Y-Axis Stalling (With Video) on PRO60120

My machine will randomly stall on the Y-axis. I managed to capture it on video: AVID CNC Stopping - YouTube

It almost seems like one side is hitting the brakes while the other keeps going. Maybe intermittent connection on one side? Anyone have experience with this issue?

Also, I bought this machine used and that ‘grinding’ type noise has always been present - is that normal?

Did you get a control computer with the machine or did you install Mach4 on your own?

I installed it on my own. Been running it about 6 months before it started doing this.

Hi, there are many things that could do this I would first start by cleaning the rack and pinion and check if everything in the stepper motor side is holding right then check for alignment along the y axis with a dial indicator. In the software side you can lower the velocity/feed rate as a temporary solution. Good luck.


I have had the same problem on occasion. Running a full AVID machine. Has not happened recently and never did find out the cause.
The noise is more than likely worn gears. AVID sells a maintenance package as they do wear out.

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I restarted Mach4 and the issue went away. Kind of terrifying. Hope it doesn’t happen when I’m cutting something important…

the noise too, or just the stalling?

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Just the stalling. Noise is still there.

Its hard to tell from a video without being there, but the stall to me doesn’t sound like when a stepper stops suddenly, it sounded more like a mechanical interference, like maybe your gears are so worn that every once in a while they shift enough so that the teeth land on top of each other. It also looked like it stalled at the joint between the two racks. Maybe the gears are worn, and there is a little more alighment error at the joint and it is getting hung up there sometimes. It also would go with that aweful grinding noise that sounds like worn gears to me.

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I’ll get some new gears ordered, thank you.

Does this happen in the same spot every time? Is it where the 2 racks line up on each other?

My machine did that when I first assembled it. Even though I used their guide for lining the 2 racks up. It’s now gone away with use…However I am having a issue with accuracy on my machine (I made a post about it and still troubleshooting) and was told my drive spindles may be worn out.

So I find that strange. Machine is a little over a year old and it’s hardly used. Maybe a few hours a month when I’m home, and I’m home a week a month.

But now seeing I’m not the only person who have had issues with the machine when it comes to traveling the length of the machine I’m starting to wonder if there’s a design flaw with the racks when buying larger machines and the split racks we have.

I had the same issue recently, and eventually traced it back to the gantry being misaligned. With the rack and pinion drives disengaged, one side of my gantry would hit the end stop about 1/8" before the other side. The gantry is flexible enough that the homing routine compensated for it, but it was enough uneven pressure to cause binding in the right conditions. I shimmed my gantry back into square, and it’s been smooth sailing since.