28.116
Figure 6-48.--A split-shell expansion mandrel.
ends of the mandrel when you press or drive it into the
the shell, causing it to expand until it holds the work
work. A piece of work mounted on a mandrel must
properly.
have a tighter press fit to the mandrel for roughing
A GANG mandrel (fig. 6-49) is used for holding
cuts than for finishing cuts. Thick-walled work can
several duplicate pieces such as gear blanks. The
be left on the mandrel for the finishing cut, but
pieces are held tightly against a shoulder by a nut at
thin-walled work should be removed from the
the tailstock end.
mandrel after the roughing cut and lightly reloaded on
the mandrel before the finish cut is taken.
In addition to the standard lathe mandrel just
described, there are expansion mandrels, gang
mandrels, and eccentric mandrels.
An EXPANSION mandrel is used to hold work
that is reamed or bored to nonstandard size. Figure
6-48 shows an expansion mandrel composed of two
parts: a tapered pin that has a taper of approximately
1/16 inch for each inch of length and an outer split
shell that is tapered to fit the pin. The split shell is
Figure 6-49.--Gang mandrel.
placed in the work and the tapered pin is forced into
6-28