Bearing not turning smoothly - advice?

When first leveling my spoil board, it warped as the day went on, despite the nylon screws, and it got gouged. I screwed the spoil board down tight, and since run the leveling gcode at least 100 hours with the machine travelling nicely back and forth. I vacuum the area clean, but lots of dust has gotten on the steel tubes. The Y-Axis is now sticking every other movement command and has started shuddering. Checking the bearings, most turn smoothly, but several of the Y-Axis bearings do not turn as easily and one will hardly rotate at all. So my questions are:

  • Will sawdust cause the bearings to seize up?
  • Do I need to take the whole MPCNC apart and examine each bearing and replace them?
  • Are there better, more reliable bearings? Such as the ones mentioned in the other forum post? Or are V1 Engineering bearings I already have ceramic and that would not help?
  • Should I add the vacuum shoe before doing any more cutting?
I was holding off adding the vacuum shoe cause I just wanted to cut my MP3DP parts. I was about to do that today and Bam! It no longer working :(. I read through a bunch of forum posts and found this one about the bearings, which is why my questions are focusing on that potential problem. Thank you for any advice.


Standard 608 RS bearings are good. Don’t get ones with the metal shield, they aren’t as good at keeping stuff out.

A ton of crap will cause the bearings to slow down a bit, but I ran my mpcnc in terrible conditions for a while without them actually jamming. I wouldn’t go through the hassle with inspecting each and every bearing. The bearings the mpcnc are overkill in every way pretty much. As long as they turn at all, you’re fine.

Don’t get ceramic bearings. The benefits of ceramic bearings will not get utilized whatsoever in an mpcnc. They’re stupid expensive.

If you got a couple that dont turn at all, just replace them. 608 bearings are so common, they can be picked up for 20 cents a piece.

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I am getting a hint of a little too much tension, maybe back off the tension bolts a quarter turn.

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I’ve gotten that ‘shudder’ effect as well.

during my testing i would allow one of the steppers to skip a number of teeth on the belt.


I have auto squaring and that didn’t take care of difference.

i found that if i:

turn off power, unplug x2, power up, Home X

turn off power, plug in X2, unplug X1. power up, Home X

turn off power, plug in X1, power up, it Homes fine


That fixed the problem, auto square works fine

and will take care of small differences



JonJ, That sounds like a a few things. I think it would be best to start a new troubleshooting thread and start with answering the questions in the sticky.

I was able to reduce, but not completely eliminate, the sticking and shuddering. A number of the bearing were not moving smoothly. My bolts were not to tight as far as I could tell. But a sort of black gummy substance was on a lot of the outside and top/bottoms of the bearings. Maybe residue from the MDF spoil board? I cleaned the outsides with a flat screw driver and pried a little to get them to turn more smoothly. Better. Not perfect, but I cut something and looks good. I am going to make another forum post on the next issue that has come up -not cutting to expected depth.

If you are not using the 2RS variation of the bearings, dust will get in and pull the grease out.