Problem with x-axis

So, I’m getting refusal to move at the ends of the x-axis, mostly on the left, but also on the right. We went through the process of getting the x-axis gantry installed per the instructions, but you can see in these pictures, it bows our as the gantry gets to either end. Do I need to redo the gantry alignment?

The X and Y bearing mounts for the lead screws are different lengths. Make sure you didn’t install a Y mount on the X axis.


Ya, we did that at first, figured it out the day we assembled (because it really bowed out) and fixed it. now it just looks like the lead screw is 1/8"+ too far out.

I would loosen the two bolts holding the x-axis lead nut, and the two cap screws holding the x-axis lead nut mounting tab, move the x-axis as far positive as you can, and go through the tightening steps again as described in step 15 section a7 of the assembly manual.

If that doesn’t help, I’d probably reach out to Langmuir and see what they say.


Were you careful on this step? Did you use a protractor before tightening?

B3 Secure the X Axis Lead Screw Bearing Mount to the Gantry Tube using the remaining Bag 6 screws. Note that the bearing counterbore must be facing to the right when looking at the gantry from the front. Before fully tightening the cap screws, use a protractor to square the X Axis Lead Screw Bearing Mount to the Gantry Tube. Please note that the X-Axis lead screw bearing mount is shorter than the Y-Axis lead screw bearing mounts (2).

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My gantry tube has a pretty good bow in it, and it doesn’t stall the motor. It’s visible to the naked eye with the tube off the table and very evident when you put a straight edge on it. I would double check the bearing and motor mount blocks, and the lead nut attaching hardware, as has been said. These tables tolerate a fair bit of bad geometry before they actually manifest an issue.

What’s happening is the coupler at the motor spins. I’ve had one couple go bad on me already. I’ve tightened this one as much as I feel safe (broke the end of the hex key). Should I ask Langmuir to send me yet another coupler?

Yes, we were very careful. But … the steps would not seem to prevent this from happening.

I bought some of these as suggested by @Bigdaddy2166. When mine fail I have them ready to go. I don’t think I’d waste any effort replacing them with more aluminum ones.


Ok I thought you were convinced it was misaliagned I guess my assumption was you had checked coupling tightness. You could ask Langmuir for more but others here seem to be replacing them with a different type.

Just based on the way the lead screw is bowing away from the gantry there is a misalignment somewhere, and since it is binding at both ends the most likely culprit is either the motor/bearing mounts (not likely based on the direction the lead screw is bowing, also @boughtnotbuilt says he has already corrected this), or the lead nut. Based on the pics it appears the lead nut is too far from the gantry and pushing the lead screw away, which causes binding as the carriage gets closer to the ends. The coupler shouldn’t cause this problem, although the binding could cause the coupler to slip as the leadscrew becomes bound up at each end.

On a side note, the new machines are shipping with steel, 4 screw couplers now, at least mine came with them.

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Okay, I’m ordering those couplers. And, when I have some time, I’m going to re-align the X-axis gantry.

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So, moving the gantry to one end, loosening the screws that hold the lead nut bracket to the gantry and it moved into place. Also swapped out the coupler with the after market one recommended elsewhere on this site.

This taught me you can’t really set the X-axis gantry up centered, the lead screw is just to flexible.

This page helped me out!. Mine was having the same issues it would stop towards the ends. Turns out the coupler was loose. The half that holds the motor were loose for some reason. Tighten back up and works good now.

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