Re: [CAD_CAM_EDM_DRO] Re: Re: Re: Step resolution question, dividing head

Alan:

I am only a hobbiest when it comes to "being a machine-shop", but I did some
stepper-driver electronics for a "professional" machine-shop 15 years back,
and they attached a size-34 stepper to a "dividing head", but as I recall,
they put the motor "in place of" the handwheel/crank the dividing-head CAME
with, and it had something like a 10-turn-per-degree ratio, as I recall.
That is, one had to turn the crank 10 turns to get ONE degree out of the
chuck on the head. In other words, to make exactly one turn of the
dividing-head, the stepper had to step 720,000 steps. Or something like
that. I didn't keep the info, as it was a "one-timer" for that one firm, and
they went away with the "whole thing", so no point in keeping such details
(they did the "hardware work", anyway).

I admit I have no clue if "store-bought" dividing-heads have handwheels,
ratios, gears, nor what; or, if some are made "to order", or whatever. I see
talk of pulleys and timing-belts (toothed belts) in this group, and that
makes me wonder, HOW tight folks expect to MAKE that, cause the
"tensioning-up" when starting/reversing would equal a step or several, it
seems to me! Tight gears, maybe, but a rubber belt, even with "teeth"???
Nah... Direct-drive! Or, tightly-loaded Berg cable-chain stuff. (No
backlash kinda stuff. Expensive, but "right"!)

Hmmm... Will be interesting to continue reading comments on this
thread...

Jan Rowland, Troll


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