pulley ratios for timing belts

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