"Rex B" wrote in message
...
I've uploaded to the dropbox a photo of an item I qcquired last weekend.

http://www.metalworking.com/dropbox/Indexer-1.jpg

It's either a dividing head or a rotary indexer.

Looks like a dividing head.

It only has the one
plate, and the numbers on it seem odd, something like "3 7 13 17 23 etc"

Primes, although your list is missing 2, 5 and 19. You'd multiply and
divide in factors of primes to figure what number of steps on what series of
holes you need to travel to get the desired rotation (e.g., in gear
cutting).

What is it properly called - rotary indexer, dividing head?

Either I suppose, although indexing to a specific angle would be a little
cumbersome.

Are additional plates available?

Could always make more. Dave Gingery describes the process in the 7th
shop-from-scrap book, deluxe accessories.

How is it used, what is it good for?

I don't know exactly, but Dave's model is used by pulling the pin, rotating
the arm a certain number of holes around the disc and setting the pin into
the next hole. The arm is connected to a worm gear which divides the
rotation to the shaft. Yours looks similar enough. Can't say I know the
brand or internal ratio.

Do I need to keep it or sell it? I have a 9" logan lathe, shopping for
a mill.
Value? Unless I can be convinced I need it, it may be available for
offers.

You'd be best using it on a mill, horizontal preferred but it works
"sideways" too. I suppose you could set it on the cross slide somehow and
use it on a lathe.

Tim

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