FANCY TURNING.
[Illustration: Fig. 51.]
Fig. 51 is another, a little more ornate and of a different pattern.
The process is essentially the same, except that there are no spurs and
a solid disk is left inside. This disk is turned out of a ball, left
inside the exterior shell. One side of it is squared up before the ball
is cut free from the globe, and the job is then reversed and the other
side squared. The ball is then cut free, and the loose disk is held
fast between a flat-ended driver in the live spindle, and a loose,
flat-ended button on the back center. The diameter is then decided
through the hole which is toward the reader.
[Illustration: Fig. 52.]
A little tool, which is very convenient for making small screws, is
here shown in Fig. 52, rather out of place, but it was overlooked
before. In construction it explains itself. Holes of different sizes
are made in a steel rod, and the end filed into shape, as seen. It has
been found difficult by some to make these cutters work, but that was
because they were not properly made. The trouble lies in drilling the
hole. When the drill starts at first, the hole is larger on the
outside, so that the screw blank, when cut, gets tighter as it goes in,
and twists it off.
The remedy is, to drill the hole in some distance and then turn off the
outside end, so that it gets where the bore is the same size. This
refers only to small bolts, a sixteenth of an inch in diameter; where
they are large, the trouble mentioned is not experienced.
It is convenient to have two sizes in the tool so that the heaviest
part of the work can be done by one cutter, the tool reversed by
turning it over in the fork of the jaws, and finishing the blank with
the last cutter. A watchmaker’s fine saw is to be used to sever the
screw from the rod. The tool itself is to fit in the spindle of the
tail stock, and the screw wire is held by a drill chuck.
In the matter of ornamental work, there are other details and plans in
vogue among experienced turners, which can only be alluded to, not
discussed at length, for the reason that the styles are so numerous
that an elaborate work might be made of them alone, with great profit.
The scroll chuck or geometrical chuck, as it is sometimes called, is a
complicated piece of mechanism, too costly for general use, and too
limited in its application, to mechanics in general, to be of much
utility. It does such work as may be seen on bank bills. The chuck
plate, on which the work is fixed, is connected, by a train of gearing
on its back, with a fixed gear about the spindle on the head stock, so
that when the relation these gears bear to one another is altered, the
motion of the work on the chuck is accelerated or retarded, or is made
to assume certain positions. An elliptic chuck is quite another thing,
the work done by it is shown in Fig. 53, which consists, chiefly, of
ornamental designs disposed in a certain order. In fact, the changes
that can be made are infinite.
[Illustration: Fig. 53.]
Mandrels—arbors, as many call them—are very useful tools. Mandrels
are made of wood and steel—usually steel, and never of wood, unless
for some special reason. As, for instance, when a large brass ring has
to be turned. For this use a wooden mandrel is cheaper and more quickly
made than a steel one. Besides, it is quite as good. Wooden mandrels
should have iron center plates let in them, so that they will run true;
if the center was made in the wood itself, it would be liable to run
out. Take a piece of sheet iron, one eighth of an inch thick and one
inch square, hammer the corners thin, then turn them over at right
angles with the plate. This gives four sharp corners, so that, when
driven in the end of a block, it will not slip; three small screws will
hold the plate to the mandrel so that it cannot get loose. The center
must then be countersunk, as any other is. Such a mandrel, made of hard
wood, hickory for instance, will last a long time.
Fibrous wood such as white oak, makes a good mandrel, for the reason
that work, driven on it, compresses the fibers instead of scraping
them, so that the size of the mandrel is unchanged.
Steel mandrels should be turned two in one, or largest in the middle,
for small work, each end being a different size. Each end should be
thoroughly centered with a drill, and countersunk, and a flat place
filed so that the dog will hold; not a scratch with a tool should ever
be made in one, though few persons will take the pains to avoid doing
this.
It is unnecessary to tell the mechanic he must have a rack for his
tools, but we may tell the beginner so, and he will find it a great
convenience.
Now-a-days, the twist drills, made and sold in all the tool stores, are
so uniformly superior to any thing that can be made by hand, or by
individuals, and are, moreover, so cheap, that it is foolish to make
drills. Those who have never used them, should not fail to order sets.
They run all sizes, from a needle to an inch.
There are not a few turners who spoil work simply from heedlessness.
Not because they do not know any better, but because they are averse to
taking a little extra pains. If a mandrel runs out of truth a very
little, sooner than alter it, or make a new one, they will try to “make
it do.” The result is easily seen when work is to be put together.
Moreover, many persons use little caution in setting their work in the
lathe. Instead of always putting it in the same place, driving it from
the same side of the face plate, it is entered at hap-hazard. It is not
good to get into the habit of doing work in this way, for it soon leads
to recklessness.
Some are too lazy to go and grind their tools, when they know it should
be done, and continue to use them to the ultimate damage of the work.
It is easy for the practiced eye to see these apparently small things,
for they constitute a great part of the difference between a good
workman and a bad one.