[Illustration: Fig. 19. Turning Gasoline Engine Flywheel--Second Position]
[Illustration: Fig. 20. Diagrams showing How Successive Operations are Performed by Different Tools in the Turret]
The main turret is next indexed one-sixth of a revolution which brings the broad finishing tools _B_ into position, and the side turret is also turned to locate finishing tool _B_{ 1}_ at the front. (The indexing of the main turret on this particular machine is effected by loosening binder lever n and raising the turret lock-pin by means of lever _p_.) The hub, side and periphery of the blank are then finished. When tools _B_ are clamped in the tool-blocks, they are, of course, set for turning the hub to the required height. The third operation is performed by the tools at _C_, one of which "breaks" or chamfers the corner of the cored hole in the hub, to provide a starting surface for drill _D_, and the other turns the outside of the hub, after the chamfering tool is removed. The four-lipped shell-drill _D_ is next used to drill the cored hole and then this hole is bored close to the finished size and concentric with the circumference of the blank by boring tool _E_, which is followed by the finishing reamer _F_. When the drill, boring tool and reamer are being used, the turret is set over the center or axis of the table, by means of a positive center stop on the left-side of the turret saddle. If it is necessary to move the turret beyond the central position, this stop can be swung out of the way.
Figs. 18 and 19 illustrate the turning of an automobile flywheel, which is another typical example of work for a machine of this type. The flywheel is finished in two settings. Its position for the first series of operations is shown in Fig. 18, and the successive order of the four operations for the first setting is shown by the diagrams, Fig. 20. The first operation requires four tools which act simultaneously. The three held in tool-block _A_ of the turret, face the hub, the web and the rim of the flywheel, while tool _a_ in the side-head rough turns the outside diameter. The outside diameter is also finished by broad-nosed tool _b_ which is given a coarse feed. In the second operation, the under face of the rim is finished by tool _c_, the outer corners are rounded by tool _d_ and the inner surface of the rim is rough turned by a bent tool _B_, which is moved into position by indexing the main turret. In the third operation, the side-head is moved out of the way and the inside of the rim is finished by another bent tool _B_{ 1}_. The final operation at this setting is the boring of the central hole, which is done with a bar _C_ having interchangeable cutters which make it possible to finish the hole at one setting of the turret.