Machinery Repairman

The compound rest swivel (2), which can be
swung around to any desired angle and
clamped in position. It is graduated over an arc
of 90° on each side of its center position for
ease in setting to the angle you select. This
feature is used in machining short, steep tapers
such as the angle on bevel gears, valve disks,
and lathe centers.
The compound rest top, or topslide (3), is
mounted as shown on the swivel section (2) on
a dovetailed slide. It is moved along the slide
by the compound rest feed screw turning in the
nut (4), operated by the handle (5), in a manner
similar to the cross feed described previously
(fig. 6-8). This provides for feeding at any
angle (determined by the angular setting of the
swivel section), while the cross-slide feed
provides only for feeding at a right angle to the
axis of the lathe. The graduated collar on the
compound rest feed screw reads in thousandths
of an inch for fine adjustment in regulating the
depth of cut.
ATTACHMENTS AND ACCESSORIES
Accessories are the tools and equipment used in
routine lathe machining operations. Attachments are
Figure 6-13.—Castle-type toolpost and toolholder.
6-11
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special fixtures that may be secured to the lathe to
extend the versatility of the lathe to include
taper-cutting, milling, and grinding. Some of the
common accessories and attachments used on lathes
are described in the following paragraphs.
TOOLPOSTS
Three popular types—standard, castle, and quick
change—are discussed in the following paragraphs.
The sole purpose of the toolpost is to provide a rigid
support for the toolholder.
The standard toolpost is mounted in the T-slot of
the compound rest top as shown in figure 6-12. A
toolholder (13) is inserted in the slot in the toolpost
and rests on the toolpost wedge (11) and the toolpost
ring (12). By tightening the setscrew (10), you clamp
the whole unit firmly in place with the tool in the
desired position.
The castle-type toolpost (fig. 6-13) is used with
boring bar-type toolholders. It mounts in the T-slot
and the toolholder (boring bar) passes through it and
the holddown bolt. By tightening the locking nut, you
clamp the entire unit firmly in place. Various size
holes through the toolpost allow the use of assorted
diameter boring bars.