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

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> 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