Re: [CAD_CAM_EDM_DRO] stepper vs. servo

----- Original Message -----
From: "Raymond Heckert" <jnr@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, February 10, 2004 7:20 PM
Subject: Re: [CAD_CAM_EDM_DRO] stepper vs. servo


> Has anybody ever designed a micro-stepping driver that outputs
> approximations of sine/cos to two adjacent coils. I understand that you
> develop max torque at any rpm, up to the max (which is higher than the
> square-wave input). Is this true? How much would it take to develop,
> assuming no one already has? BTW does anybody know anything about Don
> Lancaster's (tenaja.com) Magic Sine Waves, and if they can be applied to
> this application.
>
> RayHex
>
> ----------
> > From: Jon Elson <elson@...>
> >
> > Given the Gecko 320 as the driver for the servos, I think there are a
> > couple of significant advantages over steppers. First, the servos are
> > usually capable of a greater speed range, while steppers rapidly lose
> > torque at higher speeds. With servos, you rarely have to worry about
> > resonance issues. You don't say whether you will use belts, rack and
> pinion
> > or leadscrews to drive this machine, but the servo will likely provide
> > smoother motion, and be less perturbed by some backlash in the
mechanics.
> > Steppers can go wild when rack and pinion drive is used, and rattle the
> > gears
> > something awful. Finally, if you lose a step with a stepper drive, you
> > won't know it until you measure the finished part. With the gecko 320,
> > it won't allow small errors to build up, and will fault if the drive
> binds
> > up or crashes. This can be sensed by the computer and cause it to stop
> > all axes.
> >
> > Jon
>
>
>
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