Jerky motion in all axes...

[Clockworld]

I am merrily using my X4+ working at a 'standard' height with tooling above the work piece and all is good.

Yesterday, I needed to use a large drill and jogged the head up considerably higher than I ever use to install the chuck and drill. It started to become jerky. Thinking this could be a mechanical issue I did some investigation - no clues.
(The machine works fine in manual mode, so I don't believe it to be mechanical)
What I then noticed that when the Z axis is jerky, then bot h x & Y are as well. This does not manifest itself when the head is lower but only whne raised up.
I can only assume it is something to do with MACH3 or a controller.


Any thoughts as to where to start looking?

Matt

Similar Threads:

• Jerky motion with Davinci
• Need Help!- Jerky 3D motion
• Jerky motion
• Jerky CNC Motion
• Jerky motion with CV on (solution)

[awerby]

If the "jerky" motion was restricted to the Z axis, I'd say it was probably stiction, and advise more lubrication. But if it really affects all your axes, I'd have to say something else is going on. Are you sure you didn't change anything else? Is the G-code program you used one that you've used successfully before? Does it have a G64 command (continuous contouring) or a G61 (exact stop)? If it's in "exact stop" mode, then the end of every little line segment will jerk it to a stop before it continues on.

[Clockworld]

Thanks Andrew. I am beginning to think I have a wiring issue. I opened up the cabinet and joggled a few wires and voila, things were much better. Matbe the wires to the Z-axis are suspect (?)
I'm thinking a complete check on connectors etc may help me out.
Matt

[awerby]

I hadn't thought of that but sure - intermittent connections can also cause the machine to move in fits and starts. Go through all the wiring. fix anything that's loose, and let us know if your problems go away.

[neilw20]

I have seen identical problem, (not on an X4. It was a custom machine), that was traced to a driver (leadshine) that was faulting,
and reflecting spikes back through the system.
All the while, opto isolation still in use masked the issue. Inductively coupled spikes from power cables were the cause.
A new driver, or not using the bad axis made the problems disappear.

[Clockworld]

Thanks Neil. When back from my hols, I will try and trace the fault, whether wiring or driver. and report back in due course.