Machinery Repairman

The workpiece may be held in a chuck or a collet,
attached to the dividing head spindle, or held between
a live center in the dividing index head and a dead
center in the footstock. The center of the footstock
can be raised or lowered to set up tapered workpieces.
The center rest can be used to support long slender
work.
Figure 7-13 shows the internal components of the
dividing head. The ratio between the worm and the
gear is 40 to 1. By turning the worm one turn, you
rotate the spindle 1/40 of a revolution. The index
plate has a series of concentric circles of holes. You
can use these holes to gauge partial turns of the worm
shaft and to turn the spindle accurately in amounts
smaller than 1/40 of a revolution. You can secure the
index plate either to the dividing head housing or to a
rotating shaft and you can adjust the crankpin radially
for use in any circle of holes. You can also set the
sector arms as a guide to span any number of holes in
the index plate to provide a guide to rotate the index
crank for partial turns. To rotate the workpiece, you
Figure 7-12.—Indexing equipment.
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can turn the dividing head spindle one of two ways:
Do it directly by hand by disengaging the worm and
drawing the plunger back, or by the index crank
through the worm and worm gear.
The spindle is set in a swivel block so you can set
the spindle at any angle from slightly below
horizontal to slightly past vertical. We said earlier
Figure 7-13.—Dividing head mechanism.