Re: [CAD_CAM_EDM_DRO] Stepper motors as encoders

grant.fair@... wrote:

> I am thinking of playing with stepper motors as shaft encoders. Has
> anyone had any luck with this approach?
>
> In practical terms, 100 pulses per revolution is the best resolution
> which would be available. The main virtue of this approach would be
> low cost, since .9 degree/steppers (which give only 100 ppr) seems to
> be the smallest step size widely available from surplus sources, where
> they are available in the $2 range. The electronics to interface a
> stepper so it outputs 5V pulses is cheap - 2 comparators, and a few
> R's, C's and diodes, plus a 5V power supply.
>
> Any comments? Would 100 ppr have any value with DRO's? Of course
> greater resolution could be achieved mechanically.

100 PPR is not so great for measurement systems, but is great for hand
encoders, AKA jog dials or MPGs (Manual Pulse generators).

The problem I worry about is losing counts when moving slowly. Low cost
mechanical encoders and slightly more expensive optical encoders are
available in that and better resolutions for about $10. These generate
clean
quadrature pulses at TTL levels all in one piece, without any added
electronics.

Jon