X-Axis issue on Shapeoko XL

I built my machine and have everything working. However I am running into a problem when carving. It will work for a while then sometimes the carriage will not travel far enough in the X-axis. I’ve attached a couple of photos to show what happens.

I thought I had fixed it by tightening the x belt, but it still occurs. I noticed a couple of things. If try to stop the the carriage with my hand while moving in the Y-axis, I can’t really do it (unless I push super hard). However in the X, it hardly takes any pressure to stop the carriage. I looked closely and the shaft is spinning freely in the pulley. Do I just need to tighten the pulley bolts? The plates on my machine came pre-assembled.

Any help would be great, thanks!

Another image of the issue:

Okay, a given axis is controlled by:

  • stepper driver — on some controllers there’s an option to adjust the current for this — but no on the Carbide Motion Machine Control Board — some boards will require active cooling so as to not overheat and go into thermal shutdown (shouldn’t be the case w/ a CM board)
  • wires conducting current — usually if there’s a bad / loose connection it will sound awful and will (eventually) blow the stepper driver
  • motor — sometimes these are bad — test by swapping w/ another motor
  • belt pulley — check the set screw. If there isn’t a flat on the motor shaft, consider (carefully) filing one (in such a way as to not risk getting metal shavings anywhere they might cause harm — put the motor in a zip lock bag, poke the shaft through the bag, file the flat, clean up the shavings, then remove from the bag)
  • belt / belt tension — careful when setting tension not to overdo it and bend the shaft — a bad belt is a remote possibility

Thanks Will. To me it looks like the pulley needs to be tightened, I’ll try look into that first. I followed the instructions for tightening the belts, so I don’t think they have been overtightened.

sounds like belt pulley or belt tension to me,def check for the flat spot as stated in wills post

I tightened the pulley, it no longer slips when I use my hand to try and stop it when jogging. I’ll run a test later.
Thanks for the help!

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I noticed the same thing with my machine and thought that I had the gantry out of square somehow. Turns out the shaft set screws were a little loose on each side. Be careful that you loosen both set screws slightly on the pulley and then tighten the screw that is on the flat machined portion of the motor shaft while gently rotating back and forth so that you can assure that you get the set screw as flat as possible to the surface. This will help keep it from loosening back up and then tighten the other set screw to snug. Also, be careful not to strip the screws.

I hope this helps you as well,


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I had a similar issue. The set screws on the Z axis belt pulley were loose. Of course I only figured that out after taking the entire Z axis cartridge apart.

My pulley screws came loose and caused the same issue. I went ahead and checked every screw on the machine and applied loctite to them. Most of them will vibrate loose at some point if you have one of the early units unless you do what I did. There wasn’t much (if any) QA when the early XXL kits went out. I’m assuming that’s probably under better control by now.

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Hi Guys, thanks for all the suggestions. I took the pulley off, it was not aligned with the flat part of the shaft. Put it back properly and it is all good. Loctite would probably be a good idea for those bolts. I will make sure all the other motors are set up correctly as well.


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Be careful with lock tite on the pulley screws. It may flow onto the shaft and make pulling the pulleys off very difficult.

Speaking from experience.

I plan on using another set screw to lock in the first one like Is used on a table saw arbor pulley.

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If that happens, some heat from a heat gun (or very carefully using a torch) is enough to break the bond of the loctite. Works like a charm.