RE: [CAD_CAM_EDM_DRO] RE: Stepper questions

HI Andy,

OK! I had the right CAUSE, but wrong RESULT! Thanks for the clarification.

I'd like to be able to fully plan the torque needs of a stepper project,
then go out and BUY just the right driver and stepper, but what usually
happens is I try to use the surplus I've got on hand! I DO get to try a
couple of steppers, and hopefully choose (both electrically and physically)
a good fit.

My current PCB router project will get to try the EAS drivers, and some
dandy little steppers I found on e-bay. Rough estimates are that there
should be plenty of power for the light loads of the router.

Alan KM6VV

>
> Alan:
>
> The way I understand it is, because the bipolar drive actually reverses
> the polarity of the voltages to the winding, it can reverse the field
> more quickly than if one end of the winding is at circuit ground.
>
> Andy Wander
>
>
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Alan Marconett
>
> HI Dave,
>
> That's an interesting point! I don't recall reading anything like that,
> I
> could be wrong. Basically the windings do not interact as far as I
> know.
> Actually, one would think that "turning around" a winding, as in a
> bipolar
> drive would take longer. The field would have to collapse before it
> could
> build up in the opposite direction. Therefore wouldn't a unipolar
> drive,
> with its four windings have the advantage? And I'd think that the
> unipolar
> stepper would have the further advantage of having two windings
> available
> for microstepping. Half-stepping of a unipolar stepper is relatively
> easy!
> Just alternate one winding on and two windings on! Ever see a 5 phase
> stepper? I still haven't figured out the stepping sequence for that,
> but
> they do 400 steps!
>
> I'd like to see the "dual" specs for such a stepper. I'm guessing that
> they
> rely on a difference in current, and possibly some dissipation
> differences
> between the two modes. Same current * turns = same torque!
>
> I have the opinion that it's better to use ALL of the windings
> available.
> But maybe it doesn't matter.
>
> Alan KM6VV
>