odd stalling behavior - CRP pro 48x48 with mach4

[Fabrik8r_K]

The other day I was running a program and it was going perfectly until one particular G0 command sent it in a Y direction it didn't like. It seemed to stall all of a sudden and then picked up at the next line like nothing had happened. Of course the cut was way off the target so I stopped the build. I then looked at everything to see if it was a binding or motor issue. Everything checked out with no issues. I even thought maybe the L/R motors were out of sync or configured differently and may have been fighting each other. Checked all that and didn't seem to be the problem. No binding to be found anywhere or stepper hesitation or odd noise from the steppers.

I was able to isolate the issue by running a bunch of G0 commands to send it from point to point. But it doesn't make much sense.

1) G0 X0 Y10, G0 X0 Y0 .... no problem. I can run that all day and no issues. Tried all sorts of speeds and accelerations with no difference.
2) G0 X0 Y10, G0 X0 Y0, G0 X10 Y0 (bam).... seems like it hit something but I can continue by hitting the run gcode again and it works until that same point
3) G0 X0 Y10, G0 X0 Y0, G0 X10 Y1, G0 X0 Y0....no issue.

This is a repeatable problem even by slowing acceleration and speed way down to almost nothing.

Strange. Seems like running in X or Y and then changing to the perpendicular is when the issue pops up. No issue if I go in an angled direction (ie non perpendicular).

My machine has all the electronics provided and configured by CRP and as stated in the subject line Mach4.

I'm having a heck of a time trying to figure this one out. It's a problem I've been able to duplicate very consistently which makes the problem solving much easier and I'm sure it might be obvious to someone who knows the system very well. I do plan to get support from CRP but wanted to post just in case someone else is having the same problem.

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[ger21]

If it stalls with the accel and velocity very, very low, then it may be a bug in Mach4? Do you have the latest version?

[Fabrik8r_K]

I may have an older version so will try as you suggest. Thanks! It does seem software related. I've tried a wide range of accelerations and velocity with no affect on the output.

[Fabrik8r_K]

As Ger21 suggested, I upgraded versions of Mach4 and it seemed to fix the issue. As I was reading the Artsoft forum the exact same problem was quite extensively discussed but with Mach 3 about 5 years ago. The change in direction was introducing a very quick unexpected action that was stalling the motors. Even the moderators could not explain why but It could be turned off and on by toggling backlash compensation. Maybe by upgrading that toggle was changed or maybe they fixed the glitch. Anyhow, back in business making sawdust and chips fly

[ger21]

Mach3 and Mach4 have nothing in common, so it's probably just a coincidence.
Mach3 has a lot of little bugs like that.

[Fabrik8r_K]

Yup...most likely just coincidence. The 1% as they claim is pretty much nothing. Hopefully mach4 proves to be more robust so i don't see these mentioned little bugs pop up.