Re: Stepper current - how bad is underdriving a motor?

At 12:18 21/12/2002 +0000, you wrote:

>I just acquired a NEMA42 stepper,
>
>840 oz-in,
>1.45V
>15.2amps !!
>
>I was wondering how much torque I
>sould expect out of it when running
>on a Gecko at 7A? I do know that
>whatever torque I get will stay
>there to a rather high speed, thanks
>to the very low voltage.

You would expect to get approx 1/2 the torque at low speeds, but as you
say, the low voltage gives plenty of headroom to get good performance at
high speeds.

You haven't said whether the motor is 4, 6, or 8 wire. If it is 6 or 8
wire, the alternative is to use it in full coil (6-wire) or series
connected (8-wire) at 7A; you should then get close to the rated torque at
low speeds.


Regards,
Tony