ges; tools _C_ face the outer
sides of the flanges, while tools _D_ turn the faces of the flanges. At
the third position of the turret, tools _E_ finish-turn the inside of
the flanges; tools _F_ finish-turn the outside of the flanges, while
tools _G_ finish the faces of the flanges. At the fourth position of the
turret, tools _H_ finish-bore the sprockets; tools _I_ complete the
turning on the outside of the flanges, while tools _J_ accurately size
the interior of the flanges.

With the double-spindle flat turret lathe, each operation is a double
operation, and the speeds are varied according to the nature of the cut;
thus, if at one position of the turret, the tools are required to rough
out the work, this may be done rapidly, for it has no bearing on the
other operations that are subsequently performed. Furthermore, if the
following operation has to be performed with great care, this may be
done without reducing the speed of the less exacting operations.

[Illustration: Fig. 32. Potter & Johnston Automatic Chucking and Turning
Machine]

=Automatic Chucking and Turning Machine.=--The chucking and turning
machine shown in Fig. 32 is automatic in its operation, the feeding of
the tools, indexing of the turret, etc., being done automatically after
the machine is properly arranged, and the work is placed in the chuck.
This machine is adapted to turning and boring a great variety of
castings, forgings or parts from bar stock, and it is often used in
preference to the hand-operated turret lathe, especially when a great
many duplicate parts are required. It is provided with mechanism for
operating the cross-slide, feeding the turret slide forward, returning
it rapidly, rotating the turret to a new position, and feeding it
forward quickly for taking a new cut. The cross-slide and turret-slide
movements are effected by cams mounted on the large drum _E_ seen
beneath the turret, while the various speed and feed changes are
effected by dogs and pins carried on disk _D_ which is keyed to the same
shaft that the cam drum is mounted upon. This shaft with the cam drum
and governing disk _D_, makes one revolution for each piece of work
completed. The cams for operating the turret slide are mounted upon the
periphery of drum _E_. The roll which engages the angular faces of these
cams and imparts movement to the turret is carried by an intermediate
slide which has rack teeth engaging a pinion on the square shaft _C_. By
turning this