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Copyright © 2021 Quality Machine Tools, LLC
PM-1340GT v8 2021-04
TAILSTOCK
The tai
lstock leadscrew is 10 TPI, with a travel of 4 inch
-
es. Like the compound, the tailstock has two graduat
-
ed collars, one reading 0.001”/division, the other 0.02
mm/division. To remove tooling from the tailstock taper
(MT3) turn the handwheel counter-clockwise (handle
end view) until resistance is felt, then turn the handle a
little more to eject the tool. Conversely, to install a taper
tool make certain that the quill is out far enough to allow
firm seating.
Figure 3-19
Tang slot in tailstock quill
For taper turning the tailstock may be offset by adjusting
the set screws on either side, Figure 3-20. To move the
tailstock to the rear, for instance, the screw on the lever
side would be unscrewed, then the opposing set screw
would be screwed in to move the upper assembly.
Figure 3-20
Offset adjustment
A visual indication of the offset is provided by the scale,
but this is not a reliable measure for precise work. In
practice, the only way to determine the offset precisely
is to "cut and try' on the workpiece, homing in on the
correct degree of offset in small increments.
The same issues arise when re-establishing "true zero"
of the tailstock, in other words returning it to the normal
axis for routine operations. One way to avoid cut-and-try
is to prepare in advance a bar of (say) 1" diameter qual
-
ity ground stock, with
precise center drillings
at both
ends (do this by indicating for zero TIR in a 4-jaw chuck,
not in a 3-jaw unless known to be equally accurate). The
prepared bar can then be installed between centers and
indicated along its length.
STEADY & FOLLOWER RESTS
The hinge-type steady rest, Figure 3-21, can be mount-
ed anywhere along the lathe bed. It makes possible
cutting operations on long, slender workpieces between
centers, or held at one end by chuck. The steady rest
is often used in combination with the carriage-mounted
follower rest, Figure 3-22.
To set the fingers on the workpiece, first swing open the
upper casting. Make certain that all three fingers are
freely adjustable by thumbwheel. If not, loosen and re-
lock the set screws. Raise the two lower fingers to just
touch the workpiece — not deflecting it — then close
and secure the upper casting. Lower the top finger to
Figure 3-21
Steady rest
