Machinery Repairman

Figure 6-23.—Rubber flex collet chuck.
Drill chucks are used to hold center drills, straight
shank drills, reamers, taps, and small rods. The drill
chuck is mounted on a tapered shank or arbor that fits
the Morse taper hole in either the headstock or
tailstock spindle. Figure 6-24 shows the three-jaw
type. A revolving sleeve operated by a key opens or
closes the three jaws simultaneously to clamp and
center the drill in the chuck.
Faceplates are used for holding work that cannot
be swung on centers or in a chuck because of its shape
or dimensions. The T-slots and other openings on the
surface of the faceplate provide convenient anchor
points for bolts and clamps used to secure the work to
the faceplate. The faceplate is mounted on the nose of
the spindle.
The driving plate is similar to a small faceplate
and is used primarily for driving work that is held
between centers. A radial slot receives the bent tail of
a lathe dog clamped to the work to transmit rotary
motion to the work.
28.306 Figure 6-24.—Drill chuck.
6-15
LATHE CENTERS
The lathe centers shown in figure 6-25 provide a
means for holding the work between points so it can
be turned accurately on its axis. The headstock
spindle center is called the LIVE center because it
revolves with the work. The tailstock center is called
the DEAD center because it does not turn. Both live
and dead centers have shanks turned to a Morse taper
to fit the tapered holes in the spindles; both have
points finished to an angle of 60°. They differ only in
that the dead center is hardened and tempered to resist
the wearing effect of the work revolving on it. The
live center revolves with the work and is usually left
soft. The dead center and live center must NEVER
Figure 6-25.—Lathe centers.