully marked by means of a
square_) is equal, it is no matter whether C and D are also equal. We
have only to take care to let them into the mortices to a greater or less
depth, until the line comes exactly even with the inside edge of the
legs. Again, it is possible that when the table is placed upon its legs,
these may not rest truly on the floor. Probably one or two of the frame
pieces run up like E, instead of standing at right angles to the legs.
This results from the mortice not being cut correctly; and as you cannot,
in this case, mark both sides and cut from both, as you did in making
the towel-horse, this is not unlikely to happen. It will not, therefore,
signify much if you purposely cut your mortices a little too _long_,
and then, when you have placed the table on its legs, after gluing up
the frame, and before it is dry, you can force it to stand truly, and
then wedge up with glued wedges where necessary. You cannot, however,
do this with the _sides_ of your mortices, because you require these to
fit exactly; you must therefore use extra care in keeping these as true
as possible. In many cases you can wedge the _ends_ of tenons to correct
a bad fit, but never the sides. These are the probable, or I will say
_possible_, faults against which to be on your guard.
[Illustration: Fig. 27.]
In making a similar table with a drawer, the same operations have to be
gone through, but the upper frame is somewhat differently constructed,
and the corners of the drawer are united with dovetails. Plane up the
legs as before, but cut mortices as at A. Fig. 27, which represents the
right-hand hinder leg as you would see it standing in front of the table,
and before the framework had been fitted in its place. B is the other
hind leg, with the tenoned strips just ready to be driven in. The piece
E is made as before, as is also C and its opposite piece at the _ends_
of the table. But this pair of mortices, you see, are made shorter than
before, and the strip C is notched at the bottom as well as at the top,
forming a regular _tenon_, as it is called. Below this first is a second
mortice, cut the other way, the longest side standing _across_ the leg
to receive a strip, D, upon which afterwards another strip, X, will be
nailed or glued, forming the rebate in which the drawer will slide, and
of which the upper surface must be level with that of the strip M. There
is a plane for cutting out rebates without the necessity of adding a
strip, but I do not suppose you as yet to have such a one. When these
pieces, C and D, are driven up close into their places, they will touch
along their sides, so that on the outside they will appear as one piece.
Of course there will be a similar pair on the right-hand side of the
table. D ought to be tenoned, so that the side on which X is to be nailed
will lie flush or level with the corner of the leg, so that the strip X
shall project wholly beyond it.
The left-hand _front_ leg is shown at P, with its mortices, and the
tenoned strips between which the front of the drawer will lie, closely
fitting when shut. These front strips should be each 2 inches wide, the
mortices 1 inch long, or as long as you can safely cut them; you must
tenon the cross pieces, of course, to fit these.
All the rails may be of half-inch board. Mark all tenons across with the
square as before, so as to give the exact _inside_ dimensions, and you
cannot well go wrong. These lines, too, will guide you in keeping the
framework square and true; for if you have planed the legs correctly, and
your strips are inserted exactly to the aforesaid lines, it stands to
reason the work will be satisfactory. To make the drawer, observe, first,
that it is not like a box as most boys would make it, for when turned
upside down, as in Fig. 28, Fig. B, you will find the sides projecting
beyond the bottom, which projections rest in the rebate, X, of the last
figure, and take the whole weight of the drawer, enabling it to slide
easily and smoothly in and out, especially if those surfaces which are in
contact are rubbed with soap or blacklead, or a mixture of the two. At C
you have a drawing of the same, with the bottom removed. This, you see,
is a square or oblong frame dovetailed together, and when it is glued and
dry, the bottom is slid in along the grooves in the sides (one of which
is seen at _x x_), and a couple of brads driven through it into the back
rail, K, fixes it completely. The front board of the drawer is cut and
planed to fit exactly between the two rails which were morticed into the
legs, as shown in the last fig., and is always of thicker stuff than the
sides or bottom. It may, in the present case, be half-inch, and the rest
quarter-inch.
[Illustration: Fig. 28.]
If you look at C, you will observe that the front and sides of the drawer
are of the same depth, and that only the back is narrower. (Remember that
in this cut the drawer is seen from below, the groove _x x_ being near
the bottom of the sides, and level with the bottom of the back.)
To cut dovetails is not difficult, but requires neatness and care—a fine
saw (dovetail or light tenon-saw) and a really sharp chisel; and, above
all things, remember not to cut out the lines which have been drawn
as guides. H is the _end_ of the front of the drawer; L the left side.
Having cut out the latter, and planed it up nicely, draw a line, by the
aid of the square, one quarter or three eighths of an inch from the end
_across_ it. This will be the line _o p_ of the bottom of the dovetails.
Then mark and cut out two or three, as seen in the drawing, using the saw
where you are able, and clearing out with the chisel in other places.
From _o p_, measure the exact _inside_ width of your drawer, and beyond
the second line made across at that distance, leave a quarter of an inch
for the second dovetails, and cut them out as you did the first. Now,
prepare a second precisely similar piece for the opposite side. Next
lay L in place upon H very truly, and with a fine-pointed hard pencil,
or a scriber (a sharp-pointed steel marker), trace round the dovetails,
marking them on the end of H, and with a sharp chisel cut them in a
quarter of an inch deep, which will allow them to take the side piece
exactly flush and level. Mark these two which have been so fitted, and
proceed to do the same at the other end of the front piece, tracing
these, as before, from the dovetails of the opposite side, which are
to be there inserted. You do exactly the same with the back piece; but
as this is both narrower and thinner, the dovetails will be cut quite
through it, and will be seen on both pieces after being glued up, and
there will only be room for one dovetail, instead of two. When all are
cut, lay the pieces in position, glue quickly, press all together, and
contrive to wedge up or bind round the whole until dry, testing with the
square and adjusting, as maybe necessary. We shall return to dovetailing
again, but these not requiring _excessive_ neatness, will be a good
beginning, and show you in what special points care is needed in such
work. Nothing remains but to plane a piece for the bottom, and slide it
into place.
CHAPTER V.
In the last chapter we entered a little upon the matter of dovetails, but
as the mode of uniting the angles of boxes, drawers, and such like, is
of almost universal application, it will be as well to devote a separate
short chapter to the subject.
There are several different kinds of dovetails used, according as it may
be desired to let them appear upon the finished work, or wholly or in
part to conceal them. Carpenters generally use the kind which is visible
on both sides, cabinetmakers, as a rule, take special pains to conceal
it, only using the other form upon work that is to be afterwards covered
with veneer (a thin covering of some ornamental and more expensive wood
glued upon the surface of that which is of less value, and of which the
article is made).
The dovetail described in the last chapter, as proper for the attachment
of the sides to the front of a drawer, is not that which is ordinarily
used by the carpenters, but the following, which is somewhat more easy
to make, and is the same as would be used for the other corners of such a
common drawer as that described.
I must at the outset remind my young readers once again of the standard
rule, without due attention to which they have _no hope of success_ in
this neat and delicate operation of carpentry. _Never cut out your guide
lines, but leave them upon your work_, and use your square diligently
upon the _edges_ of your work, the bottom of the dovetails, sides of the
same, and upon the sides of the pins. Never mind the _time_ necessary for
this. You are doing work, remember, that is to bear inspection,—work that
will stand wear, and be really useful in the household to which you have
the honour to belong. You would not therefore like to see open spaces
here and there, requiring to be filled up with putty, or the side of the
box not truly square to the back and front. And it may be noted here,
that if dovetails are properly fitted together, the box or other article
will stand firm, even before the glue is added; but if the same are badly
cut, and put together carelessly, no amount of glue will avail to hold
the work securely; and it would have been as well or better never to
have attempted dovetailing, as such bad work would be stronger united by
nails, and in any case is but a disgrace to the young amateur mechanic,
whose motto should always be, “_Whatever is worth doing at all is worth
doing well_.”
[Illustration: Fig. 29.]
You will remember how you were taught to wedge up mortice and tenon
joints with glued wedges, which, becoming part of the tenon, and
rendering it larger below than above, prevents it from being withdrawn
from the mortice. Now, a single dovetail has the same effect, and is in
point of fact of the same shape and size as the tenon with its wedges
attached. See Fig. 29, A and B, the first being a wedged tenon, the
second a dovetail.
We shall begin with a single dovetail, which is applied to the
construction of presses used by bookbinders and others, and also
domestically for house-linen. In these there is a strong tendency to
draw the sides upwards, and to tear them from the bottom—a strain which
this form of joint is exactly calculated to withstand. The same is also
used in making many kinds of frames, where similar strength in one
direction is necessary. If you have no special need of such at present,
you should nevertheless make one or two for practice, and to give you a
better insight into their construction. Indeed, if you cannot make single
dovetails well, you will hardly succeed in making a whole row of them
exactly alike, for joining together other articles, as drawers, boxes,
and cabinets. C of this fig. represents a bar of wood truly squared up,
and ready for being marked out. The square is laid across it as seen,
and a line drawn on each side by its assistance, as far from one end as
is the thickness of the other piece to which it is to be attached, and a
little over (say one-eighth of an inch) which will afterwards be neatly
planed off. This is allowed merely because the extreme angles at _e e_
sometimes get damaged in cutting out the dovetail, and if they are, they
will have to be removed. Having drawn the above line all round the piece,
divide it into three by the aid of your compasses, as shown, on what we
may call the front and back, and then on both these sides draw lines, _e
e_, to the angle. You now have the dovetail, or rather the pin of the
dovetail, marked, and with a fine saw you have only to cut out this piece
as you see at D, taking great care to cut accurately close to the lines,
but to leave them, nevertheless, on the edge of the piece you are about
to use.
If you can saw truly, you should not have to touch these pieces with a
chisel, but if not, you must take a _very sharp_ one, and pare the wood
exactly true to the lines which you have marked. Now the dovetail made
by dividing the width of the stuff into three, as given here, will not
answer so well for pine, which is liable to split off in the line H H
of the fig. D; but for ash, beech, elm, and such like, it is a good
proportion. If the material, therefore, is pine, divide it into four
instead of three, as seen at E, and draw lines to the angles from the two
outer marks; or, without any such division, set out equal distances from
each side, so as to give about this proportion to the pieces which are to
be cut out.
Where there are a row of dovetails to be made (as in cabinet work), even
this latter measurement into four would make them too angular, as you
will learn presently. You must now fix upright in your vice the piece
in which is to be cut the dovetail to receive this pin; and laying the
latter in place as it will be when the frame or other work is put
together, draw round it with a sharp pencil or scriber, as seen on the
end of K (the lines _c d_, at such distance from the end of the piece as
is the _thickness_ of the pin, and the perpendiculars, _a b_, are to be
drawn with the square); and if the angles of such pin do not reach the
angles of that in which the dovetail is to be cut, as will often be the
case, the lines on the opposite side similar to _a b_ must be also drawn
with the square. So you see that I was quite right in directing you to
add a square to your box of tools, even before many other requisites of
carpentry.
If it is not considered desirable that the dovetail should reach the
extreme angles of the pieces, as _a b_, fig. K, the pin piece is first
marked as if for an ordinary tenon, and the dovetailed pin marked on
this, as M. When the fellow-piece is cut out, it will then appear as N.
The effect will be the same as the last, except that the end of the pin
will be more conspicuous. A great deal depends upon the material, and on
the intended use of the finished article, therefore you must use your own
judgment, or consult that of others better acquainted with the art than
yourself. L shows the dovetailed joint complete as last described.
[Illustration: Fig. 30.]
We now recur to the row of dovetails and pins—or dovetails and _sockets_,
as the part is often called which is to receive the pins. The most common
kind is that represented by A B, Fig. 30; and as you ought now to be
thinking of a larger tool-box, and would not like it roughly nailed
together like the first, you might try your skill by constructing one
more worthy of the name, and with a drawer or two in it. You must begin,
as before, by marking the two lines across your work by the edge of the
square, or, if you prefer it, by your gauge, which, when set to the
thickness of one piece, will mark the others correctly; and remember to
mark _both sides_. Then set out your dovetails, but do not make them so
angular as you did the single one; for remember you have a whole row of
them to assist in holding the work together, and when glued, this will be
of necessity a very strong and reliable joint, if well made.
Always make the pins before the sockets, and mark round them as closely
as possible, and take great care when sawing not to break them, and if
possible keep their angles also very sharp and clean. It is solely care
in these particulars, and accurate cutting just to the gauge lines and
no further, that makes carpenters’ work generally so superior to that of
amateurs, and boys especially are generally careless, and in too great a
hurry to get the work done, that they may go to something else. Remember,
therefore, that when you begin to hurry your work, you begin to spoil it.
I have made the drawings of the three principal dovetailed joints so
plain as to render special description almost unnecessary after the
remarks already made. The second and third, however, may need a few
words, as they differ slightly from that used in the drawer, of which
a description has been given, chiefly because the piece in which the
dovetails are, is, in this case, as thick as that used for the sockets.
Suppose the dovetails _and pins_ marked out ready to be cut. Take your
marking-gauge and set the slide about a quarter of an inch from the
point, and run a line across the ends of the two pieces at A B, and at C
D, and also at E F. Stop at A B when you cut the sockets, and take care
to get the bottoms of these quite square and even. Cut the dovetails or
pins as directed in making the drawer, but stop on the lines _e f_ and _g
h_ (the latter also to be made with the gauge on both edges of the work),
thus the two pieces will, of necessity, fit nicely together, and only a
single line will appear a little way from one corner. If all lines are
made with gauge and square, this form of dovetail may require neatness
and care, but will not be beyond the skill even of a young mechanic. I
should indeed advise that every opportunity be taken of joining pieces of
wood with tenon or with dovetail, because, after all, these are the chief
difficulties to be encountered. If you can square up your work, and make
true-fitting joints, there is little in carpentry and joinery that you
cannot accomplish.
The third example is worked exactly like the second, but instead of
leaving square the pieces projecting beyond the dovetails and pins,
these are sloped off or bevelled carefully from the extreme corners
down to the pins and sockets. The result is, that when put together, no
joint appears, as it is exactly _upon_ the angle. There is no neater or
stronger method than this of joining the sides of drawers, boxes, trays,
and such like articles. The cabinetmaker employs no other for heavy work;
only when it is very light does he make use of a plan, the appearance of
which is (when finished) like the last-described, but it is less trouble
to make, and less strong, yet sufficiently so for many purposes. This
method is called _mitring_, and is accomplished in the following way.
The wood (let it be for a small tray) is prepared as usual, truly and
evenly, and the ends exactly square to the sides. If you use stuff about
a quarter or half an inch thick, or even an eighth (the first or last
being suitable for such light work), you can make a mitred joint with the
help of the gauge alone, but frequently a _mitre-board_ or _mitre-box_
is used, which saves some trouble in measuring and marking. It is well,
however, that you should begin with this trouble, and take up the easier
method afterwards; especially as it will in this case give you a simple
lesson in mathematics, and teach you some of the properties of the figure
called a square. Let us commence with this lesson.
A, B, C, D, Fig. 31, is a square; the lines at the opposite sides are
parallel,—that is, they are exactly the same distance apart from one
end to the other. To make this clear, E and F are given, which are not
parallel, for they are further apart at one end than they are at the
other. And as A B is parallel to C D, and A C parallel to B D, so A B
is perpendicular to B D and to A C, or what we have called _square_ to
it, as you would find with your square, which is made, as you know, to
prove your work in this respect. The consequence is, that the angles (or
corners) are all alike, and are called right angles. Understand what is
meant by angles being the same size or alike. M and H are alike, though
the lines of one are a great deal longer than those of the other; but
though the lines of K and H are the same length, the angle K is much
smaller than that at H.
[Illustration: Fig. 31.]
As I have gone a little into this subject, I will go a little further,
for it is as well that you should learn all about the sizes of angles,
and I only know of one way in which to make the matter clear.
Every circle, no matter how small or large, is supposed to be divided
into 360 equal parts, called degrees. That large circle which forms the
circumference of the earth is considered to be so divided. Now, if we
draw lines from all these divisions to the centre, they will meet there,
and form a number of equal angles. I have not divided the circle P all
round, because it would make so many angles that you could not see them
clearly; but I have put 360 at the top, and then 45, which means, that
if I had marked all the divisions, there would be 45 up to that point.
Then at 45 more I have marked 90, and so on, marking each 45th division,
and from these I have drawn lines to the centre of the circle. Now, if
you understand me so far, we shall get on famously. Look at the line from
360 to the centre, and that from 90°, and see where they join. This is
a right angle, and this is the angle at each corner of a square. At N,
I have drawn this separately to make it clear, and you see I have taken
a quarter of the circle, or the _quadrant_, as it is called, of 90°.
And you now see that I might extend the lines beyond the circle to any
extent, but it would make no difference,—we should still have 90° of a
circle, only the circle would be larger, as those which are partly drawn
with the dotted lines.
Now, all angles are thus measured by the divisions of a circle; the line
at 45, which meets the line from 360 at the centre, makes with it an
angle of 45°, which is half a right angle. A line drawn at 30° would
make an angle of 30 with the same line from 360, and so on right round;
only when two lines come _exactly_ opposite one another, as 360 and 180,
or 270 and 90, these make _no angles_—they are but one straight line
passing through the centre, and are called diameters of the circle,
a word which means _measure through_, or across the circle. Now, the
corners of a square frame, or of a drawer or box, are right angles of
90°. At R, I have drawn such a corner of a frame, and if I place one
point of a pair of compasses at _e_, and draw a circle cutting through
the lines of the sides of the frame, you see I should make it 90°, or a
quadrant, like N. Moreover, if I draw the sides of the frame as if they
crossed as at _e_ R, I draw a small square, and the line _e_ R is the
diagonal of such square: _e_ R _is the mitred joint I have to cut_. Look
at T S and you will see this, as here the two sides of the frame are
represented as cut ready to be joined together.
A square has another quality: all its sides are equal, and this is very
important, and will help us in cutting out the work. _x_ Y represents the
strip of wood to be properly sloped off for a mitred joint. With a gauge
such as that just above _x_, or your regular marking gauge, set off on
the side Y a distance equal to _x x_ (the _width of the_ pieces); join _x
b_ by a line, and you will have the right slope. Why? Because when you
measured with the gauge you marked the _two equal sides of a square,
and x b is the diagonal of it_, which is exactly the same as you had at
_e_ R. By measuring in this way, therefore, you can, if your strips are
already truly squared up, always mark out a mitred joint correctly. The
two little angles at _x_ and _b_ are also, I should point out, equal—each
half of a right angle or 45°, and the other strip or side of the frame
will make up the other half right angle, or complete the exact square of
90°.
In all this I have clearly laid down the principles of mitred joints,
and given you a lesson in mathematics. I shall now, therefore, go on to
the work of practical construction (Fig. 32). You must be very careful
to make the edge B square to the side A, as in all other work which I
have explained to you; or, if this side is moulded like the front of a
picture-frame, you must square the edge with the back. After having cut
all the pieces, you have to glue them and fasten them together. Warm
them, and use the glue boiling, as directed before, and quickly lay the
pieces together. To do so effectually, you must place them flat on a
board or on your bench, and having adjusted them, you can tie a strong
cord round the whole, putting little bits of wood close to the corners,
so that the string shall not mark your work, if such marks would be of
consequence. Or you can wedge up strongly in another way. If you look at
C you will see a square representing a frame with eight spots round it.
These are nail heads, and mark the position of eight nails driven round
but not touching the frame into the bench. Then, having prepared eight
small wedges, drive them in between the frame and the nails.
You will find this as simple and easy a way of keeping the frame together
as any, and all must remain till the glue is dry and hard—probably till
the same hour on the following day? Then remove the wedges and take up
your frame, which should be trim and strong. Nevertheless, you are now to
add considerably to the strength of it in one or both of the following
ways.
[Illustration: Fig. 32.]
With a mitre-saw or tenon-saw cut one or two slits at each angle, as
seen at D, Fig. 32, _e_ and _f_. Cut little pieces of thin wood, and
having glued them, drive them into these slits. If you saw them slanting,
some tending upwards and some downwards, it will be better than cutting
straight into the frame. Then, when all is dry, neatly trim off these
pieces even with the frame. You may also, if the work is of a more heavy
kind, as a large picture-frame, finish with keyed mitres, _g_. Cut a
place with a chisel of the shape here shown, about one-eighth of an inch
deep, half into one piece and half into the other. Then cut out a key
of the same form of thin hard wood, to fit exactly, and glue it in. The
shape of the key prevents the joint from coming apart, and makes it very
strong and durable. A very large number of light boxes are made with
mitred joints, as workboxes, water-colour boxes, compass-boxes, and such
like; and you can examine these for yourself; but you will not often
see the keys at the angles, because most of such boxes are veneered, or
covered when finished with a thin layer of some ornamental wood.
I shall now proceed to show you how these joints can be cut at once
without the trouble of gauging and measuring to find the proper angle.
Therefore I shall let you into the secret of mitring boxes and mitring
boards, which, if you had much to do of this kind, would shorten your
work considerably.
Fig. 33, A, represents a mitring-board, B a mitring-box. We must go into
a little mathematics again, and try to understand these, because, if you
do so, you may devise others, occasionally more suitable for any special
work you have in hand.
[Illustration: Fig. 33.]
First, look at D of this figure. You have a line, _a b_, standing upon
another C D, and perpendicular to it—that is, it leans neither to the
right nor to the left. It makes two angles at _b_, one on each side of
_a b_, and these are angles of 90°, or right angles, as I explained.
Now, if one line like _a b_ stands on another, these two angles are
_together_ equal to 180°, or twice 90°, whether this line is or is not
upright or perpendicular to the other. Look at fig. C. Here you have the
line _x x_, and standing on it several others; one, _a b_, is upright or
perpendicular, making with it two angles of 90° each, or 180° together.
Now, take _f b_, and suppose this to make 45° on the right-hand side,
you see it makes therefore a proportionately larger angle on the other.
It makes, in fact, an angle of 135°. But 135° added to 45° equals 180°,
which is the same as before, and whichever line you take, the angles
together made by it at _b_ will equal 180° of the circle—that is, they
will equal two right-angles.
Now, if I take the fig. D again, and carry on the line _a b_ right
through _c d_, where it is dotted, two angles will be made on the other
side of _c d_, which will each be right angles of 90° as before, so that
all the four angles thus made are equal. It follows from this, that
whenever any two lines cut each other—E Q and R S for instance—the angles
at T _equal_ four right angles, no matter whether the lines are or are
not perpendicular to each other: and what is more (and what I specially
want you to note), the _opposite_ angles _are equal_—_i.e._, the two
small ones, or the two large ones.
The action of a mitre-block or mitre-box depends upon the principles
here laid down, so you see that although few carpenters understand much
about mathematics, and simply work as they were taught, without knowing
or caring why, those who planned the method of work, and invented
mitre-boards and such like devices to shorten work and lessen labour,
must have understood a great deal about such things. And so it is
generally, as you will find with inventions: things look easy enough, and
natural enough, when we see them every day; but it has taken a great deal
of thought and sound knowledge to invent them in the first place, and a
great deal of practical experience to construct them so neatly. Even a
common pin goes through such a number of processes as would surprise you,
if you have never been able to see them made.
Look carefully at A. It represents a block of wood, about 1½ or 2
inches thick, and 3 or 4 wide, firmly screwed on the top of a board 1
inch thick. The length is about 18 inches. Two saw-cuts are made with a
tenon-saw, right through the block to the board, at angles of 45° with
the line _a b_. These are guides for the saw to work in. The wood to be
cut is laid against the edge of the block, and rests on the board, and
the saw is then applied in one of the grooves while the wood is being cut
by it. Let H be such a piece. If the saw is put in the left-hand slit,
it will cut it like _y_; if in the other, it will cut it the other way,
like _x_; and thus, if a piece is taken off at each end, it will be as
you see, ready to become one side of a frame. Now, examine K, which shows
all the lines or edges of the mitring-board, as seen from above, with
the strip _a b_ sawn across in the line _c a_. The lines _a b_ and _c a_
cross each other, making the opposite angles equal; and as one angle is
45° the other must be 45° also, so that the right-hand side of the strip
is correctly cut. But so also is the other end, and if we turn it over,
it will exactly fit, and the two will form two sides of a square. I could
prove to you that the second strip contains angles exactly similar to the
first, but you ought to be able now to detect the reason for yourself,
and I do not want to teach you more mathematics at present, as I am
afraid you are tired of these, and will want to go on with the real work
of fitting and making. I have, however, said enough, I think, to make you
comprehend _why_ the two saw-cuts must be at an angle of 45° with the
edge of the top board.
Perhaps you wish to make your own board, however, and would like to know
an easy way to get the saw-cuts at the right angle? I shall therefore
show you how to do this, but you must be very exact in your workmanship.
A B, Fig. 34, is the piece of thick board as seen from above, and close
to it is a perspective view of the same which shows the thickness. Set
off a distance, A E, equal to A C, and join C E. The dotted line shows
you that C E is the diagonal of a square, and the angles at C and E
are consequently each 45°; but we do not want this line to end at C,
it is too exactly at the corner for convenience. Measure, therefore,
a distance, E _b_ and C _a_, equal, and join _a b_, which will be the
place for the saw-cut; and the other can be marked out in exactly the
same way. _a x_, in the perspective view, must be carefully marked by the
help of the square. Take care to mark the line on the bottom board, where
the edge of this upper thick piece will fall, and screw the two firmly
together. If the edge and face of the thick piece are not truly square to
each other, the mitres cut thus will not be correct; but, if all is well
made, they may be glued at once together, no paring of the chisel being
necessary or desirable.
The mitre-box, Fig. 33, B, is on precisely the same principle, but is
chiefly used to cut narrow strips not over 2 inches wide; it should be
neatly made of mahogany, half an inch thick. There is also generally made
a saw-cut straight across, at right angles to the length of the box or
board, which is convenient in sawing across such strips of wood, as it
saves the necessity of marking lines against the edge of the square: of
course, it is specially used where a large number of strips have to be
cut square across. In all these you observe one saw-cut leaning to the
right, the other to the left. This is necessary when picture-frames or
moulded pieces have to be cut to 45°, because you cannot, of course, turn
such pieces over and use either side, which you can do when the piece has
no such mouldings.
[Illustration: Fig. 34.]
Several modifications exist of mitring-boards; some arranged for sawing,
and some for planing; and where thousands of frames have to be cheaply
made, the angles are cut off with circular saws, of which I need not
speak particularly here, but which I shall probably have to describe
in a future page. In Fig. 34, K, I have shown one corner of a simple
picture-frame, covered with what is called rustic work, that is—short
pieces of oak, ash, or other wood cut from the tree, left with the bark
on, or peeled and varnished. These are nailed on with small brads; and,
if well assorted and arranged, this will have a very neat appearance,
suiting well for rooms fitted up in oak, as many studies and libraries
are. In picture-frames, however, a rebate (called rabbit) has to be made
at the back, like L, in which the picture with its glass and back-board
has to rest; and this requires a special plane. The front also is always
either sloped off or moulded. I shall therefore make this kind of work
the subject of my next chapter, and describe the operations of rebating,
grooving, tongueing, and moulding.
CHAPTER VI.
These operations, which are frequently required in carpentry, are done
on a small scale by planes. On a larger scale, circular saws and other
machinery are widely and extensively made use of for the same purpose,
as being much more rapid and economical. Of course, the young mechanic
will employ the more usual method, and the present chapter will therefore
treat of the planes necessary for the above work, and the method of using
them.
The common rebate or rabbit plane comes first. This is of various widths;
an inch being a very useful size. It is different in many respects from
the smoothing-plane, being made with a single iron only, which is so
arranged as to reach into angular recesses, which could not be touched
by the ordinary plane, of which the iron does not extend quite to either
side of the sole. Fig. 35, A and B, will illustrate this. A represents
the plane as seen from above and at one side, B gives the perspective
view of the sole, C represents the iron, D the wedge. Let us suppose a
rebate required upon a strip 1 inch thick, the same to be half an inch
wide and deep. A gauge is first set to the required distance, and a line
is marked on both faces, as a guide for the action of the plane. After
a little practice it will be found easy to guide the entry of the plane
with the left hand, grasping it so as partly to overlap the sole, and
thus determine the width of the cut, which must not at first be carried
to the full width required, but may be brought within an eighth of an
inch of such gauge line, and the material removed sometimes from one face
of the rebate and sometimes from the other, taking care to keep it nicely
square.
[Illustration: Fig. 35.]
At first it is an easier plan to nail on with brads a strip of wood
accurately planed, which in this case, as the sole of the plane is 1 inch
wide, must cover it from end to end to a width of half an inch. This
will prevent the possibility of going too deep into cut, and insure the
correctness of the rebate, Fig. 35, H. The injury to the sole will not be
great if small brads are used, but at the same time it is better to learn
the art of using the hand as a guide, which is the more general method of
the working carpenter. As for the use of rebates, there are few pieces
of cabinet-work or joinery in which they are not found, and as stated
in the previous chapter, no picture-frame can be made without them. The
shavings which escape from the rebate-frame do not rise out of the top,
as in the smoothing-plane, but from the side, which is hollowed out for
the purpose, as seen in the drawing.
The skew rebate-plane is made like the preceding one, but the iron,
instead of standing at right angles to the sides, is placed at an angle.
With this you can plane across the grain of the wood.
The next plane to be noticed, is that with which grooves are cut,
such as you will often see in the sides of book-shelves, in which the
several shelves slide. The same is done where two boards are to be
joined lengthwise, and there is danger of their becoming separated as
the wood shrinks in drying. The panels of doors, too, are slid into
similar grooves in the styles and rails of the framework, and there are
innumerable other cases in which this mode of work is carried out. These
grooves are generally cut with the plough, a curious-looking tool, by
no means like a plane in appearance, but of great use to the carpenter.
Of course, we require various widths of such grooves, according to the
special purpose intended, and these are determined by various widths of
the cutting irons, which, however, all fix into the same stock; a dozen
or more of such irons are sold with a single plane.
[Illustration: Fig. 36.]
In Fig. 36 is a set of drawings explanatory of the above tool. The
central part, or stock, is that which corresponds to the same in other
planes, and it is only modified to suit the other parts, which simply act
as guides or gauges regulating the distance of the grooves from the edge
of the board, and the depth to which they are to be cut. When the arms, A
A, are removed, you have the plane as it appears with a brass fence, _b_,
at one side, which can be raised or lowered at pleasure, and set at any
point by the screw C; _d_ is an iron plate which acts as the sole of the
plane, the cutting edge being set to project a very little way below it.
The arms A A carry the fence _g_, which is flat on the inside next the
plane, and moulded (merely for appearance sake) on the outside. The arms
slide in two holes in the body of the plane, and can be drawn out at
pleasure, and fixed by little wooden wedges, _e e_. Thus, while in use,
the fence rubs along the edge of the board, while the groove is being
cut at such distance as the fence is fixed, and to such a depth as is
allowed by the position of the brass check or guide. Complex, therefore,
as this tool appears, it is not so in reality. We shall presently
describe a chest of drawers or cabinet calculated to receive small tools,
or specimens of coins, shells, and such like, in which another kind of
grooving-plane has to come into use, called (with its fellow, which makes
a tenon to fit such groove) a match plane. This is of extensive use, less
expensive than the plough, and on the whole more likely to be useful to
the young mechanic. Indeed, although the plough has been here described
and illustrated, it is not by any means to be considered essential,
and its purchase may well be deferred until other tools of greater
importance has been effected. The side or sash fillister to be presently
described, for instance, would be more useful.
[Illustration: Fig. 37.]
Fig. 37 is such a cabinet, with six drawers, dovetailed at the corners as
usual. The bottom, however, projects beyond the sides, so that the latter
are not made lower than the back, as was the case with the table-drawer
previously described. The top and sides may be of mahogany, the back
and bottom of pine (stained or not at pleasure), or if cost is an
object, the whole may be of any other wood; but the grooves in which the
drawers slide, can be cut more sharply and neatly in harder wood than
pine—birch, for instance, which is very fit for the purpose, and will
take a good polish. The outer case is first made like an open box. The
dimensions may be regulated according to the intended use, but generally
the drawers increase in depth downwards. The top and bottom overlap the
sides, the latter to a somewhat greater width than the former. The sides
can therefore only be dovetailed to the back; the bottom may be attached
with screws, and the top likewise, but the holes must then be plugged to
conceal them. If the whole is of deal, and to be painted or veneered,
this would be the best plan; but if the top is of mahogany, it is not
so easy to fill up the holes above the heads of the screws so as to
thoroughly conceal them. If, however, you have no plough to cut a groove
to let the sides and back a little way into the top, glue alone will not
hold sufficiently. In this case smaller holes may be made to admit 2-inch
brads to assist the glue, such holes being easily filled with putty
stained to imitate mahogany.
The peculiarity of the drawers consists in their meeting each other quite
closely when shut, without the intermediate divisions ordinarily seen.
Hence the necessity for a different arrangement of the sliding surfaces
as before referred to. The insides of the case have _five_ grooves
ploughed across them, as seen at C of this figure, the sixth drawer only
being made as usual to slide upon the bottom of the case, and having its
sides made lower than the back for this purpose.
In the grooves thus cut, the projecting part of the bottom of the drawers
is made to fit and slide, and they will run more smoothly if cut so that
the grain of the wood shall run across the bottom, from front to back,
and not from side to side. The bottom of the drawer must not come below
the level of the front, but either the front should be rebated to take
one edge of it, as seen at E, which is the best way, or a slip of wood
should be glued along as at F, on which that edge may rest, and to which
it can be attached. D exhibits this distinctly, as it is drawn as if the
nearest end was removed to show the position of the other parts. The
bottom, therefore, will be let into the front, and nailed under the back
and sides, and will project rather less than half an inch each way, to
fit the grooves in which it is to slide. Another way to effect the same
is to make the drawers as usual, with no such projections, and to nail
a strip to run in the grooves in the middle of the side pieces, or, if
preferred, near the top. The effect is, of course, the same, and such
strips being planed up nicely, with the grain running lengthwise, will
cause the drawers to work in and out very smoothly.
There is no neater way than this to make a cabinet; and sometimes the
whole is closed with a panelled door, for which purpose the case is
left to project beyond the drawers. Unless well supplied in the matter
of planes, which is hardly to be expected, you will not be able to cut
the grooves in the side of the outer case in any way but the following,
which, however, will answer very well when the piece in which they are
to be cut is not above 9 inches or 1 foot wide. Mark out the places,
spacing them with the greatest care, and cut just within the lines with a
tenon-saw; then cut out with a chisel the narrow piece which intervenes.
There is a plane called a routing-plane used for this by cabinetmakers
and joiners, but you may as well exercise your ingenuity to do without
it. If you have a plough, you may remove the fence, and let it follow up
the saw and chisel, but it will be hardly required if you use the chisel
carefully.
I shall now introduce to your notice another very excellent plane, called
a side or sash fillister, for cutting rebates of any required depth and
width. It is very like the plough in appearance, with a similar wooden
guide or fence on two arms to regulate the width, and another of metal,
moved by a screw at the top, to regulate the depth of the cut. Fig. 38,
A, shows one side of this plane, and B the other. The cutting edge comes
down to the level of _c d_ in fig. A; the fence, of which the edge is
seen at _h_, will draw up to the level of _a b_, or lower to that of the
edge. This plane, therefore, is but a more complete rebate-plane, fitted
with guides for depth and width. It does its work very perfectly, and is
of extensive use.
[Illustration: Fig. 38.]
I have given descriptions of these planes, although the young mechanic
will not at first possess them, as they are somewhat expensive, because
I feel it as well to let him know how work is done by the trade, and
why it is that such work is effected more rapidly and better than he
himself can do it; but at the same time it is far better that he should,
for a long time, work at a disadvantage, by using few tools, and those
of the simplest construction, before taking in hand others which cost a
good deal of money, which might often be better spent. A look back over
these pages will show that with a long (or jack) plane, a smoothing-plane
and a rebate-plane, all the work previously alluded to can be done. As,
however, I am writing upon the subject of planes, I may as well mention
two more—match-planes and beading-planes—to which may be added those
for moulding, being an extension only of the last named. Match-planes
are always in pairs. Their use is to cut, the one a groove, Fig. 39, A,
the other a tenon or tongue, or feather, as it is sometimes called, as
Fig. 39, B, down the long sides (with the grain) of boards that are to
be joined lengthwise (Fig. 39). If the plough is used, a groove is cut
in both pieces, and a slip of board planed up to fit them; either method
will answer equally well. When boards joined thus shrink, the tongue or
slip fills up space.
[Illustration: Fig. 39.]
There is no necessity for illustrating the planes used for beading
and moulding after the description already given of others. The irons,
instead of being flat, are filed into grooves and hollows of the required
pattern, and of course transfer their own form to the wood upon which
they are used. They are held on the slope of the moulding to be cut.
When blunt, they have to be sharpened with slips of oilstone, which can
be had for the purpose, of square and round section; sometimes they are
sufficiently soft to be filed into shape, but a keen edge cannot thus
be obtained. Mouldings, however, are generally finished off with fine
sandpaper. They are always planed lengthwise of the grain in long strips,
and are cut to the required lengths (generally with mitres). When very
broad, they are made up of several narrower ones, glued side by side.
The young mechanic had better get them cut for him by some friendly
carpenter, as it is hardly worth his while to buy planes for which he
will have comparatively little use.
I shall conclude these papers on carpentry by describing the method
of making such a door as would suit the cabinet already described,
especially as it will explain the way in which all panelling is done,
whether for doors, shutters, or other similar articles. Panelling is
indeed of very general application in every household, and it is well
worth while even for the young mechanic to learn how it is accomplished.
It is absolutely necessary, however, that he should be possessed either
of a plough or match-planes for routing out the grooves in which the
panels slide.
Nearly all panels have a beading or a moulding running round them as a
finish.
[Illustration: Fig. 40.]
Fig. 40 illustrates the method of panelling. A, B, C are the styles, D,
E, F, G the rails. The mortices and tenons are cut as usual. The inside
edges of C, B, D, G are then grooved with the plough, and both edges of
the other pieces. The panels are carefully squared up, and then bevelled
off at the edges so as to fit the grooves. To put such a door together,
A, D, G, E, and F would be first arranged, then the panels slid in
from the outside, and afterwards the styles B and C put in place. The
part beyond the outer mortices in the latter pieces, which are left for
safety in cutting these mortices, and to prevent splitting when D and
G are driven home, are not cut off until the glue is dry. The process
is simple, but it requires great care, both in setting out the various
measurements, and in squaring up the different pieces composing the
whole. After the whole is dry, strips of moulding, cut to mitre-joints at
the corners, are nailed on with brads round the panels to give the whole
a finished appearance.
In the above examples, in which I have gone from the more simple to
the more complicated, are comprised the main principles of the art of
carpentry. At any rate, when the young mechanic can do _as much_, he will
be able to accomplish a great deal more.
CHAPTER VII.
There are a number of useful and ornamental articles which cannot be
made with the carpenter’s tools alone, but which need a lathe for their
construction. Wooden boxes of circular section, wooden and metal wheels
and pulleys, ornamental chair and table legs, and a countless number of
similar articles, all depend upon the skill of the turner. Models too
of engines and machinery of all sizes and shapes, bring the lathe into
constant requisition.
No one can say to whom this machine is to be attributed. Probably it has
been developed by slow and imperceptible steps, from the potter’s wheel
to its present elaborate and perfect form. As for the part that old
Dædalus had in it, I believe he had just as much to do with it as he had
with the saw, which he is said to have invented from seeing the backbone
of a fish. Now, the backbone of a fish is not a bit like a saw, but the
jaw of a shark is, and very quickly it amputates legs, arms, and heads,
when unfortunately the chance is given to it. We need not, however, stay
to discuss this unimportant point; we will leave it to the researches
of the Antediluvian Society, or Noahican Brethren, or any other known
or unknown learned body, and proceed to consider the lathe as it is
now generally constructed—the ambition of boys, the delight of adult
possessors, and, to the writer, “gem of gems!”
At the very time I write, I am engaged in fitting up two lathes; one of
which is for just such a “young mechanic” as this book is intended to
instruct. The bed will be of dry hard beech, the fly-wheel of iron turned
up with five grooves or speeds, as they are called. The heads, which are
the only really important part, are to be made by a well-known London
maker, whose work is sure to be the best possible at the price afforded.
Nevertheless, this lathe will cost several pounds, although it is to be
fitted for hand-turning only, and it is possible in London to find a much
cheaper (not better) article.
When I was myself a “young mechanic,” so many years ago that I find I
do not quite like to count them, I had a lathe at £2, rather shaky,
wooden fly-wheel, wooden head—not at all the thing to recommend. Then
I had another made by a gunsmith—all iron—for it was what is called a
triangle-bar lathe; the bed being a bar of triangular section, on which
the heads or poppits slid, and also the rest. I think now it was not a
bad lathe; but I am afraid the work I did on it was scarcely first-class;
and I sold the machine one fine day under the impression that if I had a
better I should do better work. This, however, proved a terrible fallacy;
so I set myself upon high as a warning to young mechanics, who always
fancy that their clumsy, bad work is due to some fault in their tools,
whereas, after all, it is generally their own.
Well, I had a succession of lathes, after that triangle-bar one had
passed into oblivion, by various makers; some good, some indifferent,
some for heavy, and some for light work; and I fancy I am now fairly able
to give an opinion upon the merits or demerits of any particular lathe
which may come under my notice.
I was going to write a piece of advice, “_Don’t give too much for a
lathe_,” when I remembered that I was scribbling for the edification
first of boys; and experience tells me the caution is by no means
generally necessary, few boys’ pockets being very heavily lined, owing
to the constant claims upon them for peg-tops, knives, string, and
etceteras—not to say lollipops and bulls’ eyes, and similar unwholesome
luxuries.
I suppose, however, I must give some idea of cost, if only as a partial
guide; but all depends upon the special object for which the lathe is to
be used. If for models, for instance, it would not be so expensive as
if it was desired for elaborate ornamental work in wood or ivory, when
the young mechanic has grown whiskers, and become an adult enthusiast at
this delightful recreation. For there are all kinds of lathes to be had;
some that will answer well for beginners, and for rough work in after
years; some beautifully finished, intended to be used first for simple
hand-turning, but which are of best construction, and therefore worth
adding to from time to time; and if carefully used, will descend in good
order from father to son. Then there are lathes for heavier work, and for
screw cutting and engine making, fit for engineers; and others of minute
size and exquisite finish, adapted to the special requirements of watch
and clock makers—lathes you could put in your waistcoat pocket.
Now, if I were sure you would be very, very careful, I should like
to recommend a good lathe, worth adding to as you grew more and more
experienced; but these, even of simplest make, are costly, and not within
reach of half my readers. I shall therefore say—get a good, plain,
strong tool that will bear a little rough usage, and which will cost you
as little as it is possible to make them for: and if you find, after a
year or two, that you are becoming a proficient, and therefore not so
likely to damage a _good_ lathe, you can set this, your first, on one
side, and let it become your _hack_ to do any odd jobs, and buy yourself
both a larger and a better one. I know this will be a _double_ outlay;
but experience tells me it will be the best way and the cheapest in the
long run. Perhaps you may like to go on as you are. Your small lathe may
prove an accurate one, and quite sufficient for your need. In such case,
of course, a new one will not be required at all. But if it should be
otherwise, and circumstances allow you to improve upon it, you may rest
assured your old friend will be ever a handy assistant, and save your
better lathe very considerably in many ways.
You can get a lathe for about $20 to $25, with iron bed complete; and I
really think it impossible to obtain a cheaper one. Of course it will be
small, and of the plainest possible construction. It will, nevertheless,
answer for light work in wood and metal, being designed to assist the
young mechanic in making model engines and similar curiosities. From this
you may go, pound by pound, to good, serviceable tools; and these to a
£300 lathe for rose engine-work, and elaborate ornamentation in ivory
and other costly materials. Most probably I shall be able to give you a
catalogue or two at the end of this book, published by makers of such
lathes, and you can then judge of the probable cost of your workshop. The
drawing of the lathe (Fig. 41) will be readily understood even by those
boys who have had no opportunity of seeing any work of this kind. There
are, however, few towns or villages in which a lathe does not exist, and
may not be examined by any boy who desires to learn its construction and
use. Its object is to give rotary movement to any material it is desired
to form into a circular or cylindrical shape.
[Illustration: Fig. 41.]
Motion being given to the fly-wheel by means of the treadle and crank,
is communicated to the pulley upon the mandrel. Upon the screw of this
mandrel, B, the work is fixed; being usually held in a chuck suited
to its particular form, but sometimes it is screwed directly upon the
mandrel. The rest, C, is then fixed near it, and the tool is supported
thereon and held firmly while the work revolves against it. All this
is easy to understand—it is _not_ so easy to carry it into practice.
Attention to the following directions will enable the young mechanic to
become a good turner in course of time; but the art cannot be practically
learned in a day, and it needs experience and considerable practice to
become anything like a proficient.
If the construction of the lathe itself is understood, the first
consideration is what tools and chucks are necessary. I shall speak
of the latter first, as little or nothing can be done without them.
First comes the prong-chuck, for soft wood (Fig. 41, A). This, like all
others, is made to screw upon the mandrel. Its use is to hold one end of
any piece of wood while the other is supported by the point, E, of the
poppit, H, which poppit can be moved at pleasure along the lathe-bed,
and fixed at any given place by a hand-nut below. The point itself can
be advanced or drawn back by turning the handle, K. A piece of wood thus
mounted must of necessity revolve with the mandrel, because, although
it can and will turn round upon the point of the back poppit, it cannot
do so upon the fork or prong, which enters and holds it securely.
This chuck, or one of the same nature, is always used for cylinders of
soft wood, which can be supported at both ends, such as tool-handles,
chair-legs, and other work not requiring to be hollowed out.
It sometimes happens, however, especially if the work is at all rough, or
considerably out of truth, that the piece slips round upon the fork or
prong, especially if it does not enter deeply enough; and in addition,
tool-handles and round rulers, and many articles that have to be
similarly supported at both ends, are made of hard wood, into which this
prong will not readily enter.
In such cases, and indeed as a general substitute for the first, a chuck
called a “cross-chuck” is to be used (Fig. 41, L, M). The _centre of
the little_ cross (which is of steel, and fits into the same square or
round hole in the socket which carries the prong, and which is also used
to hold drills, pieces of iron rod which are to be turned, and other
articles) is made to revolve in the precise axial line of the mandrel, or
to run _true_ with it, as it is called. The arms of the cross are to be
imbedded in the work, which is best effected by making in the latter two
saw-cuts at right angles with each other (Fig. 41, N), which represents a
piece ready for mounting.
The next chuck is equally necessary (Fig. 41, O). It is a taper screw of
steel, fixed in a socket which can be attached to the mandrel. Two sizes
of this chuck would be useful for a large lathe, but for such a one as
will probably be purchased by the young amateur, one only, with a screw
of medium size, will suffice. The use of this chuck is to hold pieces
which only require to be supported at one end, so that a tool can be used
to work upon the other, either to mould it into the required form, or to
hollow it out for a box or bowl. Of course you might screw such work on
the mandrel-nose itself, but it would make a very large hole in the end,
whereas this taper screw only requires a moderately sized gimlet-hole. It
is therefore a much more convenient way of attaching work to the mandrel,
and is of extensive use.
The cup-chuck is the last required. It is sketched at P, and is sometimes
of iron, but generally of brass. There are several sizes made and sold
with lathes, but you need not have at most more than one or two, as I
shall show you how to make wooden ones, which answer as well, if not
better. The flat plates, R, R², can scarcely be called chucks, but they
generally come into the list of such. The latter has five projecting
points, which, sticking into such a thing as a flat-board (like a
bread-platter, or round pulley), hold it sufficiently firm when the back
centre is brought up against the other side of the piece, to allow of its
being turned. The other is merely a flat plate with holes in it, through
which screws can be passed from behind into any odd bit of wood of 2
or 3 inches in thickness, whereby a chuck can be quickly made to suit
any required purpose. Two or three of these would be convenient, one of
which should be nearly as large as the lathe will carry; and in this one
a great many holes and slots should be made. This is called a face-plate,
and, in addition to the ordinary screws, whereby pieces of wood are
attached to it, it is fitted with clamps and bolts of various forms, for
the purpose of holding securely upon its face all kinds of flat works in
wood or metal,—such as cog-wheels, which have to be bored out and faced.
The young model-maker will find a face-plate of great service. The larger
one should be of iron, as it will be cheaper than brass.
We now pass on to chucks for metal turning. These are of various shapes.
First in order comes the centre chuck and dog, for holding rods of iron
which can be supported at both ends. The commonest form is represented in
Fig. 41, S, T. S is such a face-plate almost as I have described, but it
has a pin projecting from it, and also a steel centre-point. The latter
is often made to screw out and in, which is the best plan. The pin can be
slid to any point in the face-plate, and clamped by a nut at the back. T
is called a dog, and of these two at least will be required, if the young
mechanic intends to work in metal.
The way of using these is shown at T². The rod of iron has a hole drilled
at each end, as nearly in the centre as possible. It is first indented
with a punch, then a drill is put into the drill chuck, and one end
of the rod brought against it as it revolves, while the back poppit
centre-point is screwed against the indentation at the other end. A
little oil is applied to the drill to assist its working, and the rod
itself is prevented from turning round either by grasping it with the
hand or screwing a hand-vice upon it, so that this comes against the bed
or the rest; or it can be held in the hand, which has one advantage,
namely, that the operator can feel exactly what is the resistance caused
by the drill, and can regulate the pressure accordingly. The screw of the
poppit is, of course, to be very slowly and steadily advanced during the
process. All _drilling_ in the lathe is done in this way, but in boring
out long holes, the action is often reversed, the work being kept in
motion while the tool is advanced, without being allowed to revolve. You
need not bore more than one-eighth of an inch for light work, but must do
the same at each end of the rod. The holes thus made should be of such
a size as not to let the extreme end of the back centre-point touch the
bottom, or it will soon be worn down and blunted;—remember this in all
future work.
Supposing the rod to be thus bored at each end, place the centre-chuck
upon the mandrel, instead of the drill-chuck, and mount the bar between
this and the point of the back-centre. Thus placed, it will be accurately
supported, but if the lathe is put in motion, it will not turn round.
Now come into use the little dogs. Remove the bar, and choosing a dog of
which the open part is tolerably near the size of it, slip it over the
end about half an inch, and there fix it by tightening the little screw,
which, you observe, will drive the bar as far as possible towards the
smaller part of the opening, and when it can go no farther, will secure
it as in a vice. It is a good plan to file a slight flat upon the bar,
just where the screw of the carrier will come. Now replace the bar, and
when the lathe is put in motion, the tail of the carrier should come
against the projecting pin in the face of the face-plate, which will
compel the iron to go round with it. This is the way all bars of metal
are mounted. I shall not tell you yet how they are to be turned, because
this would interfere with the order of my description.
To mount in the lathe such pieces as cylinders of engines, which require
to be bored, or any other objects which have to be turned on one or both
faces, the young mechanic must make wooden chucks, and bore them out
exactly to fit the article and hold it securely. There are metal chucks
expressly made to take all work of this kind, and which are so contrived
that they will also hold it truly central, but they are costly, and need
not be obtained with the first lathe—at any rate, not until _absolutely
required_, and that will be, I know, a long time hence; ay, a _very_ long
time, for many good workmen have never even _seen_, much less possessed
one of them. Perhaps I may draw and explain one in a future page, as well
as some other chucks, which it is not necessary to notice here.
The chucks then absolutely necessary are these—
1. SQUARE HOLE CHUCK, which will take the prong, the cross, the
drills, and short bits of iron to be turned.
2. THE TAPER SCREW.
3. FLANGE or FACE CHUCKS, one with five points, and two with
holes for screws, also one larger for a face-plate.
4. Two or three CUP-CHUCKS (I can, however, scarcely call these
_absolutely_ necessary).
5. CHUCK FOR IRON, viz., face-plate with centre-point, and two
dogs to take iron from 1 inch diameter down to quarter-inch.
These should have pear-shaped openings, not round; any
blacksmith can make them, but somehow they do such work
generally in a clumsy fashion; and they cost but 35 to 75
cents, according to size, beautifully made with turned screws.
Now as to tools. Their name is legion—tools for iron, brass, ivory,
hard and soft wood; and many an odd shilling will be well laid out from
time to time in adding to the stock. Happily those most needed are not
costly—about $3 a dozen without handles, which latter may be had at 10
cents each and upwards, according to the material and finish, all with
iron or brass ferules, so necessary to prevent splitting. You may buy
your first few simple tools handled, but after you have these you can
turn as many handles as you like, and you can buy ferules of all sizes at
any regular tool-shop.
I may as well tell you that in a great many country towns you will be
unable to obtain turning tools except gouges and chisels, so that when
you buy your lathe in London, as you will find the best plan (or in
Manchester, Birmingham, or other manufacturing town, if nearer to you),
you must lay in a little stock of tools at the same time, and take future
opportunities of getting more. In regular tool-shops you will have them
laid before you by dozens of every conceivable shape and size, so that
your great difficulty would be what to pick out if it were not for some
such directions as I am now about to give you.
First, you will want gouges and chisels. Begin with two sizes of each—one
of half an inch, the other of 1 inch in width. These are to be mounted in
long handles.
Now, with these alone you can do all the plain work in soft wood which
does not require to be hollowed out, tool-handles, chair-legs, legs of
towel-horses, round rulers, and all sorts of things, and to a certain
extent you can turn out the insides of wooden chucks, bowls, and boxes,
but not very easily with these alone. Hence you must add some of those
shown in Fig. 42. These I shall endeavour to assort as follows:—
A to F are for hollowing out hard woods; G and H are hook-tools (very
difficult to use) for hollowing out soft wood boxes and bowls.
[Illustration: Fig. 42.]
I and K show the edge and side of a parting tool for cutting off the ends
of cylindrical pieces, separating the turned from the unturned parts, and
for all similar work. [A tenon-saw held still against a piece revolving
in the lathe will often serve to cut it in two, but parting tools must
also be had, and two are better than one, as a thick one should be kept
for common woods, and a thin one for ivory and precious materials;
sometimes one with a _notched_ edge is used for cutting off soft wood.]
L to O are for turning iron and steel. The first is a _graver_, of which
all sizes are made; one of a quarter inch width on either face is large
enough. It is a square bar of steel ground off cornerwise so as to form a
lozenge-shaped face. This is an essential tool for iron, and will do all
sorts of work.
M is a hook or heel tool, made sometimes with a flat edge and sometimes
with a rounded one, the latter being most useful. It is a very powerful
tool, much used by some, especially for heavy work—I don’t think you need
get one at present. If I am able to teach you to use a graver it will
do almost as much work, and is a neater tool. If you use a tool of the
nature of heel-tools at all, I think, on the whole, the nail-head tool,
N, either round or square, is the best. It is at all events handy for
roughing down work, and when it is reduced nearly to the size required,
and is partly smoothed, the graver will finish it.
O is an inside tool for hollowing out iron. There are different shapes
of this used, each turner giving the preference to some particular
pattern to which he has habituated himself. None of these tools for
metal have sharp edges—at least they would not appear so to an ordinary
observer. The angle of the edge is 60° to 80°, or even 90°, which is, as
you know, a right angle, and is that most generally used for the cutting
edges of tools intended for brass, as U, V, W, of which V is a most
useful pattern. Those for hard wood have edges a little more keen, but
after all they scrape rather than cut; the only tools for wood with keen
edges being the gouge and chisel.
P are callipers for measuring the _outside_ of work of all kinds. Q and R
are the same, arranged for in and outside work. The first is an ordinary
pair closed until the ends have crossed, which they will all do; but if
the inside of hollow work to be gauged is small, they will not enter it.
In this case none are so generally useful as the in-and-out callipers,
R, for when accurately made (and if not you can easily correct them with
a small file), the one end will measure the external diameter of work,
and at the same time the other end will be found to have its points
separated to such a distance, that if you were to turn a box or chuck to
this inside measure, the cylinder first turned will exactly fit it. Thus
if you turn a box-cover, and take the size of it with the straight end of
the callipers, and then turn down the rim of the box until it is just the
size indicated by the curved ends, the one will exactly fit the other.
In turning a piston to fit the cylinder of an engine, you would work with
this useful tool.
S is the turner’s square. The blade slides stiffly and accurately in a
slot in the brass, being kept by a spring at one side from working loose.
This square is used to gauge the depth of boxes and other works which are
to be turned to an exact size, and it also serves to test the squareness
of many kinds of work. Suppose, for instance, you had turned a box, you
would put the blade of this tool against the bottom and press upon it
till the brass rested across the rim, touching it in two opposite places.
Now possibly the inside may be smaller at the bottom than at the top.
Test it by bringing the steel blade edgewise against it. You will see
whether the brass still touches in two places across the mouth of the
box. The squareness of the outside with the top or bottom can be tested
in a similar way. We shall have occasion to recur to this when we come to
boring and fitting engine cylinders.
S² is another small square, which is often serviceable where the
carpenter’s square cannot be used. If you intend to make models, you will
want both of these; at the same time, it is quite possible to make the
latter of iron, or even thick tin, if you have the former, as an accurate
guide to work by.
T represents a pair of spring-compasses or callipers. They are used to
set off distances, and have the advantage of not being liable to shift
their position when once they are set to any required width. You will
require a pair of compasses of some sort, and if not already provided,
these are the best you can have.
There are many other tools, which, though not absolutely turning tools,
are more or less used in connection with the lathe, but these need not
now be further alluded to, and I shall go on to describe as clearly as
possible the method of working at the lathe with hand-tools, commencing
with the operation of turning soft wood with the gouge and chisel; but I
must first give a short chapter upon the nature of woods used.
CHAPTER VIII.
As different materials require somewhat different management, and even in
the matter of wood alone this rule holds good, it may be as well to have
some idea of what is meant by _hard_ and _soft_ wood.
The young mechanic has most likely hitherto considered all wood under
one head; but there is a vast difference, nevertheless, in the internal
structure, even of such kinds as grow in England; and the woods of
foreign countries differ again from these, some being of such close
texture that it is almost impossible to work them with ordinary tools,
and some (such as the palm) being little else than gigantic ferns,
and in structure like that much-dreaded implement of flagellation—the
schoolmaster’s cane.
In England the hardest wood found is that of the box-tree, the chief
place of which is in Surrey, at Box Hill; it is, nevertheless, found
scattered here and there in all parts of the country, but not generally
of a size greater than 3 inches in diameter. It is of very slow growth,
and our own country would not nearly satisfy the demand made for it by
various trades. Hence a large quantity of box, of larger growth, and
generally of harder and better quality, is imported every year from
Turkey, to be used in the construction of blocks for engravers, who alone
require many tons weight annually, and for carpenters’ rules, mallets,
turned boxes, and tool-handles; to which I may add the important item
of peg-tops. I fear some of my readers may think I should have placed
these first on the list! Opinions, however, I imagine, differ in this
particular, as in most others, and upon all subjects.
The grain of boxwood is so close and even that it is one of the most
valuable turning materials we possess. It takes excellent screw-threads,
provided they are not too fine; is a very general material for boxes of
all kinds, and also for chucks, although there is really no reason why
it should be wasted in so applying it, when other woods of less value
make such efficient substitutes. Probably its use for this purpose arose
from the facility with which a screw can be cut in it to fit that on the
mandrel, and that it is so hard as not to allow the collar beyond the
screw to make much impression upon it. In consequence, when it is well
fitted, such a chuck can be screwed on many times exactly to the same
point, and will continue to run true. But I myself have found that if the
mandrel-screw is not very coarse, the threads cut in the inside of the
chuck are apt to break off.
Somewhat similar in texture, though by no means generally used, is the
wood of the ELDER, which is quite different, be it observed, from the
ALDER, although I often hear the names confounded together. The wood
I allude to is that of the tree which bears umbels of sweet, white
blossoms, which give place to those jet-black berries we find upon them
late in summer, and which are made into elder-wine, for home consumption
at Christmas, when, no doubt, most of my readers have drunk it, hot and
spicy and sugary, to keep out the wintry cold. From the same tree are
commonly made those harmless engines of mimic warfare—pop-guns!
If it were not for the presence of the pith, which is in fact the very
quality which makes it valuable to boys for the latter purpose, this wood
would certainly have been eagerly seized upon by turners. Even with this
defect, it is used instead of box for the inferior kinds of carpenter’s
rules and other purposes, and the larger pieces will make very good
chucks, if a little care is exercised to prevent splitting them. It is
indeed a wood that might be far more extensively used in this way than it
is.
The YEW, perhaps, should come next in order, for this too is very
close-grained and very beautiful, and when highly polished it will bear
comparison with many foreign woods which we import at a high price; it
is, however, brittle and apt to splinter.
WALNUT varies considerably in quality, some being harder and richer in
grain than others. This wood, however, is not to be classed among those
which are properly speaking _hard_, as it can be cut with ease, and can
only be planed and worked as deal would be, viz., _with the grain_;
whereas the hard woods work with _almost_ equal facility in either
direction. This indeed in a great measure constitutes the difference
between soft and hard woods, in the turner’s sense of the words. If you
were to hold a chisel flat on the rest, so as to let it scrape a cylinder
of wood as it revolved in the lathe, you would find in some cases that
it would tear out the fibres in shreds—_these are soft woods_. In other
cases it would leave the surface rough but otherwise tolerably even, and
with some it would leave the same fairly turned.
I cannot call to mind any English wood but box that can be turned by a
chisel held so as to scrape it, but the greater number of foreign woods
are always turned in this manner, being hard and close in the grain.
BIRCH.—Oh, once-dreaded tree! birch! with its long, swaying, switchy
boughs, drooping as in sorrow at the mean uses to which it was applied!
It is nevertheless a very useful tree, and the young mechanic can take
full revenge upon it by cutting, and chipping, and turning it into all
sorts of useful articles. It is, however, now more generally used in
cabinetmaking, for wardrobes, bedsteads, chests of drawers, and such
like, as it looks very neat when planed and varnished. Perhaps, as a wood
for the exercise of the turner’s art, it must give place to
BEECH, which is a common and excellent material for the essays of
beginners, who can turn tool handles especially from the small trimmed
billets of it which are kept by the chairmakers, and which can generally
be bought for a trifling sum in any town, and in many villages. If not,
the wheelwright may be applied to for a supply, as he uses it rather
extensively for the felloes of his wheels. It is peculiarly liable to the
attacks of the little worm, weevil or maggot, who drills such innumerable
and such beautifully round holes in furniture that stands long unused.
Beech is often used for the screws of carpenters’ benches, as it takes
very well a thread of such size as is required for that purpose. It will
also, for the same reason, answer very well for chucks, for which it has
the recommendation of cheapness and toughness.
ASH seems to come next upon the list. It is probably the most useful
of all English woods, and where toughness, pliability, with moderate
hardness, are valuable qualities, no English wood can exceed it. For
frames of carts and carriages, shafts, agricultural implements,
wheelbarrows, and smaller articles of husbandry, it is precisely what
is needed, and in the workshop of the turner it is equally valuable.
Tool-handles of ash are very durable, and hold the tool with great
firmness, owing to the natural elasticity of the material. It may be
stained and polished, and is then, for real _work_, preferable to the
more costly hard woods of which handles are very generally made for the
workshops of rich amateur mechanics.
OAK is little used for turning, the grain being too coarse. The young
mechanic need never make use of it for this purpose, and the same may be
said of the elm.
ELM is, nevertheless, used by turners for the wooden buckets of pumps,
and is a generally useful wood. Bulk for bulk, it is lighter than beech,
and it makes a good material, it is said, for lathe beds, though beech
is more frequently used. It will answer for chucks, as indeed most woods
will that can be cut into screws; it is very tough.
EVERGREEN OAK, or HOLM OAK, as it is called, is very different to the
forest tree, and might be classed among shrubs. When dry, it is by no
means a bad wood to turn, and will take a good screw thread, and make
excellent chucks.
ACACIA is an excellent wood. It is of a yellowish brown colour, tolerably
hard, and will take a good polish. It is most certainly to be set down
among the woods valuable to the turner.
SYCAMORE is white, very soft until old, when it becomes much harder. This
is also a turner’s wood, and used extensively for wooden bowls, backs of
brushes, turned boxes, and what is generally called “turnery.” A little
of this will be useful to the young mechanic. It will make excellent
bread platters, stands for hot water jugs, and such like.
HOLLY.—The Christmas garland, with its red berries decorating even the
poorest homes in midwinter, is a tree well worth the attention of the
young mechanic. It is his substitute for the more precious material
ivory, and from it he will turn the white draught or chess men, boxes,
and many small articles. But it is necessary that this material should be
perfectly dry, and to get it in perfection, carefully preserved to insure
its whiteness, it will be generally necessary to procure it ready for
the lathe at some lathemaker’s, or at first-class cabinetmakers’. If cut
green, it requires long seasoning, during which it shrinks considerably.
In fact, it takes some years entirely to rid it of the great quantity of
moisture which it contains. It is well worth procuring, nevertheless, for
it is nearly as white and free from grain as ivory.
Many of the fruit-trees of our orchards and gardens supply good material
to the turner. APPLE, PEAR, CHERRY, PLUM, and some others, are all more
or less useful. The grain of the first is rather dark, the fibres often
twisted. It looks well when polished.
PEAR has a very fine, even grain, and is largely used for making the
curved templates (or patterns of curves for architects and engineers); it
will make good boxes, and is fairly serviceable to the turner. Its colour
is light brown, but darkens by exposure.
The PLUM has a wood veined very like that of the elm, but is a finer and
better wood for the lathe. This is the _wild_ plum, and not the grafted
fruit-tree of our gardens, which is not nearly so good. The wild plum is
excellent for small boxes, and looks well when nicely turned and polished.
CHERRY is a very excellent wood, and naughty, fast boys, who take to
smoking, like young Americans, when they ought to be filling their young
brains with knowledge instead of narcotics, know very well that it is
made into pipes and stems of pipes. Happily this is not its only use,
for it is fit for many other purposes; and for light, elegant furniture,
it is scarcely to be equalled. Dipped in lime-water, it darkens, and by
doing this here and there, a beautiful mottled appearance is given to it.
It takes an excellent polish, and should be among the stores of the young
mechanic.
We now come to another soft, white wood. The LIME, which, as it is
more even in grain, more easily cut in any direction than most woods,
is greatly used by carvers and pattern-makers (_i.e._, those who make
wooden patterns of wheels, or lathes, or machinery, which are to be cast
in metal). [The pattern is pressed into damp sand, and then removed, and
the melted metal is then poured into the impression thus made. If the
sand is too wet, the process will not only fail, but the hot metal will
be scattered on all sides, inflicting dreadful burns and injuries; but
with care, the young amateur may make castings in tin or lead, as will be
explained by and by.] Even with a penknife alone, very pretty ornaments
may be carved from the wood of the lime, and also from that which follows.
WILLOW.—This is even softer than the last, and will plane into long,
thin shavings, which are made into hats. (Once on a time I should have
said “_and bonnets_,” but in these days no one would recognise such
articles. They are fast fading out of existence; but I think quite as
much sound sense used to be found under them as is now found under the
very inefficient substitutes worn by ladies of the present day.) This
wood will, of course, turn very easily, but requires very keen tools. In
fact, _sharp_ gouges and chisels are invariably necessary for soft wood
turning. Get some dry willow by all means, if you can.
The last wood of English growth which the young mechanic is likely to
meet with is the thorn. This grows to a tolerably large size, and
is hard, close-grained, white, and altogether a good and serviceable
wood. It will make capital chucks, taking a clean screw-thread, is
easily procured, and is therefore strongly recommended to the notice
of the young mechanic. The woods above named, except box, are all to
be considered _soft_ woods, and will work with gouge and chisel; but
box, thorn, elder, and one or two of the more close-grained, will turn
pretty well, and can be smoothly hollowed out, with hard wood tools held
horizontally upon the rest.
HARD WOODS.
All those woods, properly called _hard_, including the best box, are
of foreign growth, mostly coming from the Tropics. I do not know why
they should be so much harder than those of temperate climes, but so it
is. There are, however, woods in New Zealand, of which the temperature
is similar to that of our own country, which are also exceedingly hard
and difficult to work. A very large number of foreign woods are yearly
brought to England in logs or billets or planks, some of very large size,
and all of great weight. They are mostly liable to one defect, viz.,
rottenness of the core or heart, which limits the size of the pieces
which can be cut from them. They can all be procured from the London
lathe and tool shops, and there are also dealers in these woods (Jacques
of Covent Garden, Mundy & Berrie of Bunhill Row, and some others). It is
almost impossible to procure them in the country, but rosewood, ebony,
kingwood, &c., may be sometimes had in such small pieces as the young
mechanic may require, at the cabinetmakers’. Among the most useful are—
EBONY, of which there are two or three kinds, some harder and more
close-grained and blacker than others, and one which is called green
ebony, which is like lignum-vitæ (an English wood, but which grows to a
larger size abroad; indeed, many so called English woods are not really
so, but have been brought from other countries to be grown here). The
general colour is green, but the veins are rather darker. Bowls and
skittle-balls are made of it. It is not, however, of the same general use
as the black ebony, which is very largely used both for cabinet-work and
turning.
BLACK EBONY is very close and hard, and, of course, proportionately
heavy. It splits readily, but when chopped, the chips come off more like
charcoal, showing no consistency. This is the kind imported from the
Indies, and especially from Madagascar and Mauritius, and is the best
for all kinds of turned work. Portugal affords another kind, which bears
the same name, but is more brown than black, and softer, less compact in
grain, and generally of less value. Ebony will bear eccentric work, and
all kinds of beautiful carving and ornamentation in the lathe.
ROSE-WOOD is very commonly used for furniture and turned work. It is a
rich red wood, grained with black. It is not _very_ hard, less so than
ebony, and has more evident grain or fibre. It turns well, and some
pieces are very handsome.
AFRICAN BLACK-WOOD is in appearance similar to ebony, but it is even more
close and compact, and is the most valuable of all to the ornamental
turner. When this or ebony is set off by being inlaid with ivory, or
even holly, it is very lovely in its intense and brilliant blackness.
Either this or ebony is used for black pieces for the chessboard or
draughtboard, though stained boxwood, being less costly, is sometimes
made to take its place.
AFRICAN CAM-WOOD is a very beautiful material when first cut. Its
rich red tint is diversified with the most brilliant yellow streaks.
Unfortunately, however, these are not lasting. Exposed to the air, they
gradually become darker, until they become red like the rest of the wood.
This material, however, has a fine, close grain, is a genuine _hard_
wood, and of general use to the turner for ornamental articles of various
kinds.
TULIP-WOOD is not very hard. Cut across the log, the appearance is fine,
owing to the rings of growth being wavy and irregular, in dark and light
red alternations, that reminds one of the flower after which it is
called. This tree, indeed, which grows to a large size, bears flowers
similar to those of our gardens imported from Holland, which grow upon
short perpendicular stems. The centre or core of tulip-wood is generally
rotten. It sucks up a good deal of polish before the grain shows out
brightly and strongly, from being less hard and more fibrous than many
others named above.
PARTRIDGE-WOOD is a nice, hard, and very pretty wood, rather dark or
gray. The fibres seem to run both ways, giving a mottled appearance when
turned.
CORAL-WOOD is bright red, hard, and close in grain, well suited for red
chessmen, where that colour is preferred to black. It looks very handsome
in the midst of other coloured specimens; otherwise, like all material
of one tint and free from veined lines, there is too much uniformity
of appearance to make it pleasing to the eye of one who is gifted with
appreciation of colour.
It is not necessary for me to go in order through a long list of foreign
woods. The very young mechanic, unless living in London, will seldom meet
with many of them; and a very good selection for the advanced turner will
be composed of the following:—
BLACK EBONY.
COCOA or COCUS, which is not the cocoa-nut tree, this being a palm, the
wood of which is stringy like a fern or a cane; whereas, cocoa or cocus
is firm, hard, and excellent.
BLACK-WOOD, which cuts finely with tools for eccentric work.
KING-WOOD, a good and useful wood, something akin in appearance to
rosewood.
SATIN-WOOD, pale yellow grain, like watered silk, turns very well, but is
by no means hard; there is also a red satinwood.
ROSE-WOOD, already described; it loses colour after exposure, and is most
beautiful newly cut.
If the above are added to the most useful of the English woods described
above, it will scarcely be worth while to add to them except as
_specimens_. It is, however, very interesting to collect and arrange
these, and it is an employment well worthy of the attention of the
young mechanic. Thin slices cut across the grain, and sometimes, or in
addition, slices cut with the grain, should be arranged in order after
being trimmed to shape (round, square, or triangular, or even six-sided).
They should be very carefully polished to bring up the grain, and
labelled with the common and Latin (or botanical) name. The country from
which procured, with short notes relative to the size and general growth
of the tree, should be added. This will compel inquiry, and a great deal
of information will be thus gained and stored up. A similar collection of
English woods may be made, and, of course, with much greater ease.
It will be observed that I have said nothing of the pines, deal, and
larch. They are extensively turned in the lathe, the greater part
of the common painted furniture being made therefrom; but deal is,
nevertheless, not a turning wood. It splits easily, has an open grain,
with fibres loosely connected, and although it can be cut into mouldings
with sharp chisels and gouges, it generally needs a little rubbing with
Dutch rush, fish-skin, or glass-paper; after which, a handful of its own
shavings held against it as it revolves rapidly in the lathe, is the best
polisher. Of course, however, it may be varnished, and of late years it
has become fashionable, when thus finished, for bedroom furniture. It
is, however, in this case generally improved and embellished, by having
thin strips of coloured woods inlaid in its surface. It is useless for
_hollow_ work; and wood that cannot be hollowed out satisfactorily, is
not to be classed among those suitable for the turner.
Whenever you have time to spare, and are not inclined to turn, yet
feel disposed to wander into your workshop, it is a good plan to trim
and prepare pieces of wood for the lathe. You need a chopping-block,
which is the end of a stick of timber sawn evenly across, and stood
up in some out-of-the-way corner where chips will not be much in the
way, and a light axe or adze, which latter is said to be the best. It
is called the bassoohlah or Indian adze, but I never had one, nor ever
saw it mentioned, except in one very excellent book by the late Charles
Holtzappffel of London, who, indeed, keeps these tools. But a light axe
is easily obtained, and will do very well. Take care to saw the pieces
off truly square—I mean straight across the log, and not slanting either
way. Cut some from your evergreen oak, or beech, or elm, for chucks,
remembering to have length for the mandrel screw, beyond what you will
probably need for hollowing out, to take the pieces to be turned. Cut
some longer than others, and from larger or smaller pieces; from 2-inch
diameter to 4, which is a useful general size. But your lathe of 5-inch
centre will take chucks or work of nearly 10 inches, so you can cut some
few pieces rather larger. Probably, your only work of 6 to 9 inches
diameter will be an occasional bread-platter, or a stand of some sort;
your general work will be much less. Besides chucks, of which the number
is in time very great, you will be constantly wanting tool-handles. Cut
some for these, and placing one end on the chopping-block, trim them to
something like the required size, but a good deal larger round than you
think necessary, because you will find that the size will deceive you
frequently.
[Illustration: Fig. 43.]
For finally trimming up short pieces, a peculiar knife is used by the
lathe and tool makers; and when you can spare the money you should get
one, as you will find it easy to use, and it will save you many a cut
from the axe. In fact, I never advise _very_ young mechanics to make use
of the latter tool. It requires practice, strength, and a good deal of
skill to use it well; and nothing is more easy than to lop off the end
of a finger or thumb, and, unfortunately, nothing is more difficult than
to repair the damage. The paring-knife for short thick pieces mentioned
above, is made like D, Fig. 43. It consists of a long and curved handle,
turned up at one end to fit under a staple, E, with a cross piece of wood
for the hand at the other end, and a broad strong blade with one bevel
in the middle—(by one bevel I mean, that the edge is not like that of an
axe, but like that of a carpenter’s chisel, the bevel or sloping part
being outside). C is the piece of wood to be pared, A the bottom board or
platform, B a block fastened to it, and made on a slope to prevent the
tendency of the wood to slip away from the knife. The whole of this may
be screwed down to the bench, or to a heavy stool when in use. The hook
and ferule should not be made so large and loose as in the drawing, and
a better joint is that of an ordinary hinge. If made loosely, the blade
twists about too much from side to side, escaping from the wood. There is
no danger to the fingers from this useful tool, which the young mechanic
should add to his workshop as soon as he can.
Another useful and easily-constructed apparatus for the preparation of
long pieces is the shave-stool, used by coopers and chairmakers to hold
the pieces securely while they are being shaped by the double-handled
shave or drawknife, as it is often called, a tool omitted from our list,
but very useful all the same. This is sketched at B, Fig. 43. It is often
very roughly made, the chief necessity being that it shall be strong. It
answers also for a sawing-stool. Upon the stool or bench, A, is fixed
a sloping block, B. A swinging frame, C, is hinged or pivoted at D, so
that if the lower part is pushed back from left to right, the upper
cross-bar, E, will come forward and almost touch the highest part of the
sloping block, B, so that any piece of wood, such as F, will thereby
be pinched and held tightly between the rail, E, and the block. The
workman sits astride of the stool at A, facing the block, and his feet
are placed on the bar C. When he wishes to hold the wood which is to be
shaved by the drawknife C, he presses _from_ him with his feet the lower
part of the frame, and he can instantly loosen the wood by drawing his
feet towards him. The movement is made in a moment, and the wood shifted
round as required, and alternately turned about and held tight, while
the drawknife is used almost ceaselessly. A very few minutes generally
suffices thus to pare down a rough piece for the lathe. The cross-bar,
E, should be tolerably strong, and is better if not rounded very nicely,
as the edges help to hold the wood. The latter is sure not to slip away,
because the pull of the drawknife tends to draw it up higher on the slope
of the block, which pulls it into a still narrower opening. Nothing can
exceed the ease with which this appliance is used, and the rapidity with
which the required operation can be carried on. No wood-turner’s shop
should be without one.
ORDER AND ARRANGEMENT OF TOOLS.
[Illustration: Fig. 44.]
I must say a word or two as to neatness and order, especially in the
arrangement of tools and appliances for the lathe. Whether you have a
dozen tools or a hundred, always put them in the _same place_, so that
any particular article can be found instantly, no time being wasted
hunting up and down, or examining a long row of tools for the one
required at that particular time. Turning tools, moreover, should be
kept distinct from those used for carpentry, and in a special rack by
themselves. The best tool-rack, I think, which can be made, is one like
Fig. 44. This may be made of deal, but the pieces between the holes are
thus liable to get split off, and beech or ash is therefore preferable.
The whole frame is made to be screwed to the wall; or, if the latter is
damp, the frame should be first screwed to a board covered with baize,
and this, in turn, fixed to the wall. Thus arranged, it will have a very
neat appearance, and the tools being kept dry, will remain generally
free from rust. They should, nevertheless, be carefully looked over once
a week and wiped, when those requiring to be ground should be subjected
to that operation, and thus be ready for future use when required. They
are bad workmen who allow blunt or damaged tools to accumulate, instead
of at once setting them in order. The horizontal bars are bored with
holes by means of a centrebit. The holes must be arranged as to size by
the measurement of the _ferules_ of the tool handles, some being larger
and some smaller, so that when the tool is placed in any hole, the handle
will drop in to the depth of the ferule and fit. Thus the tools will
all stand upright, instead of leaning from one side or the other. After
the holes are made, a piece is cut out (see fig. B) at the front edge,
because the blades of some tools are wider than the ferules, and, in
addition, if this were not done, the different tool-rails must be as far
apart as the whole length of the tool (handle and all included), to allow
of the latter being lifted sufficiently high to drop into the holes.
The strips for the holes should be about 2 inches wide, the lower one,
for the larger chisels and gouges, rather wider than the upper ones.
Sometimes these tool-racks are fitted up inside a cabinet, whose doors
have similar racks; thus all can be shut in out of the reach of dust
and dirt. Holtzappffel, the great lathemaker of London, fits up such
cabinets complete in oak or mahogany, all the tools being handled in
hard wood and turned to one pattern. The cost, however, £5 and upwards,
renders such less desirable to the young mechanic, who can rig up a
common tool-rack, which will serve his purpose equally well. It is also
far more satisfactory, in looking round your workshop, to feel that you
have at all events been as little extravagant as possible, for amateurs
get no return for outlay as tradesmen do.
CHAPTER IX.
There is no operation in which the young mechanic is so much at fault as
in that of grinding and setting in order the various tools he has to use.
Nevertheless he will never become either an independent workman or a good
one, if he has to depend upon others for this necessary labour.
No doubt, to sharpen a tool which is in very bad order is a tedious and
tiresome job; but it is not so wearisome an affair to keep tools in
condition for work, after they have been once thoroughly sharpened by one
who understands how to do it. Never, therefore, use a blunt tool, but
at once go to the hone or grindstone with it, and put it in first-rate
order. Time thus employed is never wasted, but rather saved; and the
result will appear invariably in the work which you are engaged upon.
You must, in the first place, understand precisely what it is you have
to do; and although the following details may be by some considered
more adapted for advanced students than for young mechanics, a little
attention to the explanations will render the matter clear to any boy
of age and intelligence to take in hand, with reasonable prospect of
success, the tools of the carpenter, turner, and fitter. I can only say,
that boys of this generation are wonderfully well off in having these
things explained to them. Twenty years ago young mechanics had to grope
along in the dark, ignorant to a great extent of the _principles_ of
work, and almost equally uninstructed in the practical part of it.
In Fig. 45 are represented similar angles to those already explained to
you, and you will quickly understand how useful is a little knowledge of
the elements of mathematics. Suppose A to be a tool, the angle of the
point is a right angle, or 90°. B is another of 60° at the point, and I
have drawn a line across to show you that the three sides of this figure
(called a triangle) are equal. So remember that if you want an angle of
60°, you have only to draw a triangle of three equal sides, and each of
these angles will be 60°. Again, I may as well remind you that three
times 60° equals 180°, which is equal to _two right angles_, so we find
here that the three angles of an equal-sided triangle equal two right
angles, and even if the sides are not equal, the same thing is true. For
instance, look at the first tool, across which I have also drawn a line
to make a triangle. The point we know is 90°, and if the sides, _a b_,
are equal (although the third line is _not_ equal to either), the two
small angles are each 45°, _i.e._, 90° between them, so the three angles
again equal 180°.
[Illustration: Fig. 45.]
The third tool (which we may suppose a turner’s chisel held _edgewise_)
is shown to have an angle of 30°, and I have added one more which has an
angle of 45°. Now all tools, if _well_ ground, are ground to a certain
known angle, according to the material which they are intended to cut.
Tools intended to cut soft woods, like deal, are ground to an angle of
20° to 30°, like the chisel seen edgewise. I shall have a word to say
presently as to the direction in which such tools are to be held, in
order to make them cut as well as possible. A tool for hard wood is given
next at E. The angle is now at least 40°, and it ranges up to 80°, giving
a stronger, thicker edge, but not so keen a one. We have, therefore, more
of a scraping tool than a cutting one,—at least, in the way it is usually
held. Then we come to the tools with which iron is turned and steel also.
Fig. F is one of these, and the usual angle is 60°, and thence it ranges
to 90°. Thus you see, advancing from soft wood tools to those for hard
wood, and thence to a substance still harder, we have increased the angle
of the edge, beginning at 30° and ending with 80° or 90°. But now we come
to a material which is harder than wood and not so hard as iron, yet we
use tools with an angle of 90°, which is still greater, and 70° is the
least angle ever used for this metal.
Experience only has taught the proper angle for tools, and it is found,
that if brass and gun-metal are turned with tools of a less angle
than 70°, they only catch into the material, and do not work at all
satisfactorily. You can, however, _scrape_ brass, as a finish, with the
thin edge of a common chisel; but then the tool is held so as to scrape
very lightly and polish; and its edge will not remain many minutes,
unless the maker (intending it to be so used) has made it much harder
than he would make it for soft wood cutting.
If you buy your tools at any _good_ shop, you will find that they are
already ground to nearly the angles named, and when you re-grind them,
you must endeavour to keep them to the same. The _bevel_, as it is
called, of many tools need not be ground at all, as they may be sharpened
solely by rubbing the upper face on a hone, or grinding it, holding it
so that the stone shall act equally on all parts of it. If, however, the
tool should become notched, you must grind the bevel of it, and then you
must try and keep the intended angle. One tool, however, or rather one
pair of tools, viz., turning-gouges and chisels, are very seldom ground
with a sufficiently long bevel when they first come from the maker. The
usual shape of the edge is like G, whereas the angle should be much less,
as seen at H. This you must correct when you first grind the tools for
use, and keep the same long bevel and small angle of edge continually
afterwards, for you will never make good work on soft wood if your
chisels and gouges are ground with too short a bevel.
I must also guard you against another common error, which, however, is
very difficult to avoid at first, and only long practice will enable
you entirely to overcome it. I, is the chisel (held edgewise as before)
ground as it ought to be; K is the same tool ground as it generally is
by young hands, or, even if it is correctly formed at the grindstone,
one or two applications to the oilstone almost invariably round it off
as shown. The bevel of _all_ tools must be kept quite flat and even, and
when the tool is afterwards rubbed on the oilstone to give a finish to
the edge, another flat, even bevel should be made. In the same figure at
L is an exaggerated view of the chisel, with its first long bevel formed
at the grindstone, and the second very small bright bevel seen at the
extreme edge of all such tools when they have been set upon the oilstone.
This second bevel, slight as it is, you will at once understand makes the
angle of the edge a little larger, therefore you must allow for it, and
grind a little keener edge than you really require.
Now, all this is very simple and easy to understand, and when you have
mastered this much, you will be in a fair way to understand more. The
second part of the subject, nevertheless, requires very close attention,
and very likely may not become quite clear to you when explained. I shall
therefore draw a line here, and make this lesson a special paragraph,
which you can look back to some other day, when you are grown from
a boy-mechanic to a man, and have had more experience in cutting and
turning wood and metal.
The tools above described have their cutting edges formed by the meeting
of two planes at a given angle,—these planes being the flat bevels (or
the flat top and one bevel) formed by the grindstone. But in some tools
three planes meet to form an edge instead of two, and the angle of
the cutting edge is not the same as that of either of these, although
it depends upon them, and can be nicely calculated. This calculation,
however, requires a knowledge of some higher branches of mathematics than
the young mechanic is supposed to be acquainted with, and therefore a
table is added instead, by which, when the angles of two of these planes
are known, the third may be at once seen, which last determines, of
course, the angle of the edge.
As an example, take the graver, of which you will find a drawing among
the other tools, but which I give again in this place. M, Fig. 45, is
the tool, looking at the face or bevel which has been ground upon it,
making a lozenge-shape or diamond. But this face is a _third plane_, and
the cutting edges, _a_ and _b_, depend for their angles upon all three
of these. Now, for iron we want an angle of 60°. How are we to make
the edges, _a b_, of that exact size? The bar is first of all square
in section, like N, which would be its shape before the third face or
bevel is ground, and all the angles are now right angles of 90° each.
But instead of this, we want two of them 60°, the other two being of no
importance. We simply proceed thus:—Determine which angle is to become
the point of the tool (it is no matter in the present case, as all are
alike), then grind away underneath till the new bevel forms an angle of
45° with the back (by which I mean the edge which runs along from the
sharp point towards the handle—the edge _x_ in fig. O). Trigonometry
enables us to find out that an angle of 45° is the one required, but you
will find it in the table annexed to this chapter, and an explanation of
this table is also given to enable you to use it easily. Thus ground, the
edges _a b_ of fig. O will be each formed of two planes meeting at an
angle of 60°. You can make a gauge of card or tin, P, to work by, of the
required angle.
[Illustration: Fig. 46.]
[Illustration: Fig. 47.]
In order to understand the use of this table, it is necessary to give
names to the several angles of a tool. That upon the front or face of
the tool, as A of the point-tool, is called the plan-angle; that made
by the upper surface and the front edge, as B (_a_, being the angle in
question), is called the section angle, because, if you were to saw
right through the central line lengthwise, this is the angle that would
appear at the point, viewing it sideways. Now, if we look at C, Fig. 47,
we shall be able to understand how the front line, _b c_, is obtained,
which constitutes one side of the section angle of a tool. It results
from the meeting of the two diamond-shaped planes at the sides formed
by the grindstone, but is dependent also on the plan-angle. These two
side-planes are to be generally ground at an angle of about 3° from the
vertical, which is to give the clearance of the tool if held in a fixed
position, as in the tool-holder of a slide-rest, the tool being supposed
horizontal. This is in accordance with what I have before told you, viz.,
that the cutting edge should be presented to the work at the smallest
possible angle, 3° being very small indeed. This angle is generally
measured by placing the side ground in contact with a cone of wood or
metal, turned to an angle of 3°, such as D,—_k_ being a tool the front
of which is evidently 3°; or a piece of tin, _l_, cut to the same angle,
and stood on its edge, will answer the same purpose. By 3°, I mean an
angle of 3° measured on the circumference of a circle, as I have already
explained in a former page, such angle being of course at the centre
of the circle where the lines drawn from the several degrees on the
circumference meet.
Now, when you have ground these two surfaces, the line _b c_ of B (or
C) will have a certain slope or inclination depending on the plan-angle
of the point. The exact inclination of it may be therefore said to be
accidental; but, whatever it is, it becomes of great importance in the
final result, being one side of the angle which will give any particular
angle of cutting edge. And here the table comes into use:—Suppose I wish
to have an edge of 60°, for cutting iron. Measure the _plan_-angle,—say
it is 90°, which is that of the graver; then, on the table, under the
words “plan angle,” you will see 90°, and opposite, above 60° of “cutting
edges,” you will see 45°. You have only to grind back the upper face of
the tool, until it makes an angle of 45° (section angle) with the front
edge or line, _b c_, and the edges _x x_ will be angles of 60°. Or take
the tool E, of which the plan angle is 120°, and suppose you want cutting
edges of 80°, for brass, opposite 120°, and above 80°, is 78° 5″. Grind
back the top face to an angle of 78° 5″ (or 78½) with the point line, and
it is done.
Until you have practically proved it, you can have no idea of the vast
importance of having correctly-formed cutting edges, and of placing them
within a hair’s-breadth of the proper position. But it is in slide-rest
work especially, and in cutting metal with tools held rigidly in one
position, that this is of such paramount importance. It makes all the
difference between cutting off a clean shaving, and tearing from the
material by main force a quantity of disjointed particles, the latter
process leaving a rough unfinished surface, the former producing one
as smooth and polished as a sheet of glass; and the advantage of this
short table is, that you can at any time shape your own tools for the
particular work in hand.
After you have had some practice in turning, you should certainly learn
to shape your tools from square bars of steel, worn files, and broken
steel tools of various kinds; and before you have arrived at sufficient
dexterity to do this entirely by yourself, you will get them roughly
shaped for you by the blacksmith, and then with grindstone and file you
will further perfect the angles for use. Steel does not require, and
must on no account be subjected to, a white heat, or you will spoil it
hopelessly; and you can always heat it in a common fire, or in the little
stove that I shall describe in a subsequent chapter, to a temperature
that will allow you to bend it into any required form with the hammer and
anvil—a bright red being the utmost heat it must be brought to.
POSITION OF CUTTING TOOLS.
We must now consider the mode of applying the edge of a tool to the work,
so as to produce the best effect. First, we will consider the case of a
gouge and chisel acting upon soft wood.
[Illustration: Fig. 48.]
In Fig. 48, A represents a piece of wood in the lathe, as you would see
it if you stood at one end of it, and a chisel is being held against
it. The arrow shows the direction in which the wood is supposed to be
revolving. Held thus, the chisel would scrape, and its edge would be
carried off at once; it could not possibly cut. But, held as at B,
it would cut off a clean and continuous shaving as the wood revolved
against it, and this shaving would slide off along the upper face, _b_,
of the tool, so that you can see that this face ought to offer the least
possible resistance to it. The tool acts, in fact, like a very thin,
sharp wedge, which divides the material by pressure, which has to be
great or slight according as the edge is sharp and thin or the contrary.
Now, if you again look at A, you will see that this wedge-like action
cannot take place, so that the tool is in its worst possible position.
Between the two positions, however, here shown, are several others at
a greater or less angle to the surface of the wood; but the smallest
possible angle it can make is the best, so long as the thickness of
shaving removed will suffice for your purpose. This rule holds good
with all tools, whether carpenters’ or turners’, which are made with
sharp-cutting edges. Care must be taken, however, that the lower face
of the tool does not rub against the work, which, again, it is evident,
limits to a given degree the angle at which the cutting edge is to be
applied to the work.
We now pass on to C, which represents the ordinary tool for turning iron,
held flat upon the rest, the position it usually occupies. We see at once
that in this case also we have a scraping tool only, and that, although
the angle of the edge is far greater than that of the chisel, it must
soon be ground off by the action of the metal to which it is applied, or
of the hard wood, which is also cut in this way. But with this form of
tool we shall find it impossible to apply it so as to cut in the best
way; because if we lower the handle, as we did that of the chisel, the
part below the edge will rub against the work, while the edge itself
will be moved out of contact with it. Thus we are obliged to hold the
tool in the position first shown; but we may therefore conclude that the
_tool itself is a badly formed one_ for the intended purpose; and so it
is, although you will see it in almost every workshop in the kingdom.
Let us see what can be done to improve it. At D, I have represented the
same tool, but the blackened part shows what has been filed away from the
upper face, and the dotted lines show that, when this has been done, a
tool is made very similar to the chisel for wood, and that it is also now
in a good position for _cutting_ (_not scraping_), although it is still
held horizontally upon the rest. Shavings of iron curl off the upper face
of this, as wood shavings curl off upon a chisel.
If the angle, however, is too small, the edge will soon be broken off,
and the tool will dig into the work; hence the necessity of knowing
at what angle a tool ought to be ground to cut any particular metal
successfully.
Such a tool as the last named, which is intended only to cut with the
front edge, and which is represented in E, is called a single-edged one,
because it only cuts in one direction, but many others are double-edged,
cutting the shaving at once on the flat and edge—that is, paring it off
from the material below and also from the side. For instance, F is a
cylinder of iron, from which a shaving is supposed to be in process
of being cut. It has to be removed from the shoulder to which it is
represented as still adhering, and also from the flat surface, _e b_,
around which it was, as it were, once coiled. But this requires two
cutting edges, both acting at the same time, but in different directions;
and good mechanics therefore so form the tools, and so use them, as to
cut in both directions, which leaves the work beautifully smooth and even.
These tools are mostly used in the slide-rest, where their true position,
once determined, can be accurately maintained; and it is, perhaps, only
with the slide-rest that perfect work can be done. There is, however,
no reason why you should not use tools of all kinds intelligently, and
understand exactly how they should be formed, and how held. Suppose you
have a tool correctly made by the aid of the table of tool angles already
explained, still looking at fig. F, you can see that the smaller part of
the roller is that which is to be left finished, and that it ought to
be quite smooth, but the shoulder at _a_ is not of the same degree of
importance. A tool fit for such work would evidently be shaped on its
_plan-angle_ or face, like H in fig. C or I; and, if held as seen, both
edges would be brought into action at the same time, as will be at once
evident on inspection. In practice, however, the two edges would not be
allowed to touch for their whole length, or the angle on the right would
leave a scratch upon the finished work; therefore it would be eased off
a little, as at K, L. But this is evidently as nearly as possible the
shape and position to be given to such a tool, and the edge which has to
leave the finished surface should, as it were, _follow_ the other; the
right-hand angle being _just_ and _only just_ kept out of cut.
The hand-tools you will generally use are the heel-tool, M, held on
the rest as shown, which, you see, brings the edge into cut at the
least possible angle to the work, and the nail-head, which is in fact
a heel-tool of four faces, or, if round, a heel-tool _all edge_, and
which can be rolled over as it gets blunted. To these add the graver,
of which I have already spoken. I have tried to show its position at O,
with the bevel of the face pointed in the direction of the shoulder, and
downwards; but it can be held face upwards also, and in one or two other
positions. Always remember that the cutting edge is to be presented at a
small angle with the work, and you cannot go wrong if the tool is well
formed. The nail-head and heel-tools are single edged, and easily ground
without the table of angles, but the graver is a double-edged tool,
properly speaking, although only one edge may perhaps be used.
Having explained the principles upon which you have to work as regards
grinding your tools and holding them when in use, I shall merely add a
few remarks as to the action of the grindstone and oilstone, and the
proper way of using them.
Always let the stone revolve towards you, as if you had to turn it smooth
with the tool you have to sharpen, except when you cannot possibly do so
without cutting grooves in it. Chisels, knives, axes, planes, and all
similar tools with flat edges, are to be ground with the stone running in
that direction, by which means you will avoid giving them a wire edge,
as it is called (_i.e._, a ragged-looking edge), and it will instead be
even and sharp; the filament of metal being, as it were, driven back into
the substance of the tool, instead of drawn away from it. Gouges may be
ground in the same way, but must be rolled about to keep up the form of
edge. It is indeed the easiest way with these to hold them _across_ the
stone, in the same direction as its axis, and then, by rolling them over
backwards and forwards, you can give a very good shape to the edge, which
should run slightly to a point, or rather _tend_ to one. They are never
to be ground square across, like that of the carpenter.
It is generally necessary to have some sort of rest upon which to lay
the tools during the operation of grinding, but do not trust to special
contrivances for holding them at the precise angle needed; rather trust
to your own skill, which will increase more and more by being severely
exercised. Always remember to grind your tools to a sharper angle than
will be ultimately required, that the final angle may be given by the
oilstone. Of the latter there are many kinds. Nothing probably can
surpass a Turkey stone, if good, but this varies considerably in hardness
and other qualities. There is a very quick-cutting, slightly coarse stone
from Nova Scotia, which is very serviceable, as it does this tedious work
with great rapidity, not, however, putting on the tools a very fine edge,
but one that admirably suits for such as are to be used on metal. With
the rest, a rub or two on Turkey, or Arkansas, or Chorley Forest stone,
will impart a finish. Arkansas stone, however, may be had coarse as well
as fine; it is much liked by some, but I prefer the Nova Scotia, as it
cuts more keenly, and even with the sharpest stone, setting tools is a
most laborious process.
The young mechanic will find it very difficult at first to hold the tool
steady, and to move it to and fro upon the oilstone so as not to give it
any rolling movement, by which the edge and bevel would be rounded, as I
before explained, which would in effect enlarge the angle of the cutting
edge, besides preventing it from being held at a sufficiently small angle
to the work to cut effectively. Nothing but practice will overcome this
difficulty; I shall not therefore attempt to describe exactly how the
tool should be held and the sharpening effected, such description being
not only difficult, but, as experience has proved to me, impossible.
CHAPTER X.
We now enter upon the actual work of the lathe, which should be
comparatively easy to understand after the foregoing observations.
Your raw material having been chopped or shaved into a rough cylindrical
form, you have to mount it in the lathe. I may suppose it a piece of
beech for a tool-handle. If you have the cross-chuck, you should use it;
if not, you may use the prong instead. In either case, centre the wood as
truly as you can, so that, when the rest is fixed near it, the piece may
not be much farther from it, as it revolves, in one place than another.
Mind and screw down the back poppit tightly upon the lathe-bed, and also
the rest, putting the latter as near the work as you can without touching
it. Now set the lathe in motion,—this is tolerably easy, but to keep it
in motion will probably not be easy at all. It is one of those operations
which require practice, because while your leg is at work upon the
treadle, your body must be firm and still, so that you feel yourself free
to use the tools without giving much attention to what your leg is doing.
After a while you will do this with perfect ease. The wood is, of course,
to rotate towards you, and the surface will come in contact with the
edge of the tool as the latter is _held tightly down on the rest_. Now,
this is, after all, the real difficulty, for every projection striking
the tool tends to jerk it off the rest, and this has to be resisted with
some force. There is, however, this advantage in hand-tools, viz., that
they may be held rigidly yet be allowed some slight play, according to
the peculiar exigencies of the work; and at first you will save the tool
by allowing it to yield slightly until the roughest part has been cut
away. Afterwards, there is to be no movement except that required to make
it follow the curves or level parts of the work. Do your best first to
produce a cylinder, _i.e._, a straight, even piece of wood, as long as
the required handle, and as large round as the largest part proposed to
be given it. It is the best plan at first to copy a well-shaped handle,
and to turn as many as you want of that size exactly to the same pattern.
This will give you such an amount of practice in copying form, as will
stand you in good stead in after days; for it is not easy at first to
turn even two things exactly to pattern and to _size_.
You must not expect to be able to run your tools along the work like a
professional or old hand at the lathe; you must do the best you can. Hold
the handle in the right hand, and with the left grasp both rest and tool
together, and you will hold it firmly. Then you _ought_ to run it along
right or left at the right speed and the right angle, but you will be
unable to do so yet;—never mind. Remember the _principle_ I have laid
down as to the position and angles of cutting tools, and trust to time
and perseverance to make you a good workman.
The gouge is the easiest and best tool to use at first; and you can do a
fair amount of _smooth_ work with it if you know how, although smoothing
and levelling is the special work of the chisel. The gouge, however, is
used for all sorts of curves and hollows, and though the actual point
will only turn a groove if held still, the _side_ of the cutting part
will, if the tool is steadily advanced, turn very fair surfaces indeed.
I strongly advise practice with this tool before attempting to use any
other. Your early work is of little importance, and you may make up your
mind to cut several pieces into shavings and chips without very grand
success, even though you use a chisel; so I repeat, stick to the gouge
only for some time, until you can use it towards left or right, and with
either hand grasping the handle.
With the chisel, far more care is required than with the last named.
It is altogether a more difficult tool to use. Its position may be
described as follows, but practice alone will render its use easy. Lay
it first flat on the rest as you would the gouge, and let it point
upwards at a similar angle, until it also is in the position the gouge
would take, ready to cut the piece of wood in the lathe, already turned
to the cylindrical form by the latter tool. You will find one point or
angle of the edge, the sharpest, reach the wood before the other, and
will see at once that this would be liable to catch in, if the lathe
were in motion—and so it would. I shall suppose that this sharpest angle
is on the right-hand side as it lies flat on the rest, and against the
wood. Raise that angle so that the tool lies a little edgewise on the
rest instead of quite flat, when the angle of the tool that is highest
on the wood will be also raised off it; the lower angle and remainder of
the edge still being in contact with it. This is its proper position,
with the upper angle out of contact with the work. You may turn it over
so that the keenest angle is the lower one, but then you must raise the
other, which is now the upper one, for under no circumstances must the
one that is uppermost touch the wood. The chisel, therefore, never lies
flat on the rest or on the work, but always slightly raised to clear the
upper point, and in this position you have to keep it, making it descend
into hollows, and rise over mouldings, and cut level places, almost
without stopping an instant; and for wood, especially soft wood, the
lathe is always itself to be run at a very high speed, by putting the
cord on the largest part of the fly-wheel and smallest part of the pulley.
To return to the supposed tool-handle. Having turned a cylinder, begin
at the ferule, which you must cut off a brass or iron tube, or, which is
easier, buy by the dozen or by the pound ready cut. You will want them
three-quarters of an inch for your largest tools, and about three-eighths
for the smallest, with some of half an inch, and you can then bore your
tool-rack exactly true with centrebits of these sizes. Turn the place
down for the ferule, and take care that you make a tight fit. Gauge with
the callipers first of all, and turn almost to size, then try it on once
or twice until it fits exactly.
If you use the cross-chuck, you have this one great advantage—you can
take out your work to put on the ferule, and replace it exactly as it was
before, and it will continue to run true. As, however, the piece in the
present case is but partially turned, it can be replaced with sufficient
accuracy upon the prong-chuck, especially if you mark the side of the
chuck, and of the piece of wood, and take care to replace them in the
same relative position. You must now try with gouge and chisel to imitate
the pattern handle, remembering always to work downwards from right and
left into the various hollows—(you cannot cut the fibres neatly if you
try to go up-hill); and where the two cuts meet in the hollows, you must
do your best not to leave the least ridge or mark. You will be sure to
need a little glasscloth to finish off your work, but do without it as
much as possible, because it spoils the shape of mouldings, rubbing off
the sharp angles, which in many cases add beauty to the work. If the
piece of wood is longer than necessary, cut it off with the chisel. In
any case, you must cut off a piece at the chuck end; and this being the
end of the handle which you will hold in your hand, the ferule being at
the end next to the back poppit, you will cut it off neatly with the
chisel in finishing it to the required shape.
You would hardly suppose it possible to turn off the end of a piece
squarely and accurately with the gouge, but it is a good tool for the
purpose. You must lay it on its side upon the rest, so that its back or
bevel rests flat against the end of the piece from which the superfluous
wood is to be taken; the edge or point of the tool is then allowed to cut
the work by a slight movement of the handle. You can only do it in this
way, with the bevel against the piece from which the cut is to be taken.
Turned over to its usual position, it will hitch in and spoil the work
in a moment. In the same way you can face up a bread-platter or similar
flat work; but such articles as these are not mounted between centres,
but screwed upon the taper screw-chuck or the flat plate with the
screw-holes, so that you can get to the face of them. At first, however,
until the work gets tolerably level, you may bring up the back-centre,
which will prevent the taper screw of the chuck from being accidentally
bent; and when all the rough part is cut away, and the rim turned down,
you can remove the back-centre to finish the facing up. In this work,
however, the back and face do not need much turning, because the platter
is turned from plank wood, planed up truly on each side, and cut roughly
into the form of a circle. If accurately planed, it will run true at
once, and the small amount of facing may be done with the gouge held as
directed. Afterwards it may be necessary to take a light _scrape_ with a
_carpenter’s_ chisel, which answers well for this. Then finish up with
glass or sand paper. Take care to make a neat moulding to the edge, which
will be about an inch thick, and will therefore look very heavy unless
turned off so as to thin it down. A platter is a very good and useful
work for a beginner.
In turning a platter you will certainly learn one lesson in mechanics.
You will find that it is very hard work to turn anything that is larger
than the pulley of your lathe, and you will only be able to take a very
light cut. Probably you will find it the easiest plan to set the lathe
in rapid movement, and apply the turning-tool only for an instant, and
then to remove it until the work has recovered its impetus, thus cutting
it, as it were, by repeated brief applications of the tool, instead of by
one continuous cut. I do not mean that the tool is to be removed from
the rest, but only eased off for a second from the work. If the latter is
very large, and the pulley on the mandrel much less in size, you can only
work in this way, finishing with a very light cut. There is a tool for
the face of such flat works, called a broad. It is like a broad chisel
with the end turned up at right angles to the side, only the edge is a
bevelled one and thick. They work well in hands accustomed to them, but
the gouge and chisel are sufficient for your present need.
I shall sketch here (Fig. 49) one or two articles not requiring to
be much hollowed out, which will help you to decide upon such work
as is suitable to a young mechanic desiring, by steady practice and
application, to become a proficient at the lathe, and as soft-wood
turning will teach you more than that in hard wood, I shall direct all
the following to be made of it by gouge and chisel alone.
[Illustration: Fig. 49.]
These examples are not given as specimens of the rich work which can be
done in the lathe, but as easy examples of elementary turning. No. 1 is a
stand for an urn or hot water jug, and a slight recess may be made in the
upper surface, in which a piece of cloth, or carpet, or oilcloth can be
glued, which will make a neat finish. No. 2 is a bread-platter, showing
how a little neat moulding takes away the clumsy appearance of the thick
board necessary for this purpose. No. 3 is a candlestick. The lower part
or stand is to be turned from a separate piece of thick board screwed
upon the taper-screw chuck. While it is in the lathe, the hole must be
made in the centre (or marked, if the piece is not very thick) by holding
a pointed tool a little on one side of the centre, so as to describe a
circle of the requisite size. Into this will be fitted a tenon, fig. 3 B,
which is turned on the pedestal, and which is to be glued into its place.
By and by you will learn how to cut a screw upon such a tenon, which is a
far more satisfactory method of proceeding; at present glue will answer
just as well. You can make the upper part separate, forming the junction
at the line C (Fig. 49, No. 3), if you prefer it, or if your wood is not
long enough; but as you will not hollow out the top, you may as well let
it be cut out of one piece with the pedestal. Turn the top quite level,
drive in a piece of stout wire, and point the end of it. Cut out a round
piece of tin to fit, and make a hole in the middle of it to let the wire
through; drop it over the point, and let it rest on the candlestick; a
wax candle can be spiked upon the wire, and will stand firm.
Figs. 7 and 8 are drawings of tool-handles. These are the best shape to
grasp in the hand, and they look neat in the tool-rack. Tool-handles
with a number of mouldings, are not only absurd, but are uncomfortable
to hold, and not at all suited to their intended purpose. 9 and 10 are
other forms of mouldings, and are given merely to show how angular and
rounded forms should be combined to produce a good effect. If these were
to be made in hard wood, they might be turned with beading and moulding
tools similar to those at A, B, C, D of this figure; such tools are
bevelled only on one side, and being held flat upon the rest, cut the
curves and hollows rapidly, and clean. Sometimes a number of these are
arranged side by side, so as together to make up the outline of the
intended moulding, and being held in position by a handle designed for
the purpose, are presented all at once to the work as it revolves. In
other cases, a flat plate of steel is filed into shape, and bevelled to
form a compound moulding tool. Of course, such contrivances greatly help
the turner, especially if he has to turn a number of articles of exactly
the same pattern, such as the pawns of a set of chessmen, or a set of
draughtsmen; but none of these tools answer upon soft wood, because, as
already explained, tools which have to be held horizontally will cut and
tear up the fibres of all woods that are not very hard and compact in
grain.
Fig. 6 is a profile of a draughtsman, and fig. 6 B shows how they ought
to be made, but for this you cannot use soft wood, and had better make
them of box and ebony, or holly and ebony—(and, by and by, of black-wood
and ivory). A cylinder is first turned, then marked off as shown with
grooves cut by a parting-tool. The pieces are then separated with a fine
saw, and a chuck is hollowed out to fit them so that each can be readily
turned upon the face. The desired mouldings having been made on one side,
the disc is turned over in the chuck, and the other side operated upon in
the same manner.
It is quite _possible_, you must understand, to cut these out of soft
wood, even pine or deal. We often see boxes of toys, children’s wooden
plates and cups, turned very neatly of this material; but it is not worth
while to use it if you can obtain boxwood. Moreover, box can be stained
black to imitate ebony, and is very often made to serve instead of it.
Figs. 4 and 5 are ring-stands for the toilette-table—very useful presents
these to mothers, sisters, and, last but not least, lady cousins, and
other young ladies too, perhaps, who are not cousins. These can be made
in a variety of ways, and give great scope for the exercise of your
powers of design. The first is a simple pedestal on a stand, turned quite
smooth in an elegant and simple curve. The stand is also made without
elaborate mouldings, giving altogether a chaste and elegant appearance
to the design. The extremity is tipped with ivory, and an ivory ring
surrounds the bottom of the pedestal. If this is made in plain deal,
and thoroughly well finished and varnished, it will look very well. The
nicest soft English wood, however, for this is certainly yew, some of
which is beautifully fine in grain; and as it will take an excellent
polish, it always looks well; moreover, it can be turned entirely with
gouge and chisel.
This ring-stand will be made in two parts; the pedestal being separately
turned at one end, a tenon will have to be made as in the case of the
candlestick, and just above it the wood is to be turned off a little
as if you were going to make a larger tenon. Over this a ring of ivory
may be slipped and glued on, and the two can then be turned together.
A carpenter’s chisel will do for the ivory, which will be scraped into
form by it. It may be polished with a little chalk on a moist rag or
flannel. You can buy odds and ends of ivory from the turners in rings and
solid pieces, which will come in for all sorts of decorations, and you
should save all old handles of knives, tooth-brushes, and such like, for
a similar purpose. Both ivory and bone smell very disagreeably when in
process of being turned. To tip such articles with ivory, you can drill a
small hole in the top of the pedestal with great care, and fit the ivory
after being turned into it; or you can, if the work is larger, bore the
ivory and slip it on the wood;—much depends upon the size and nature of
the work.
The second ring-stand is of rather more elaborate construction. The
baskets are made of little turned pedestals fitted into a round piece of
wood to form the bottom, and into a ring which makes the rim. Baskets of
this form (even apart from the ring-stand) are very neat and useful.
It is very easy to turn rings of any size. Mount a piece of board in the
lathe on the taper screw chuck—it need not even be cut to a round form;
then determine the size of the proposed ring, and, holding a parting-tool
upon the rest turned round to face the work, mark two circles, and deepen
the cuts, until the ring falls off. Take care that the outer one is cut
through first. The ring thus cut may be afterwards placed upon a cylinder
turned to fit it, and finished upon the outside, and then placed inside
a chuck of wood bored out to suit the work, and neatly rounded off upon
the interior surface. Of course, if you have to make rings of bone or
ivory which are already hollow, you can at once run a mandrel or spindle
of wood or metal through them and subject them to the various operations
required.
Mandrels, or tapered cylinders of brass or iron, fitted as chucks to the
mandrel of the lathe, are sold on purpose for this work, but a wooden
rod answers just as well, and costs nothing. Turn such a rod a little
tapering, and take care not to drive the work too far upon it, because,
although at first you can safely drive it on very tightly, if it is of
ivory or bone, you will frequently find your ring suddenly split and
open when its thickness has been reduced to the required standard. If a
number of equal rings are required, it is the best plan to turn a hollow
cylinder and then saw off the rings as you are directed to saw off the
draughtsmen. They will, of course, have to be finished in a chuck.
If you look round any fancy warehouse in which Swiss carvings are sold,
you will see how beautifully soft white pine can be worked in the lathe
by keen tools and clever hands. In Tunbridge, too, many thousands of
soft-wood articles are manufactured yearly, some plain and merely
varnished, and some curiously inlaid with coloured woods, so that you
need not despise such materials as willow and sycamore and the various
pine woods, which are all capable of being made into pretty articles of
one kind or another. The varnish, however, for these is such as to coat
them with a glassy layer which does not sink into the wood. Common rosin
dissolved in turpentine or in linseed oil, kept on the hob so as to get
warm, answers well for these deal articles, and is extensively used where
the slight tinge of yellow is not considered important. There are many
other much paler varnishes for works of greater value, or where the white
wood is to be carefully preserved. Any of these can be had at oil and
colour shops.
[Illustration: Fig. 50.]
You will certainly find a difficulty in turning all exactly alike the
little pillars of these baskets. You should turn several at once out of
the same piece, separating them afterwards. Thus your pattern will always
be close to the half-executed copy, which will somewhat assist you. Do
your best in this respect, but be specially careful, at any rate, to
make all exactly the same length. One pillar is shown separate, but you
can design a pattern for yourself.
Begin by turning a long cylinder; then set off the respective lengths of
the pillars. Turn one complete as a pattern, and set the callipers to
the largest part of it. Then go to work upon a second, using callipers
freely at all parts of it. As these pillars will all be slender, you will
be in great danger of breaking them; therefore use your tools lightly,
taking only a very slight cut. But with all your care you will find it
difficult to turn a row of more than two or three of the size wanted for
such little baskets. I shall therefore show you how to make a support to
fit at the back of the bar you are at work upon to support it against the
pressure of the tool.
Fig. 50 gives a representation of one or two such supports, which are
often required in turning. The first is the most simple, and is the one
most generally in use, because easy to make and to apply, and it answers
tolerably well. A is merely a piece of wood, about three-quarters of an
inch thick, cut as shown. This is stood up between the lathe-beds, like
C, and fastened with a wedge before and behind. It allows the work in the
lathe to revolve in the notch which is cut in it, as is evident from the
drawing. One, two, or more such may be used if necessary. They must be
carefully adjusted, so as not to bend the piece which is to be turned,
and which is to be just supported, but no more. Where the _back-stay_,
as this contrivance is called, comes in contact with the work, the latter
is to be left of the size it was when this was adjusted to it as long as
possible. It must then be shifted a little, and that part which formerly
rested against it finished.
B is another simple form of back-stay, capable of nicer adjustment. The
foot is that of a common rest, but if you have not a spare one, any
wooden support is quite as good. Into this fits a turned part of the
upright _x y_,—the upper part, _y_, of this being planed flat. Neither
should be of deal; ash or elm is preferable. Thus the part _x y_ can be
raised and lowered at pleasure in the rest-socket. The top part is made
of a half-inch board, about 2 or 2½ inches wide; a slit is cut in it,
and it is fastened to _x y_ by a short bolt and nut. Thus it is easy to
raise and lower the end of this part, and to put it nearer to, or farther
from, the work in the lathe, against which it can be adjusted with great
nicety. Although there are several forms of back-stay, of more or less
complicated construction, I know of none more generally serviceable than
this last, which the young mechanic can make for himself. The notch
should be lubricated with soap, or, if the blackness is not of importance
(as when this part, which rotates in the notch, has finally to be cut
away), with a mixture of soap and blacklead. This, remember, is always to
be applied to wooden surfaces that are to work easily upon each other.
It will sometimes happen that you require to bore a hole through a long
piece of wood, as would be the case in making a wooden pipe, flute,
bodkin-case, and many similar articles. To hold these in a chuck only
would be often impossible, because the hole in the chuck would have to be
as deep at least as half the length of the piece to be bored.
For this kind of work, therefore, and for turning up a point on the
end of a cylinder of iron or steel, like that of your back poppit,
the following contrivance is used, which is called a boring-collar or
cone-plate. It is represented in Fig. 50, D and E. This consists of a
circular plate of metal, three-quarters of an inch thick, turning upon
a large screw or pivot at its centre, by which pivot it is attached to
a short poppit head, fitting between the bearers of the lathe as usual.
There are six or eight conical holes bored round the circular plate, each
of a different size; and these are so arranged as to height, or distance
from the centre, that the top one (being in a perpendicular line passing
through its centre and that of the bolt) is exactly as high as the axis
of the mandrel. Thus, if it is clamped in that position, with the largest
side of the conical holes next the mandrel, a piece of wood might be held
at one end in a chuck, while the other might rest in such hole as was
best suited to its size, not actually passing through it, but resting
in the inside of the conical hole, in which it would rotate almost as
freely and as truly as if it were supported by the ordinary point of the
back poppit.
Sometimes it may be preferred to allow the end of such a piece of work to
project through the cone-plate, a collar being turned on it to prevent it
from going too far. A tool-handle, for instance, of the pattern before
given, may be beautifully bored in the lathe by allowing the ferule
to rotate in one of the holes of the cone-plate, the shoulder behind
preventing it from going too far. The rest is brought round in front of
the end of the handle, and a hole bored by a drill for wood; or, the
point of a drill is brought against it, while the other end (having had a
slight hole made by a centre-punch for the purpose) is allowed to centre
itself on the point of the back poppit. The screw of the latter is then
advanced, and the drill being prevented from itself revolving either by
being grasped by the hand or a vice, a beautifully straight and even hole
is rapidly made.
Fig. 50, F, shows the position of the various pieces. The drill is here
kept from rotating by a small spanner, the handle of which comes against
the bed of the lathe. A great deal of work, both in wood and metal, is
always drilled in this way.
For wood, a small nose-bit, or auger-bit, or one of the American
twist-drills, can be used, and this may be succeeded by a larger, until
the hole will allow of the introduction of a finishing-tool of some
kind, held in the hand. Of course the latter is not necessary in boring
out handles for the tang of a tool, but only in turning boxes for
pencils, needles, or other articles, which require to be neatly finished
inside as well as out; all these are to be bored before the work is cut
free from the superfluous wood out of which it was turned. You can even
use the cross-chuck for this work.
It matters little, when using the cone-plate, whether you finish
the turning of the outside before or after the boring is done. Very
generally the box or other article is bored first, quite in its rough
state, except that a short piece is turned down to fit into a hole of
the cone-plate; and, keeping the latter in its place all the while, the
wood is turned down and polished before removing it from the lathe.
Sometimes, especially with metal, which is in no danger of splitting, the
cone-plate is removed as soon as the hole has been made and replaced by
the back-centre, the point of which, entering the hole, retains the work
in its place while the outside is being fashioned. This of course insures
the exterior surface being exactly concentric with the inside, which is
often absolutely necessary in parts of machinery; but if wooden articles
are finished in this way, there is great danger of their being split by
the pressure of the back-centre as the work grows thinner and thinner
under the action of the tools. Moreover, it must be remembered that the
back-centre, being itself of a conical form, will injure the form of the
hole in metal by making it wider at the mouth if used in this way, and
sometimes this may be of importance.
There is a fault in the cone-plate which boys will understand, and men,
too, I imagine. _It costs money!_ Therefore I shall now show you how
to make a substitute, which will cost something under a shilling, if
you do not mind a little trouble; but, if you do, you will never make a
good workman, nor will you be good for much, I fear, in any way! A metal
cone-plate for a 5-inch lathe costs £2 at least.
I shall suppose you want a cone-plate in which to bore your tool-handles,
for it is not easy to do this with a gimlet, so that the tools, when
inserted, shall stand straight in their handles. If you have a 5-inch
centre lathe, _i.e._, a lathe in which the central line or axis of the
mandrel is 5 inches from the lathe-bed (in which case you can turn
anything nearly 10 inches in diameter), cut out of a piece of beech, 3
inches thick, a short poppit 3½ inches high, of some such shape as seen
in the fig. G; and in the lower part (which must be cut to fit between
the lathe-bearers, and must be made square at the sides and true, so
that the whole will stand squarely across the lathe-bed), either cut a
mortice, _a_, for a wedge, or bore a hole for a screw, which must have
a plate and nut to fasten under the bed like other poppits. Near the
top, and exactly in the centre, bore a hole to receive the bolt K,
similar to that in the metal cone-plate already described, and which
will be tightened by a nut at the back. This supplies the place of the
short iron poppit, and now you have to contrive something to replace the
circular plate of holes. Cut two or three strips of any tolerably hard
wood, H (beech will answer very well), 6 inches long, half an inch thick,
and 2 inches wide. Cut in these a slot and a round hole, which must be
carefully made with a centrebit. This hole is to be for one of those in
the usual round plate, so be careful in making it. Work thus: Plane up
the piece from wood rather more than the half inch required; draw a line
exactly down the middle of it on both sides _e_, _f_; choose a centrebit
of the size you require; put the point upon this line, about 1½ inches
or more, according to the size of the required hole, and bore steadily a
little way into the wood. Then turn it over, measure carefully so as to
get the precise spot right, and finish from that side. If the centrebit
is sharp, and the wood sound, you will now have a neat round hole. Let
the slot be also cut from both sides of the piece of wood with a sharp
chisel, taking care that the centre of it agrees with the line that you
made for a guide.
Three or four of these should be made, each with a different sized hole,
or more if required; but you can add new ones at any time. The bolt, K,
is to be made with a large head flat on the under side, and the upper
part, above the screw, is to be square for three-eighths of an inch, and
the slot in the pieces of wood must just fit this squared part. Now, as
this is three-eighths only, and the thickness of the wood is four-eighths
or half an inch, it is plain that the nut will draw, and the head of the
screw clamp this tightly. You can, if you like, however, make the hole
in the poppit square also, and then let the squared part of the screw be
long enough to reach _almost_ entirely through both pieces. Then slip
a washer (an iron plate with a hole in it like L) over the end of the
screw, and fix all with the nut. Thus you have a boring collar with _one_
hole, and this you can raise or lower the length of the slot so as to get
it exactly the right height, and when it is so arranged, one turn of the
nut at the back will fix it.
This you will find a very simple form of boring-collar, easy to make, and
of practical use. If you really take all the care you can, and follow
the directions I have given, I do not see how you can possibly fail in
constructing one. You should have a sliding-plate with a hole for each
size of tool-handle ferule used, as you will frequently be making these.
HOLLOWING OUT WORK.
As I have spoken of boring, I will go on to treat now of the general
practice of hollowing out chucks and boxes, and such like. If this is to
be done in soft wood, such as willow, no tool will answer so well as the
hook-tools, of which I have given drawings. But these are very difficult
indeed to use, owing to their tendency to catch in, or take suddenly a
deeper cut than was intended. Nothing but practice will teach exactly how
to use these tools; but then, when the difficulty of so doing is once
mastered, nothing can be more rapid or more satisfactory than the work
which they will do. Small bowls are hollowed almost instantaneously by
their means in skilled hands; whereas, with other tools, it becomes not
only a tedious job, but if it is done at all, it is but roughly, the wood
having to be rather scraped out than cut. Using, however, the back of the
gouge as explained before, in the directions given for squaring up the
end of a cylinder with this tool, it is possible to hollow out soft wood
with it, but not very satisfactorily. In any case, other tools (generally
a carpenter’s chisel) must be used to work into the angle which neither
the gouge nor hook-tool can, of course, reach. Hence it is generally so
much easier to cut out boxes and such like articles in box or _hard_
wood, that this is nearly always used by amateurs.
The ordinary way to turn a box is as follows:—Prepare the wood as usual,
turning it cylindrical, using any chuck you please for this work; cut off
with the parting-tool rather more than the box and its cover together
will require, and drive the piece thus separated into a cup-chuck. [You
may, if you prefer it, screw upon the nose of the mandrel, or upon the
taper screw-chuck, the rough piece of the proper length, instead of first
turning a cylinder to cut from. If you have several boxes to make of one
size, the cylinder method is to be preferred.] Turn it up again quite
true, for although it was correct before you cut it off, it will not be
so now. Square up the end, and turning round the rest so as to stand
across the face of the wood, begin to hollow out _the cover_. Use either
the round end or pointed tool at first, and then a carpenter’s chisel or
flat tool to finish. Be very careful that the sides (I must call it by
this name, although a circle has not more sides than a plum-pudding) are
turned square to the bottom, or else, when the cover is put on, it will
perhaps fit just at the entry, and be quite loose when fairly on; or, it
may be that it will be easy at first, and when you press it on, it will
be tighter and become split,—a very common but unpleasant occurrence. Do
not, moreover, turn down these sides as thin as they will ultimately be;
because, after the box is hollowed and the cover fitted on, both will
have to be slightly turned together to finish them nicely. Moreover, you
may not wish your box to have plain sides, but may prefer to mould them
into a more elegant form. All these little questions have to be duly
considered in turning, for a mistake is often made, and the work spoiled,
for want of a little timely consideration.
The next point on which you have to be on your guard is this,—having
turned out the cover, you have to cut it off, not with a saw, but with
your parting-tool. Now, be sure to leave thickness enough for the top
of the cover; or, just as you think you have nearly severed the latter
from the rest of the piece of wood, you will see a beautiful little ring
tumble off,—sad relict of your box cover, which has come to an untimely
end.
The sliding square of the turner, of which I gave a description among
the list of tools, will always enable you to gauge both the depth to
which the work is hollowed out, and also the squareness of the inside
to the bottom. But if you have no turner’s square, you can easily gauge
the depth inside, and thus see how much is necessary to be allowed for
the thickness of the top. Keep the parting-tool edgewise on the rest,
which should be raised to such a height that, when this tool is laid
horizontally across it, it will point nearly to the centre of the work,
_i.e._, the axis of it. After the parting-tool has cut into the wood a
little way, widen the groove a little, and continue to give the tool a
little play right and left, unless its end is so much wider than its
blade generally that it will clear itself perfectly as it goes deeper and
deeper into cut. If it should bind, it is almost certain to break, for
it is a very thin tool; and it is better to waste a little more of your
material than to have to replace a spoiled tool.
I shall suppose that you have now succeeded in cutting off the cover;
pick it up and lay it near you. Directions are given generally to turn
down next the flange upon which the cover of the box is to be fitted, but
this is not to be wholly done yet, and you may proceed to hollow it out
as soon as you have turned down just so much of this flange as will show
you how much to leave in hollowing out the box. If you _fit_ the cover
before you have hollowed out the box, you will have the mortification of
finding it a great deal too loose when the box is finished, because the
latter will contract in size as soon as ever the solid core is removed
from it. _After_ you have hollowed it out, you must gauge the inside of
the cover, and the outside of the place that it is to occupy, with the
in-and-out callipers, or with a common pair, and turn the flange till
it is almost correct to this gauge, and only a very little larger than
it ought to be. When this is the case, do not trust any longer to the
callipers, but try on the cover again and again until you get a nice fit.
You must finish the flange with a chisel, held flat; and again I repeat
the caution about keeping it truly square, so that the cover will hold
equally tight in all positions. When this is the case, leave it on, and
give a last touch to both box and cover together, when you ought barely
to be able to see the joint.
You have now only to cut off the box as you did the cover, using the same
precautions. Before it is quite severed, however, you should give it a
polish. Pick up a handful of shavings, and while the work is revolving as
rapidly as possible, hold them with some pressure against it. Every fibre
will be at once laid smooth, and it will look nice and bright at once.
You can varnish it afterwards if you like, or French-polish it. Varnish
is best for boxwood, and French-polishing requires special directions,
which I shall give you separately in a future page.
To be able to make a box _well_, with its cover well fitted, is to
be able to do all kinds of similar work. Yet in these may be special
_details_ deserving notice. Probably, therefore, when speaking in a
future page of particular objects which have to be turned, such special
details will be more fitting than if given here. I shall therefore pass
on to another part of the subject, namely, screwed and twisted work.
SCREWS AND TWISTS.
Neither of these can be very accurately made without special and somewhat
expensive apparatus; but both can with practice be done tolerably well
by the young mechanic with ordinary simple means. I need not describe
a screw, for all boys know what it is; and sporting boys, of which
in these days there are many, know what sort of _animal_ a screw is.
Well, never mind. I am always riding a screw, I believe, for it is my
hobby, and there is a great deal of science in a screw; and as for the
_variety_ of the manufactured article, there is plenty of it. There is
the corkscrew, which is, after all, not a screw, but a twist,—and this is
often the means of making men screwed; and the miserly screw, who skins
fleas for the sake of their fat; and there is the mythical, invisible,
moral (and im-moral) screw, which hard-fisted men inflict upon their
weaker brethren; and there is the gigantic screw of the _Great Eastern_
steamship; and the minute, microscopic screw of the lady’s tiny jewelled
watch.
There are several modes of cutting screws, in the lathe and out of
it. The small ones required for holding together the different parts
of machinery, as well as larger ones for the same purpose, are always
cut with stock and dies. The very small ones used by watchmakers, and
all below one-eighth of an inch diameter, are made by the screw-plate.
But when either large or small screws are required of great accuracy,
they are invariably cut in the lathe, and with the aid of mechanical
appliances of the most delicately accurate description. These are all
metal screws. But the young mechanic will often wish to put screwed
covers to his boxes, and to join various parts of his work by screwed
connections instead of glue; and all these may be cut in the lathe
by simple hand-tools skilfully applied, although the operation is
sufficiently fraught with difficulty to require a great deal of practice
before it can be done with certainty of success. At the same time, my
young friends cannot possibly do better than practise this operation, for
there are numberless cases in which screws cannot be conveniently cut in
any other way, and it is, further, an accomplishment that will at once
stamp them as skilful workmen.
[Illustration: Fig. 51.]
The tools required are represented at A, B, Fig. 51. A is an outside,
and B an inside screw chasing-tool. These are always made in pairs, of
exactly the same pitch, _i.e._, the outside tool being applied to the
inside, the respective notches and points will exactly fit into each
other. If you were to examine the under side of these tools, shown at C,
you would notice that the notches do not run straight, but slanting. They
are in fact parts of screw threads; and you could make a tool of this
kind out of a common screw nut, as I have shown you at D, only it would
be too much hollowed out to make a good tool.
Now, supposing you were to hold the tool A flat on the rest, while a
cylindrical piece of wood revolved in contact with it, you would cut
a series of rings only; but if you were at the same time to slide the
tool sideways upon the rest, so that by the time the wood had revolved
once, the first point of the tool would have just reached the spot which
was occupied by the second when you started, you would have traced a
screw thread of that particular pitch. This is what you have to learn
to do always, and with certainty, no matter what pitch of tool you may
be using, and it is easy to understand how difficult the operation must
be to a beginner. Indeed, there are numbers of otherwise good turners
who have never succeeded in mastering this work. Nevertheless it can
be done, and, although difficult, it is not so much so as might be
supposed. Indeed, at first sight it would hardly be believed _possible_,
because each different pitch of tool, and each different-sized piece of
work, requires a different speed of traverse to be given to the tool.
But a practised hand will strike thread after thread without failure,
and those whose trade is to make all sorts of screw-covered boxes and
similar articles, will execute the work with as much speed and apparent
ease, as they would any ordinary operation of turning. I shall tell
you by and by, however, of several ways to escape this difficulty
of screw-cutting,—lathes being fitted in various ways to insure good
work, in some cases by carrying forward the tool at exactly the right
rate of traverse, and at others by moving along the work itself at the
proper speed, while the cutting tool is held immovably fixed in one
position,—and I will give one tool of great service which will guide you
in starting the ordinary chasing-tool; and a good start is here truly
“half the battle.”
The chasing-tool must run from right to left for an ordinary right-handed
screw (and a left-handed one is very seldom required), so that the young
mechanic need not trouble himself about it. Precise directions cannot be
given further than to have a rest with a very smooth and even edge, which
will not in the least hinder the traverse of the chasing-tool, and to
get the lathe into steady, equable motion. Then hold the tool lightly,
but firmly, keeping it at right angles with the work. Allow it only
just to touch until you find you have got into the right _swing_. It is
all a matter of knack and practice; and if you succeed quickly, you may
congratulate yourself.
The inside chasing-tool is used in precisely the same way, running it
from the outer edge of the hole inwards. To some this is an easier
tool to use than the outside chaser. I cannot say that I find it so;
especially as one has to work more in the dark; unless the work is
of large diameter like the cover of a box, and even then the work
is sufficiently difficult owing to the shallowness of the lid, which
necessitates the instant stopping of the tool for a fresh cut. For
you must understand that you have to deepen the screw-threads very
gradually, and it will take several traverses of the tool to cut them to
a sufficient depth.
The chasers require to be very sharp to cut wooden screws neatly, but
observe you must only rub the upper flat face upon the oilstone, or, if
a notch has been made by using the tools upon metal (they will cut brass
well with care), grind them in the same way; the great secret being to
hold the tool quite flat on the stone. You will thus, even by continual
grinding, only thin the blade of the chaser, which will thus last for a
long time. A practised hand will even cut a good thread with any flat
piece of steel filed into equal notches, but a screw-chaser is the only
tool really fit for the purpose.
[Illustration: Fig. 52.]
The most effectual remedy for the screw-cutting difficulty, is
unfortunately rather expensive in its best form. But in another, it is by
no means costly; and although it may not look so well as the first, it
is equally effective, and extensively used by the turners at Tunbridge
Wells, who make those beautiful little inlaid boxes and other articles. I
shall explain this to you, therefore, first:—
A, is a lathe-head, something like the one I have already described,
but you will notice that the mandrel is a much longer one, and has
several short screws cut upon it, each one being of a different “thread”
or “pitch.”[1] This mandrel runs through two collars, so that, besides
turning round, it can be pushed endwise. Now, supposing I was to hold
the point of a tool firmly against either of the screws, and at the same
time was to turn the pulley and mandrel, you will understand that it
would run backwards or forwards in its collars, at such a rate as the
screw-thread compelled it to move. This is the plan of the traversing
mandrel; and now supposing that you had a box held as usual in a chuck,
and while the mandrel was compelled to move endwise as described, you
were to hold a pointed tool against it, the tool would evidently cut a
screw-thread of exactly the same pitch as that upon the mandrel against
which the pointed tool first spoken of was applied. But in practice, a
single-pointed tool held against the mandrel would not answer very well,
and so the following plan is adopted instead, which answers perfectly.
Fig. 52, C, is called a half-nut. It has a set of screw-threads, cut
where the semicircular hollow is, which threads fit one of the screws on
the mandrel. A whole row of these half-nuts are fitted to turn at one
end upon a long bar, so that either one can be raised up at pleasure to
touch the screw upon the mandrel, which has threads of the same pitch
as itself, B. These, then, are ranged under the mandrel, and when it
is desired to make it traverse in its collars, one of these half-nuts
is raised and kept up by a wedge placed underneath it. When no screw
is required, a somewhat similar half-nut, but with merely a sharp edge
instead of a thread, is raised, and this edge falls into a notch or
groove turned upon the mandrel, or sometimes a back centre-screw is added
like D, and when no screw has to be cut, this is run up against the
mandrel like an ordinary lathe.
In the more expensive traversing mandrels, although the principle is the
same, there is a little difference in the arrangement of the different
parts. The mandrel is not very much longer than usual; and it has no
screw-threads cut upon it. But a number of ferules like K, are made each
with a screw upon its edge, and one of these of the desired pitch is slid
upon the end of the mandrel at _b_, fig. P, and is there held by a nut or
otherwise, so that it cannot move out of its place. The half-nut is seen
at _a_. It consists of a piece of brass or steel of the form shown with a
hole in the middle, and a screw cut upon _each hollow_, so that it is a
circle or set of half-nuts of different pitches. This slips over a pin at
_a_, and when the screw _b_ is turned, it draws up this pin and the nut
attached, until the latter comes in contact with the ferule upon the end
of the mandrel. This is very neat but expensive. Now, by far the cheapest
and best way for the young mechanic, is to set boldly to work to conquer
the difficulty of chasing screws by hand. There are even disadvantages
in the expensive form of a traversing mandrel, which render it by no
means a desirable mode of fitting up a lathe, and after all, the length
of screw which it enables one to cut is very limited, and in addition,
it is not every day, nor probably once a month, that screw-cutting will
be necessary at all. My advice, therefore, is, do not get a traversing
mandrel until you can cut screws well with the chaser. When you can do
this, you will be able to judge of the advantage or disadvantage of one.
By far the greater number of common screws are cut without the lathe,
by screw-plates, or stocks and dies, and the nut, or hole into which
such screws are to fit, is cut with a tap. A screw-plate is a simple
affair,—a mere flat plate of steel, in which several holes are drilled,
which are afterwards threaded by screwing into them taps, or hard cutting
steel screws of the size required; the plate is then hardened by being
heated red-hot and suddenly cooled, after which being much harder than
brass, iron, or steel which has not gone through such process, it will
in turn cut a thread upon any of these by simply screwing them into it.
But although this will answer for small and common screws, it is not at
all suitable for better ones, because the thread is _burred_ up, not
_cut_ cleanly as it would be with a proper tool. A far better plan is a
stock and dies; the latter being practically a hardened steel nut sawn in
half, and fitted so that the two halves can be pressed nearer and nearer
together as the screw thread becomes deeper. The dies are screwed up by
means of a thumbscrew opposite to the handle.
To use it, a piece of iron is filed up or turned to the required size,
which must be exactly that of the finished screw. The dies are then
loosened and slipped on to the end of this screw-blank as it is called,
and are then slightly tightened upon it. All that is now required is to
keep turning the tool round and round upon the pin, which it will soon
cut into a screw thread. When the stock is at the bottom or top, you may
tighten the dies, and so work up or down; but never tighten them in any
other part. If iron or steel is to be cut, use oil with the tool, but
brass may be dry. If the screw is of steel, heat it red-hot and let it
cool very gradually, to make it as soft as possible.
The hole or nut, into which the screw is to fit, is to be drilled so as
just to allow the taper tap to enter about a couple of threads; a wrench,
or, if small, a hand-vice is then applied to twist it forcibly into the
hole, when the thread will be completed. Take great care to hold the tap
upright, or else, if it is a screw with a flat head which has to fit into
it, it will not lie correctly, but one side of the head will touch while
the other is more or less raised.
There are other modes of screw cutting, but at present I need only
mention one, which is used for wooden screws alone. It is called a
screw-box, and is only made to cut one size, a tap being always sold to
match. You can, however, purchase any size you like, from a quarter of an
inch to 2 or 3 inches; but the latter are only intended for very large
screws, such as are used for carpenters’ benches and various kinds of
presses. A screw-box looks like a small block of wood with a hole in it,
but if you take out two screws you will find a blade of a peculiar shape,
which forms the thread by cutting the wood as it is screwed into the hole
in the box.
CHAPTER XI.
HARD-WOOD TURNING.
We now discard almost entirely the gouge and chisel used for soft woods,
and fall back upon an entirely different set of tools, similar to those
used for metal, but ground to rather more acute angles. These tools are
held horizontally upon the rest, because depressing the handles causes
the bevel below the edge to rub upon the work; and in addition, the grain
of hard foreign woods is such that it cannot well be cut by placing
the tool at a more acute angle, as would theoretically be required.
Hence we can only regard these as scraping tools; but as such they will
do excellent work in skilful hands. I have said that we discard the
gouge, but there are some woods that will bear this tool, to take off
the roughest parts of the work, before the application of others. The
roughing-tool, however, may now be considered to be the point-tool, and
the round-end tool, or “round” as it is often called; a narrow one makes
a good tool for this purpose.
Hard wood is easier on the whole to work than soft, because we have for
the purpose a large stock of tools of all shapes, suitable to the various
mouldings required. Hollows, round-beading tools, compound and simple
moulding tools of various sizes, to say nothing of those which are made
for use with ornamental apparatus, such as are required for fluting,
beading, and eccentric work, spirals, and so forth. It is indeed in hard
wood that most amateurs are accustomed to work; ebony and ivory, singly
or in combination, being more extensively used than any other.
To turn a cylinder, or any work requiring to be held at both ends,
you will invariably find the cross-chuck the best to use,—the fork or
prong not taking hold in the hard material. Rough down to shape as
before, using the gouge if it will work, but keeping the rest as close
as possible, and only taking a light cut. Then finish roughing with
a round-tool, and proceed generally as in soft wood turning, except
inasmuch as you have to scrape instead of cutting the work into form.
In addition to the tools already described, you will have to obtain a few
beading-tools, if you want to do very good work, for these give far more
beautiful mouldings than you can cut in any other manner. Fig. 53, A to
C, represent these. The bevel is on the under side, and it is better to
interfere with it as little as possible, by always sharpening the flat
face only. If it should be _necessary_, however, to touch the bevel, it
must be rubbed by a slip of oilstone, rounded on the edge, as used for
sharpening gouges. Conical grinders, revolving in the lathe, are also
used, especially for small beading-tools, to be fixed in the slide-rest.
In the same figure, D and E represent another useful hard-wood and
ivory tool. It is called the side-parting tool; and it is usual to have
several of these, the hooks increasing in length. The edge is only on the
extreme end of the hook. These tools are used for economy’s sake to cut
solid blocks of ivory and hard-wood from the inside of boxes, instead of
cutting the material into a heap of useless shavings. Similar tools, G,
H, curved instead of rectangular, serve to cut out a solid piece from
the inside of a bowl. In ivory work it is essential to use these tools,
because such material is very costly; $2.50 a lb., and upwards, being a
common price.
[Illustration: Fig. 53.]
K is given to show what are meant by beadings. If these are exactly
semicircular in section, they are far more beautiful in appearance than
if of such curves as can be roughly cut by a chisel. The bead-tools are
beautifully formed for this very purpose. To use the same side-parting
tool, you must proceed as follows, which you will understand by the fig.
L:—A common straight parting-tool or narrow chisel is first applied to
the face of the work to cut a deep circular groove or channel, as shown
by the white space at N, and in section at L. This allows the narrowest
of the hooked tools to be applied to _under-cut_ the solid core _x_. This
being withdrawn, a rather longer hook is applied, the hook being held
downwards as at O, until it reaches the spot where it is to work, when it
is gradually turned up (bevel below). Eventually, it is plain that the
solid core or centre block _x_ will fall out entire, which may be used
for other purposes. M shows how a similar but curved block can be removed
from the inside of a cup or bowl, the curved tool not requiring an entry
to be made for it, as it cuts its own way entirely from first to last.
P and Q show a ring-tool and the method of using it. A recess is turned
in the face of a piece of wood as if it was intended to hollow out a box.
The ring-tool is then applied bevel downwards, and with the left cutting
edge a bead is cut half-through from the inside. The right edge is then
applied to the outside, and when the cuts meet the ring neatly finished,
will fall off. With this tool you can turn them very rapidly, and they
will require only a rub of sand-paper to finish them.
R, S, T are three more tools for hard wood. The first two cut on the
outside of the curved part all round. These would be used to hollow out
humming-tops and all similar articles, and to finish the insides of
bowls, for which T is also designed. Indeed, I might go on to describe
all possible shapes of curved tools, each intended for some special work;
but you will not do better than to go to Fenn, Buck, or any tool-maker in
London, or elsewhere, and pick out at 7s., or so, per dozen, all shapes
and sizes, or if you live at a distance and write to either of the above,
they will select you the most useful; and you can trust these tradesmen
and all first-class ones to send you no tools which are not of the best
quality.
In finishing best work in hard wood, be very careful of all sharp edges
of mouldings. Sand and glass paper round off these, and spoil the beauty
of the work. If you are _obliged_ to use such substances, touch off again
the edges with very keen tools, which ought to leave brighter and more
beautiful surfaces than any sand-paper can produce. Indeed, the secret
of _finished_ work in hard wood is to have tools whose edges and bevels
are _polished_. In ornamental eccentric and rose-engine turning, where to
use sand-paper would be to ruin the appearance of it, the little drills
and cutters pass through three stages of sharpening, being ground on the
oilstone, finished on a slab of brass, fed with oil and oilstone powder,
and polished on a slab of iron with oil alone or oil and rouge. After
this every cut that is made with them reflects the light; and as the
surface is otherwise purposely grailed or dulled by cutting a series of
fine light rings with a point tool, the pattern itself shows out clearly
and lustrously.
TURNING BRASS AND OTHER METALS.
I shall now teach you how to turn iron and brass, which, though harder
than wood, are not very difficult to cut, if you go to work in a proper
manner and understand how to use your tools. What these are like I have
already told you, and also how to mount a bar in the lathe by using the
driver or point-chuck with a carrier. If the piece to be turned is _not_
a bar, you will have to drive it into a chuck of wood, or clamp it upon a
face-plate, or in a self-centring chuck if you have one.
I shall suppose, first of all, a mere straight bar of iron, centred at
the ends, as I have shown you. Take off the lathe-cord that you use for
wood, and fit one to go upon the largest part of the mandrel pulley, and
the smallest upon the fly-wheel. When you now put your foot upon the
treadle to work at your usual speed, you will find the mandrel turn quite
slowly; but I may at once tell you, that what you lose in speed you gain
in power. Set your rest for iron (which is not that used for wood, but
one with a broad, flat top) so that it stands a little below the central
line of the lathe mandrel and work, which will bring the edge of the tool
exactly _upon_ that line. This is always the position of the tool for
metal-turning, at any rate for iron.
Begin by trimming the end of the bar next to the back centre. Use a
graver, held as I directed you; that is, with the bevel flat upon the
_face_ of the iron, which is in this case the _end_ of it. Only let the
point cut, and a very little of the edge beyond it, and do not expect to
take a _deep_ cut so as to bring off a thick shaving. In metal work you
will always have to proceed slowly, but nothing is more pleasant when
once you can do it well.
You will at first have to experimentalise a little as to the exact
angle at which to hold the tool, but you will soon find out this; and
the advantage of hand-tools is, that you can always _feel_ as well as
_see_ how they are working, and can ease them here and there to suit
the material. It is rather difficult at first to hold the tool still in
metal-working, but, like all else, it becomes easy by practice; so much
so, that to hold the tool steadily in one hand is not only possible, but
is the mode always followed by watchmakers. While you are about it, you
should turn the graver over and try it in other positions; for although
the two sides of the bevel nearest to the point are the only ones to
be used, these may be applied in either direction, because they are
both sharpened to angles of 60°, and so long as you present them at the
correct angle (the smallest possible in respect of the work), it matters
not which face of the tool lies uppermost. After squaring off one end,
the approved plan is to remove the carrier, reverse the bar, and do the
same to the other end. Then begin to turn from the right hand. Place the
graver as before, with the point overlapping the end very slightly (so as
only to use the extremity of the cutting edge close to the point), and
take off a light shaving along the bar for a distance of about half an
inch, or even a quarter, keeping the edge of the graver which is on the
rest in one position, and moving the tool, not by sliding it along the
rest, but by using the point upon which it lies as a pivot. It is very
difficult to describe this exactly, but Fig. 52, O, will help to explain
it. The tool is to rest upon one spot, and the point to move in short
curves like the dotted lines, being shifted to a new position as you feel
it get _out of cut_. The left hand should grasp the blade and hold it
tightly down upon the rest, while the right moves the handle to and fro
as required. The curved dotted lines are necessarily exaggerated, but the
_principle_ of the work is this, whether you use a graver or a heel-tool.
You should turn about half an inch quite round, and then go on to the
next, by which you will always have a little _shoulder_ upon the work for
the tool to start upon, and this will be nice, clean, bright metal, and
will not blunt the tool. But if you go to work differently, so that the
edge of the tool comes continually in contact with the rough outside of
the iron caused by the heat of the fire, and which is exceedingly hard,
the point of the tool will be quickly ground down, while the iron will
not be cut into at all.
I need tell you no more about turning a _bar_ of iron in the lathe,
because the above directions apply in all cases; but if you have to
turn the _face_ of a piece of metal that is carried in a chuck of some
kind, you should always work _from_ the middle towards the edge, and
if the graver is used, its bevelled face will lie towards you during
the process. Take care to chuck the metal very firmly, for it is most
annoying to have it suddenly leave the chuck or shift its position after
you have been at the trouble of turning part of it truly. In such case it
is very difficult to replace it exactly as it was before, and all your
work has in consequence to be gone over again. When taking the final cut,
or before, if you like, dip the end of the tool into water, or soap and
water, and see the effect. The surface turned in this way will be highly
polished at once, and the tool will cut with much greater ease, so that
a large, clean shaving will come off. When using a slide-rest, you will
find it always better to keep water just dripping upon the work and point
of the tool; but there is a drawback, nevertheless, to this plan, for, as
might be expected, it makes a mess and rusts the lathe, and sometimes the
work as well, so the water must be constantly wiped off it.
THE SLIDE-REST.
I shall now pass on to describe a mechanical arrangement called a
slide-rest, of which there are two separate and distinct forms, one
for metal and one for ornamental turning in ivory and hard wood. The
ornamental work that can be done I shall pass by for the present,
because few boys are provided with the costly apparatus required, and
I am rather addressing those young mechanics whose tastes incline them
to model machinery and to practise the various operations of mechanical
engineering on a small scale. To such a slide-rest is an _almost_
necessary addition to the lathe, for there is a great deal of work which,
I may say, cannot be done without it; for instance, boring the cylinders
of engines (except small ones of brass), turning the piston-rods and
various pieces which require to be accurately cylindrical and of
equal size, perhaps for the length of a foot or more. Hand-work has
accomplished _something_ in this way in olden days, but the inability
of workmen to advance beyond a certain standard of perfection with
hand-tools alone, became such a hindrance to the manufacture of the
steam-engine, as improved by Watt and others, that had not Maudsley,
Naysmith, and others developed the principle of the slide-rest and
planing machine, we should not yet have lived to see those gigantic
engines which tear along like demon horses with breath of fire, at the
rate of sixty miles or more in as many minutes. So likewise would various
other machines, which now appear absolutely necessary to supply our
various wants, have stood in their primitive and imperfectly developed
forms; for it is necessary, before constructing a machine, to have the
means of turning cylindrical parts truly, and producing perfectly level
plates where required.
The object of a slide-rest is to provide means for holding a tool firmly,
and giving it a power to traverse to and fro and from side to side, so
that by the first we may be able to cause such tool to approach or recede
from the work, and by the second we may cause it to move in a perfectly
straight line along its surface from end to end. This is accomplished
in the following manner:—The drawing being a representation of one of
the first machines constructed for the purpose. A rectangular frame,
A, of iron is carried by a pair of strong uprights, B B, fixed to the
sole-plate, C, by which it is attached by a bolt to the bed of the lathe.
Lengthwise of this frame runs a screw, prevented by collars from moving
endwise, but which can be turned round by the winch-handle, D. Thus a
nut through which this screw passes, and which only has endwise motion,
will, when the latter is turned by its handle, traverse it from end to
end in either direction, according as the screw may be turned from right
to left or the contrary. This nut is attached to the under part of a
sliding-plate, E, which has a part projecting between the sides of the
frame, and also two others on its outside, by which it grasps the same
with great accuracy, and is prevented from any shake or play as the
whole with the nut is made to traverse to and fro along the frame.
Lengthwise of this sliding-plate, that is, in a direction the opposite to
that of its own traverse, are two bars bevelled underneath, fixed exactly
parallel to each other, which are so arranged to guide the cross traverse
of another plate with chamfered edges to fit the bevels of the guide
bars. This second plate has on its upper surface two clamps which secure
the tool. It is plain, then, that by this arrangement the two required
movements are attained, the lower plate sliding along in one direction
parallel with the lathe-bed, and the other across it. In the original
rests, this upper plate with the tool was moved by hand, and in the
modern rest for ornamental turning (which this was also constructed for)
the same is done, but a hand-lever is added for the purpose.
But although a similar arrangement is needed for metal, it is plain
that the top plate should have a more easily regulated motion, and
that we should be able to advance the tool as near the work as may be
desired, and then to retain it securely at that distance while giving the
necessary movement in the direction of the length of the object to be
turned. The method of effecting this is at once suggested by the screw
and nut of the lower part, and by merely adding to the top a similar
arrangement, the desired end is at once attained.
[Illustration: Fig. 54.]
The actual construction of such rest varies somewhat, but Fig. 54, H,
shows it in its most ordinary form. The lower part is, of course, to be
clamped down securely to the lathe-bed, there being a projection below
which is made to fit accurately between the bearers similar to that
beneath the poppits. This projection secures the correct position of
the rest, of which one frame or plate will travel lengthwise of the
bed, while the other will move exactly at right angles to it. But in
the _compound_ slide-rest, which is very general, there is also a third
circular motion, by which the upper part can be set at any angle with
the lower, instead of being permanently fixed at right angles to it. By
this the tool can be made to approach the work more and more as it passes
along it; and it will therefore cut deeper at one end of its traverse
than at the other. The result will be that what is thus turned will not
be a true cylinder, but a cone, _i.e._, it will be larger at one end than
the other, although otherwise smooth and even.
We are thus provided with the most valuable addition to the lathe ever
devised by mechanics, and it is no longer a question of the strength and
skill of the workman whether we can produce a perfect piece of work, but
simply of the accuracy with which the lathe and rest are constructed, and
of the form and condition of the tools to be used. The latter are not
exactly like those ordinarily used, although the principle of the cutting
angles already laid down needs to be adhered to even with more unfailing
attention than that required for the correct formation of hand-tools.
Moreover, it is plain that—here we shall no longer feel whether the tool
is working as it ought to do—we shall be unconscious of the precise
amount of _strain_ that is being brought to bear against its edge, and if
it is by chance working in a bad position, at a wrong angle, we cannot
re-adjust it in a moment as we could a hand-tool by a slight movement of
the fingers or wrist.
Hence you will see at once how very important it is that tools for the
slide-rest should be shaped with the _most rigid adherence_ to correct
principles; and, further, that they should be so fixed in the slide-rest
as to meet the work at the precise angle, and at the height exactly
suited to the material of which it is composed. As regards the latter
point, it may be taken as an almost invariable rule that the work should
be attacked on its axial line (that is, a line that would run from end
to end of it dividing it lengthwise into equal parts, or, as it would
commonly be named, its _middle_ line). If the tool meets it above this,
it is most likely that it will rub against it, and the point will be out
of cut. If it meets it below, there will be a tendency for the point to
catch in, and the work to roll up upon the face of the tool, which, in
fact, it very often does with careless workmen, and then there comes a
smash of some kind—lathe centres snapped off, the tool broken, the bar
bent beyond remedy, and possibly the operator’s toes made unpleasantly
tender.
The most common slide-rest tool for outside work is that given at H².
It is made straight, as shown, or bent sideways to right or left to
cut shoulders on the work, or enter hollows, or creep sneakingly round
corners, or any other of those crooked ways in which man delights; but
whether straight or not, these tools have all most commonly the cranked
form shown here. This gives the tools a _slight_ degree of elasticity—not
very much, because that would only injure the perfection of the work;
therefore they are not very considerably cranked. The angles are ground
as directed in the table of tool-angles, and if the point is too low,
slips of iron are placed below the shank upon the tool-plate of the
slide-rest; if too high, the grindstone must be resorted to; and the
advantage of these cranked tools is, that they can be ground down several
times without being brought too low to be packed up with iron slips to
the right level. Thus a cranked tool is by far more advantageous for the
slide-rest than one made straight like those used for hand-turning. For
inside work, however, or “holing,” the crank form is not possible, unless
the hole is of large size, and so, for this purpose, straight side-tools
are used, like K.
If the tool is well placed, as well as correctly made, nothing can be
more easy and delightful than slide-rest work. You merely advance the
tool to take the required cut (beginning generally at the right-hand end
of the bar), and then gently turning the other handle, you will see it
traverse along, as if work was a pleasure to it, as it ought to be to all
young mechanics. Not infrequently, however, instead of this even, steady
work, the tool jumps and catches, or rubs and shrieks: it is out of
temper, I suppose; at any rate, in some one or more particulars it needs
correction.
Although with the slide-rest you can generally venture upon taking a
deeper cut than you could with hand-tools, it is by no means well to
hurry the work. At first, especially before it has become cylindrical,
the tool will only cut partly round its surface, and the work is done in
an uncomfortable, jerking, dissatisfied sort of way, and the deeper you
drive the tool the worse it is; but as soon as the outer skin is off, and
the work has become cylindrical, a long, clear, bright shaving curls off
pleasantly from end to end, and the surface ought, if the tool is wetted,
to become at once of a finished appearance.
You should always, with a slide-rest, take the whole run of the piece
from end to end to a certain depth, and then, commencing again at the
end, repeat the same process, and so on until the required size is almost
attained. When it is, take out the tool with the pointed end which has
been in use, and insert one freshly sharpened with a broad point, getting
it so placed as to cut the shaving both from the surface below, and from
the shoulder to which it is attached at the side, as I explained to you
in the chapter on grinding and setting tools, and which must be well
understood before you can hope to make good work with tools rigidly fixed
in a slide-rest. With this tool, kept wet with soap and water (or soda
water, which is better for this than for your stomach), take a _very_
light shaving from end to end, taking especial care to turn the handle
which gives the traverse slowly and _evenly_. If you stop, or almost
stop, the tool will be sure to draw a little deeper into cut, which will
make a scratch upon the work, or, it may be, plough a groove, and so far
spoil the appearance of it.
Whenever you finish turning any bar that has been centred at each end,
be careful to leave the centre marks just as they were when the work was
in the lathe. The ends will have been otherwise trimmed off at the very
commencement, and it may happen that at some future day it may be desired
to re-mount the piece for repair, when, if these marks are gone, and new
centres have to be drilled, the whole will run so much out of truth that
it will have to be entirely re-turned from the commencement. Do not,
therefore, fancy that these centre marks are unsightly, and forthwith
file them out, but be content to leave them.
Slide-rest tools, made in the ordinary way, are so far troublesome in use
that if they get broken you must have them re-forged, and few country
smiths know anything about such matters. I have a tool now lying by me
made by a smith (true, it was a Welsh smith), and although I stood by
and explained how it should be done, and cut one out of a piece of wood,
it never arrived at a proper shape, and was never even placed upon the
rest. I keep it as old Izaak Walton kept the Londoner’s artificial fly,
viz., “to laugh at,” and as a caution to all concerned, never to go to a
country blacksmith for slide-rest tools. The following plan answers very
well for many kinds of outside work, and is on the whole a plan that may
be satisfactorily followed by the young mechanic.
Instead of having the tools constructed from a large bar of steel half
an inch or so in the square, they are made of short pieces about an inch
long, fitted into a peculiar holder.
The advantage of this arrangement consists in the ease with which you can
make your own tools out of broken round, triangular, or square pillar
files, small chisels and such like. These can be shaped by the grindstone
alone, and the blacksmith will not have to be called into requisition. I
shall give you two forms of tool-holders, more or less simple, because I
may suppose my young mechanic to be fast growing into an old hand, and
able to appreciate differences in these arrangements.
Fig. 55, A, B, represents two of such holders, one for round, the other
for flat steel cutters. You can see at once that when these are upon
the bed of the rest, they form a tool with cranked end, as previously
described, and can therefore be used in precisely the same manner. I
shall give no directions for _making_ these tool-holders, which are,
nevertheless, very simple affairs, and can be readily understood from the
drawings here given.
[Illustration: Fig. 55.]
Another form is shown at C. The part _d e_ is a clamp, which is
separately drawn at _f_. This, like the last, enables one to use all
sorts of odds and ends for tools. There are several other patterns
of tool-holders, arranged either to use the little pieces of square,
round, or triangular steel bars, so that one side, at least, of these
may remain without grinding, and others in which two entirely new faces
must be given to the tool by the grindstone. The latter are, perhaps,
generally the best, because you can then, with the aid of the table of
tool-angles, shape your cutters very accurately to the work required of
them.
Although such tool-holders and cutters are generally used for metals,
there are others intended for wood; and constructed to hold miniature
gouges and chisels, which perform their work admirably. A capital tool
for outside work, Fig. 55, E, which was used extensively at Portsmouth
dockyard for brass turning, is made simply by filing off at an angle of
about 45° a round short bar of steel. This angle, however, is unusually
small for brass and gun-metal, 80° being better. For iron it will answer
better, because though filed, or rather ground at 45°, the cutting edge,
a little way from what may be called the point of the tool, is nearer 60°.
Similar to these last are the tube gouges, short bits of steel tube
ground off and sharpened. These fixed in a holder answer beautifully for
soft wood, and do not “catch in.” If the holder is bent so as to bring
the tool into proper position, inside work can be rapidly effected by
these, such as hollowing out large bowls and similar heavy work. All this
can, of course, be done rapidly with the slide-rest, so far as regards
the removal of the greater part of the wood. But in the case of a bowl,
in which a curve predominates over a straight line, hand-tools must be
used to finish it (generally the inside hook-tool). This last is, in
fact, almost identical with the tube gouge; for the slide-rest, and that
which makes it so difficult a tool to use, is that, being a hand-tool,
and subject to slight unintentional changes of position upon the part of
the workman, it catches in, and is either wrenched out of the hand, or a
piece is chopped off the wood. Rigidly held in the slide-rest, the exact
angle, once found, is of course maintained.
CHAPTER XII.
I now propose to assist the young mechanic in special work, instead of
continuing general directions. This will enable me to explain to him
various lathe appliances, and other details of mechanical work hitherto
passed by.
Of all models which boys (and very big boys too) are desirous to
construct, the steam-engine holds the chief place, and deservedly so; for
every boy calling himself mechanical, ought to know how this is made,
and the general _principles_ of its construction as well. However, I am
aware, from experience, that many a youngster, who is even in possession
of a model engine, is utterly ignorant of the cause of its motion;
although it is a great delight to them to see the steam puffing out, and
the wheel revolving “nineteen to the dozen,” as schoolboys say. Now, an
engine is a very simple affair, and can be easily explained; and, as I
wish my readers to work rationally, I shall show them what they have to
do before I tell them how to do it.
[Illustration: Fig. 56.]
A, Fig. 56, represents a cubical vessel of tin or any other substance.
By cubical, I mean that all its sides are squares, and all exactly equal;
each side in the present case is to be 1 inch wide and long, or a square
inch. B is a similar vessel, 1 foot cube. It contains, therefore, 1728
cubic inches, or is 1728 times as large in capacity as the first. Now, if
I were to fill the little vessel with water and tip it into the second,
and put a lamp under it, the water would all soon boil away, as it is
called. It would be converted into steam; and the quantity of steam it
would produce would exactly fill the larger vessel, without exciting any
particular pressure upon its sides.
Steam, thus allowed plenty of elbow room, is like a lazy boy; it will
play and curl about very prettily, but will do no work. We must put some
sort of pressure, therefore, upon it—confine it, and we shall soon see
that, by struggling to escape, it will serve our purpose, and become
a most obedient workman. We have, therefore, only to put double the
quantity of water into our larger vessel, that is, _two_ cubic inches.
We will put on a cover tightly, adding a pipe through which to pour in
the water. Soon we shall have the steam formed as before; but it has no
longer room enough, and out it comes fizzing and roaring, very savage at
having been shut up in so small a cage. And we can make it work too, for
if we set up a little fan-wheel of tin right in its way, we shall see
it spin round merrily enough; or if we cork the tube lightly, we shall
find this cork soon come out with a bang. We have, in fact, already
constructed a steam-engine and a steam-gun on a small scale. The pressure
in this case is, indeed, not great, but what it is I must now try to
explain.
The air or atmosphere, which surrounds us on all sides, exercises a
pressure upon everything of 15 lbs. on every square inch of surface. If
our little cubical inch box of tin had no air inside it, and no steam,
but was absolutely empty, each side, and top, and bottom would have 15
lbs. pressure upon it; which would be evident if it were not very strong,
for it would sink in on all sides directly, just as much as if you
were to _add_ a weight of 15 lbs. when it was full of air, as it would
ordinarily be.
When I spoke of the larger box being exactly filled with steam from the
evaporation of the cubic inch of water poured from the smaller box,
I supposed it empty of air. The steam from that quantity of water,
occupying the place of the air, would also be of the same pressure, 15
lbs. per square inch of surface; and as this only balances the pressure
of the atmosphere, which would be, in such a case, pressing in on all
sides, the steam would not show any pressure; just as, if you put equal
weights into each scale of a balance, the beam of it would remain
horizontal, neither scale showing to the outward senses that it had any
pressure upon it. But in the second case, we have doubled the quantity of
steam, but compelled it to occupy the same space; therefore we have now
real, visible pressure of 15 lbs. upon each square inch; and if we again
halve the space which the steam has to occupy, or double the quantity of
water, we shall obtain a pressure of 30 lbs. beyond the pressure of the
atmosphere.
Let us now disregard atmospheric pressure, and fit up such an apparatus
as Fig. 56, D. Here we have first our small box, closed on all sides,
and from it a small tube rising and entering into the bottom of a larger
one, which is very smooth in the inside; in this is a round plate or
disc, called a piston, which fits the tube nicely, but not so tight as to
prevent it from moving up and down easily; and let a weight of 15 lbs. be
laid upon it. Let us suppose this large tube or cylinder to be 1700 times
larger than the cubic inch box, into which water is to be poured till
full. Now we heat it as before, and when 212° of heat are attained by the
water (which is its boiling-point) when it begins to be converted into
steam, the piston will be seen to rise, and will gradually ascend, until
quite at the top of the tube, because the steam required exactly that
amount of room.
Now we have arrived at the same conclusion which we came to before;
for you see that not only has the cubic inch of water become a cubic
foot of steam (_about_ 1700 to 1728 of its former volume), but it is
supporting 15 lbs. weight, which represents that of the atmosphere, and
if we could get rid of the latter, a solid weight of 15 lbs. would be
thus supported. Now, still neglecting the atmospheric pressure, suppose
instead of 15 lbs. we add another 15 lbs., making the weight 30 lbs.,
down goes our piston again, and stands at about half the height it did
before. We have thus, as we had previously, a cubic foot of steam made to
occupy half a cubic foot of space, giving a pressure (which is the same
as supporting a weight) of 30 lbs.
I ought, perhaps, to add in this place, however, that under 30 lbs.
pressure, or atmospheric weight and 15 lbs. additional, the water would
not become steam at a temperature of 212°, but it would have to be made
much hotter, until a thermometer placed in it would show 252°.
So far we have seen what a cubic inch of water will do when heated to a
certain degree, and at first sight it may not seem a great deal. Far from
being light work, however, this is actually equal to the work of raising
a weight of 1 ton a foot high. Let us prove the fact. Suppose the tube or
cylinder to be square instead of round, and that its surface is exactly 1
square inch, how can we give 1700 times the room which is occupied by the
water? It is plain that the piston must rise 1700 inches in the 1-inch
cylinder or tube, carrying with it, as before, its weight of 15 lbs.—that
is, it has raised 15 lbs. 1700 inches, or about 142 _feet_. But this is
the same as 15 times 142 feet raised 1 foot, which is 2130 lbs. raised 1
foot, very nearly a ton, the latter being 2240 lbs. So, after all, you
see that our little cubic inch of water is a very good labourer, doing a
great deal of work if we supply him with sufficient warmth.
Now this is exactly the principle of the ordinary steam-engine: we have
a cylinder in which a piston is very nicely fitted, and we put this
cylinder in connection with a boiler, the steam from which drives the
piston from one end of the cylinder to the other. In the first engine
that was made, the cylinder actually occupied the very position it does
in our sketch; it was made to stand upon the top of the boiler, a tap
being added in the short pipe below the cylinder, so that the steam could
be admitted or shut off at pleasure. But it is plain that although our
little engine has done some work, it has stopped at a certain point;
there is the piston at the top, and it cannot go any farther; we must get
it down again before it can repeat its labour.
How would you do this, boys? Push it down, eh? If you did, you would find
it spring up again when you removed your hand, just as if there were
underneath it a coiled steel spring; by which, however, you would learn
practically what is meant by the _elasticity_ of steam. Besides this,
if you push it down, you become the workman, and the engine is only the
passive recipient of your own labour. Try another plan; remove the lamp,
and see the result—gradually, _very_ gradually, the piston begins to
descend.
Take a squirt or syringe, and squirt cold water against the apparatus.
Presto! down it goes, now very quickly indeed, and is soon at the bottom
of the cylinder. But we may as well try to get useful work done by the
descent of the piston as well as by its ascent.
Set it up like Fig. 56, E. Here is a rod or beam, _b a c_, the middle of
which is supported like that of a pair of scales. From one end we hang
a scale, and place in it 15 lbs.; and as the piston sinks the weight is
raised, and exactly the same work is done as before. Thus was the first
engine constructed; but instead of the scale-pan and weight, a pump-rod
was attached, and as the piston descended in the cylinder this rod was
raised, and the water drawn from the well. This, however, was not called
a steam-engine, because the work is not really the effect of the steam,
which is only used to produce what is called a vacuum (_i.e._, an empty
space, devoid of air) under the piston. In fact, the up-stroke of the
piston was only partly caused by steam, and the rod of the pump was
weighted, which helped to draw it up.
I must get you to understand this clearly, so that the principle may
become plain—“clear as mud,” as Paddy would say. I told you that the
air pressed on every square inch of surface with a force of about 15
lbs. We do not feel it, because we are equally pressed on all sides—from
within as well as from without—so that atmospheric pressure is balanced.
Sometimes this is a very good thing. We should, I think, hardly like to
carry about the huge weight pressing upon our shoulders, if something
did not counteract it for us, so that we cannot feel it. Indeed, if it
were otherwise, we should become flat as pancakes in no time—“totally
chawed up.”
But sometimes we should prefer to get rid of the air altogether—and I
can tell you it is not easy to do so, unless we put something into its
place; and we want perhaps simply to get rid of it, and make use of the
room it occupied. We require to do this in the present instance, and in
fact we have just done it. If the whole space below the piston, when
we begin to work, is filled with water, it is plain there can be no
air below it; and when the steam has raised it, there is still no air
below it, but only steam. We then apply cold to the cylinder by removing
the lamp and squirting cold water against it, which has the effect of
reducing the steam to water again, which will occupy 1 inch of space
only. We, therefore, now have a space of 1600 cubic inches with neither
air nor water in it; and so, if the piston is 1 inch in size, there will
be the 15 lb. pressure of the atmosphere upon it, and nothing below to
balance it, for we have formed a vacuum below it, and of course this
15 lb. weight will press it rapidly down. It did so; and we therefore
were enabled to raise 15 lb. in the scale-pan. You will know, therefore,
henceforth, exactly what I mean by a vacuum and atmospheric pressure. It
is, you see, the latter which does the work when a vacuum is formed as
above; but you can easily understand that it might be possible to use
both the atmospheric pressure _and_ the pressure of steam as well, which
is done in the condensing steam-engine.
In the earliest engine, called the _Atmospheric_ for the reason above
stated, the top of the cylinder was left entirely open, as in our sketch;
but the condensing water was not applied outside the cylinder, but
descended from a cistern above, and formed a little jet or fountain in
the bottom of the cylinder at the very moment that the piston reached its
highest point. Down it, therefore, came, drawing up the pump-rod. When
at the bottom the jet of water ceased. Steam was again formed below the
piston, which raised it as before; and the process being repeated, the
required work was done. A boy, to turn a couple of taps, to let on or off
the water or steam, was all the attendance required.
For some time the atmospheric engine, the invention of Newcomen, was the
only one in general use; and even this was, in those days (1705-1720),
so difficult to construct that its great power was comparatively seldom
resorted to, even for pumping, for which it was nevertheless admirably
suited. The huge cylinder required to be accurately bored, while there
were no adequate means of doing such work; and although the piston was
“packed,” by being wound round with hemp, it was difficult to keep it
sufficiently tight, yet at the same time to give it adequate “play.”
Then, another drawback appeared, which, though of less importance in some
districts, absolutely prevented the introduction of this engine into many
parts of the country. The consumption of coal was enormous in proportion
to the power gained. We can easily understand the reason of this, when
we consider the means used for producing a vacuum in the cylinder below
the piston. The water introduced for the purpose, chilled, not only the
steam, but cylinder and piston also; and therefore, before a second
stroke could be made, these had to be again heated to the temperature of
boiling water. The coal required for the latter purpose was therefore
wasted, causing a dead loss to the proprietor.
So matters continued for some time, until a mathematical instrument-maker
of Glasgow, named Watt, about the year 1760, began to turn his attention
to the subject; and having to repair a model of Newcomen’s engine
belonging to the University of Glasgow, the idea seems to have first
struck him of condensing the steam in a separate vessel, so as to avoid
cooling the cylinder after each upward stroke of the piston. This was the
grand secret which gave the first impetus to the use of steam-engines;
and from that day to this these mighty workmen, whose muscles and sinews
never become weary, have been gradually attaining perfection. Yet it
may be fairly stated that the most modern form of condensing engine in
use is but an improvement upon Watt’s in details of construction and
accuracy of workmanship. For Watt did not stand still in his work; but
after having devised a separate condenser, he further suggested the idea
of closing the top of the cylinder, which had hitherto been left open to
the influence of the atmosphere; and rejecting the latter as the means
of giving motion to the piston, he made use of the expansive power of
steam on each side of the piston alternately, while a vacuum was also
alternately produced on either side of it by the condensation of the
steam.
The atmospheric engine was thus wholly displaced. The saving of fuel in
the working of the machine was so great, that the stipulation of the
inventor, that one-third of the money so saved should be his, raised
him from comparative poverty to affluence in a very short time. Watt,
however, had still to contend with great difficulties in the actual
construction of his engines. He was in the same “fix” as some of my young
readers, who are very desirous to make some small model, but have little
else than a pocket-knife and gimblet to do it with. For there were no
large steam-lathes, slide-rests, planing and boring machines, procurable
in those days, and even the heaviest work had to be done by hand, if
indeed those can be called hand-tools which had frequently to be _sat
upon_ to keep them up to cut. It was therefore impossible for Watt to
carry out his designs with anything like accuracy of workmanship, else
it is probable that he would have advanced the steam-engine even further
towards perfection than he did. In spite of these drawbacks, however,
this great inventor lived to see his merits universally acknowledged, and
to witness the actual working of very many of these wonderful and useful
machines.
The first necessity which occurred from closing the cylinder at both
ends was the devising some means to allow the piston-rod to pass and
repass through one end without permitting the steam to escape. This was
effected by a stuffing-box, which is represented in Fig. 57, A, B,—the
first being a sectional drawing, which you must learn to understand, as
it is the only way to show the working details of any piece of machinery.
We have here a cylinder cover, _a_, which bolts firmly to the top of the
cylinder, there being a similar one (generally without any stuffing-box)
at the other end or bottom of the same. On the top of this you will
observe another piece, which is marked _b_, and which is indeed part of
the first and cast in one piece with it. Through the cylinder cover, _a_,
is bored a hole of the exact size of the rod attached to the piston,
which has to pass through it, but which hole, however well made, would
allow the steam to leak considerably during the working of the piston-rod.
[Illustration: Fig. 57.]
To obviate this, the part _b_ is bored out larger, and has a cup-shaped
cavity formed in it, as you will see by inspecting the drawings. Into
this cavity fits the gland, _c_, which also has a hole in it, to allow of
the passage of the piston-rod. This gland is made to fit into the cavity
in _b_ as accurately as possible; and it can be held by bolts as in the
fig. A, or be screwed on the surface as shown at B, in which latter case
the greater part of the interior of _b_ is screwed with a similar thread.
The piston-rod being in place, hemp is wound round it (or india-rubber
packing-rings are fitted over it), and the gland is then fitted in upon
it, and screwed down, thus squeezing the hemp or rubber tightly, and
compelling it to embrace the piston-rod so closely, that leakage of steam
is wholly prevented. Whenever you have, therefore, to prevent steam or
water escaping round a similar moving-rod in modelling pumps or engines,
you will have to effect it in this way. The piston was also packed with
hemp or tow, either loosely-plaited or simply wound round the metal in a
groove formed for the purpose. In Fig. 57, C and D, I have added drawings
of a piston, so made, partly for the purpose of again explaining the
nature of sectional drawings. In this one, C, you are shown the end of
the piston-rod passing through the piston, and fastened by a screwed nut
below, a shoulder preventing the rod from being drawn through by the
action of this nut. The hemp packing is also shown in section, but in the
drawing D the groove is left for the sake of clearness.
In all your smaller models you will have to pack your piston in this
way, except in those where you entirely give up all idea of _power_. The
little engines, for example, sold at $1 and upwards, with oscillating
cylinders, have neither packed pistons nor stuffing-boxes; the friction
of those would stop them, and escape of steam is of no great consequence.
It will, however, be found advantageous to turn a few shallow grooves
round these unpacked pistons after they have been made to fit their
cylinders as accurately as possible, like fig. C. These fill with water
from the condensation of steam, which always occurs at first until the
engine gets hot; and thus a kind of packing is made which is fairly
effectual.
In Fig. 58 I have given a drawing of Newcomen’s engine, in case you
would like to make a model of one; but I do not think it will repay you
as well for your labour as some others. There is the difficulty of the
cistern of cold water and the waste-well; and the condensation of the
steam is a troublesome affair in a small model, so that, on the whole,
I should not recommend you to begin your attempts at model-making with
the construction of one of these. I shall, however, add a few directions
for this work, because what I have to say about boring, screwing, and so
forth, will apply to all other models you may desire to construct.
The cylinder, in this case, will be more easily made by obtaining a
piece of brass tubing, which can be had of any size, from 3 or 4 inches
diameter to the size of a small quill. The first you will often use for
boilers, the latter for steam or water pipes. You can also obtain at
the model makers—Bateman, for instance, of High Holborn—small taps and
screws, and cocks for the admission of water and steam, and all kinds of
little requisites which you would find great difficulty in making, and
which would cost you more in spoiling and muddling than you would spend
in buying them ready made.
[Illustration: Fig. 58.]
The drawing is given on purpose to show the best and easiest arrangement
for a model. It has all parts, therefore, arranged with a view to
simplicity. A is the boiler made of a piece of 3-inch brass tubing, as
far as _a_, _b_, _c_, _d_, the bottom being either of brass or copper
at the level of _a_, _b_; the upper domed part may be made by hammering
a piece of sheet brass, copper, or even tin, with a round-ended boxwood
mallet upon a hollowed boxwood block, of which T, T is a section. You
should make one of these if it is your intention to make models your
hobby, as it will enable you to do several jobs of the same kind as the
present. Probably you will not be able to make the dome semicircular, or
rather hemispherical; but at all events, make it as deeply cupped as you
can—after which, turn down the extreme edge one-sixteenth of an inch all
round to fit the cupped part exactly. This requires a good deal of care
and some skill. If you find that you cannot manage it, make your boiler
with a flat top instead. Whichever way you make it, a very good joint to
connect the parts is that shown in section at V.[2] The edge of the lower
part is turned outwards all round; that of the upper part is also turned
outwards, first of all to double the width of the other, and is then bent
over again, first with a pair of pliers and afterwards with a hammer,
a block or support being placed underneath it. All this is done by the
manufacturer with a stamping machine on purpose, and would be completed
by the Birmingham brass-workers before I could write the description. It
can, however, be done without any more tools than shown.
You will often need a tinman’s boxwood mallet with one rounded end and
one flat one, which, of course, you can now turn for yourself, as it is
an easy bit of work. With the rounded end you can cup any round piece of
tin; but it requires gentle work; do it gradually by hammering the centre
more than the edges. I will show you presently how to do similar work by
spinning in the lathe, which is a curious but tolerably easy method of
making hollow articles of many kinds from round discs of metal without
any seam.
After you have hammered the joint of the upper and middle parts together,
you must solder them all round with tinman’s solder. For this purpose
you require a soldering-iron represented at W. This is a rod of iron,
flattened and split at the end, holding between the forked part a piece
of copper, which is secured to the iron by rivets. I should not recommend
a heavy one, not so heavy nearly as what you may see at any blacksmith’s
or tinman’s shop, because your work will be generally light, and such
irons are all top heavy to use. The end, which may be curved over as
shown, will require to be _tinned_, for without this it will not work
at all well. File the end bright, and heat it in the fire nearly red
hot. Get a common brick, and with an old knife or anything else, make a
hollow place in it—a kind of long-cupped recess like a mussel shell, if
you know what that is, and put a little rosin into it. Take your iron
from the fire, and holding it down close to the brick, touch it with a
strip of solder, which will melt and run into the cavity. Now rub the
iron well in the solder and rosin, rub it pretty hard upon the brick,
and presently you will see it covered with bright solder, from which
wipe what remains in drops with a piece of tow. The iron is now fit for
immediate use; but remember, the first time you heat it red-hot, you
will burn off the tinning, and you must file it bright again, and repeat
the process. So when you want to solder, heat the iron in a clean fire,
until, when you hold it a foot from your nose, you find it pretty warm;
and avoid a _red_ heat. You will now find, that when the soldering-iron
is hot, it will not only melt but pick up the drop of solder; and as you
draw it slowly along a joint (previously sprinkled with powdered rosin,
or wetted with chloride of zinc, or with Baker’s soldering fluid), the
solder will gradually leave the iron, and attach itself to the work in a
thinly-spread, even coat.
The secret of soldering is to have the iron well-heated, and wiped clean
with a bit of tow, and to apply it along the joint so slowly and steadily
that the tin or other metal will become hot enough just to melt solder.
Try to solder, for instance, a thick lump of brass; file it bright if
at all tarnished—for this must invariably be done with all metals. You
will be unable to do it at first, for the moment the solder touches it,
it will be chilled, and rest in lumps, which you can knock off directly
when cold. Now place the brass on the fire for a few seconds until hot,
and try again; the solder will flow readily as the iron passes along
it, for it is kept up to the melting-point until it has fairly adhered.
This is why in heavy work a large iron is required; it retains heat
longer, and imparts more of it to the metal to be soldered. But you
will find it often better to use a light soldering-iron, and to place
the brass-casting upon the bar of the grate for a short time. You may,
indeed, often work without any soldering-iron as follows:—
Heat the pieces to be soldered (suppose them castings and not thin
_sheets_ of metal) until they will melt solder. Take a stick of the
latter, and just dip it in one of the soldering solutions named, and rub
it upon the work previously brightened. The solder will adhere to both
such pieces. Now, while still hot, put them together and screw in a vice,
or keep them pinched in any way for a few minutes, and you will find them
perfectly secured. In making chucks for the lathe, and in forming many
parts of your models, you will find it advantageous to work in this way;
but, notwithstanding, you will often require a light soldering-iron, and
sometimes also a blowpipe, which I shall likewise teach you to use, as
also how to make a neat little fireplace or furnace to stand on your
bench by which to heat the iron.
I must now suppose that you have carefully soldered the dome to the
middle of your boiler; and as the solder will be underneath, the joint
will be concealed even if (as is likely) you should not have made a
very neat piece of work. Before you put on the bottom of the boiler,
you will have to make two holes in the top—one for the steam-pipe
three-eighths of an inch in diameter, the other for the safety-valve also
three-eighths—because this will require a plug of brass to be soldered
in, which plug will have a hole drilled through it of a quarter of an
inch diameter. These may be punched through from the inside, or drilled;
they are easily made, but should be as round and even as possible.
Take a piece of three-eighths-inch tubing, with a stop-cock soldered into
the middle of it. I shall suppose you have bought this. It need not be
over an inch in length altogether; and you must put it through the hole
in the top of the boiler, and solder it round on the inside of the same.
The nearer you can get the stop-cock to the bottom of the cylinder the
better the engine will work, because the steam will have to rise through
whatever water is left in this pipe from the jet used to cool the steam.
You will see that it cannot run off by the pipe C into the pump well,
like that which collects in the cylinder itself. In a real engine the
steam-tap was a flat plate which slid to and fro sideways, level with
the bottom of the cylinder; but this you would not make easily at present.
The plug for the safety-valve you must turn out of a little lump of
brass. It must be about three-eighths of an inch long; and you must drill
a quarter-inch hole through it, and countersink one end of the hole
(that is, make it wider and conical by turning a rosebit or larger drill
round in it a few times), to make a nice seat, as it is called, for the
valve itself, which need not be now attended to. Remember you can buy
at Bateman’s, or any model-maker’s in London, beautiful safety-valves
ready-made, as well as any part of a model engine that you cannot make
yourself; and indeed it is so far a good plan at first that it saves
you from becoming tired and disgusted with your work, owing to repeated
failures. If you buy them, therefore, you must do so before you make the
holes above alluded to, but in some respects it will be more to your
advantage to try and make all the details for yourself. I cannot call it
making an engine, if, like many, you buy all the parts and have little
left to do but screw them, or solder them, together. Don’t do this, or
you will never become a modeller.
Your boiler from _c_ to _a_ is, in height, maybe 2 inches, the dome 1½ or
thereabout. This will slip inside the part that you see in the drawing,
and which I here sketch again separately.[3]
[Illustration: Fig. 59.]
A is the boiler lifted out of B, the outer case or stand, which you can
make out of tin, and paint to imitate bricks. It is almost a pity to
waste sheet-brass upon it, because it is not very important, its object
being only to carry the boiler. It is like D before being folded round
and fastened (not with solder, which would soon melt, but) by a double
fold of the joint, similar to that which you made round the boiler
itself, but turned over once more and hammered down. The holes are
punched with any round or square punch with a flat end, and are intended
to give more air to the lamp C, which should have three wicks, or two at
the least, to keep up a good supply of steam. I have shown the _flat_
piece of tin with three legs only, which is as well as if it were made
with four; but you can please yourself in this matter.
The lamp I need hardly tell you how to make, for it is easier than the
boiler, being merely a round tin box, in the top of which are soldered
three little bits of brass tube for the wicks, and a fourth for the oil
to be poured in—the latter being stopped with a cork.
You should remember that no soldered work, like the inside of the boiler,
must come in contact with the heat of the lamp, unless it has water
about it, because if the water should at any time entirely boil away,
the boiler will leak and be spoiled. A little care in this respect will
insure the preservation of a model engine for a long time; but boys
_generally_ destroy them quickly by careless treatment.
Let us now turn our attention to the cylinder. Cut off a piece of
three-quarter-inch brass tube, 2½ inches in length—you can do this with a
three-square file—mount it in the lathe by making a chuck like Fig. 59,
E, of wood, the flange of which is just able to go tightly into one end
of the tube. The other end will probably centre upon the conical point
of the back poppit, over which it will go for only a certain distance.
If your back centre will not answer on account of its small size, you
must make a similar flange to go into the other end; but take care that
when the back centre is placed against it, it runs truly. If the chuck is
well made, it will do so. You can now with any pointed tool turn off the
ends of the tube quite squarely to the side; but you should only waste
one-quarter of an inch altogether, leaving it 2¼ inches long. When this
is done, take it out of the lathe, and in place of it, mount a disc of
brass rather more than one-eighth of an inch thick, or if you have none
at hand, take an _old_ half-penny or penny piece, which is of copper, and
lay it upon the flat face of a wooden chuck, driving four nails round
its edge to hold it, and with a point-tool cut out neatly the centre, of
a size to fit inside your tube. You will scarcely, however, effect this
perfectly without further turning; so take care to cut it too large; but
before you cut it completely through, make the hole for the tube which
you soldered into the top of the boiler, which is three-eighths diameter.
This you can do beautifully in the lathe with a pointed tool, or with
a drill, centred against the point of the back poppit, as I showed you
before.
Cut the disc quite out (too large, mind) and then turn a spindle like G,
mount the disc upon it as shown, by its central hole, and turn the edge
with a graver or flat tool, such as is used for brass, until it will
exactly fit the brass tube. You can cut out round discs of one-eighth
or one-fourth sheet-brass by mounting any _square_ piece on a wooden
face chuck, keeping it down by four nails or screws, and then with a
point-tool cutting a circle in it until the disc falls out. You will
often save time by so doing. You now have a disc of brass or copper
with a hole three-eighths of an inch wide in it; and as the disc is
three-fourths of an inch in diameter (_i.e._, six-eighths), you will have
three-eighths remaining, or three-sixteenths, each way on the diameter
between the edge of the hole and that of the disc. This will just give
room for the two small holes required, one on each side of the central
one, for the pipes from the cold-water cistern and to the well below the
pump. These must both be of brass; and the first should be turned up and
end in a jet, like a blowpipe, so as to make the water rise in a spray
under the piston; the other should be as long as can be conveniently
arranged.
The bottom of the cold-water cistern is drawn a little above the top of
the cylinder, which is 2¼ inches high. A jet would theoretically rise in
the cylinder to nearly the height of the level of water in the cistern;
but with a small pipe, and other drawbacks inseparable from a model, you
must not reckon on more than about half that height, which should be
sufficient to condense the steam. The piston had better be nicely fitted,
but not packed. You cut a disc of brass as before, drill the hole for
the piston, make a spindle, or put in the piston-rod, and centre this
as a spindle, which is the _best_ plan, and then with a flat brass tool
turn the piston accurately to fit the tube. Or, if you think it easier,
or wish to fasten the piston with a nut, as drawn, you can, if you like,
turn it on a separate spindle; and thirdly, you may tap the hole in the
piston, and screw the end of the piston-rod. The great thing to attend to
is, to turn the edge of the piston square to the sides.
For the piston-rod, a steel knitting needle or piece of straight iron
wire will do very well; but it will have to be flattened at the upper
end, or screwed into a little piece of brass, which must be sawn across
to make a fork by which the chain can be attached which goes over the
beam. Do not solder the cistern pipes in just yet, but go on to other
parts.
The cistern itself can be made out of any tin box. A seidlitz-powder box
will answer well, or you can make one about that size, say 4 inches
long, 2½ wide, and 2 deep. The cistern for the pump will, of course,
require to be the same size or a little larger; it may stand on legs or
be fastened to the bed-plate direct.
This bed-plate is shown below the picture of the engine. It is merely
an oblong plate of iron one-sixteenth inch thick, or in this particular
engine may be of tin neatly fastened to a half-inch mahogany board, which
will keep all firm. The white places show the position of the boiler and
of the pump cistern, the inner rounds indicating the lamp, and pump, and
cylinder. The square is merely made to show a boiler of that shape, which
some prefer;—it is not so good as a cylindrical one.
Whenever you have to make an engine, you should draw upon the bed-plate
the position of each part, as I have done here, because it will serve
you as a guide for measurement of the several pieces. The four small
circles at S S show the positions of the legs of the support C, which
carries the beam. In the drawing only two are given, but there would be
a similar triangular frame upon this side. This may be made very well of
stout brass wire, but in a bought engine it would be a casting of brass,
painted or filed bright.
The beam itself should be of mahogany, 6 inches long, half an inch wide
(on the _side_), and a quarter of an inch thick. The curved pieces you
will turn as a ring 3 inches diameter with a square groove cut in the
edge for the chain. You can then saw into four, and use two of these,
morticing the strip of mahogany neatly into them. Then finish with four
brass wires, as shown, which will keep the curved ends stiff and give a
finished appearance. The pin in the centre should be also of brass, as a
few bright bars and studs of this metal upon the mahogany give a handsome
look to the engine.
The pump will be of brass tube, made like the cylinder, but the bucket
may be of boxwood, and so may the lower valve, each being merely a disc
with a hole in it, and a leather flap to rise upwards. The bucket,
however, should have a groove turned in its edge, to receive a ring of
india-rubber, or a light packing of tow. The end of the pump-rod must
be split to make a fork like Y, to allow the valve to rise. You can get
just such a fork ready to hand out of an umbrella, if you can find an old
one; if not, and you cannot split the wire, make the rod rather stouter,
and bend it, as shown, so as to form only one side of a fork, which will
probably answer the same purpose in so light a pump.
The valve in both of these may be made of a flap of leather—bookbinder’s
calf, or something not too thick—and it may be fastened at one edge by
any cement that will not be affected by water, or by a small pin,—cut
off the head of a pin with half an inch of its shank, and point it up
to form a small tack. If the valve-box is of boxwood, you must drill a
hole;—you may make it, if preferred, of softer wood.
There is no support shown in the drawing for the cold-water cistern; but
you must stand it on four stout wires, or on a wooden (mahogany) frame,
which can be attached to the bed-plate. As this last is always of some
importance, I shall add it again in this place (Fig. 60), to a scale of
three-quarters of an inch to the foot, showing the position of each part.
[Illustration: Fig. 60.]
Always begin with a centre line and take each measure from it, and draw
another across for the same purpose, at right angles to the first. You
will quickly see the use of this. We draw two lines as described A, B,
C, D, crossing in _o_. The longest is the centre line of beam, cylinder,
and pump. The beam is to be 6 inches long to the outside of the middle
of each arc, whence the chain is to hang. We, therefore, from the centre
point, set off 3 inches each way. At the exact 3 inches will be the
centres of the cylinder and pump;—set these off, therefore, on the plan.
The end of the tank we must have near the cylinder, because we have to
bring a pipe from it into the bottom of the cylinder. Set off, therefore,
the end of the tank 2½ inches—_i.e._, 1¼ on each side of the central
line, and draw it 4 inches in length. N shows the position of the pipe
close to the end and on the line. The centre of the boiler is the same
as that of the cylinder, so we draw a circle round it with a radius of 1½
inches, which gives us the 3-inch circle of the boiler. Then we may set
off equal distances, N, N, for the extremities of the legs of the frame
which is to support the beam, and we complete our plan. M is the waste
pipe, and K is the opening for the water to flow into the tank. We now
find, therefore, that the bed-plate must be 13 inches long and 6 inches
wide to take the engine of the proposed size, and we may, of course,
extend this a little, if thought desirable. Mark off on the bed all the
lines of the plan as here given, and always start any measurement from
one of the two foundation lines, or else, if you make one false measure,
you will carry it on, probably increasing the amount of error at every
fresh measurement. Let this be with you a rule without exception. It is
plain that if you work all parts of your engine to size, you can set it
up on the marked bed-plate with perfect accuracy.
The description I have given will not only enable you to make a Newcomen
engine with very little difficulty, but will give you an insight
generally into this kind of work; and you will learn, too, a practical
lesson in soldering, turning, and fitting. I must, nevertheless, help you
a little in putting your work together.
You had better begin by soldering into the bottom of the cylinder the end
of the _steam-pipe_, which you have already fixed upright in the middle
of the dome of the boiler, taking care that it stands squarely across
the pipe, or your cylinder will not be upright. Then place the boiler
in position, and you may fix it by turning out slightly the ends of the
legs, and putting a tack through, or screwing, if the bed-plate is of
iron,—or with help of Baker’s fluid you can solder; but this is hardly
safe work, and you had better have a wooden plate, covered with tin, and
tack down the legs. I have drawn you a circular lamp, and given three and
four legs to the boiler-stand; but take care that you so arrange size of
lamp and openings of the stand as to enable you to withdraw the former
for trimming and filling. Now fit in the two small pipes, previously
bent as required. To bend them, if hard soldered or brazed, fill with
melted lead, and then bend; after which melt out the lead again. If soft
soldered, you must fill with a more fusible metal. There is a composition
called “fusible metal,” very convenient for this work, and well worth
making, because you will often need to bend small pipes into various
forms. Melt zinc, 1 oz.; bismuth and lead, of each the same quantity—this
will melt in _hot_ water; 8 parts bismuth, 5 lead, and 3 tin, will melt
in _boiling_ water. You can buy these at any _operative_ chemist’s,
either mixed, ready for use, or separately. Rosin and sand are also
used for bending tin pipes, the sole object being so to fill them that
they will become like a solid strip of metal, and thus bend slowly and
equally, with rounded and not sharp angles.
Pass the two pipes through from beneath the bottom of the cylinder, and
solder them on the upper side of it, so that when the cylinder itself is
added these two joints will not be visible. Then set up the cold-water
cistern; block it up with anything you like so as to keep it in position,
and, inserting the pipe from below, solder this also from above, _i.e._,
on the _inside_ of the cistern. Now, arrange the frame that is to support
it, either stout wire or wood, and set it up so as finally to secure
it in its place. Now, you had better set up the pump cistern, so as to
secure the other small pipe in position, and prevent it from becoming
displaced by any accidental blow. Fix this cistern therefore also, but
leave the cover off for the present, that you may be able to solder the
small pipe _inside_ it.
You will now, at all events, have secured the position of the most
important parts, and you may drop the cylinder into place, and solder
this also round the bottom. This would be facilitated by turning a
slight rebate, Fig. 60, S, round the disc which forms the bottom of the
cylinder, so that the smaller part of it will just fit inside it; but you
will be able to manage it without. Let the cylinder project a very little
beyond the bottom, just to allow a kind of corner for the solder to run
in; it will not show when all is fixed. Do this as quickly as you can, so
as not to melt off the solder round the small pipes. Now, make the pair
of A-shaped supports for the beam. Measure the height of your cylinder
top, above the bed-plate, and allow about another inch, and you will get
the perpendicular height to the axis of the beam. Allow 3 inches more
for each side, that is, in all for _each_ side, 3 inches longer than if
it was to be perpendicular instead of spreading. Take enough brass wire,
about as thick as a small quill, to make two such legs. Bend it in the
middle, like T, Fig. 60, and flatten the bent part by hammering, so as
to allow you to drill a hole to take the pivot on which the beam is to
oscillate. If you like to flatten all of it, and then touch it up with a
file, so as to get quite straight edges, it will look much more handsome.
Make two such pieces exactly alike, and, at distances alike in each, put
cross-bars. File a little way into each, making square, flat notches,
which will just take two flattened bars of the same wire; heat them,
and solder very neatly, so that no solder appears on the outside; file
all flat and true. In this way you can make almost as neat supports as
if they were of cast brass, and you are saved all the trouble of making
patterns. By and by, nevertheless, you must do better.
As I have directed you in this instance to put a wooden bed-plate to your
engine, you may point the ends of the wires, and, making holes sloping at
the same angle in the wooden stand, drive the wires into them. You have
an advantage here, inasmuch as you can raise or lower your stand until
the position of the beam comes exactly right, and you find the ends drop
over the centre of the cylinder and pump-barrel as it ought to do. When
this is the case, you can cut off any wire that projects below the stand
and file it level, for it will not be likely to need more secure fixing.
The pump may now be soldered into the cover of the cistern (before the
cover itself is fastened on), and a hole must be then cut to receive the
water that will flow from the spout, and then the cover can be fitted on.
There is no need to solder it, if it is made to _fit_ over-tightly; and
you may wish, perhaps, to get at the lower valve of the pump now and then.
The only thing left to do is to arrange the safety-valve of the boiler,
which is in many cases the place through which the water is poured to
charge it. In this engine it is, however, plain that you can fill the
boiler by turning both the taps at the same time. A little will run off
by the waste-pipe, but not enough to signify, because the tube below the
cylinder is so much the larger of the two. The safety-valve is a little
bit of brass turned conical to fit the “seat,” made by counter-sinking
the hole. It is shown at K, Fig. 59, N being the seat, O P the dome of
the boiler, and close to O is the gauge-tap for ascertaining the height
of water in the boiler. L M is a lever of flattened wire, pivoted to turn
on a pin at L,—L O being an upright wire soldered to the boiler. A notch
is filed across the top of the valve, on which the lever, L M, rests. The
weight is at M. One, as large as a big pea, hung at the end of a lever 2
inches long, the valve at half an inch from the other end, will probably
suffice for this engine.
CHAPTER XIII.
WATT’S ENGINE.
I have already told you that Watt suggested the use of steam alternately
on each side of the piston; and carried it out by closing the top of
the cylinder, and allowing the rod of the piston to pass through a
stuffing-box or gland. I now have to explain to you how this alternate
admission of the steam may be effected.
You evidently require first an opening at the top and bottom of the
cylinder, communicating with the boiler, one only being open at a time;
but in this case, where is the steam to escape that was on one side
of the piston when the opposite side was being acted upon? It must go
somewhere, but evidently must not return to the boiler. Hence, some
method has to be contrived by which, when one end of the cylinder is
open to the boiler, the other may be open to the air or to the condenser
(in which the steam is cooled under Watt’s plan). Fig. 61 will, I think,
render clear one or two of these arrangements.
[Illustration: Fig. 61.]
The first is the four-way cock, a very simple contrivance, easily and
frequently used in models. You must first understand how a common water
or beer tap is made. Fig. 61, A, represents one in section, turned so
as to open the passage along the pipe to which it is attached; C is the
pipe in which is the tap, a conical tube of brass set upright, and with
a hole right and left made through it, fixed into a short horizontal
tube (generally cast with it in one piece). Into this fits very exactly
the conical plug B, also with a hole through it sideways. When this is
put into place, no water or other liquid can pass, unless the hole in
the plug is in the same direction with the hollow tube forming an open
passage. If a key is put on the square part of the plug, and it is turned
half round, the passage through the pipe will be closed. A steam tap
would be made in a similar manner, if its only office were to open and
close a passage in a tube. But we now want two passages closed and two
opened, and then the alternate pair closed and opened. This is cleverly
effected by a four-way cock.
At D is shown a section of the steam cylinder and piston, with the
stuffing-box and all complete. A pipe enters this at the top and bottom,
and another crosses it in the middle, making four passages. Shaded
black is the four-way cock, the white places showing the open channels
through the plug. When this plug stands as at D, steam can pass from
the boiler to the top of the cylinder only, above the piston, which it
drives downward; the steam below the piston escapes through the other
open-curved channel into the air, or to the condenser. Just as the piston
reaches the bottom of the cylinder, the tap is turned, and the passage
stands as seen at E. Steam now passes to the bottom below the piston,
driving it upward, and the steam above it, which has done its work,
passes outward through the other open channel of the tap.
You must understand that when Newcomen first set up his engine, a man had
to turn the taps at the proper moment; and it is said that one Humphrey
Potter, a boy, being left in charge, and getting tired of this work,
first devised means to make the engine itself do this, by connecting
strings tied to the handles of the taps to the beam that moved up and
down above his head. Beighton and others improved on this, and very soon
it became unnecessary for the attendant to do anything but keep up a good
fire, and attend to the quantity of water in the boiler, and the pressure
of the steam.
In the model I gave you of Newcomen’s engine, I purposely left the taps
to be moved by hand; but F of the present figure shows how, by bringing
them near together, and adding cogged wheels or pulleys, you would make
one handle answer for both; and I shall leave you to devise an easy
method of making the engine work this one handle for itself. When Watt
made his first engine, therefore, this work had been already done, and he
only had to improve upon it, and to make it work more accurately to suit
the engine designed by himself.
If you should chance to pay a visit to the Museum at South Kensington,
you may see, I believe, Watt’s original engine, if not Newcomen’s. The
cylinders are so large and cumbrous, that the wonder is they were ever
bored by the inefficient means then in use; and the beam is a most
unwieldy mass of timber and iron, that looks as if no power of steam
could ever have made it oscillate. Yet it was in its day a successful
engine, the wonder of the age; and did good work for its inventor and
purchaser. I strongly advise my readers to try and visit Kensington, for
there are many interesting models there, besides engines and appliances
of older days. They will thus learn what rapid progress has been made
since the days of Savery, Newcomen, and Watt; not only in the improvement
of the arrangement of the parts, but in the workmanship, which last is
mainly due to the invention of the slide-rest and planing-machine.
We must now return to the double-acting or real steam engine, and
consider a second means whereby the steam can be alternately admitted and
exhausted.
The four-way cock, already explained, was found to wear very considerably
in practice, and hence work loose, and a new contrivance, called the
slide-valve, soon took its place. Of this there are two patterns, the
long D-valve and the short one, which latter is used for locomotives.
There is also a form called a tappet-valve, often used for large
stationary engines, but which is noisy and subject to rapid wear. I shall
describe the long D first, in the form in which it would be most easily
made for a model engine.
The two ports by which steam passes to the cylinder are shown at _d_,
_e_, of H, Fig. 61. C is the passage to the boiler, K is that to the
condenser. These are openings in a tube smoothly bored within, and having
at the top a stuffing-box like that on the cylinder. Within this tube
works an inner one, _b_, having rings or projections at the ends fitting
perfectly, and which are packed with india-rubber, hemp (or, in modern
days, with metal), to make a close fit. In a model, two bosses of brass,
K, soldered on the tube and then turned, make the best packing. These
packed portions of the inner tube form the stoppers to the steam ports,
_e e_, alternately, at the top and bottom. The upper part of the inner
tube has a cross arm, 3, affixed, from the centre of which rises the
valve-rod by which it is moved up and down. In the position 1, the steam
can pass from _c_ round the tube to _d_, and thence to the top of the
cylinder to which _d_ is attached. The exhaust steam passes from _e_
below the piston by _k_ to the condenser. In the second position, 2, the
steam is evidently shut off from _d_, but can pass out at _e e_ below the
cylinder, while the communication is still open to the condenser from
_d_, through the middle of the tube to K. This is a very good form of
valve, because the exhaust is always open, and the motion is smooth and
equal.
[Illustration: Fig. 62.]
There are many modifications of the long D-valve, but the principle of
all is the same; I shall therefore describe the short slide-valve which
is nearly always used in the models which are purchased at the shops.
This, too, is the usual form of valve in locomotives, traction-engines,
and the majority of those in use for agricultural and similar purposes.
A, Fig. 62, is the cylinder as before in section with piston. A thick
piece is cast with the cylinder, on one side of it, having steam ports
also cast in it, which are here left white. The two as before go to
the top and bottom of the cylinder, and have no communication with the
central one, which is bored straight into the boss, and generally is
turned at right angles and connected with the condenser, or with a pipe
opening into the chimney of the engine to increase the draught by means
of the jets of steam, as is the case always in locomotives, or into the
air, which is less usual. Seen from behind, these ports are like B,
being cast and cut rectangular; and the face, B, is planed quite level,
which is absolutely necessary to the proper action of the slide-valve
which has to work upon it. This valve is a box of iron, C, with a wide
flange or rim, this flange being of sufficient width to close either
port. If this valve is placed as it stands when the engine is at rest,
_b_ covers the upper steam port, and _a_ the lower; while the exhaust or
middle port is open to the hollow part of the box. Now, if we slide the
valve downwards until the upper port is open, the other two will be in
communication, being united by being both together in the inside of this
box or valve. Suppose the valve then cased in, and that steam is admitted
from the boiler into the case, it is evident that such steam could freely
pass to the top of the cylinder above the piston to force it downwards,
while that which was below would escape by the lower port into the box,
and thence pass to the condenser. If, instead of pushing down the valve,
we had drawn it upwards, the lower port would have been opened, and the
upper and middle would have been brought into communication inside the
valve, and the contrary effect would have been produced upon the piston.
This is the arrangement adopted, and which will be clearly understood
from the following sectional drawing, D. _a_, _a_, is the thick casting
upon the cylinder, with the upper and lower steam ports, which end
towards the middle of the cylinder, with the third port lying between;
then _b_ is a section of the valve, in such a position that the flange
of it no longer covers the lower steam port, while the other two are
open together on the inside of the valve. The latter is cased in by the
valve-box, _e e_, in the back of which is the steam pipe _f_ coming from
the boiler. The valve-rod, which is moved by the engine, passes at _o_
through a stuffing-box. It is evidently necessary that this slide-valve
should fit, and work very smoothly and correctly against the face of the
ports, so as not to allow any escape of the steam. It is not, however,
packed in any way at the back (although springs have been sometimes
added), because, as the back is subjected to the full pressure of the
steam from the boiler, this keeps it quite close to its seat. The rod,
however, by which it is worked, might prevent this close contact of the
two surfaces if it was screwed into the valve; it is therefore made with
a cross, E, at the end, which falls into a notch in a boss cast upon the
back of the valve as seen at F. This allows a certain degree of play in
one direction, and permits the steam to press it close even after it has
become worn by use.
You will, I think, now clearly understand how steam can be admitted
alternately to the top and bottom of a cylinder, and how the exhausted
steam that has done its work escapes. I must therefore now tell you how
the rod of the slide-valve is moved up and down by the engine, but to do
this, I must draw such engine complete.
[Illustration: Fig. 63.]
The cylinder, A, is screwed down on its side upon the bed-plate, R R, out
of which are cut two holes, one for the fly-wheel, P, of which part only
appears for want of space, the other for the crank, L, on the end of the
axle, M M, running through bearings, N N. The slide-valve-box is at B,
C being the steam-pipe from the boiler. The piston-rod has necessarily
to move only in a straight line in the direction of its length, but
the crank which it has to work to turn the fly-wheel must needs move
round in a circle. Hence, a poker-and-tongs joint, F O F, is arranged.
The connecting-rod, H, which is attached to the crank by brasses at K,
divides or is attached to a forked piece, at the lower end of which are
a pair of bearings or brasses, F F. The piston-rod carries the piece O,
the cross-bar of which is turned, being, in fact, the pin which passes
into these bearings at F F. This forms, therefore, a hinge-joint at this
place, so that although the piston-rod cannot leave the right line, and
can only slide in the guide, E, the rod, H, has an up-and-down motion
upon this hinge, allowing the revolution of the crank-pin to take place.
D is the valve-rod, in which is a hinge at S, which suffices for the
slight movement required in the rod, as it rises and falls by the action
of the eccentric, T, the motion and effect of which I now have to explain.
V is a round disc of metal with a recess on its edge, so that it is like
an ordinary pulley, but large in proportion to its thickness. A hole
for the main crank axle, to which it has to be firmly keyed, is made
through it, but _not in its centre_ (hence its name, eccentric—out of the
centre). As the axle revolves, it is evident that this disc revolving
with it will carry any point, Y, of its surface round in a circle; the
centre of which is on the central line or axis of the crank-shaft. I have
drawn such circle as described by the point Y, farthest from the axis;
but any and all points describe larger or lesser circles round the same
centre. The point Y may, therefore, be considered as the centre of a
crank-pin; and the eccentric might, so far as its effects are concerned,
be replaced by a crank. Now, if you turn the fly-wheel of your lathe by
hand, the crank will revolve, but the treadle will rise and fall only
in a straight line; and you will presently see how the eccentric, in
its revolution, gives just such a to-and-fro motion to the rod D, and
consequently also to the slide-valve, which it has to move.
Round the disc V, closely encircling it, is a flat ring, shown separately
at X, with a rod, W, attached to and part of it. This ring is generally
made in separate halves, united by bolts passing through projecting lugs
or ears. The ring also fits into the groove turned on the edge of the
disc V, so that it cannot slip off sideways. This outer ring is turned
quite smooth and true on the inside, so that the eccentric disc can
revolve within it. In doing so, it is plain that the whole ring will
rise and fall, and that the rod W will move up and down, or to and fro,
like the treadle of the lathe, thereby giving motion to the valve-rod,
which is a continuation of the rod W. As the upper end, however, of this
rod has an oscillating, or up-and-down motion, this is imparted, in a
certain degree, to its other end, at the farthest distance from the
eccentric; and hence the necessity for a hinged joint at S, to prevent
the valve-rod from partaking of this movement. It is, however, very
slight, so that the rod of the valve is not often made to pass through
guides like the piston. The whole movement of the valve-rod is very
limited, its traverse only being required to be sufficient to shift
the valve the width of one of its ports at each stroke. The length of
_stroke_ or traverse which can be obtained by the eccentric is always
equal to twice the distance between its real centre, and that on which it
turns, which will always be a guide to you in making an engine.
[Illustration: Fig. 64.]
The drawing here described is a plan, _i.e._, a drawing viewed directly
from above; therefore I cannot show you the perspective view of the
parts, which are, indeed, in many cases only suggested by the shading.
I have, therefore, added a second drawing of the several details. This
engine is, in construction, the simplest that can be devised with
a slide-valve, there being no additions beyond what are absolutely
necessary to make it work; the exhaust-port is below, opposite to the
letter B on the valve-box. A, Fig. 64, is the forked connecting-rod,
marked H in the previous drawing. This is cast with forked ends, _x_, and
_x_ Y (the latter being F F of Fig. 63). These ends receive brasses in
the following way, the end _x_ being represented on a larger scale at B,
with such brasses in place; of these there are two shaped like D. One of
these lies in the fork of the connecting-rod end. A second similar one
lies in the strap of iron C, which reaches beyond the first. A cotter or
key, which is, in fact, a wedge of iron, is then passed through a slot
in the strap, and a similar one in the rod; and being driven home, draws
the two brasses tightly together, causing them to embrace the crank-pin,
L, Fig. 63, or any similar bearing. All shafts that revolve in bearings
are made to pass through brasses, and whenever these occur at the end
of a rod, they are fitted as here described. E is another bearing of
cast-iron, also fitted with brasses; but in a case like this, a plate
lies on the upper one, and is screwed down by bolts and nuts as required.
This bearing would do very well at E, Fig. 63, as a guide for the
piston-rod; but in models such guide is commonly made without brasses,
like F or G of the present drawing.
At H, I have shown the part F O F of the drawing 63. The middle is
of brass or iron; if of the former, _g g_ must be separate, as these
gudgeons would not be substantial enough, unless of iron or steel. It
is essential that K L, the piston-rod, should be in one right line;
but, if this is attended to, they need not necessarily be one piece;
and frequently the piston-rod, L, is fixed into one end of the central
casting, and another rod, K, is screwed into the other. In a model, the
piston-rod should pass quite through, and _g g_ should be two separate
gudgeons screwed in, and then turned together in the lathe, to insure
their being exactly in one line. These go into the brasses in the forked
ends of the connecting-rod, to form a hinge at that part, as will be
understood by a reference to Fig. 63.
At M, I have shown another simple eccentric and rod, which is less
trouble to make in a model than the other. In this the ring is made in
one piece, with a round rod screwing into it. The disc has a slight
groove turned in its edge, and a small screw, P, passes through the
ring and falls into this groove. This suffices to prevent the ring
from falling off sideways, and of course is not screwed down so tight
as to prevent the disc from revolving. This is a very easy way to fit
the eccentric, and is generally followed in small engines. The lattice
eccentric rod is nearly always used in large beam engines.
I do not think the reader will now have any difficulty in understanding
the precise arrangement of the various parts in the simple horizontal
engine of which I have given a sketch. It is a neat and convenient form,
easily arranged as a model, and I shall proceed at once to the practical
work of constructing this, and engines in general, presupposing a
knowledge of the use of the lathe, and of the few tools required.
CHAPTER XIV.
HOW TO MAKE AN ENGINE.
The very first mechanical work of difficulty, but of pre-eminent
importance, in making an engine, is boring the cylinder, that is, if
the same is a casting, and not a piece of tube ready made and smooth on
the inside. This is, properly speaking, lathe work, yet may be done in
a different way. Suppose you have bought your entire set of castings,
which is the best way, and that the cylinder is half an inch diameter
inside, which is a manageable size to work upon. Get a half-inch rosebit,
which is very like the countersinks sold with the carpenter’s brace and
bits. Mount it in the lathe in a chuck, A, Fig. 65. Unscrew the point of
the back poppit, and slip over the spindle a boring-flange, B, which is
merely a flat plate like a surface chuck, only the socket is not screwed
but bored out, generally large enough to slip over the spindle. Sometimes
there is, however, a screw at the back, to screw _into_ the spindle, the
same as the points or centres. On the face of this lay a piece of board
of equal thickness, but it is as well if not planed, as its object is
partly to prevent the cylinder from slipping about during the operation,
as it is sometimes inclined to do upon the smooth metal flange, and
partly to prevent the borer or rosebit from coming in contact with the
flange when it has passed through the cylinder. Grasp the latter in the
left hand, and you can easily prevent it from revolving with the drill,
which will go through rapidly, and leave the hole beautifully finished
and quite true from end to end,—indeed, I have bored iron also, rapidly
and with great ease, with this tool.
[Illustration: Fig. 65.]
It is absolutely necessary, remember, that this hole bored in the
cylinder should be at right angles to the _ends_ of the same, and to
secure this you must now make use of it to mount the cylinder in the
lathe to turn these ends or flanges. I will show you a simple and easy
way to do this. C is a bar of iron or steel, preferably of the latter,
about 6 inches long, and three-eighths diameter, filed into six sides.
It is a good plan to have three or four sizes of such bars, with centre
holes drilled carefully into each end, so that you can mount them with a
carrier-chuck, as you would if you were going to turn them. Taking one of
about the size named, mount upon it a piece of wood, and turn this down
until your cylinder will just go tightly upon it. Being a six-sided bar,
it is easy to mount the wood upon it by boring the latter with a gimlet
and then driving the bar into it. It will hold tightly, and not turn
round upon the metal. The cylinder being fixed in this way, you must turn
the two flanges with a graver if the cylinder is of iron, but with a flat
tool or the four-sided brass tool if of the latter metal; and also turn
the edges of the flanges. The rest of the cylinder will be left in the
rough, and may be painted green or black. I should advise you always to
bore the cylinder first when possible, and then to mount it as described
and turn it on the ends, which are thus sure to be correctly at right
angles to the bore. Some cylinders, however, especially short ones, may
be squared up first, and then mounted on a face-plate and bored. Unless,
however, you have either a grip-chuck, which is self-centring, or some
clamps properly constructed for this particular work, you will find the
first method the easiest, especially for small light work.
You should now make the ports for steam and exhaust. Mark them upon the
flat part of the casting, after you have filed this as level as you can,
and do not mark them so long as not to leave you room beyond the _ends_
of the ports for the steam-box or case which has to be placed here. The
upper and lower ports are to be the same size, but the middle one may be
a trifle larger with advantage. In larger engines these are cast in the
metal, and have only to be trimmed and faced; but in the small models
you have to drill them out in the boss cast on the cylinder. Drill down
from the top, as shown at D by the dotted lines, but take great care
not to go farther than the _outer_ ports, which are to be therefore
first made, so that you can tell when the drill has gone far enough. If
you pierce the middle port from either end, the cylinder is spoiled.
To cut the middle one, you merely drill a hole straight in towards the
cylinder, and meet it by another drilled from the side, into which the
pipe for the exhaust is to be screwed. You also drill straight through
into the cylinder at _a b_, and you then plug the end of _f_, and that at
the other end of the cylinder. Your port faces, however, are generally
oblong, and not round. Make a row of holes with the drill, and then, with
a little narrow steel chisel and light hammer, chip out the superfluous
metal, and finish with a small file. You can always make narrow channels
with squared sides by thus drilling two or more holes, and throwing them
into one with a file; but in reality, for these small engines, it is very
little matter whether the ports are round in section or square.
The bottom and top of the cylinder demand our next attention. E and F
show these. They are easily and instantly mounted in a self-centring
chuck, but can be held very well in one of wood carefully bored with a
recess of the right size and depth. You must here, nevertheless, be very
particular, else you will get your work untrue at this point, and then
your piston-rod will stand awry, and all your subsequent fitting will
be badly done. I therefore give you at G a section of the chuck bored
to take the cover truly. Recess the part down to the line _a b_, to fit
the cover exactly, taking care to level very carefully the bottom of
the recess. Below this cut a deeper hole, to allow the flange in which
the stuffing-box will be to go into it. It need not, however, _fit_ the
flange. The rough casting will hold very well in a chuck like this, even
if it is of iron. You now carefully face the bottom of the cover, and
turn the slight flange exactly to fit into the cylinder; then reverse it
in the chuck, so as to get the stuffing-box outside; and in doing so,
take the greatest care that it beds flat upon the bottom of the chuck.
Turn off level the top of the flange first at _x_ of fig. E, and then
place a drill with its point against the middle of this, and its other
end (with a little hole punched in it to keep it steady) against the back
poppit centre, and carefully drill a hole down to the level of _c_, large
enough to admit the gland of the stuffing-box or nearly so; but remember
that you must not go too far, because the rest of the hole must only just
allow the piston-rod to go through it. Therefore, after you have drilled
about three-fourths of the distance, replace this drill by a smaller one,
and with it bore quite through. The advantage of beginning in this way
is, that you can now bring up the back centre of your lathe to steady
the cylinder cover while you finish turning it; and as you will have to
make a chuck only to take hold of the flange _b_, while you turn the
edge, you will need probably some extra support of this kind. I have,
nevertheless, turned an iron cylinder cover 2½ inches diameter without
any such support; the actual strain not being very severe, provided you
understand how a tool should be made and held.
The above directions apply equally to the cylinder bottom, the great
secret in this and all similar work being to take care to bed the work
well and truly against the bottom of the recess, turned in the chuck;
this being neglected, will result in the two faces not being parallel,
which will terribly throw out of truth the rest of your work. Indeed, in
all fitting of this kind, it is absolutely necessary to be exact in the
squaring and truing of each several piece that has to be turned or filed;
otherwise no planning or clumsy arrangement will make your mechanism work
as it ought to do. Take a week, if necessary, over any part, and don’t be
content until it is _well_ done.
Your cylinder ought now to have a finished appearance when the cover and
bottom are placed in position, but the latter have to be permanently
attached by small screws, and these I strongly advise you to buy. They
cost about 50 cents a dozen, including a tap with which to make a thread
in the holes made to receive them; or, if you prefer it, you can buy
miniature bolts and nuts at almost as cheap a rate, which would cost you
much time and trouble to make for yourself, if, indeed, you succeeded
at all. You will want four of these for the top, and the same for the
bottom, the holes for which you will make with a small archimedean or
other drill.
The mention I have made of this reminds me that I am gradually adding
considerably to your list of tools, and it is necessary to do so if you
take up model-making. Set down, at any rate, the following:—
ARCHIMEDEAN DRILL-STOCK and 6 DRILLS.
TABLE-VICE.
HAND-VICE or PIN-VICE.
SMALL BRASS-BACK SAWS for METAL.
PAIR of SMALL PLIERS.
And for use in the lathe, either two or three sizes of rose-bits, or
engineer’s half-round boring bits, of which I shall have to speak
presently; and, unless you buy _all_ screws and nuts, you will want
screw-plate and taps, or small stock and dies. Files of square, round,
and oblong section are matters of course. Remember, too, that after a
file has been used on iron and steel, it is useless for brass; so use
new ones on the latter metal first, and after such use they will answer
for cast iron and then for wrought iron. You will find the cost of files
rather heavy unless you attend to this. Have neat handles to all your
smaller files, with ferules to prevent splitting.
When you purchase the castings of the engine, you will find a valve-box
to enclose the slide and become a steam-chest, as explained. It is like
a box with neither top nor bottom, but with a flange, or turned-out
edge all round, for the screws by which it is to be attached to the
valve-facings of the cylinder. This box must have its flanges filed up
bright on their flat sides and edges—the rest may be painted. It will
exercise your skill to get the two faces flat and true, to fit upon the
cylinder; and at last you will find it expedient to put a brown paper rim
or washer between the surfaces, or a bit of very thin sheet lead, to make
a steam-tight joint. Do not solder it, if it is possible to use screws,
because this is nearly certain to get melted off; and, if not, it is not
nearly so neat and workmanlike a way of uniting the parts. You should,
indeed, in all models, put them together in such a way as to be able at
any time to separate the different pieces again, either for the purpose
of cleaning or repair; and, if you solder, you cannot easily do this.
The valve-casing and its back are generally put on together; four screws
at the corners passing through the back and _both_ flanges into the flat
side of the cylinder. This depends, however, upon the exact shape of
these different pieces; and I can give you no special directions for a
particular case unless I could see the castings which you have to fit
together. The stuffing-box you will make quite separate, both its outer
and inner part, and screw or solder the former into place. It is seldom
cast upon the valve-casing, because of the difficulty of chucking a
cubical object safely so as to turn any part of it.
You are not to screw or solder the valve-box to the cylinder until you
have carefully filed up the valve itself to slide upon the port face,
without the possibility of any escape of steam taking place. This needs
the greatest possible care; and probably, after doing what you can with
a flat file, you will have to put a little emery and oil between the
surfaces, and grind them to a perfect fit, by rubbing them together. This
grinding with emery is an operation frequently required in mechanical
engineering. Lathe-mandrels are fitted in this way into the collars; the
cylinder is also ground into the back poppit-head. It is not a very long
or difficult operation, but whenever you have had to use it, take care
to wipe off the emery, or it will keep on grinding. It is indeed very
difficult to do this perfectly; and for very fine work, such as fitting
the mandrel of a screw-cutting lathe (_i.e._, a _traversing_ mandrel),
oilstone powder and crocus are used, in place of emery. These, however,
cut very slowly, making the operation of grinding exceedingly tedious;
and in the present instance, emery will answer quite well enough. In
_very_ small engines, a stroke or two of a file is all that is needed to
fit the valve, which is so small as hardly to be worthy of the name; but
in an engine with cylinder of 1 or 2-inch bore, it will be impossible to
do with file alone, as well as you can with grinding.
The piston and piston-rod should be turned at the same time, as already
suggested in treating of the atmospheric engine of Newcomen. By this, you
will avoid getting the piston “out of square” with its rod, as if you had
bored the hole for the latter askew—a not unusual occurrence.
I do not mean to say that it is absolutely necessary for you to turn
the piston-_rod_ at all, for, in models, it is generally of round iron
or steel-wire, which is as cylindrical as you can possibly make it.
Knitting-needles are in general use for this, as being well finished and
equalised from end to end. But these are rather hard, being tempered only
to about the degree of steel-springs; therefore you must never attempt
to cut a screw on them until you have first heated the end to be screwed
red-hot, and allowed it to cool again very slowly. If you do this, a
screw-plate will put a sufficiently good thread to allow you to attach
either the piston, or the small piece of brass necessary to form the
hinge, upon the other end of the rod—that is to say, the piece marked
H in Fig. 64. Leave this for the present, however, not attempting at
present to cut either the piston-rod or valve-rod to its intended length.
You cannot do this until you have laid down the exact plan of the engine,
and marked on the bed-plate the position of all the parts.
I shall now suppose that you have finished the cylinder, with its
slide-valve, casing, stuffing-boxes, and piston, so that you have these
in exactly the state in which you might buy them at Bateman’s and
elsewhere, if you preferred, to spare yourself the trouble of boring the
cylinder and fitting it. You can buy them just in this condition, with
the rest of the castings in the rough; but I rather hope you may prefer
to try and do for yourself the not _very_ heavy or difficult work which I
have described.
I suppose you, indeed, to have bought the forked connecting-rod, either
arranged for brasses, or with holes drilled (or to be drilled) in the
ends, which would probably be the case for a model of the size named, and
also the various bearings, guides, and so forth required—some of which
would have to be turned, and some filed, but which ought now to present
little difficulty to our young mechanic.
Try to keep sharp edges to all your filed work, unless _evidently_
intending to round them; for surfaces pretending to be flat, but
partaking of a curved sectional form, characterise the workman as
undeniably a bad hand with the file, and not worth his wages. Still I
may tell you at once that nothing is so difficult as to use a file well.
It has a knack of rounding off edges, which always get more than their
proper share of its work. But this being the case, you will know what to
try and avoid. Therefore, always endeavour in filing a flat surface to
make it slightly hollow in the middle, which it is scarcely possible,
however, for you to do; but the endeavour to effect this by filing the
middle more than the edges will help you wonderfully in keeping the
latter sharp. Those, for instance, on the fork of the connecting-rod,
especially the inside ones, should be as straight and sharp as possible;
and if you round the outside edge, take care to do it so that it shall be
evident you intended it; and so with all edges, whether turned or filed.
The disc of the eccentric can only be turned by letting it into a chuck
to something less than half its thickness, and levelling one side and
half the edge, and then reversing it; unless you prefer to drill and
mount it on a spindle upon its centre. If you do this, you will of course
eventually have two holes in it; because this first one is not that by
which it will be mounted when in place. This second hole is not, however,
of the least importance, and may be left without plugging, and, if
preferred, may become in part ornamented by drilling additional holes,
and filing them into some pattern; or if it is desired to conceal the
one it was turned upon, this can be plugged and faced off, and will then
not be the least apparent. If the outer ring, or strap, as it is called,
is to be made in two pieces, with projecting lugs, it is evident the
outside edge cannot well be turned; and, unless you have that most useful
addition to the lathe, a grip or jaw-chuck, you will have some little
difficulty in letting the ring into a wooden chuck, so as to turn the
inside. The solid ring is, therefore, preferable (if you use the first,
however, you turn it up as a single ring, and then saw it across through
the lugs), which can be let into a common chuck, with a place chiselled
out to allow the boss to project, into which the eccentric rod has to
be screwed. This boss also has to be drilled and turned on the outside.
There are several modes of chucking it which can be applied, but the
simplest is to use the carrier-chuck, and to let the ring become its own
carrier by coming against the pin, as shown in Fig. 66, A.
When the ring is _very_ small, I should first drill the hole for the wire
rod, and then screw and mount it upon a little wire spindle, as in fig.
B, aiding this, if necessary, by the back centre. But the smallest models
require to be put into a watchmaker’s lathe or throw, and, except as
curiosities, are scarcely worth making.
I have already told you never to undertake engine-making without first
laying down a full-sized plan on paper, with centre lines through the
principal parts, from which to take all measurements, and to mark these
upon the base-plate, as a guide to the perfect adjustment of the various
parts. Some of these are capable of a little extra adjustment after
being put in place: the eccentric rod, for instance, can be lengthened
or shortened by screwing into or out of the eccentric ring; and the
piston-rod, too, may be similarly lengthened or shortened slightly; but
try to work as near as you can to precise measure without such adjustment.
To turn the fly-wheel, which is the last operation (including the
crank-axle), it is better carefully to drill the boss, if not already
done, marking the centre on each side, and working half through from
each, so as to insure the squareness of the hole with the side of the
wheel, which is very important. Then mount it at once upon its axle,
previously turned slightly conical, where the wheel is to be placed, and
run both together in the lathe. This will insure the wheel running true
when the engine is put together.
In the horizontal engine which I have sketched, the crank is quite
separate from the axle; and this is the easiest way to make it. The crank
itself is filed up, like C of fig. 66, and drilled for the axle and the
pin upon which the brasses on the connecting-rod work. Turn down the end
of the crank-shaft _very_ slightly conical, until the crank will _almost_
go over it. Then heat the crank, which will expand it and enable you to
slip it on the shaft. Dip it in cold water, and it will be as firm as if
made in one piece with the axle. This is called shrinking it on, and the
operation will often stand you in good stead, and save the trouble of
filing key-ways and making the small wedges called keys. The pin D can
in this case be turned up separately, and screwed in, which will complete
the work.
The eccentric must evidently be placed in position before the crank is
added, and this, too, might be shrunk on, were it not that it cannot
easily be fixed in a model until the engine is set up. The best way,
therefore, is, in this case, to turn the eccentric with a little
projecting boss to take a set screw, E, Fig. 66.
Where the axle has to pass through bearings, it must be turned down at
these parts, so that the whole will be like F. First on the right is
the journal, _e_, then the place for the fly-wheel, _d_, very slightly
conical—the smallest part being towards _e_—then the second journal, and
then another slightly conical part, the smallest end towards _a_, to take
the eccentric and crank. The fly-wheel you will key on shaft, thus:—G
represents the boss or centre of the wheel bored for the axle, and a
key-way or slot filed on one side at _a_. There is a flat place filed on
the axle, and the wheel is turned round to bring this opposite to the
key-way. A wedge or key, _b_, is then driven in, which keeps the wheel
secure, and prevents it from turning round or working loose on the axle.
If inconvenient to turn a boss and add a set-screw to the eccentric, this
also may be keyed in its place after its position has been found; but,
for the latter purpose, it should fit rather tightly on the axle, so that
it can be just moved round with the finger stiffly until its position
with respect to the crank is ascertained.
[Illustration: Fig. 66.]
This position I shall now endeavour to explain, using a diagram from an
American work, in which this generally supposed difficult point is thus
ably and satisfactorily explained. First, put your engine together as
if for work, and having cut the eccentric rod to about the length you
seem to require, judging from your plan drawn upon the bed-plate, turn
round the eccentric, with your fingers upon the crank-shaft, and, having
removed the cover of the valve-box, so that you can see the action on
the valve, watch the motion of the latter. Doubtless, the result will be
that one of the steam-ports will be opened clear to the exhaust-port,
while the other is nearly or entirely shut. The rod is then too long or
too short. If in a horizontal engine the port nearest to the crank is
wide open and the other shut, the rod is too long, and must be shortened
_half_ the difference only (_you_ will do this by screwing it farther
into the eccentric hoop). When the valve “runs square,” or opens and
shuts the ports correctly, set the eccentric as in the diagram, H, in
respect to the crank, _i.e._, with its widest part at right angles to
it. By running square is meant that when the eccentric is turned round
as described, the valve opens the ports equally, and does not affect one
more than the other. The line _a_ of the diagram shows that the position
of the eccentric may advantageously be a little _beyond_ the right angle
to the crank, to give what is called “lead,” _i.e._, to open the valve a
little before the piston commences its return-stroke.
The boilers of model engines are made of tin, sheet-brass, or copper;
seldom of the latter, which is, nevertheless, by far the best material,
and one that you can braze, rivet, or solder satisfactorily, or bend into
any shape with a hammer or wooden mallet. When polished, too, its rich
red colour is very handsome. Brass is chiefly used from the facility of
obtaining tubes of it ready brazed or soldered, from which any desired
length can be cut. A brazed copper boiler will stand a great deal of
pressure; will tear, and not fly into pieces when it bursts; and may be
heated after the water has boiled away without suffering any injury. It
would certainly not be worth while to make one for a model engine with a
half-inch cylinder, but for one of 1 inch diameter and 2½ stroke; and for
larger sizes, it will amply repay the trouble; and I will show you how to
make one, with a tube or flue inside to add to the heating surface.
I shall endeavour presently to give the proper dimensions of boilers
to work cylinders of given diameters, but the general directions here
subjoined apply to all boilers of models, whether large or small. The
main body of the boiler is generally cylindrical, and is, in fact, a
tube of sheet-metal, with riveted, brazed, or soldered seams, the last
greatly predominating in the toy engines; the result of which is, that
the first time the water gets too low, out drops the bottom, or, at the
least, divers leaky places appear, and the boiler is obliged to go to the
tinman’s for repair, its beauty being ever after a thing of the past. It
is difficult to braze in an ordinary fire; because even if, by blowing it
with a pair of bellows, you get sufficient heat, you cannot always manage
to apply your work in a good position, as you can over the hot coals of
a forge fire, where there are no bars, hobs, or other parts of the grate
standing in the way. Moreover, you often want both hands free just as the
solder commences to “run,” and forge-bellows will keep up the blast for
a few seconds after your hand is taken from the staff or handle of them.
Still, if you have no forge, which is probable, you should make a fire of
cinders or coke (the latter if possible); and if you can contrive a grate
by putting together a few bricks in some out-house, with a bar or two
of hoop-iron below for the coke to rest upon, you will have a far more
convenient fire to work at than can possibly be obtained in any ordinary
household grate or stove. You will require a pair of light tongs, which
_ought_ to be something like A, Fig. 67; but it is quite possible to
do without these if you can hold your work in any other way; as, for
instance, with a loop of iron wire twisted round it and left long enough
to form a handle.
The first thing to do is to cut a strip of copper large enough to make
the required tube. A piece 6 inches wide will roll up into a cylinder of
about 2 inches diameter (the circumference of a circle being nearly equal
in all cases to three times its diameter, or measure through the centre).
If, therefore, you want one 6 inches across, which is the smallest size
that can be advantageously fitted with a flue or internal tube, you must
cut it out 18 inches wide, and if it is 8 in length to the bottom of the
steam dome, it will be a large and serviceable boiler, fit to work an
engine with a cylinder of 1½ bore by 2½ or 3 inch stroke, which would
drive a small lathe. But observe that if you really have pluck and skill
enough to try your hand upon an engine that will give you real _power_,
you must take care to remember that “the strength of anything is the
strength of its _weakest_ part.” So don’t make the very common mistake
of having a good boiler and ample cylinder, and then fit the engine with
piston-rod, valve-rod, and such like, too small to bear the strain which
you propose to put upon the engine. Remember that every screw and nut
and pin upon which strain is liable to fall, must be of sufficient size
and strength to bear it safely: if not, your engine will not only come
to grief in the heavy trial, but it is quite possible that you also may
become subjected to a bad scald or other disagreeable consequence of your
error.
Whatever sized strips of copper you use for a boiler, the edges have to
come together to form what is called a butt-joint; _i.e._, they do not
overlap like the ordinary joints you see made in tin. Before you coil
up the strip into a tubular shape, you have to cut out holes for any
boiler fittings you may wish to add, such as safety-valve, steam-dome,
and gauges to ascertain the level of the water. These, however, do not
all come into the cylindrical part of our present boiler; the gauge-taps
and glass water-gauge alone having to be provided for. The man-hole,
too, which is added to all large boilers, may be dispensed with, its
object being to enable one to get at the inside, which will scarcely be
necessary if our work is well done at first. A boiler of the proposed
size should be heated with charcoal, as it would require a very large
lamp; but where gas can be obtained, it may be preferably used, a
ring gas-burner being placed below within the furnace. The object of
a steam-dome, which, in a horizontal boiler, would have to be placed
somewhere on the tube itself, is to prevent what is called priming,
_i.e._, the carrying into the cylinder water as well as steam, which
arises from the spurting caused by the violent boiling of the water. The
dome merely provides a chamber for dry steam above the general level of
the boiler, the steam-pipe passing from it direct to the cylinders. Our
present boiler will be vertical like the last, but with a flue up the
middle, and a grate fitted below. It is shown complete in Fig. 67, B,
with all the fittings usually attached.
Having coiled up the tube by hammering it over a cylinder of wood turned
for the purpose, a little smaller than the intended size of the boiler
(the edges having been previously filed up bright, and a width of a
quarter of an inch of the upper being similarly cleaned on the inside
all along the seam), a few loops of iron wire are tied round it, at
intervals of 1 inch or 1½ inches; there being a short piece put round,
and twisted together at the ends by a pair of pliers. The object of
these is to prevent the seam from opening on the application of heat,
which it is otherwise certain to do by the expansion of the metal.
Some borax, pounded in a mortar, and heated to drive off the water of
crystallisation, is next mixed with a little water to form a creamy
paste, and smeared along the inside of the tube, upon the brightened
part, the full length of the seam. It is generally better to heat this
salt first sufficiently to dry it (or rather fuse it), because it swells
prodigiously by the first application of heat, and if the spelter is laid
on it, it often carries it off; after once fusing, it only melts quietly.
Before applying the little lumps of spelter, turn over the tube to heat
the part opposite to the seam, so as to equalise the expansion. Then hold
it in a pair of light tongs, lay the spelter all along upon the borax,
and expose it without actually touching the coals to the heat of the
fire, urged by a strong blast. Continue this until a blue flame arises,
which shows that the spelter has melted; this blue flame being, in
fact, that caused by the burning of the zinc in the solder—spelter being
copper and zinc fused together, or, if required softer, brass, tin, and
zinc. The former is generally used, however, on copper. When the blue
flame arises, the solder runs into the joint, and the work is done. With
the hardest of these spelters, a red heat will not seriously affect the
joint, and, therefore, if at any time the water should get below the
line of this seam, so that it becomes exposed to the heat, no harm will
be done. Nevertheless, this ought never to occur, as a gauge should be
attached to every boiler to show the exact position of the water at any
given time.
The inside tube of this boiler will be seen, from the section, to be
conical up to the level of the lower part of the chimney. This is of
copper, brazed like the cylindrical part, and is 2 inches wide below,
and 1 inch above; consequently, the strips to make it must be 6 inches
wide at one end, and taper to 3 inches at the other. If the dome
rises 2 inches from the level of the top of the cylinder, it will be
sufficient; and as this is a difficult piece of work for a boy to manage,
a coppersmith should be asked to hammer the dome into the required form,
as he will know from experience the best size of circular disc to use for
the purpose. This part is so far removed from the action of the fire that
it may safely be soldered, but it is, nevertheless, as well to rivet it,
turning _out_ both the edge of the cylinder and that of the dome. Use
copper rivets, and make the holes half an inch apart. If you find any
leakage, you can run a little solder into the joint on the inside. The
bottom of the boiler may be quite flat and brazed, a few rivets being
first put in to hold the parts accurately together. The same may be said
of the tube which passes through both this and the dome. There is nothing
equal to riveting and brazing for this kind of work.
I may as well state however here, that as such a boiler as I have now
described is worth very good work, it would be a great pity to spoil
it; and it will be better to content yourself with smaller boilers and
engines soldered, where necessary, until you have had some practice in
brazing. This indeed is not difficult in reality, but, at the same time,
requires great care, because sometimes the solder and the work melt
at so nearly the same temperature, that, like a bad tinker, you will
sometimes make two holes instead of mending one. The brass, for instance,
used for beer-taps is very soft, and contains lead, and to a certainty
would itself melt before ordinary spelter, and could not therefore be
brazed; but the best Bristol brass, or yellow metal, will braze easily.
A blacksmith, brazing a key or other iron article, will braze it in a
different way, using brass wire, with which he will envelop the parts
thickly which are to be united, after securing their position with _iron_
binding-wire. He then sprinkles with borax, and heats the work until the
wire runs into the joint; after which he files and cleans off level. This
makes a very good medium.
[Illustration: Fig. 67.]
I have spoken of _riveting_ in this place. There is no difficulty in this
work. You can buy copper rivets of all sizes, and have only to punch
holes, put a rivet in place, and hammer it so as to spread the metal to
form a second head. If the rivets are heated before being applied, they
will draw the parts closer together, because they shrink in cooling.
All large boilers are made in this way, but smaller ones of iron are
often _welded_, where such a mode of junction is possible. When you can
rivet boilers water and steam tight, you will find no difficulty in
constructing them, for you can make riveted joints where brazing would be
difficult or impossible.
[Illustration: Fig. 68.]
Fig. 67, B, is a half-section of such a boiler as I have just described.
Fig. 68, A, is the lower part, which is separate, and forms the furnace
in which the boiler stands, fitting it closely. This is drawn to scale,
and is half the real size. _a_ is the steam-pipe, fitted high up in the
dome, the tap, _b_, serving to turn on or off the supply of steam for
the cylinder; _c_ is the safety-valve shown in section, and care must
be always taken to make the conical part short and of a large angle,
or it may stick fast, and cause an explosion; _d_ is the glass gauge,
to show the exact height of the water in the boiler. Its construction
will be understood from the other which is attached, where the boiler
is seen in section. There is no need to have two, and this is added
solely to explain the nature of glass-gauges. The top and bottom are
of brass, being tubes screwing into the boiler, or fastened by a nut
inside; a tube, _g_, of thick glass, connects these two, so as to form
a continuous tube, one end of which opens into that part of the boiler
which is full of steam, the other opening below the water-level. Thus the
tube forms practically part of the boiler, and the level of the water is
clearly seen. The lower tap is used for blowing off water, to insure the
communication being kept open, as it might get stopped up with sediment.
Gauge-cocks, _e_, _f_, are generally added, even where the glass
water-gauge is used. One of these should always give steam, the other
water,—the level of the latter being between the two. If the upper one
gives water, the boiler is too full; if both give steam, the boiler needs
to have water added. With these fittings, even a soldered boiler ought
never to get burnt, and will last a long time with care.
The lower part, Fig. 67, is made like that before described, except that,
being intended for charcoal, a circular grate is used, which simply rests
upon little brackets fixed by rivets for this purpose. The flame and
heat play upon the bottom of the boiler, and also pass up the central
tube—the latter adding greatly to the quantity of steam produced. This
furnace, when lighted, may be fed with bits of coke as well as charcoal,
about the size of filberts, and will give plenty of heat. If the draught,
however, is deficient, turn the waste steam into the tube, so as to form
a jet at each stroke, and it will greatly increase it. It is in this way
that the locomotive engines are always fitted, George Stephenson having
first suggested the arrangement. Previously to this a fan had been fitted
below the grate, which was put in rapid motion by the engine, and thus a
sufficient draught was obtained.
THE SAFETY-VALVE.
To find out what pressure is exerted by the safety-valve, it must be
clearly understood upon what principle it acts. I have in a previous
chapter told you that the atmospheric pressure equals 15 lbs. on each
square inch, so that if the surface of the valve which is exposed to the
air is 1 inch in area or surface, it is pressed down with a force of 15
lbs. The steam, therefore, inside the boiler will not raise it until its
elasticity exceeds this atmospheric pressure. If, therefore, we desire
to have only just 15 lbs. per square inch pressing against the inside of
the boiler (_i.e._, a pressure of “one atmosphere,” as it is called),
we have only to load the valve so that, inclusive of its own weight, it
shall equal 15 lbs. But it is plain that we must not load it at all in
reality; for a flat plate, 1 inch square, of _no weight_, is all that
is needed, the atmosphere itself being the load. Suppose, then, that we
_do_ load it with 15 lbs. in addition to the 15 lbs. with which nature
has loaded it, we shall not find the steam escape until it presses with a
force of 30 lbs. on the square inch, or two atmospheres (which, however,
is not 30 lbs. of _useful_ pressure upon one side of the piston, if the
cylinder is open as in an atmospheric engine, but only 15 lbs.) This is
not the _strain_ which the boiler has to stand, because the atmosphere
is pressing upon it and counteracting it up to the 15 lbs., so that
this strain tending to burst it is but 15 lbs. The number of pounds,
therefore, which is straining the boiler can readily be seen; being
always that with which the safety-valve is loaded, and this is also the
useful pressure for doing any required work. Unfortunately, however, even
in the best constructed engines, a pressure of 15 lbs. upon the boiler by
no means represents that in the cylinder. Now it would be inconvenient
to place weights upon the safety-valve itself, and therefore a lever is
added, as seen in the sketch, with a weight hung at one end of it. This
is shown at B, Fig. 68, where a section of the valve is given with its
stem passing through a guide to insure the correct motion of the valve.
The lever is hinged at one end; and the rule of the pressure or weight
which is brought to bear upon the valve is, that it is multiplied by the
distance at which the weight hangs from the valve, compared with its
distance from the hinge or fulcrum. If a weight of 7 lbs. is hung at 1,
_i.e._, at a distance as far on that side of the valve as the fulcrum
is on the other side of it, 7 lbs. will be the actual power exerted; at
2, where it is twice the distance, it will be doubled, and, as shown
in the drawing, a pressure of 14 lbs. will be brought to bear upon the
valve; while, if the weight is hung at 3, it will exercise a force of 21
lbs. This is very easy to understand and to remember. Sometimes (always
in locomotives) the weight is removed and a spring balance is attached
at the long end. Upon this is marked the actual pressure exerted; there
being a nut to screw down, and thus bring any desired strain upon the
spring. Mind, however, in case you should try this in any of your models,
that the scale marked on the balance when you buy it must be multiplied,
as before, according to the length of your lever. Thus, if I attach such
a balance at 3 of the drawing, a real weight of 5 lbs. shown by the
balance will be 3 × 5, or 15 lbs. upon the valve, and a balance _made
for such engine_ would be marked 15 lbs., to prevent the possibility of
dangerous error.
ENGINES WITHOUT SLIDE-VALVES EASY TO MAKE.
Having been led on from the atmospheric engine to that of Watt’s, and
to slide-valve engines generally, I am now going backward a little to
a class easier to make, because they have no slide-valves, nor even
four-way cocks; and then I shall have done with engines. But I dare
say some of my readers will wonder why I have said so little about
condensers and condensing engines. I am sure they will wonder at it if
they understood what I explained of the advantage of a vacuum under
the piston; so that 15 lbs. pressure upon the piston means 15 lbs. of
_useful_ work, instead of 30 lbs. being required for that purpose. But
condensing engines are utterly beyond a boy’s power. They require not
only a vessel into which the steam is injected at each stroke, but there
must be a pump to raise and inject cold water to condense the steam, and
a pump to extract from the vessel again this water, after it has been
used, and a cistern, and cold and hot wells; and all this is difficult to
make _so as to act_; and I am sure no boy cares for a steam engine that
will not work. Moreover, I have given you difficult work as it is—work
that many of my readers will no doubt be afraid to try—yet I did it on
purpose; because if small boys are unequal to some of it, their big
brothers are not, or ought not to be; and mechanical boys must look at
difficulties as a trained hunter looks at a hedge—viz., with a strong
desire to go over it, or through it, or any how and some how to get to
the other side of it. Indeed, you must ride your mechanical hobby very
boldly and with great pluck, or you won’t half enjoy the ride. However,
I am quite aware that I have led you into several difficulties, and
therefore now I propose to set before you some easy work as a kind of
holiday task which will send you with fresh vigour to what is _not_ so
easy.
The engines without slide-valves have also no eccentrics and no
connecting-rods. There is just a boiler, a cylinder, piston, piston-rod,
and crank, and you have the sum total, save and except the fly-wheel.
These are direct-action engines, the cylinders of which oscillate like a
pendulum, and the piston-rod itself is connected to the crank, doing away
with the necessity for guides.
Fig. 69, A, shows one of these engines, and you see that the cylinder
leans to the left when the crank is turned to that side; and if you
turn the wheel to the right, the crank will presently cause it to lean
the other way; and thus, as it turns on a pin, or “trunnion,” as it is
called, it keeps on swinging from side to side as the wheel goes round.
Now, when it is in its first position, the piston is at the bottom of the
cylinder, and it then needs to have the steam admitted below it to drive
up the piston; but when this has passed its highest position, and the
cylinder is turned a little to the _right_, the piston must be allowed to
descend, and, therefore, we must let out the steam below it. We _ought_,
at the same time, to admit steam above the piston to force it down; but,
in the simplest models, which are called single-action engines, this is
not done. The fly-wheel, having been set in motion, keeps on revolving,
and, by its impetus, sends down the piston quite powerfully enough to
overcome the slight resistance which is offered by the friction of the
parts.
Now, you can, I daresay, easily understand that it is possible to
make this to-and-fro motion of the oscillating cylinder open first a
steam-port to allow steam to raise the piston, and then an exhaust-port
to let it blow off into the air. This is exactly what is done in
practice, and it is managed in the following manner:—
[Illustration: Fig. 69.]
B, of Fig. 69, shows the bottom of the cylinder, which is a solid piece
of brass filed quite flat on one side, and turned out to receive the end
of the brass tube, which, generally speaking, is screwed into it to form
the cylinder, this being the easiest way to make it. In the middle of
the upper part of the flat side you see a white steam-port, and below it
a round white spot, which is the position of the pin, or trunnion, on
which it oscillates. Fig. 69, C, is a similar piece of brass, which is
fixed to the top of the boiler. In this, on the _left_ of the upper part,
is also a port, which is connected with the boiler by a hole drilled
below it to admit steam. On the right is also a port, which is merely cut
like a notch, or it may go a little way into the boss, and then be met
by a hole drilled to meet it, so as to form the escape or exhaust port.
Between and below these is the hole for the trunnion.
Now, you can, I think, see that if the cylinder stands upright against
this block, as it does when the crank is vertical (or upright) and on
its dead points, the port at the bottom of the cylinder would fall
between the two on this block of brass, and, as they are both flat and
fit closely, no steam from the boiler can enter the cylinder. Nor do we
want it to do so, because, if the crank is on a dead point, no amount
of steam can make the piston rise so as to move it. But now, if we move
the cylinder to the left, which we can do by turning the wheel, we shall
presently get the crank at right angles to its former position, and,
also, we shall bring the steam-ports in the cylinder and block together,
so that steam will enter below the piston. But, practically to get as
long a stroke as possible, steam is not allowed to enter fully until the
crank is further on than in a horizontal position, that is, _approaching_
its lower dead point; and this is the position in which to put it to
start the engine. By altering the shape or the position of the port a
little, we can so arrange matters as to let steam enter at any required
moment.
Steam having entered, the piston will rise rapidly, forcing up the
piston, and presently, by the consequent revolution of the fly-wheel,
the cylinder will be found leaning to the left, and at this moment the
piston must evidently begin to descend. At this very time the steam-ports
will have ceased to correspond, but the port in the _cylinder_ will come
opposite the exhaust-port in the brass block, and this port is made of
such size and shape that the two shall continue to be together all the
time the piston is descending; but, the moment it has reached the end
of its downward stroke, they cease to correspond in position, and the
steam-port begins again to admit a fresh supply of steam.
The pillar attached to the brass boss has nothing to do with it, but is
one of the supports of the axle of the fly-wheel, as you will understand
by inspection of A of this same drawing.
Such is the single-action model engine, _of no power_, but a very
interesting toy and real _steam_ engine.
The double-action engine is very superior to the foregoing, which, I may
remark, has no stuffing-box, and of which the piston is never packed. I
may also add, that the crank is formed generally by merely bending the
wire that forms the axle of the wheel, and putting the bent end through
the hole of a little boss or knob of brass, screwed to the end of the
piston-rod. Here you have no boring of cylinders to accomplish, but the
cylinder cover, piston, and wheel (often of lead or tin) require the
lathe to make them neatly. Many an engine, however, has been made without
a lathe, and I have seen one with a bit of gun-barrel for a cylinder,
and a four-way cock of very rough construction, that was used to turn a
coffee-mill, and did its work very well too.
But I must go at once to the double-action oscillating cylinder, in
which, although a similar mode of admitting steam is used, it is arranged
to admit it alternately above and below the piston, the exhaust also
acting in a similar manner.
After the explanation I have given you, however, of the single-action
engine, you will, some of you, I think, jump at a conclusion almost
directly, and perhaps be able to plan for yourselves a very easy
arrangement to accomplish the desired end. All boys, however, are not
“wax to receive, and adamant to retain” an impression; for I have known
some who need an idea to be driven into their brains with a good deal of
hard hammering. Stupid?—No. Dull?—No, only slow in _getting hold_, and
none the worse for that generally, if the master will but have a little
patience; for when they _do_ get hold, they are very like bulldogs, they
won’t let go in a hurry, but store up in most retentive minds what they
learned with such deliberation.
THE DOUBLE-ACTION OSCILLATING ENGINE.
The cylinder of the double-action engine is of necessity made with ports
very similar to those of the horizontal engine already described. There
is a solid piece attached to the cylinder as before, which is drilled
down to the upper and lower part respectively of a central boss, turned
very flat upon the face, and which has to work against a similar flat
surface as in the last engine. But the ports in the latter are four
instead of two, and in an engine with upright cylinder would be cut as
follows, and as shown in Fig. 70, C.
[Illustration: Fig. 70.]
Those on the right marked _st_ are steam-ports, which, being drilled into
one behind, are connected with the boiler. The other two marked _ex_,
are similarly exhaust-ports opening into the air. The spaces between _a
b_ and _c d_ of fig. C must be wide enough to close the steam-ports in
the cylinder, when the latter is perpendicular and the engine at rest.
When the cylinder leans to the left, oscillating on the central pin
between the ports in the middle of the circle, the lower port of it will
evidently be in connection with the steam-port in C, while the upper
port of the cylinder will be opposite to the exhaust. As the cylinder
is carried over towards the right, the upper steam-ports will come into
action in a similar way, while the lower exhaust-port is also carrying
off in turn the waste steam. The impetus, therefore, of the fly-wheel
has here only to carry the ports over the spaces _a b_, _c d_, and to
prevent the crank stopping on the two dead points. This, therefore, is
a genuine double-action engine, and will answer, even on a large scale,
very satisfactorily. If you do not quite understand the action of these
ports, cut out two pieces of card, E F. Let E represent the cylinder.
Draw circles, and cut two ports. Cut another piece of card to represent
the brass block, with ports, _c d_; pin them together through the centres
of the circles, and they will easily turn on the pin. Mark the ports, so
that you will see at a glance which are steam and which exhaust. Now cut
out the ports with a penknife, and as you work the two cards together,
swaying that which represents the cylinder to and fro upon the other,
you will see when the ports in each card agree with one another, and
which are opposite to which. This will teach you far better than any
further written explanation. You will also see that, instead of making
the steam and exhaust ports respectively with a division between, the two
steam-ports may be in one curve united, and likewise the two exhausts;
but take care not to unite the exhaust with the steam-ports. There is no
way so easy as this of reversing the action of the steam; it is, in fact,
a circular slide-valve, but wonderfully easy to make, because you have no
steam-case to make, nor any attachments whatever.
The faces of the valve are kept in close contact in one of two
ways—either the centre-pin is fixed into the cylinder face, and after
passing through the brass boss with the ports, is screwed up with a nut
at the back; or else there is fixed a small pillar or upright on the
opposite side of the cylinder, and a little pointed screw passing through
this presses against the cylinder, and makes a point of resistance,
against which it centres, and on which it turns. This is shown at fig.
A. A small indentation is made where the point comes in contact with the
cylinder.
In a locomotive engine there are two such cylinders, working against
opposite faces of the same brass block containing the ports. The cranks
are also two, on the shaft of the driving-wheels, and are at right
angles to each other; so that when one piston is at the middle of its
stroke, the other is nearly or quite at the end of it. Thus, between
the two there is always some force being exerted by the steam; and the
dead points of one crank agree with the greatest leverage of the other.
In locomotives, too, the cylinders generally are made as in the present
drawing, viz., to oscillate on a point at the middle of their length;
but it is just as easy to have the two ports meet at the bottom instead,
so that the point of oscillation may be low down, like the single-acting
cylinders of the last sketch, and this is generally done when the
cylinder is to stand upright.
There is no occasion for me to draw an engine with double-acting
oscillating cylinders, because in appearance it would be like the
single-acting one; but whereas the latter is of absolutely no use,
seeing that the greater part of its motion depends on the impetus of the
fly-wheel, the former can be made to do real work, and is the form to
be used for marine and locomotive engines. For the former, oscillating
cylinders with slide-valves are used in practice; but for real
locomotives fixed cylinders are always used. Of course either will answer
in models, and it will be good practice to try both.
I have now given sufficient explanation of how engines work, and how they
may be made, to enable my young mechanic to try his hand at such work.
The double-action oscillating engines especially are well worthy of his
attention, as he may with these fit up working models of steam-boats and
railway trains, which are far more difficult to construct with fixed
cylinders and slide-valves. I shall therefore close this part of my work
with a description of one or two useful appliances to help him in the
manipulative portion of his labour,—for here, as in most other matters,
head and hand and heart must work together. The heart desires, the head
plans, the hands execute. I think, indeed, I might without irreverence
bring forward a quotation, written a very long time ago by a very clever
and scientific man, in a very Holy Book: “Whatsoever thy hand findeth to
do, do it with all thy might.” Depend upon it, success in life depends
mainly upon carrying into practice this excellent advice. If you take
up one piece of work, and carelessly and listlessly play at doing it,
and then lay it down to begin with equal indifference something else,
you will never become either a good mechanic or a useful man. If you
read of those who have been _great_ men—lights in their generation—you
will find generally that they became such simply by their observance
of that ancient precept of the wise man. They were not so marvellously
clever—they seldom had any unusual worldly advantages; but they worked
“with all their might,” and success crowned their efforts, as it will
crown yours if you do the same.
CHAPTER XV.
HARDENING AND TEMPERING TOOLS.
I promised in a previous page to describe a little stove for heating
soldering-irons, and doing other light work. It is made as follows, and
will be found very useful.
Fig. 71, A, is a tube of sheet-iron, which forms the body of the little
stove. Four light iron rods stand out from it, which form handles, but
these are forked at the ends, and thus become rests for the handles of
soldering-irons, or any light bars that are to be heated at the ends.
Below is a tray, also of sheet-iron, upon short legs to keep it off the
table—for this is a little table-stove. C is the cast-iron grate. You can
buy this for a few pence first of all, and then you fit your sheet-metal
to it. It will rest on three or four little studs or projections riveted
to the stove inside; or you can cut three or four little places like D,
not cutting them at the bottom line, _a b_, but only on three sides, and
then bend in the little piece so as to make a shelf. If the stove is
about 4 inches high above the grate, and 2 or 3 inches below it, and 6
inches diameter, it will be sufficiently large for many small operations;
but that the fuel may keep falling downwards as it burns, the lower part
should be larger than the upper, and, to admit plenty of air, should
be cut into legs as shown. Round the top are cut semicircular hollows,
in which the irons rest. To increase the heat, a chimney or blower, B,
is fitted, which has also openings cut out to match those of the lower
part, so that the soldering-irons can be inserted when this chimney is
put on. If, however, this is not required, but only a strong draught, by
turning the chimney a little, all the openings will be closed. A still
longer chimney can be added at pleasure. A hole should be made at the
level of the grate to admit the nozzle of an ordinary pair of bellows.
This stove you would find of great service, and it may be fed with coke
and charcoal in small lumps. Now you _may_ make the above far more
useful. It will make a regular little furnace, and not burn through, if
you can line it with fireclay. In London and large towns you can obtain
this; and it only needs to be mixed up with water, like mortar, when
you can plaster your stove inside an inch thick or more, making it so
much larger on purpose. There is no need to do this below the level of
the grate; but if you cannot get fireclay, you may do almost as well by
getting a blacklead-meltingpot from any ironfoundry, and boring a few
holes round the bottom for air, and fitting it inside your little iron
stove. In this you can obtain heat enough to melt brass, and it will last
a great deal longer than the iron alone, which will burn through if you
blow the fire much; but for general soldering, tempering small tools,
and so forth, you need not blow the fire, as the hood and chimney will
sufficiently increase the heat. There is no danger in the use of this
little fireplace, but of course you would not stand it near a heap of
shavings, unless you are yourself a very careless young “shaver.”
[Illustration: Fig. 71.]
HOW TO TEMPER TOOLS.
There is no reason why the young mechanic should not be told how to make
his own tools, and how to harden and temper them, because he ought to be
a sort of jack-of-all-trades; and perhaps he may break a drill or other
small tool just in the middle of some special bit of work, or his drill
may be just a little too small or too large, and there he will be stuck
fast as a pig in a gate, and unable to set himself right again any more
than the noisy squeaker aforesaid. But to a workman a broken drill means
just five minutes’ delay, and all goes on again as merrily as before; and
as we wish to make our young readers workmen and not bunglers, we will
teach them this useful art at once.
Drills are made of steel wire or rods of various sizes. In old times they
were made square at one end, to fit lathe-chucks or braces, but now, for
lathe-work, they are generally made of round steel, and fastened into the
chuck with a set screw on one side. In this way they can be more easily
made to run true. But there are so many kinds of drills that I suppose I
had better go into the matter a little—only I have not room to say much
more.
[Illustration: Fig. 72.]
Look at Fig. 72, and you will see some of the more usual forms of drills
used, but these are by no means all. You will not indeed require such a
collection; and yet, if you should grow from a young mechanic into an
old one, I daresay you will find yourself in possession of several of
them. The first, labelled 1, is the little watchmaker’s drill, of which,
nevertheless, this would be considered a very large size. It is merely
a bit of steel wire, with a brass pulley upon it, formed into a point
at the largest end, and into a drill at the other. The way it is worked
is this: At the side of the table-vice—that is, at the end of its jaws
or chops or chaps—are drilled a few little shallow holes, in which the
watchmaker places the point at the thickest end; the drill-point rests
against the work, which he holds in his left hand. A bow of whalebone,
_a_, has a string of fine gut such as is used for fishing, or, if the
drill is very small, a horse-hair; and this is given one turn round the
brass pulley before the drill is placed in position. The bow is then
moved to and fro, causing the drill to revolve first in one direction and
then in the other. The general work is in thin brass, and therefore these
little tools are sufficiently strong for the purpose. Some of the drills
and broaches (four or five, or even six sided wires of steel) are so fine
that they will bend about like a hair, and yet are so beautifully made
and tempered as to cut steel.
No. 2 is a larger drill, even now much used. In principle it is exactly
similar to the last, but the pulley is replaced by a bobbin or reel of
wood, made to revolve by a steel bow with a gut string, or a strong
wooden bow. The drills, too, are separate, and fit into a socket at the
bottom of the drill-stock. The large end is pointed, as in the last,
and is made to rest in one of the holes in a steel breast-plate, _b_,
which is tied to the chest of the operator, who, by leaning against
it, keeps the drill to its work, while both hands are free to hold the
latter steady. There is a modification of this tool, invented by a Mr
Freeman, intended to do away with the bow. The bobbin or reel is turned
without raised ends, and is worked by a flat strip of wood covered with
india-rubber, and turned at one end to form a convenient handle. The
having to twist the bow-string round the drill, which is always a bother,
is thus done away with.
No. 4 is a drill-stock similar to the last, but in place of the
breast-plate a revolving head or handle is put to the top, in which the
point works. This is held in one hand, while the drill-bow is worked by
the other. This is also generally held against the chest, as the hand
alone does not give sufficient pressure. Heavy work, however, cannot well
be done by these breast-drills, and they are liable to cause spitting of
blood from the constant pressure in the region of the heart and lungs.
No. 3 is the Archimedean drill-stock, now very common, but originally
invented by a workman of Messrs Holtzappffel’s, the eminent lathemakers
of London. It now comes to us as an American drill-stock. It is a long
screw of two or more threads, with a ferule or nut working upon it. The
upper end revolves within the head, which is of wood; the lower end is
formed into a socket to receive the drills, which revolve by sliding the
ferule up and down. Some are 14 inches long, and others not more than 5.
The first are used with the pressure of the chest, the latter with that
of the left hand. For light work these are very useful, and you will
seldom need any other in the models of small engines, &c.
No. 5 is another watchmaker’s drill, but serves also as a pin-vice to
hold small pieces of wire while being turned or filed in the little
lathes which are used in that trade, and which are worked by a bow with
one hand, while the tool is held in the other. This is by no means a
useless tool, even without the pulley. It is made by taking a round
(or better, an octagon, or five or six sided) piece of steel, drilling
the end a little distance, and then sawing the whole up the middle. The
slit thus made is then filed away to widen it, and leave two jaws at the
end, which grasp the pin or drill; a ring slips over, and keeps the jaws
together.
We now come to fig. 6, which represents the best of all drills for metal.
It is _really_ American this time, and does our Transatlantic cousins
great credit, as does the machinery generally invented or made by them
(the Wheeler and Wilson sewing-machines for instance). The steel of which
this drill is made is accurately turned in a lathe, and the spiral groove
is cut by machinery. This groove acts in two ways—first, as allowing the
_shavings_ (_not powdery chips_) to escape as the tool penetrates, but
as forming the cutting edges where they (for there are two) meet at the
point. These, however, require a lathe with a self-centring chuck made on
purpose. They are sold in sets upon a stand, chuck and all complete, and
each is one-thirty-second of an inch larger than the other. Some are as
small as a darning-needle, or less, and they run up to an inch or so in
diameter. There are large and small sets.
We now pass to the old-fashioned smith’s brace, fig. 7, shown in
position, drilling the piece _e_. Pressure is kept up either by a
weighted lever, or by a screw, as shown here. The brace is moved round
by the hand of the workman. Very often this tool is arranged on the
vice-bench, so that the work can be retained in the jaws of the vice
while being drilled. Sometimes it is mounted on a separate stand, having
a stool below, and a special kind of vice or clamp is added. Well made,
this is not so bad a tool as it looks, but those used ordinarily in
smiths’ shops are very clumsy, and do not even run true, and the drills
are badly made, although by sheer force they are driven through the work.
Whatever form of drill-stock is used, the main thing is to have the
drills properly formed. You will recognise _k_ and _n_ as common forms,
than which _m_ is considerably better. For cast-iron _n_ would not be a
bad point, because the angle is great, much greater, you see, than _k_;
and the bevels which form the cutting edges of a drill should also not be
too sharp, as they are generally made, for, as they only scrape away the
metal, their edges go directly.
The common way to make a drill is this: A piece of steel wire of the
required size is heated until red hot (never to a _white_ heat, or it
would be spoiled). The end is then flattened out with a hammer, and the
point trimmed with a file. It is then again heated red hot, and dipped
into cold water for a second. Then held where the changes of colour,
which ensue as it cools, can be seen plainly; and as soon as a deep
yellow or first tinge of purple becomes visible, it is entirely cooled
in water. It is then finished, except as regards fitting it to the
drill-stock, which may be done before or after it is hardened, because
care is taken only to dip the extreme point. To get proper cutting
edges the drill is taken to the grindstone, and each side of the point
is slightly bevelled, but in opposite directions, so as to make it cut
both ways. It is not, however, left of equal width, like _o_, but the
flattened sides are ground away, so as to make more of a point, like _p_
and _n_.
Now, this is all right enough as regards forging and hardening, and
tempering, and for the _smallest_ drills this is the only way to make
them. (Only watchmakers heat them in the candle till red, and then cool
and temper by running them into the tallow.) But if you want a good
drill that will cut well and truly, you should file away the sides of a
round bar like _m_, only spreading the point very slightly indeed, just
to prevent the drill sticking fast in the work. Another drill, indeed,
is spoken of very highly, which is also carefully made like _m_, but
the places which are here flat are hollowed out or grooved lengthwise,
the section of the point—_i.e._, the appearance of the _end_ of the
drill—becomes rather curious, like _r_. I am assured by those who have
used them, that these cut quite as well as the twist drills which I have
described already. These which I am now speaking of are also American;
and I don’t know how it is, that somehow America is a far better place
for improvements in tools and machines than our own Old England. And if
I had a wonderful invention—a new birch-rod-making and flogging-machine
for very troublesome boys, for instance—I am afraid I should go to
America to patent it; but I daresay English boys would not object to that.
To teach an idle boy to read,
His mind be sure to jog;
But if he’s very bad indeed,
You’ll be obliged to flog.
Yet if you flog him day by day,
He’ll _never_ learn to read;
For boys require a lot of play
To make them work with speed.
But young mechanics, if they err
Or join the lazy team,
Would all, as I suppose, prefer
To be well flogged by steam.
If not, they had better not let me patent my flogging-machine. Luckily it
is not invented yet.
The _cutting edges_ of drills come under the same rules as other cutting
edges. You might, for instance, hold a large drill flat on the rest,
and use either edge as a turning-tool. You will see at once that these
edges will not cut if made in the usual way, but only scrape. The bevel
wants to be ground only to 3°, as before explained, to give the proper
clearance, and the cutting edge requires to be then made by grinding back
the _upper_ surface, which is just the same in effect as is produced
by twisting the metal or cutting a spiral groove, which hollows out
this upper surface and gives it cutting power. It is no use grinding a
sharper-looking bevel, or making more of a point—you only weaken the
edge; _m_ or _n_ is quite pointed enough, though the first is a right
angle and the second greater; and, for cast-iron, a rounded point,
showing no angle at all, will do just as well, or better, when once it
has begun to penetrate. Do not be deceived, therefore, by making drills
look pointed and keen, for, I repeat, they are scraping tools only,
unless you file an edge by bevelling back the upper face of each side
of the point. If you were to make a very thick, strong drill, you might
begin by grinding back the two sides to 3°, to form the accidental front
line of the point or section angle, and then grind back, _at 45° from
this line_, the upper face, by which you would do just what you did to
give the graver cutting edges of 60°—only a drill thus formed must have a
point of 90°. It would cut in two directions, like one for a drill stock
and bow.
I hope my bigger boys will not pass over the remarks on cutting edges
interspersed in this book, for, once understood, they will be found to
be most valuable. Indeed, they cannot work intelligently until they
understand exactly the nature and principles of the tools which they
have to use. In drilling iron, use water or oil, or soap and water,
or soda-water—either will do; but the holes are drilled in the ships’
armour-plating with soap and water to cool the drill; and very well it
answers, for these plates are several inches thick, but the holes are
soon made. When working in brass and gun-metal, use no water, but work
the drill quite dry. The same rules, in short, apply to drilling as to
turning or planing metal; and if you could see the action of a well-made
American twist-drill, you would recognise this similarity, for you would
see the metal come forth in long, bright curls, as pretty and shining as
those of your favourite young lady or loving sister—_one_ of which you
have, I daresay.
To give you some idea of what a straight course a drill will take, if
rightly made and skilfully used, I may tell you that a twist-drill has
been run through a lucifer-match from end to end without splitting it;
and as to the _fineness_ possible, I have seen a human hair with an eye
drilled through it, by which, needle-like, it was threaded with the other
end of itself.
I told you how to bore a cylinder, which is but drilling on a larger
scale, and in Fig. 65 I sketched the method of doing this in the lathe
with a rosebit. But I did not explain another tool used just in the same
way, but which will bore holes in solid iron wonderfully. Fig. 65, L,
H, K, is one of these. This is an engineer’s boring-bit, and is made of
all sizes, from that required to bore the stem of a tobacco-pipe—(don’t
smoke, boys, it will dry up your brains)—to that which would bore a
cannon. A rod of steel is forged with a boss or larger part at one end.
This is centred in the lathe, and the centre-marks are well drilled, and
not merely punched, especially that at the small end. The boss is then
turned quite cylindrical, after which it is filed[4] away exactly to the
diametrical line, as you will see by inspection of L. The end is then
ground off a little slanting, to give, as before, about 3° of clearance.
The cutting edge thus obtained, and the end in which the centre hole
still remains, are carefully hardened. You thus have a tool which will
bore splendidly, but you must give it entrance by turning a recess
first of all in the work, or drilling, with a drill of equal size, a
little way into the material. Used like the rosebit, this tool will run
beautifully straight, so that you can bore very deep, long holes with it,
and cylinders can be most beautifully bored with it. I think you would be
able to make these tools with a little care; but, when you harden them,
only heat and dip the extremities, or it is ten to one your steel rod
will bend and warp in cooling, and you will not be able to rectify it. If
the ends are quite hard, it is as well that the rest should be soft, as
the tool will not then be so liable to get broken.
There are many other tools used for boring iron and steel, but you need
not trouble yourself at present to learn anything of them—they are no use
to you now.
I have headed this chapter “Hardening and Tempering” tools, but as yet I
have only partially explained the process, which is a very curious one;
and though the _result_ is highly necessary in many cases, it is by no
means well understood what really takes place in the process, or why this
effect should occur in steel, but not in iron, or brass, or other metals.
If you heat a piece of bright steel over a clear gas jet or fire which
will not smoke it, you will see several colours arise as the metal
gets hotter and hotter, until finally it becomes red. These are due to
oxidation, which is so long a word that I am not sure I can stop to
explain it thoroughly. Let us see, however, what we can make of it. The
air we breathe contains two gases, oxygen and nitrogen, with a small
proportion of a third called carbonic acid. Neither of these _alone_ will
support life, or keep the fire burning, or enable vegetables to live and
grow, but it is the first which is in this the chief support. The second
is only used by Nature as we use water to brandy, viz., to dilute it and
render it less strong. If we breathed oxygen alone, we should live too
fast, and wear out our bodies in a few hours. If we breathed nitrogen
only, we should die, and so of carbonic acid. Now this oxygen seizes upon
everything in a wonderful and sometimes provoking manner. If you leave a
bright tool out of doors to get damp, down comes our friend oxygen and
rusts it. It combines with the iron and makes oxide of iron, which is
what we call rust. I suppose, however, this oxygen comes more from the
water than the air, because water is made also of two gases, hydrogen and
this same oxygen. It is certain that oxygen in this case always finds any
bright tools that we leave about in the wet, and coats them with a red
jacket very speedily. Then if you look at a blacksmith at work, you will
see scales fall from the hot iron as he hammers it. These are black, but
our old friend has been at work, and united with the red-hot metal and
formed another oxide of iron, called black oxide. We can understand this.
If a man eats a good deal, or drinks a good deal, he gets red in the
face; if he eats till he chokes himself, he gets black in the face, and
I suppose it is much the same when oxygen eats too much iron. Well, when
we begin to heat the steel, down comes oxygen and begins his work; and
first he looks very pale; then he gets more bilious and yellower; then he
gets hotter and shows a tinge of red with the yellow forming orange; then
he begins to get purple, then blue, then deeper blue; and finally black
before he gets absolutely red and white hot.
Now to temper steel, we first heat it red-hot, not minding these colours,
and then we cool it suddenly in cold water. This renders it very hard
indeed. No file will cut it, or drill penetrate it; but if we strike
it, behold it breaks like glass! This is too hard for general work,
for the edge will break and chip if it meets with any hard spot in the
metal, or chances to bite in too deep. Its teeth are too brittle, and
so get broken off. For this reason we have to “let down,” or temper,
the tool, and we proceed as follows: The part to be tempered is ground
quite bright. It is then laid upon a bar of iron heated red-hot, or
if small, it is held over a gas jet or in a candle; heated, in short,
in any way most suitable and convenient. And now, first, our friend
oxygen puts on a pale yellow face as before. This will do for turning
steel and iron, but is still too hard for general work. Then comes the
orange, and this presently tends slightly to blue; at which point, if
the tool is instantly cooled in water, it will be found to bear a good
edge, hard, but sufficiently tough for work. Most tools for metal and
drills are let down to something between the yellow and blue, and we
know that the more they approach blue, the softer they will be. Thus we
can easily manage our tools;—some to bear hard blows, like axes, which
are tempered to a blue colour; some like files, which a blow will break,
but which are famous for their own special work—these are let down only
to a pale yellow; others, like springs and saws, are let down to a more
thorough blue, because they are required to be elastic and tough, but are
not needed to be so particularly hard. Then tools like turnscrews, and
bradawls, and gimblets are left even softer, sometimes not tempered or
hardened at all, but just forged and ground to the required shape.
Now, I fancy some of my sharp boys will say that the first description
I gave of the mode of hardening and tempering was not exactly like this;
nor was it, yet in principle it is the same. For instance, if you give
a drill to a smith to make, he will do as I then said. He will heat the
extreme point red-hot, then dip the point in water, give a rub on the
stone or bricks of the forge, and watch the colours. This can be done
when the tool is of sufficient substance to retain heat enough after the
edge has been dipped to _re-heat_ that edge sufficiently. In this case
there is no need to chill the whole tool and then heat it again. But in
the case of small drills and tools, pen-knife-blades, and other articles
of this nature, there will not be sufficient heat retained, after
dipping, to bring up to the surface the desired colours; for oxygen likes
a _hot_ dinner as well as you do, and if the iron is not hot enough he
will have nothing to do with it.
One great difficulty you would find if you had much tempering to do,
viz., that the articles bend under the operation, some more than others.
Try this: Take a thin knitting-needle when the owner is not looking, and
run off with it;—it is all in the cause of science! Heat it red-hot,
and with a pair of pliers take it up and drop it _sidewise_ in a basin
of water. It will bend like a bow. Heat again, straighten it, re-heat,
and this time pop it in lengthwise—endwise, point first—I mean (don’t
you see that a round needle has _no sides_, and puts me into a perfect
quagmire of difficulty). However, you will understand this, and will
find the needle not bent nearly so much as before, but still it is not
straight. As I explain most things as I go on, I may as well explain
why this bending occurs before I tell you how to straighten your work
again. All metals expand with heat, and contract with cold. I am sure _I_
contract terribly in the winter until I have had plenty of hot soup, and
hot roast-beef, and plum-pudding; and I know my _temper_ improves, too,
when I get expanded and warm. Well now, when you dropped your sister’s
knitting-needle all hot on its side into the water, that side contracted
before the other, and consequently the needle bent; but when you put
it in the water, _end on_, it was cooled all round at once, and if you
could but cool a piece of metal equally all over, inside and out, _at
once_, all parts would shrink equally fast, and the article would remain
straight.
But there is, unfortunately, another cause of this bending, which is,
that all articles are not of such form that the same quantity of metal
is on all sides of the axial line. Take a half-round file, for instance;
one side is flat, the other curved, so that taking these two surfaces
into consideration, one contains a great deal more metal than the other,
and will not cool at the same rate. These articles are far more liable to
bend than those whose sides are parallel. Another result of the hot mass
being cooled most quickly on the outside is, that cracks are produced
in the latter, because, so to speak, the skin is contracted, and can no
longer contain all the expanded metal within it. Hence, to make a mandrel
for a lathe, it is common to bore it out first, before hardening, to
remove this mass of metal, and to allow the water to touch it inside as
well as out. Such mandrels seldom crack or bend.
The only way to straighten articles which have warped by hardening, is
by what is called hacking or hack-hammering, which is nothing more than
hammering the concave or hollow side with the edge of the steel pane of a
hammer. This spreads the metal upon the hammered side, and, by expanding
it, straightens the tool, for the hollow side, remember, is that which
was too much shrunk or contracted. This is not an operation you will have
to do, especially if you only harden the extreme points of the drills and
little tools you make.
There is another way of hardening, not steel, but iron, called “case
hardening,” because it puts a case of steel over the surface of the
metal. Obtain a salt called prussiate of potash. It is yellow, like
barley-sugar, but is poison. Heat the iron red-hot, and well rub it upon
this salt, and then cool it in water. You will find that now a file will
not touch it, its surface being as hard as glass. It is carbonised on its
exterior, and made into hard steel. This can be done in another way, as
gun-locks, snuffers, and many other things are case hardened. They are
enclosed in an iron box, with cuttings of leather and bone-dust, and
the box is luted about with clay and put in the fire. All the pieces get
red-hot, and the leather chars and blackens, and some of it combines as
before with the hot iron, and makes it into steel. And our friend oxygen
is considerably at a loss in this case to find his way in, or he would
make black scales again and spoil the work; or combine with the carbon
(or charcoal) and make it into gas. Probably, however, as we shut up a
little oxygen with the contents of the box, this change DOES take place,
but _just as the gas rises the iron seizes it_, and holds it fast.
And now, boys, I find it necessary to lay down the pen, which I see has
almost run away with me, and written a good many more pages than I at
first intended. Since I began to write I have visited the workshops at
King’s College, and seen a sight to gladden my eyes. Boys carpentering,
boys turning, boys filing; engines of real use, with single and double
cylinders, finished, and in course of construction, and all these the
work of schoolboys, whose hands and brains are alike engaged in this
delightful branch of industry. Let no one, therefore, pretend that
boys are not capable of executing good work of this kind in a masterly
manner, or that what they do is always child’s-play, or I shall take
up the cudgels in their behalf. I have also seen, in the Working-Men’s
Exhibition, a very neat little engine, made by a boy only twelve years of
age, which makes me hope and believe that the few hints upon wood and
metal work which I have here thrown together will neither be unacceptable
nor useless to those whom I address in these pages. In this hope I take
my leave, and sign myself, with gratification and pride—
The boy mechanic’s faithful friend,
THE AUTHOR.
FOOTNOTES
[1] In the drawing, they are all accidentally drawn of the same pitch.
[2] The parts so jointed are highly exaggerated; when hammered down, the
joint only forms a light beading.
[3] The bottom joint must therefore be hammered close; the upper one will
become a ledge for the boiler to rest on.
[4] In large tools this is not done by the file.
Heroes of the Nations.
EDITED BY
EVELYN ABBOTT, M.A., FELLOW OF BALLIOL COLLEGE, OXFORD.
A series of biographical studies of the lives and work of a number of
representative historical characters about whom have gathered the great
traditions of the Nations to which they belonged, and who have been
accepted, in many instances, as types of the several National ideals.
With the life of each typical character will be presented a picture of
the National conditions surrounding him during his career.
The narratives are the work of writers who are recognized authorities on
their several subjects, and, while thoroughly trustworthy as history,
will present picturesque and dramatic “stories” of the Men and of the
events connected with them.
To the Life of each “Hero” will be given one duodecimo volume, handsomely
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according to the special requirements of the several subjects. The
volumes will be sold separately as follows:
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Large paper, limited to 250 numbered copies for
subscribers to the series. These may be obtained
in sheets folded, or in cloth, uncut edges 3 50
The first group of the Series will comprise twelve volumes, as follows:
=Nelson, and the Naval Supremacy of England.= By W. CLARK
RUSSELL, author of “The Wreck of the Grosvenor,” etc.
=Gustavus Adolphus, and the Struggle of Protestantism for
Existence.= By C. R. L. FLETCHER, M.A., late Fellow of All
Souls College, Oxford.
=Pericles, and the Golden Age of Athens.= By EVELYN ABBOTT,
M.A., Fellow of Balliol College, Oxford.
=Theodoric the Goth, the Barbarian Champion of Civilization.=
By THOMAS HODGKIN, author of “Italy and Her Invaders,” etc.
=Sir Philip Sidney, and the Chivalry of England.= By H. R.
FOX-BOURNE, author of “The Life of John Locke,” etc.
=Julius Cæsar, and the Organization of the Roman Empire.= By W.
WARDE FOWLER, M.A., Fellow of Lincoln College, Oxford.
=John Wyclif, Last of the Schoolmen and First of the English
Reformers.= By LEWIS SARGEANT, author of “New Greece,” etc.
=Napoleon, Warrior and Ruler, and the Military Supremacy of
Revolutionary France.= By W. O’CONNOR MORRIS, sometime Scholar
of Oriel College, Oxford.
=Henry of Navarre, and the Huguenots in France.= By P. F.
WILLERT, M.A., Fellow of Exeter College, Oxford.
=Alexander the Great, and the Extension of Greek Rule and of
Greek Ideas.= By Prof. BENJAMIN I. WHEELER, Cornell University.
=Charlemagne, the Reorganizer of Europe.= By Prof. GEORGE L.
BURR, Cornell University.
=Louis XIV., and the Zenith of the French Monarchy.= By ARTHUR
HASSALL, M.A., Senior Student of Christ Church College, Oxford.
To be followed by:
=Cicero, and the Fall of the Roman Republic.= By J. L. STRACHAN
DAVIDSON, M.A., Fellow of Balliol College, Oxford.
=Sir Walter Raleigh, and the Adventurers of England.= By A. L.
SMITH, M.A., Fellow of Balliol College, Oxford.
=Bismarck. The New German Empire: How It Arose; What It
Replaced; and What It Stands For.= By JAMES SIME, author of “A
Life of Lessing,” etc.
=William of Orange, the Founder of the Dutch Republic.= By RUTH
PUTNAM.
=Hannibal, and the Struggle between Carthage and Rome.= By
E. A. FREEMAN, D.C.L., LL.D., Regius Prof. of History in the
University of Oxford.
=Alfred the Great, and the First Kingdom in England.= By F.
YORK POWELL, M.A., Senior Student of Christ Church College,
Oxford.
=Charles the Bold, and the Attempt to Found a Middle Kingdom.=
By R. LODGE, M.A., Fellow of Brasenose College, Oxford.
=John Calvin, the Hero of the French Protestants.= By OWEN H.
EDWARDS, Fellow of Lincoln College, Oxford.
=Oliver Cromwell, and the Rule of the Puritans in England.= By
CHARLES FIRTH, Balliol College, Oxford.
=Marlborough, and England as a Military Power.= By C. W. V.
OMAN, A.M., Fellow of All Souls College, Oxford.
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