X Axis Keeps Skipping

Hi team -

New owner of a very used X-Carve. It was pre-2021 when I bought it, so I did the belts and motors upgrade and got the CNC4Newbies risers and 7" Z axis. That z axis is a beast FWIW.

Anyway - first few test carves I was doing some vbit work on a 5" ish logo for a friend, and my X axis kept slipping so the carve ended up to the left or to the right. After the slip, the belt was loose, and I took a look, I realized that I hadn’t put the left side tensioning bolt/nut back. As such, I think the machine was pulling the belt holder along the track when it was hitting deeper pockets. During the troubleshooting process I also added zip ties and electrical tape to the belts near the brackets to hopefully ensure that the belts themselves wouldn’t slip.

After these changes, I ran a few board flattening files with a 1.5" surfacing bit (also figuring out that my z axis leaned forward a little bit causing ridges - fixes this with two of the m5 washers I had left over). Anyway - those jobs ran fine.

Also, this afternoon I cut a few fences out of 3/4" ply - cut 4 fences, 1/4" end mill going 100 in/min with .125 cut depth - absolutely no problems.

So I went back to my vbit carving. Immediate problem. 1/8" end mill, 40 in/min, cutting a 4.75" circle. As the bit was changing depth for the second pass (I think) I heard a thump and saw the x carriage/z axis shudder sort of and boom it was off. Not nearly as off as when the problem was happening yesterday pre-fixes, but off. The belt still seems to be tight tonight as well.

Since this was practice on plywood, i just jogged the machine up, reset x/y, and cut the circle again. No problems.

How likely is it that the belt is skipping over ridges on the pulley? Could the motor/pulley be skipping steps? What would cause these things to happen, if that’s in fact happening? Belt too tight maybe?

What should I check and how should I check it to see if that’s the issue - or possible find something else I’m not even thinking of?

Thanks in advance!

Not likely.

Does it always happen in the same general area on your X axis?

Check your wiring and connections for the X-axis stepper.

Same general area. I may have fixed it, and it was the dumbest of all reasons (I think). The new, larger stepper motor for the x axis was catching on the top of one of the zip ties on the cable chain. I rotated the buckle part of the zip tie down, and it moves freely now. Or at least seems to. Thanks!