to be changed unless the
total length of each piece and the depth of the center holes are the
same in each case.

=Setting the Tailstock Center with a Caliper Tool.=--Another method of
setting the tailstock center for taper turning is illustrated in Fig. 5.
The end of an engine piston-rod is to be made tapering as at A and to
dimensions _a_, _b_, _c_ and _d_. It is first turned with the centers in
line as at _B_. The end _d_ is reduced to diameter _b_ up to the
beginning of the taper and it is then turned to diameter _a_ as far as
the taper part _c_ extends. The tailstock center is next set over by
guess and a caliper tool is clamped in the toolpost. This tool, a side
view of which is shown in Fig. 6, has a pointer _p_ that is free to
swing about pivot _r_, which should be set to about the same height as
the center of the work. The tailstock center is adjusted until this
pointer just touches the work when in the positions shown by the full
and dotted lines at _C_, Fig. 5; that is, until the pointer makes
contact at the beginning and end of the taper part. The travel of the
carriage will then be parallel to a line _x--x_, representing the taper;
consequently, if a tool is started at the small end, as shown by the
dotted lines at _D_, with the nose just grazing the work, it will also
just graze it when fed to the extreme left as shown. Of course, if the
taper were at all steep, more than one cut would be taken.

[Illustration: Fig. 7. Obtaining Tailstock Center Adjustment by use of
Square]

If these various operations are carefully performed, a fairly accurate
taper can be produced. The straight end _d_ is reduced to size after the
tail-center is set back to the central position. Some mechanics turn
notches or grooves at the beginning and end of the tapering part, having
diameters equal to the largest and smallest part of the taper; the work
is then set by these grooves with a caliper tool. The advantage of the
first method is that most of the metal is removed while the centers are
in alignment.

[Illustration: Fig. 8. Second Step in Adjusting Tailstock Center by use
of Square]

=Setting the Tailstock Center with a Square.=--Still another method of
adjusting the tailstock for taper turning, which is very simple and
eliminates all figuring, is as follows: The part to be made tapering is
first turned cylindrical or straight for 3 or 4 inches of its length,
after the ends have been properly centered and faced square.