lathe group in some classes of work, owing to the simplicity of its functions,
the ease of setting-up, and its substantial build.
Illustrations of Turret Work.—Some examples of this kind, done
on lathes by Messrs. Alfred Herbert, Ltd., are given in succeeding figures.
Fig. 49 shows the distribution case of a rotary aero-engine being produced
on a combination turret lathe. The tool seen in operation is a counterbore,
the one swung round towards the front is a trepanning tool, which cuts a
recess of lo-in. bore, irV in. wide by 4 in. deep. These two tools are used
Fig. 49.—Distribution Case of a Rotary Aero-engine being turned on a Combination Turret Lathe
with feeds as coarse as 8.8 cuts per inch, and between them they remove over
100 Ib. of metal.
Fig. 50 illustrates the second operation on a propeller boss for an aero-
engine. The work is held on a face plate form of fixture, and located
from the tapered bore with a spring tapered peg. The boss is turned with
an allowance for grinding, faced and counterbored, and the hole threaded
with a collapsing tap,
Fig. 51 shows the rough-turning of the fins of an air-cooled aero cylinder,
one of which is seen on the turret. The work is being done with a gang of
tools similar to parting-tools mounted in a special tool holder at the back
of the cross slide, all operating simultaneously. The piece is chucked
with an expanding arbor, and steadied with a revolving support carried
in the turret.