Shapeoko XXL Y-Axis stalling

I assembled my Shapeoko XXL this week and am now attempting the “Hello World” file.

I’m having some bad results and I think the culprit is my left Y-axis. Its sounds like it’s too loud, and it appears to be skipping or stalling in regular increments.

At first I thought it was the belt tension, but now I’m concerned that its the motor. See the link below and let me know what you think.


With power off, check the connections for that motor.
With power on, connected to machine, can you easily move the Y-axis?

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Connections to the motor look good.

With power on, connected to the machine, The Y axis moves, but I can feel that irregular “skipping” that you’re seeing in the video.

Can you move it easily by hand, though? If so, that would suggest the motor is not connected or there is something else wrong.
The motors should lock in place when you connect.

Sorry yes, When the machine is on, the X or Y axis will not move.

Then the motor and driver is probably ok.
Could be mechanical. With power off, does the Y-axis move smoothly (move it slowly)?
Are the Y rails parallel? Machine square? V-wheels too tight?
Pulley set screws loose?

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So with the power off, the Y-axis does move, but I can feel that stutter.

I followed the instructions on squaring the machine after assembly, but I don’t know a great way to check that everything is square and parallel.

How do I check the V-wheels and set screws?

The basic points of adjustment for a machine are:

It is also important to be sure that the collet is correctly tightened, the endmill fits correctly and doesn’t slip, and the router is mounted securely in the mount, and that the mount doesn’t shift. Note than endmill pullout can happen gradually, especially when profiling against tall walls.

Thank you for the detailed response. I think i’ve found the problem.

  1. Pulley set screws seem to all be engaged.
  2. The V-wheels were not all engaged - I’ve fixed this and they are all now securely on their tracks.
  3. Belt tension was good.

After examining all the V-wheels, I noticed that one of the wheels has a small dent on the interior face. Moving the left Y-axis harness, I notice a THUMP every time this spot contacts the rail. (image attached)

I think this V-wheel needs to be replaced. Let me know. Thanks.


It might be that that’s just an indentation where the machine was resting and will go away, but best to eliminate that — let us know at and we’ll send you a replacement and some spare V wheels.

I don’t know if it is me but I think that I see the pulley slipping. The set screws may be in the wrong place when you tighten them. One of the screws has to be on the flat past of the shaft. It is also possible that you have a bad set screw. Try to look at the end of the pulley and see if you can notice if the shaft travels with the pulley by looking at the flat part of the shaft.


I’d put that one on the bottom of the rail until you get a replacement. That’ll reduce, if not eliminate the clunking.

Use a Sharpie to mark the stepper shaft. If it rotates independent of the pulley, you have a set screw issue.


That worked brilliantly. The machine is functioning much better with this change.

I was able to run the “Hello World” file and got a much better result.

I think I’ll still look for a replacement V-wheel.

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