Stepper resonance - not a problem

I spent the weekend and early part of this week polishing up the software on
my chopper drive and took the plunge last night and hooked it up to my mill.
The first move was real slow and it sounded like someone running a jack
hammer. Most of the racket was coming from the handles that were still
attached to the other end of the lead screws. I removed the handles and was
much better. I ran it through it's complete speed range with a circular
interpolation - only one axis moving though.
There were a couple speeds that made a pretty loud 'buzz' - found out that
was coming from the tooth belt. After a few cycles I went back to 0,0 and it
had not lost any steps.
I had been reluctant to use half-steps because every other step only one
field energizes and I thought it wouldn't have as much torque - after
thinking about it a bit, that's wrong. It still gets full power every other
step and even if it couldn't move at all on the half step it would surely
move on the next full step. So I tried half step and the machine moved very
smoothly at all speeds. Ran several tests and even took some cuts on a
chunk of aluminum. Never lost a step. I'm real happy with this driver.
I'm running the motor at 4amps/phase and at motor lock it's drawing about
1 amp from my 40 volt supply. At 20-25 ipm feed it draws 2 amps from the
supply. (8000 steps per inch). 20 ipm is the fastest speed that the field
coils can reach 4 amps but the machine rapids at 25 ipm just fine.
I think I'll put amp meters on my control, seems like a good indication
of machine friction/cutting loads.

That was all...

Joel