Re: [CAD_CAM_EDM_DRO] Re: Going home / more stepper speed!

Alan Marconett KM6VV wrote:

> Jon, Mariss, Ballendo and the list,
>
> I did some experimenting last night, got a current probe (2ma/mv
> Tektronix) and looked at a motor winding's current. I can see the
> triangular current waveform of the +- 2A current responds to the step
> pulses. At quite slow speeds, A pair is seen (full step). Half step
> shows one current pulse with a lower amplitude. faster speeds, and the
> previously separate pulses merge together, forming a continuous change
> from one pulse to the next. Sometimes the "sides" of the pulses are
> nice and "flowing" (a little wavy), other times the motor gets a little
> noisy, and I see "jags" on the sides of the pulses. No "ringing"
> observed. Probably not looking the right way yet. I did notice that at
> high speeds, the peeks don't make it out to +- 2v. I've got 37v from
> the raw DC of a 24v 4.8a linear supply. This is with a NEMA #34 150
> oz/in 2.54V 3.1A motor. an API CMD-50 stepper module drives it (100k
> programming resistor). Poor match, I know! Not enough drive! I'd like
> to try one of Dan's or Mariss' drives on it.

Yes, I hadn't thought about it enough, a good stepper driver provides enough
damping to suppress some of the ringing. If you put a large gear or some
other hunk of angular inertia on the shaft, it might become more prominent.

Jon