Re: [CAD_CAM_EDM_DRO] Re: Re: Re: Electronic Lead Screw & Power Cross Feed | Poor Man''s CNC ?

R Rogers wrote:

>I keep reading what Mach3 wont do in regard to encoders in theory. It's a bit frustrating as I see everyday what it does.
>
> A machine I recently retrofitted with Mach3 and encoder feedback to the PC. Put Mach in "reset" and it has a screen with nothing but DRO's for manual operation.
>
> Here are the specs:
>
> X and Y axis are 12,800 steps per inch, max rapid rate is 140+ ipm on both 5 tpi ballscrews (.200" lead) (3.2:1 belt reduction)
>
>

Yup, I did the math. 12800 * 140 / 60 = 29867 steps/second.

> Z axis is 20,000 steps per inch. 10 screw revs per inch. .100"lead (4:1 belt reduction) Z rapids at 60 ipm (driving the knee).
>
>

same formula, 20,000 steps/second.

> All three axis's are monitored by their encoder in Mach, if position is lost the machine is halted.
>
> Mach in 45 khz mode, all three axis's can be rapid simultaneously and no lost steps are encountered. It will actually go faster.
>
> Do the math on the above for the true pulse/count rates.
>
>

Yup, I did.

Oh, on my 150-lb minimill, I had 1000 cycle/rev encoders, 4:1 belt
reduction and 16 TPI screws.
That gives 4000 counts/rev * 4 * 16 = 256000 counts/inch. At 90 IPM
that is 256000 * 1.5 = 384000
counts/second. You cannot do THAT with MACH3, I assure you. I need
hardware encoder counters
to keep up with it, and use the EMC software. This is not with Gecko
drives but my own PWM
servo amplifier. See http://jelinux.pico-systems.com/smallpwm.html for
more info. The pictures
show a Taig mill which I provided as a "turnkey" system to a customer.

Jon