Did my stepper motor just die?

Hey guys - I use my OF almost every day. Recently, an intermittent issue would surface that looked like a slipping coupler. Today, it happens every time I try to move the ‘Y’. I Took the right ‘Y’ rail apart today and found no issue with the rail/bearings/etc. so I focused my attention on the stepper motor. I believe the stepper is bad. I know they rarely fail but there is basically no ‘holding’ torque. I hope it’s not a driver. Take a look at the video and let me know what you think. Thanks, Charlie

Hook the stepper to a different driver and see. Usually its the driver (at least on ither controllers Ive used). Probably not too bad to replace

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Hey @shuey911 Charlie, hey Brad,

Yes, since as you showed, when the stepper moves, all coils seem to do their job.

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yah I would have but the enclosure I built is great but blocks the opposite stepper. I didn’t have time to dis-assemble the enclosure - Support is sending me another stepper - if that doesn’t fix the machine, I will have to look at the controller/driver. I sure like their support staff

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So, I don’t have my boxes open yet (waiting on frame and roller stand) but I would think the swap could more easily happen inside of the controller. Does anyone know if one can just disconnect the cables from the driver leading to one stepper and connect it instead to a different driver? (Shouldn’t have much to do with your enclosure or the stepper motors themselves). I would surely do that before disassembling the stepper motors as a troubleshooting step. But, … I would have thought support would suggest it if it were easy ¯_(ツ)_/¯


What I thought was a bad stepper motor or driver, turns out the ball-nut on the right ‘Y’ rail is VERY difficult to turn. I disassembled the rail and removed the ball-nut. It is loaded with ball-bearings. I recaptured 30 of the bearings, not sure how many are supposed to be in the assembly. The ball nut was PACKED with sawdust and combined with oil, it was a seized up mess. I contacted support and a solution has not been reached. I have about 8 hours on it now and my patience is wearing thin. I had to remove the Y rail, suspend it from the ceiling in the shop and after extensive cleaning of the ball nut assembly, try and reload the ball bearings. I asked support if they knew how many bearings are supposed to be in the ball nut and they didn’t know. The trim ring was not seated and this may have allowed the saw-dust to enter causing the original log-jam inside the but. I reassembled the nut with the 30 bearings but it still barely turns. I am trying to stay cool but I need some assistance from OF. I received the machine in April I believe so it’s well within warranty. Any one have any input? I think the only fix at this point is for them to send me a new ball nut/screw assembly. Thanks - Charlie

I’m no expert on ball nut/screws but from what I’ve read its difficult to reload the bearings into the nut once its been removed from the screw. So I think your best bet is a new ball screw/nut assembly. I also read one of the maintenance procedures to remove debris from the nut is to flush it with lubricant. Not sure this would have worked in your case with so much sawdust packed in there.

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Hey Charlie,

Wow, this really sucks.

But this problem can only arise

  1. firstly if there is wood dust

  2. and secondly if the seal on the ball nut cannot cope with an excessive amount of the dust-oil mixture

  3. or if the seal on the ball nut comes off and the inside of the recirculating ball nut is exposed unprotected. Oviously the seal had peeled off as you wrote.

Basically when you mill wood, dust is created and it is an enemy of exposed, oil-lubricated mechanics. I would not run a machine like this without a powerful dust collection system (I think a workshop vacuum cleaner is only a temporary, less-than-ideal solution, but not the right one), not only to protect the mechanics, but also to protect yourself.

But now the mess is here and I don’t know, you put a lot of effort into cleaning everything. But I wonder if such a cleaning is not something technically very demanding.

If you say the ballscrew still hardly turns, at least I would throw away the ball nut if not the whole ball screw.

One ballnut can operate just fine despite missing a couple of balls missing, but

to maintain their inherent accuracy and ensure long life, great care is needed to avoid contamination with dirt and abrasive particles.

I think so. But since you don’t want it to happen again, I think maybe you could look at 1. and 2. mentioned above. (the repeated occurrence of 3. seems to be inherent to the machine)

PS: Note: Nice picture of how the ball nut is sealed

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Dang, that stinks. Hopefully they’ll forward a new nut.

Pushing that nut might also have damaged the driver as mentioned previously. Still worth double checking while you’re negotiating the warranty.

As per our support email, we are sending a new motor and nut.
A note to all Onefinity users: Always use proper dust collection and ensure to clean the dust and debris after each carve.
Also, while servicing the ball nut, NEVER take it off of the ball screw, or you’ll end up with tiny balls all over the floor! :stuck_out_tongue:

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Thanks for the comment/lesson. I agree - I need to be very careful now with this machine as far as dust goes. I have a 2HP dust collector plumbed into a distribution system throughout the shop and that includes the OF. Problem is it evacuates the entire enclosure with a 12" square portal on the top of the cabinet. This was meant to capture the fines that find their way to my lungs. In that regard it does it’s job. But I end up amassing saw-dust 5" thick in the rear of the machine which I do clean out thru trap doors in the enclosure made for that purpose. (I’m getting off track) - I don’t see how the teflon/HDPE wiper ring can do much at all keeping dust out. There is no real ‘seal’ of any kind. I will have to take a close look at this and come up with a better solution in addition to constant cleaning and getting an efficient dust shoe that will stop the dust at it’s source. OF is sending me a new ball-nut so let this be a lesson learned. Thanks all for your friendly input. Charlie

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Thank you very much!

Brad -Good point - They’re sending a new stepper AND ball-nut. Once reassembled, she’ll get a complete calibration and check out - Thanks for your comments - Charlie

Thanks SkyKam - They’re sending me a new one. Charlie

Hey Charlie,

Exactly, that is a serious dust extraction system, but you are right, it better should extract the dust where it arises. It will be more effective then.

I understand, but it may not be the ideal solution.

I agree. That’s why the issue keeps coming up and probably led the Onefinity makers make the video. I follow the forum since March and I have the impression that not everybody takes dust collection seriously.

I’m still planning while waiting for the machine but for me the priority is a strong dust collection before an enclosure.

Hey SkyKam,

interesting to see how fast people do this:
How to install balls into ball nut?

But obviously Charlie’s ball screw and nut was stuck with so much dust-oil-mix that it suffered wear and should be replaced.

Post mortem - I took a close look at the trim rings looking for a definitive reason for my ball-nut contamination and eventual failure. The trim rings are made from a fairly soft material, maybe TFE or HDPE, and once in place, they are ‘retained’ by allen set screws. Set screws into soft material is in my book asking for trouble. Take a look at the photo of my suspect trim-ring. You can see the damage caused by the set screw. I have to believe in this day and age of 3D printer s and other sorcery, a better solution could be fabricated that not only keeps the innards retained in the ball nut, keeps contaminants out (saw-dust), but is made from a more rigid material that can withstand a pointed set screw being driven into its side. Thoughts? - Charlie

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I’m surprised it’s not held in with a circlip that fits into a recess on the housing. Or that the set screws aren’t inserted into holes drilled into the ring (& held in place with Loctite to prevent vibration loosening). The pointy set screw approach needs to at least be in the middle of the ring vs the edge as yours were. That would likely help prevent it from tearing out as easily as there’s be more meat between it and the edge.

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Jim - Good point. In addition to the design/material issue. I think my failure in specific may point to the trim ring not being fully seated when it was assembled. I’ve wondered for a while what the purpose of the ‘toothed’ portion of the ring was. And now that I have it on the work bench I see that the only reason is to provide a place for the pointed set screw to park. If not fully seated, disaster looms. Also, when the dust settles (pun fully intended) I plan on 1 - design and build a great dust shoe to eliminate the saw-dust at the source and 2- find, create, fabricate a dust boot solution for the ball screw point of failure. Thanks for the response - Charlie


Great thread, I just had my ball screw nut fail on the X axis. I believe it was due to contamination of the ball screw nut. I think a better wiper system would be great.

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