It is now necessary to speak of hollowing out wood for the purpose
of making boxes, cup chucks, &c., and the latter, which may be made
in any quantity, and of all sizes, will afford excellent practice in
this part of the turner's art. The majority of work of this kind is
done rather by scraping or fretting out than by cutting; side tools
of the forms of Figs. 51 and 56 being used for the purpose. These
however, are specially adapted for ivory and hard woods, the grain of
which, being very compact and close, is not torn out in shreds by the
action of such tools, as would be the case with softer woods. Where
the latter material is used in quantity, as in the manufacture of
wooden bowls, hook tools, like Fig. 57, are made use of, which cut on
their upper edges. These are exceedingly difficult to use, though the
practised hands of those brought up to the art, make them cut with
a surprising ease and rapidity--fairly surrounding the lathe with a
ceaseless cloud of fine shavings removed in the progress of the work.
The difficulty experienced in the use of these tools is not confined
to the novice, for the majority of turners accustomed to hard wood
often cut a sorry figure in the manipulation of softer material with
the aid of the tools in question. The hard and soft wood turners form,
in point of fact, two distinct branches of the trade. We have in part
anticipated this section, by speaking of the making a wooden chuck
when describing the use of the metal chuck with taper screw. We shall,
therefore, proceed to describe the best method of turning a plain
wooden box with cover, but not screwed; the latter being reserved for
more extended notice hereafter. The best material to work upon is
sound Turkey boxwood, and care must be taken that it is quite dry
and well seasoned, or, after it is worked up with, it may be, great
care and trouble, the box will split, or the cover become so loose
as to fall off, either fatality being sufficiently vexatious. We may
mention, in passing, that hard woods of all descriptions may be had
in large or small quantities of Messrs. Fauntleroy[2] and Co., 110,
Bunhill-row, Finsbury, or of Jacques and Sons, Covent-garden. Most of
the lathe-makers also supply it, especially Holtzapffel and Co., of
Charing-cross, but the first-named is a large dealer, wholesale and
retail, and his charges are moderate.
[2] Now Messrs. Mundy and Berrie.
[Illustration: FIG. 51, 52, 53, 54, 55, 56, 57.]
Supposing a selection made of size proportionate to that of the
intended box, including cover and a tolerable margin for waste and
accidents, proceed as before to rough it down between two centres
and thus to reduce it to a cylindrical form--there is, however,
no occasion to use the chisel at present, as we only need a rough
cylinder. Remove this from the lathe, and if you have no brass cup
chuck into which you can fit it, proceed to make one out of a piece
of beech, ash or, if you have plenty, boxwood. Do not hurry the
work, but cut the chuck out neatly, screw and fit it, as previously
directed, on the nose of the mandrel. We shall suppose it as yet
merely a short neat cylindrical block, quite solid. Place the rest
with the tee across the end of the piece of wood, the top edge a
little below the centre (by the thickness of the blade of the tool).
For the latter select one of the three following--either will answer
well--58, 59, 60. With one or the other drill a hole in the centre,
keeping the tool quite horizontal across the rest. Enlarge this hole
by a left side tool, working from the centre of the piece towards the
outside, not taking the whole depth at once, but a quarter or half an
inch at a time. You must hollow it out about one inch, and see how
nicely you can fit the hollow to the size of the piece you are going
to turn. You will, of course, have squared up one or both ends of the
latter, which must now be driven tightly into the hollow chuck. If you
squared the ends of the cylinder correctly and left also the bottom of
your chuck level and true, you will be gratified by seeing the piece
run evenly at once.
[Illustration: FIG. 58, 59, 60.]
Fig. 61 shows a section of the chuck with the piece to be turned
fitted inside it. Now take the gouge and chisel and reduce the piece
to a plain cylinder, and take special care to square up the outer
end. This may be done by the aid of a carpenter's chisel held across
the rest, like the side-tool. If the end is much out of truth you had
better use first the round-ended tool, Fig. 60, but if you have worked
carefully from the commencement this will be unnecessary.
To ascertain the correctness of this part, apply a small steel square
like Fig. 62, the blade of which slides through the brass part and is
clamped by a small screw at the side. We show the method of applying
this tool to gauge depth, test right angles, &c., in Figs. 63 and 64.
It is a most convenient and necessary instrument, and should be at
once provided. Having thus ascertained that the end of your cylinder
is at right angles with the side, take the point tool, Fig. 58, or the
acute corner of your chisel, and, setting the lathe in motion, mark
off the intended depth of the _cover_, as D, C, Fig. 61. (Observe,
it is the cover and not the box that first demands attention.) Now
proceed to hollow out the cover as you hollowed out the chuck, but
with greater care. You must allow in the thickness of the top rather
more material than you will eventually require, the thickness of the
sides, also, may be a trifle in excess, but take the utmost care to
make the inside rectangular, that is, the line _f, g_, perpendicular
to g, D. Upon the correctness of this the fit of the cover will
depend. This being done and tested as to truth with the square, as
before, you may cut off the cover with a parting tool, Fig. 65. This
tool is thin, with a cutting edge at the end, and is held edgewise
upon the rest. The blade is made rather thicker near the end, so that
as the tool penetrates the work it may not bind, but allow the small
chips made by it to escape freely. The rest must be removed from
its former position and placed parallel to the side of the piece,
and the tee at such a height that the latter may, when the tool is
held horizontally, point to the axis of the work. The tool should be
occasionally withdrawn, and the point, instead of being kept precisely
in one position, may be slightly raised and lowered from time to
time, describing a small arc. It will soon be ascertained in what
position it cuts most easily. There are different sizes of parting
tool, some very thin in the blade, for ivory and precious woods, some
thicker, for box and less valuable stuff, some with a notched end,
forming two points, for soft woods, the action of all being similar
to a saw tooth, or, in the last, to two adjacent saw teeth set out to
clear themselves in working. Care must be taken that the thin blades
do not bend and twist while cutting, especially after the cut has
become deep. To avoid this do not hurry the work, but take a little at
a time, and be careful to keep the tool with its sides perpendicular
to the rest. With these precautions the cover will soon be cut off
neatly. If care is not taken to allow for the necessary thickness of
the cover, the turner will be mortified by finding that instead of
the latter, he has merely cut off a ring, and he will have to expiate
his want of judgment by beginning a new cover and making a shallower
box. We name this to put him on his guard. Supposing the above work
satisfactorily accomplished--the top of the cover, however, being
(as will probably be the case) either convex or concave, requiring a
little touching up and finishing, it will be necessary to turn down
on the solid bit of wood left in the chuck the part A, B (Fig. 66),
on which the cover will eventually rest. On no account, however, must
this be now turned small enough, it must be left so large as not quite
to enter the cover, because if it is now nicely fitted, and the box
subsequently hollowed out, the cover is sure to be too slack, the
wood shrinking in the process of hollowing out. This shrinking may be
accounted for by supposing the rings of woody fibre, the result of
yearly growth, naturally elastic, with a tendency to contract, each
one, like a series of india-rubber bands, embracing that within it.
The central ones being removed by the tool, permit the outer ones
to contract, their particles approaching nearer to each other and
the structure becoming more dense. This tendency causes those radial
cracks so often seen in the ends of pieces of wood sawn from the trunk
or limbs of the tree. The outer parts becoming drier than the inner,
and prevented by the latter from shrinking, necessarily split, hence,
when it can be done, the centre of such pieces is bored out, while the
wood is yet full of sap, and the rest is thereby preserved. Where this
cannot be done the ends may be covered with glue or resin; or paper
may be glued on, to prevent access of air, and thus the drying of the
outer portion may be so retarded as only to keep pace with that nearer
the centre. The concentric rings thus shrink equally, and no radial
splitting takes place.
[Illustration: FIG. 61, 62, 63, 64.]
[Illustration: FIG. 65, 68, 66.]
We will now return from this explanatory digression to the work in
hand. Having cut down the flange for the cover to nearly the required
size, proceed to hollow out the box. Work carefully, so that the
sides shall be smooth and perpendicular to the bottom, and the latter
plane and neat. Take care, as with the cover, to leave the necessary
thickness of bottom, allowing for the cut of the parting tool, and,
if possible, half an inch or more beyond it. Now finish that part on
which the cover is to rest. Take great care, as before, to secure
right angles, and cut away the wood little by little, trying on the
cover from time to time, until at last it will just go smoothly and
stiffly into its place. It must fit rather tightly, but take especial
care not to force it on, or you will split and spoil it. We shall here
introduce to the notice of the reader another form of callipers useful
in such work as the above, and in many cases absolutely necessary.
They are called in-and-out callipers, and are made as shown in Fig.
67. These are so arranged that whatever interval exists between _a_
and _b_, exists also between _c_ and _d_. If, therefore, the inside of
a box cover (or similar article) is measured by the latter, the other
end of the instrument will show the exact size to be given to the part
A, B, Fig. 66. The convenience of such an arrangement for an infinity
of cases will be apparent on an inspection of the figure.
[Illustration: FIG. 67.]
[Illustration: FIG. 69, 70.]
The cover of the box must now be put on, the lathe set in motion,
and the outside, and also the top of the cover, carefully turned and
finished. If the box is to be cylindrical, care should be taken that
it is truly so, and that the angle formed by the junction of the top
and sides is sharp. If sand-paper is used to finish the work, the
edges will be rounded and the workmanlike appearance spoiled. If,
therefore, the article is made of box or other hard close-grained
wood, this finishing-off may be done with a carpenter's chisel held
so as to act as a scraper. The turning chisel will answer the same
purpose, but it is a pity to spoil the edge, which should be always
preserved keen and fit for use. If the box is made of soft wood,
scraping will not answer; the turning chisel must then be made use
of, held as previously, described. If the cylindrical form is not
proposed, the sides of the box must be left thicker, and after the
cover is fitted on the outside may be moulded by the gouge and chisel,
and tools like 60 and 68 to 70, to any desired pattern. The only thing
remaining to be done is to cut off the box with the parting tool, the
same precautions being observed which we spoke of in separating the
cover. If there should be any defect in the bottom after the work is
detached, the box must be placed in a cup chuck turned to receive it,
and the above defects removed.
In hollowing out a piece of solid ivory or similar costly material, it
would be exceedingly wasteful if the central part were removed as in a
common box, by being reduced to small chips. It is possible to remove
the whole interior in a solid block, and with exceedingly trifling
loss of material. This is effected by means of side parting tools,
71, 72, 73. A common parting tool is first used and a groove cut
therewith in the face of the block to be turned. Fig. 74 represents
this face 75; the section after the groove is cut the depth of the
box required. The shaded part in the centre represents the part to be
removed. The smallest parting tool, Fig. 73, is now introduced, the
back of the tool being laid across the rest, so that the crook takes
a perpendicular position, A, B, Fig. 74. When at the bottom of the
groove the hook is turned to the left, so that it may cut a groove
underneath the block, until stopped by its shank. It is then withdrawn
and Fig. 72, and subsequently Fig. 71 introduced, and used in a
similar way. In Fig. 76 the black line shows the tool in position,
with the under cutting done by it. The sizes are thus increased until
the last tool removes the block entire.[3]
[3] The side parting tools are sometimes inserted in the centre
of the work, a hole being made for their introduction, they then
cut from within outwards. In this case, however, instead of a
solid piece a thick ring of the material is detached.
[Illustration: FIG. 71, 72, 73.]
[Illustration: FIG. 74, 75, 76, 77.]
We now propose to describe the method of turning a round ball or
globe, and, to make the work more interesting, it shall contain a
small box. The first thing necessary is to decide upon the diameter.
In the present case let it be an inch and a half. Turn a cylinder of
boxwood a little exceeding this, and cut off from it rather more
than an inch and a half in length. The excess is merely to allow for
waste. You will thus have a cylinder whose diameter equals its length.
Before removing it from the lathe, mark its centre by a groove with a
point tool--subdivide the outer spaces with five lines, and from the
latter remove the corners of the piece, thus reducing it to the form
77. Test the length and breadth by the callipers and take care that
the ends of the cylinder are at right angles to the sides. Now place
the piece in the chuck in the position shown in the figure, that is,
at right angles to its original position in the lathe. It must be
tested as to truth by holding a point tool on the central line E, F.
If correctly placed this will only make a dot when the lathe is put in
motion. If the piece does not lie evenly the point of the tool will
make a small circle--it must then be corrected with a light tap or
two, until it runs evenly.
If the inside of the chuck is rubbed with chalk the work will be less
liable to slip. The following operation, however, must be conducted
very gently and with exceeding care, or a satisfactory result will not
be produced. It will be observed that the central line having been
marked or cut upon the side of the cylinder is necessarily a circle,
and its revolution on its axis forms a sphere.
We have therefore only to cut away the piece truly down to this line
to finish what _ought_ to be a perfect globe. Bergeron, however,
justly remarks that although the theory is correct it is next to
impossible to manage the tools with sufficient skill to complete in
this way a true sphere. One great cause of this difficulty, is that
as the work revolves in its new position the central line is not
visible as a line, but simply becomes the boundary of the sphere. This
may be in part done away by making a _red_ line or black one (red is
the best) instead of a mark with the tool. The work will then appear
red as it revolves, and the gouge and chisel must be used to cut
away this red part, great care being taken only just to remove what
appears coloured. Thus you will in the end have cut the work away so
as _barely_ to remove the line. Work from the central part outwards,
and always with exceeding care, and you will eventually succeed to
your satisfaction. It is, nevertheless, a very difficult bit of work
to finish even fairly well--mainly on account of the great obscurity
of your landmark, the red line. For the more perfect finishing of the
above a template of steel may be made like Fig. 78, with which to
test the work--its diameter is equal to that of the sphere, and it
will serve as a gauge or scraper. It should be made of saw plate if
intended for the latter purpose, otherwise sheet brass will answer as
well. After the semi-globe has been turned in the first chuck, it will
be necessary to turn another to receive the finished part, and for
the more perfect formation of the same a semicircular template of the
same gauge as the concave one first made may be provided, as the more
nicely the ball fits the chuck, the less chance there will be of the
work shifting during the turning of the latter half of the sphere.
[Illustration: FIG. 78.]
In order to obviate the difficulty of following the diametrical line
with the cutting tool, the following contrivance has been suggested
to the author by one who has followed lathe work as a profession
for many years, and is an adept at the art. The lathe band is to be
slightly slackened by partial untwisting (a turn or two will suffice),
if of catgut, so that it will carry round the pulley, if desired, but
will slip if the hand is placed on the latter. Thus, the tool may be
applied, and a light cut taken, and the work instantly stopped for
examination without stopping the lathe, as the flywheel continues to
revolve all the time. This examination can be repeated, if necessary,
every few seconds, by merely placing the hand on the pulley, and in
this way the work being carried on little by little, a good result is
attainable with comparatively little difficulty.
The best position for the rest during the above operations will be
across the face of the work, as in hollowing out boxes, working
carefully, little by little, from centre to circumference. Towards the
finish a scraper should be used, the common carpenter's chisel being
as good a tool as any. Now to proceed with the box. Before removing
the finished ball from the chuck, bore it through with tool Fig. 59,
enlarge with Fig. 51, and make the hole conical, unscrew the chuck,
with the ball remaining in it, and put on another with a piece of
boxwood large enough to make a plug to fit this hole. This plug, when
fitted, is to be hollowed out, and converted into a box, like Fig. 79.
The latter, when put in place, must fit so neatly that only a light
circle shows its position. To conceal it still more completely, a
series of circles are to be set at each of the six sides of the ball,
as shown at Fig. 80. To remove the box, the thumb is placed at the
small end, and pressure made. This forms a neat pocket needle-case,
and may be made of ivory as a present to your lady-love.
[Illustration: FIG. 79.]
[Illustration: FIG. 80.]
There is no practical difficulty likely to be met with in the above
after the round ball is itself made, unless it may arise in respect
of the conical hole. Let this be turned out as directed, until at the
furthest (smallest) end it will just allow a gauge, like the annexed
figure, 80A, to pass through it.
[Illustration: Fig. 80A.]
Having also gauged the large end of the hole to the desired size,
take care to finish the side evenly from one to the other. The gauge
may be a disc of tin on a wire, or, still better, a short cylinder of
box wood, on a similar handle, as there will be a little difficulty
in feeling whether the disc is placed at right angles to the axis
of the hole. Unless, however, you desire to work to a pre-arranged
exact measurement, the above precautions will scarcely be necessary,
inasmuch as the hole is first bored, and the conical plug afterwards
fitted to it. The ball may, therefore, be taken from the chuck, each
end of the bore measured, and the plug gauged at each end by the
callipers, and turned to an exact fit.
In the above account the unmathematical phrase of "_six sides_ of the
_ball_" is used for want of a better; the _meaning_ of the author
will, however, be evident.