From: Roger Neal <regor@midwest.net>

If you want good performance out of your steppers, I would recommend
that you use as high of a voltage as your drives will allow. The
voltage rating of a stepper is the amount of voltage needed to cause the
recommended current to flow while stopped, you need more voltage to move
the stepper than it needs at stand still. The higher voltage you can
supply, the better your steppers will perform at higher speeds. It's
pretty common for industrial stepper drivers to just rectify 120VAC and
use capacitors, giving a buss voltage of 160-170VDC, this is fed to a
motor that's rated for under 5V. The chopper drive works as a current
regulator, it will try to hold the current at the set value, this isn't
a problem while stopped or moving slow, but it can be a problem if your
trying to move more than a couple hundred rpm or so. I used a couple of
200 oz in motors for a CNC mill table and it performed a lot better at
30V than it did at 18V. Hope this helps.
--

Roger Neal
regor@midwest.net