RE: [CAD_CAM_EDM_DRO] pulley ratios for timing belts

Forget the "EMC can only do 5KHz". While this may be true in some context it
is not true in the context of setting up your servos. You will get the best
performance out of steppermod, not freqmod but you may need to tune the
cycletime for your computer and you will need to have a PII 350 or K6 350 or
better to get good step rates.

I am running a 200(I think, it may be a 250) line encoder on a 3:1 reduction
with a 5 tpi screw (assuming it is a 200 line this gives 12,000 steps per
inch) at 135 ipm which should be 27 KHz.

This is on an AMD K6 450.

Tim
[Denver, CO]

> -----Original Message-----
>
> Hi Folks,
> I'm sitting here, stuck in my house reclining with a bad back. So I
> thought I'd run some numbers trying to decide if I wanted to
> do a 2:1 or 3:1
> reduction from the motor to the leadscrew (or ballscrew when
> I get around to
> upgrading).
>
> I'm using G320 drivers with EMC. I picked up a servo motor
> with a 250cpr
> encoder on it from Dan Mauch.
>
> I'd make a nice table, but this is ascii after all.
>
> Assumptions:
> EMC can only do 5KHz for driving the steppers. Does anyone
> know if freqmod
> will do faster?
>
> The gecko drives will take up to 25KHz for step input. They
> will fault out
> at +/- 128 counts.
>
> The motor therefore can run at 1200 rpm with a 5KHz input,
> giving 600rpm, or
> 400rpm at the lead screw.
>
> My lead screws are 10tpi (RF-31).
>
> 2:1 drive ratio
> Max err before fault: +/- 0.0254
> Max table speed at 5KHz pulse rate: 60ipm
>
> 3:1 drive
> max err: +/- 0.0169
> Max table speed at 5KHz pulse rate: 40ipm
>
> I'm probably going with the 3:1 drive.
>
> Just thought I'd share.
> --chris prosser
>

>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
>