Re: stepper motors

TADGUNINC@... wrote:

> From: TADGUNINC@...
>
> Hopefully you guys are still on......what is the difference synchronous ac
> motor, advertisement says it can be used as a dc stepper, and a stepper
> motor?

Well, usually a typical synchronous AC motor can't be used as a stepper.
But, there is a particular type, low-speed synchronous motor, as made by
Superior Electric and others, that are made exactly like steppers. The
difference is that these are usually made with 120 Volt windings, and therefore
have MASSIVE inductance, making them VERY poor steppers for motion
control applications.

> Also I haven't heard anyone say anything about step accuracy, what is
> acceptable?

Yup, I suspect that most steppers have a step accuracy of a few percent.
That will cause pretty bad cyclical errors when driving a leadscrew.
I have seen this in my photoplotter, which uses a stepper to drive an
anti-backlash Kerk leadscrew.

Jon