I’m experiencing a recurring issue with my CNC and would really appreciate your insights.
When I launch a job, the machine sometimes stops suddenly with a “Drive Fault” error. What’s strange is that it doesn’t happen consistently — if I relaunch the exact same job, it often works fine the second time. For example, if I run the same job 10 times in a day, it might fail 3 or 4 times. It usually fails when the spindle is plunging and I sometime loose accurate homing, so I always re-home the machine before running the job again.
This happens across different jobs, so it doesn’t seem to be related to a specific file.
Has anyone experienced something similar? Do you have any idea what might be causing this, or how I could troubleshoot it? I’ve attached a screenshot from the control software when the fault appears.
It happened again. And this time I took a video of it. It stops exactly at the same spot. But this time it plunged straight to my vacuum table , then stopped
I e-cycle stoped, rehomed, and start the job again. And it went fine.
Every time it fails, it fails at the same spot, unexpectingly plunging when it shouldn’t.
I’m still trying to find what is happening here. To try to preserve my vacuum table, I start this job with the hand on the hard stop. As soon as I see the spindle plunging, I press the e-stop button.
What is really weird is that when I release the hard stop button, as soon as I try to move the spindle manually with the pendant, the spindle will instantly plunge hard in the table.
It cost me a couple of bits already.
But it’s still random. When it passes that first step, it goes to the end of this one hour job without any issue.
I really don’t know what else I can check.
That video is really helpful. It looks like there are two things happening here…
When that big plunge happens and you get the drive fault the system is actually doing what it’s supposed to: going into a drive fault. That’s because you have overloaded the Z axis too much.
The other issue obviously is why it plunged that much in the first place, and I think that’s what we need to dig into. I’ll contact you directly to see if we can figure this one out.
The other issue obviously is why it plunged that much in the first place
Just to clarify: the spindle shouldn’t plunge at that point at all. It plunged to a 3mm depth of cut, then starts moving along the X axis, then it suddenly plunged — for no apparent reason. What’s strange is that it always plunges at the exact same spot, which is actually during an X move, not a Z move.
Yep no issues since - hoping that maybe we can turn that max Z feed back up a bit at some point, but for now its not crashing and only a tiny bit slower.
Did your spindle plunge too deep in a spot where it was only supposed to do a light plunge, or did it plunge right in the middle of a horizontal move? In my case, it plunged where there shouldn’t have been any Z-axis movement at all.
Eric changed a setting to make the “drive fault” error more sensitive, so now it triggers earlier — before the spindle has time to scratch my vacuum table, which is great. But we still haven’t figured out why it’s plunging during an X move. It happens randomly, but always at the same exact spot. And I’ve had this issue on two separate jobs.
I’ll keep testing and see if I can find a way to reliably reproduce it.
@nmathon Mine were occurring in what looked to be a similar spot as yours - during a lead in but during what looked like a Z- move. It could have been immediately after the Z-plunge during the lead in arc but I am not sure.
@Eric Thanks a bunch for keeping me in the loop, looks like a promising solution!
, then stopped