Re: [CAD_CAM_EDM_DRO] Stepper motors as encoders

HI,

Sounds like we're back to modified mouse electronics again here - big pulley
on the machine shaft and rubber band drive to the mouse encoder shaft?

Ian
--
Ian W. Wright
Sheffield UK
www.iw63.freeserve.co.uk

----- Original Message -----
From: "Jon Elson" <elson@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: 19 August 2001 06:39
Subject: 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
>
>
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