Re: pulley ratios for timing belts

Hi,

25kHz is the switching frequency for the PWM amplifier portion. The
25 kHz has nothing to do with the step input. The maximum step input
frequency is 250,000 steps per second. With your 250 line encoder,
the maximum motor speed would be 250 revs/sec or 15,000 RPM.

Mariss

--- In CAD_CAM_EDM_DRO@y..., "Christopher Prosser" <cprosser@a...>
wrote:

> 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