Y axis stutters trying to initialize

3 xxl: when connecting to machine and then initialize, my machine travels on the X-axis normally. When traveling on the Y-axis it “stutters” along until it gets near the end and stops travelling, but “stutters” in place until I disconnect the CNC. I’ve cleaned the tracks and tightened the belts as needed.

Please write in to us at support@carbide3d.com and we’ll do our best to assist.

Possible causes include:

  • miswired wiring extensions or motors
  • maladjusted or bad homing switch

I had to adjust the homing sensor for my Y axis when I assembled my Pro. The gantry was hitting it.

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When you move it (slowly) by hand, does it bind or is it smooth? If you move it fast by hand, you will reverse power the board and it will turn on for a second and shudder, I’m not talking about that.

Because if it is smooth on the rails and you know you cleaned then, it could be a connector issue instead. A few days ago my X axis started behaving strangely - on homing it would shudder in place and sometimes move a bit, but obviously it wasn’t working. The culprit was a loose pin on the X axis stepper motor. I had to disconnect it and seat one of the pins more firmly in the connector with some needlenose pliers.

If you post a video it could help too.

Also, as Greg says, try moving the X rail slowly by hand front to back and check that it’s not binding up and getting too stiff for the Y steppers to move. If so then loosen off the bolts on the Y rails in the rear plate and set the width again so the rail moves smoothly.

Thank you to all that replied. Problem is resolved. It was a dumb error on my part.
Again, Thank tou.

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Jim - would you mind elaborating what the issue was? I can’t imagine anyone that hasn’t been guilty of something “dumb” at least once in their lives.

Your issue/solution can still help people.


There will be others with the same issue. Please share what the problem was and your solution so that all can benefit. Thanks, Joe

@greg5 - I had the same issue with the Y homing sensor.

Regarding OP’s issue…
I noticed that I get some “stuttering” when moving the gantry along the Y axis by hand. It was really pronounced during my initial build. I suspected that I installed the belts too tightly, and when I loosened the belts a bit, most of the stuttering went away.

Interesting, I have found the same thing, almost “crunching” when moving by hand. I feel like it would be impossible to overtighten based on the setup the Pro has.

Yes, please share the problem. I am having similar issues and would like to know.

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Jason, I’m having issues with that at times. Did you just loosen the screw on the belt bracket or reposition the belt in the bracket and then fully tighten the bracket? I’m wondering if you need the bracket fully tightened down or if it’s okay to just partially tighten the screw?


Greg, I had the same issue with the white x motor wire not being fully seated in the connector. I initially had no x motion. After pushing it in, I got x motion but have had a number of stuttering issues and other issues homing the machine. I also had the gantry raise up and press against the z sensor without the sensor working and had to turn off the machine.

At this point, I’m concerned about flaky cables so I’m getting a replacement from Carbide 3D and a new z sensor. I hope this will resolve all issues and nothing intermittent will occur.



I loosened the screw and let out a tiny bit of slack, then fully tightened the screw. I did this several times until the stutter was mostly gone.

Since the belt is “toothed” I tried to only let it out one “tooth” or “click” at a time. It was time consuming, but it satisfied my borderline OCD :wink:

Looking at the build video, I tried to get the same amount of slack shown around 5:10

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Hey Jason,

I ended up getting a new x motor cable, x motor and z sensor, all of which appeared to be flakey. After installing the new components I also readjusted the x belt. I think the belt was fine to being with and probably ended up with the same tension. After all of the above, my machine is up and running beautifully! So happy!

Thanks for your help!