allows you to index divisions from 2 to 400,000. The

As with the standard dividing head, the large

wide range divider (fig. 7-19) consists of a large index

index crank rotates the spindle in the ratio of 40 to 1.

Therefore, one complete turn of the large index crank

plate and a small index plate, both with sector arms

rotates the dividing head spindle 1/40 of a turn, or 9°.

and a crank. The large index plate (A, fig. 7-19) has

By using the large index plate and the crank, you can

holes drilled on both sides and contains 11 circles of

index in the conventional manner. Machine operation

holes on each side of the plate. The number of holes

is the same as it is with the standard dividing head.

in the circles on one side are 24, 28, 30, 34, 37, 38, 39,

41, 42, 43, and 100. The other side of the plate has

circles containing 46, 47, 49, 51, 53, 54, 57, 58, 59,

When the small index crank (E, fig. 7-19) is

62, and 66 holes. The small index plate has two

rotated, the large index crank remains stationary, but

circles of holes and is drilled on one side only. The

the main shaft that drives the work revolves in the

outer circle has 100 holes and the inner circle has 54

ratio of 1 to 100. This ratio, superimposed on the 40

holes.

to 1 ratio between the worm and worm wheel

(fig. 7-20), causes the dividing head spindle to rotate

The small index plate (B, fig. 7-19) is mounted on

in the ratio of 4,000 to 1. This means that one

the housing of the planetary gearing (D, fig. 7-19),

complete revolution of the spindle will require 4,000

which is built into the index crank (F, fig. 7-19) of the

turns of the small index crank. Turning the small

large plate. As the index crank of the large plate is

crank one complete turn will rotate the dividing head

rotated, the planetary gearing assembly and the small

spindle 5 minutes, 24 seconds of a degree. If one hole

index plate and crank rotate with it.

of the 100-hole circle on the small index plate were to

7-16

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