Re: [CAD_CAM_EDM_DRO] cnc gear hobbing on a horizontal mill *info needed*

ask wrote:

> I found a little post made by john stevenson on hooking a encoder to
> the mill spindle then using some kinda divide by chip to make a stepper
> move the dividing head in time with the spindle. does any one now were
> I can find more info on this set up.

The article was in MEW entitled Gear Hobbing Without Change Gears.
Brian Thompson wrote it with some input from John :)

It uses an encoder on the spindle which was hand cut to give 1000 pulses
per rev, and uses the edges from that encoder feed to provide 8000
pulses per rev to the divide circuit, which then runs the stepper motor
(200 pulses per rev) at a ratio of the spindle. The output of the
stepper motor motor goes through a 20 to 1 worm drive, so that the final
system has an accuracy of 1/2 a rev per spindle revolution.

( I'm still trying to work HOW you use it to cut the gears ;) , but the
logic makes sense )

I have a glass 2000 lpr disk and matching sensor ready to load up on the
spindle (under £40), but I've not had time to do anything with it. Since
the worm ratio on my rotary able is 90 to 1, I either need more pulses,
or a different rotary table :)

--
Lester Caine - G8HFL
-----------------------------
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