More X-Axis Woes need help/advice

@chrismakesstuff, in an earlier post @stevendq stated that when he swapped cables at the controller he could move the Z axis with the X axis driver, but could not move the X axis with the Z axis driver. This would make me think the controller is OK and that maybe the stepper motor is bad. Actually, I’d like to think the lead screw is binding, but Steve said he could turn the lead screw manually.

@paullarson…I was thinking the same thing. The lead screw turns smoothly when turned manually. IMHO Not the cables or controller.

If it is the stepper motor, seems like its life cycle was pretty short as I have had the mill since May and have only more recently been running a few jobs per week, all with no issues.

The controller was replaced a few months ago for another problem and the coupler on that axis was replaced with the current couplers being sold with the LM. The older one failed and separated, similar to another coupler post on the forum.

@stevendq it’s getting tricky to keep up with all the info here but are you saying that no matter what driver you plug the X stepper motor into it won’t turn? In that case it would certainly be down to either the motor wire or the motor itself

@chrismakesstuff - Yes, I have swapped wires, shaft doesn’t turn. I have loosened, tightened and also reset the V-Wheels, shaft does not turn. Shaft is not spinning in the coupler. I am able to spin the Threaded rod by hand and the X-Axis moves just fine - nice and smooth.

@stevendq we don’t have motors listed individually on our shop but if you get a router mount I think that would be an similar value to one motor:

Just stick it in the order notes that you’re actually buying a stepper motor and I’ll make sure Patrik packs the right thing.

@stevendq If you don’t mind me kibbitzing, Steven, can you tell me if the motor turns properly if it is mechanically disconnected from the lead screw? I’m assuming that it does not, but I’m just nosy.

@gwilki I have not checked that, and quite frankly at this point just need to get back in business and operating. Once I have it disconnected, I will check it and report back.

@chrismakesstuff: Purchase details Receipt number: 2841967709678519 - Little disappointed this isn’t a warranty issue, but $30 US is not a killer for how much I love the LM, plus I get that you don’t know what I was cutting with the LM. It may have been concrete…at 2400mm/min. Hopefully this isn’t an issue with the motor builds and I am unique. Thanks for your help.

UPDATE: I just noticed the phone number on the order is an old cell number. Please use my email for questions and I can update that number.



@gwilki - Sorry, Grant - I didn’t mean to come off sounding pissy. This stuff always seems to happen when deadlines are looming.

I had checked the tightness of the Z Gantry on the X axis in a number of ways to see if it made a difference, from too lose to tighter and a few steps in between, returning to my current setting of barely turning the v-wheels with my fingers. Turning the lead screw by hand operated smoothly before I made the changes to check and even now.

The very loose setting only allowed the shaft to turn slightly better but still not operating under continuous jogging. I expect that with no load, the shaft may spin, but not enough to actually turn the threaded rod.

My other thought was something happened to the anti-backlash nut, but it was still set as it was installed, screw just inserted, but not deflecting the fin on the “robot”

Anyway - I will check it once I have it all disconnected - was hoping it was something easier than replacing the stepper motor, but alas, not - and will update the thread then.

@stevendq No need to apologize, Steven. After all you’ve been through with this, it was unfair of me to stick my nose in. I’ve been following your woes and wondered early on if the motor would turn properly with no load on it. To me, it would be good if it did not, as you could conclude without doubt that the load put on the motor was not an issue. If it does turn as it should with no load, it begs the question is the problem somewhere else. Clearly, it could still be the motor, though.
Anyway, it sounds like you have a new motor on its way. Please let us know how you make out.

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@gwilki Thanks, Grant, I will.

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@gwilki, @paullarson, @chrismakesstuff and the rest…

Got the new stepper motor installed and everything reset.

Turns out the shaft sheared off the old stepper motor right at the stepper motor. I know I wasn’t putting that much torque on the shaft. There was a small bump that would slightly engage the coupler moving it a little.



Must have been a defect in the shaft. The shaft shouldn’t break even if the lead screw can’t turn. Hopefully it’s a one off.

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Hopefully that’s true…

@stevendq That was going to be my next possible cause. :grinning:

I’m glad that you are finally back on the road again.

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@gwilki - Well if I had done what everyone suggested - disconnect the motor from the LM - I would have seen the problem. Wouldn’t have changed the fix, though.

The shaft is flat on one side, but the flat side only goes to the top of the motor and that’s where it sheared off.

@TightnTapered - something to look at…

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@chrismakesstuff @andy Just to let you know, I had the exact same x-axis motor shaft shearing off issue last night. All was well up to this point, I definitely suspect a defect in the stepper motor shaft.

  • Dave

Dave, how long ago did you get your LongMill? Wondering is the issue is from the same batch

@chrismakesstuff I received mine on December 5th, was Kickstarter Backer 143. I had just finished a laser engrave job where it was at 1200mm/min and doing a full 100mm travel each direction, so absolutely no load. I noticed it when I went to move it out of the way at 3000mm/min. Weird! :slight_smile:

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Ok. Steve was part of our second batch of machines so that rules out a single defective batch. I was also thinking it could be fatigue induced by the coupler but I know second batch used jaw couplers vs. solid couplers on the first / Kickstarter batch and the jaw couplers should cause less fatigue due to any misalignment.

No other ideas in my noggin for the time being. Do you need to grab a new motor Dave?

@chrismakesstuff Chris, I did have a v2 jaw coupler at first, but that coupler on that specific stepper motor failed and I replaced it with the newer coupler. I had stripped the set screw and it would not get tight enough on the shaft.