Re: Going home / more stepper speed!

Hi Jon,

I DO have a load on the stepper, after thinking about it. A 23.4:1
gearbox, and an aluminum timing gear. I disconnected the BIG load, a 1"
steel shaft driven by another timing gear and a belt, a PVC mast, and
the 144/440Mhz 6 element beam antenna. I'll probably keep lookin' at
the current and voltage waveforms, with various loads, and see what I
can learn.

Alan KM6VV
P.S. Note the 23.4:1 ratio? Empirically determined, That drove me up
the wall trying to figure out if I was loosing steps! Seems they like
to use non-integral ratios in these Dayton boxes, to avoid warring
patterns into the gears, or so I've been told.

Jon Elson wrote:

>
> 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