58 
THE YOUNG SCIENTIST. 
the fit between it and the shears or bed 
should be good, otherwise it will be im- 
possible to prevent chattering. 
The heads should stand upon long bear- 
ings. A bearing of an inch or two is too 
much like a point, and the back head will 
be very apt to rock unless the bearing is 
long. 
The back head-stock should fit accu- 
rately between the ways or shears, if this 
13 the manner in which it is attached. Of 
course, where the head-stocks slide on 
Vs, there is no danger of getting the 
centres out of line ; but if the back head 
or poppit slides on smooth ways with a 
tongue dropping down between them for 
the purpose of guiding it, unless this 
tongue fits accurately between the shears, 
the head may easily be skewed round so 
that the centres will not be in line. 
We have already spoken of the spindle 
and of the necessity for its running true. 
In order that it may run steadily, it 
should have considerable length between 
tha bearings. 
Some of the cheap lathes in market are 
wonderful specimens of fancy work, being 
gilt and painted to an extraordinary de- 
gree. Avoid all such. See that the article 
you purchase is well made and simply 
finished, but avoid all gewgaws and frip- 
pery. 
Chucking Work on the Lathe. 
BY JOSHUA ROSE, M.E. 
WOKK held in a lathe otherwise than 
by being suspended between the 
lathe-centers, is what is termed chucked. 
The simplest method of chucking is with 
a strap — that is a plate of iron bolted 
across the work. Suppose, for example, 
that it is required to turn out the hole, a, 
in Eig. 1, it would if a small piece be placed 
Fig. 1. 
against the lathe face-plate, b, in Eig. 2 ; a 
plate of iron, c, placed over it, and the 
bar, D, forced against c by the back or 
dead centre of the lathe, to hold the work 
up against the lathe face-plate while 
chucking it. 
Eigure 3 shows how the chucking is 
done. A is the work, b the lathe face- 
plate, and c the plate or clamp holding 
Fig. 2. 
Fig. 3. 
the work to b by means of the bolts, d d. 
An excellent example of chucking by 
plates is a crank, say for a model steam- 
engine, such as shown in Fig. 4. In this 
Fig. 4. 
case the plate is out of the way, so that 
the face, a, can be turned as well as the 
hole bored, hence the face is sure to be 
true with the hole. The pieces, w, are 
balance weights to counterpoise the work 
on the face-place. 
Sometimes a projection, such as b, in 
Eig. 5, prevents the work from going up 
against the face-plate, and parallel pieces 
