> Blind faith my son.
>
> Actually, blind faith in engineers' specifications.
> Stepper motors .have well defined conditions under which
> they will "follow" the "move-along-now" signals given to
> them. As long as the stepping signals stay within the speed
> range specified for the applied load then you can
> confidently expect the motor to revolve at the stepping
> rate. In this application the load is (or should be) a well
> balanced and quite light weight (hence low inertia) disk so
> the loading is almost purely inertial. As long as the disk
> is "light" (which is relative to the power of the motor
> used) then it will track properly.

If your load is light, you have to watch that your speed range doesn't
include a motor resonance.
Some motors have a very marked bite out of the speed/torque curve. If you
try and start it at that speed, it will go buzz instead of whirr and
nothing much will happen. Once started, the motor construction itself
usually has enough inertia to overcome it.

Steve.

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  Very funny Scotty.  Now beam down my clothes.
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Steve Baldwin                Electronic Product Design
TLA Microsystems Ltd         Microcontroller Specialists
PO Box 15-680                email: steveb@kcbbs.gen.nz
New Lynn, Auckland           ph  +64 9 820-2221
New Zealand                  fax +64 9 820-1929
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