Re: steppers crosslinked?

--- In CAD_CAM_EDM_DRO@y..., batwings@i... wrote:

> At 11:51 AM 3/25/02 -0500, you wrote:
> >diodes in the output stage, then all bets are off as
> >to what will happen to the driver. The application notes
> >for the L298 show how to use diodes.
>
> These are commercial drivers from Microkinetics.
>
> >As a guess to what is happening, the motor you are
> >turning is generating power that is effectively
> >rectified and fed back into the power supply and thus
> >to the other drive.
>
> I figured that much out myself. This only happens between the 'a'

and 'b'

> axes. Nothing between any other pair. I had a blown chip in 'b'

driver. Am

> not sure this phenom was happening before I fixed that. Anything

else in

> that driver that could be causing this?

The Micorkinetics drivers are not something I have
seen the insides of.... cannot comment.

> >manual controls, I suggest that you provide an
> >electrical disconnect between the motors and the
> >drivers while running manually.
>
> I'm hip to that but there seems to be some question about what a
> hypothetical fault can do when I'm under power too. Afterall, a

pulse

> linking two steppers implies a connection that shouldn't be there,

and also

> I may be having some problems with single steps on b axis anyhow;

it seems

> as if the activation of 'a' stepper may be backing me up a step

on 'b'

> during powered ops. At least I've been having some trouble hitting

final

> pass settings on 'b' in sizes of a few steps, which I set just

before

> activation of 'a' axis for the final pass itself.

Manual operation without power applied to the drives
is such a special case that I would not try to relate
anything that happens then to your problems during
normal operation. I would look to the classic problems,
electrical interference pickup in the wiring, power
supply problems, and so on. A test running continuously
back and forth on 'a' while carefully watching 'b'
seems in order.

Cheers,
Steve Stallings