Stepper comes loose from linear rail

I make sure to line up the top of the stepper motor tip so that the flat edge of the shaft lines up with one of the 2 screws that connect it to the coupling. It works fine at first but after a while the rail uncouples from the shaft.

What can I do?

Screws must be working lose… Might try something like lock tight


Thank you. I’ll try some loctite 242. Should I apply it on the threads of the little screws that hold the rail and the coupler or should I throw some onto the coupler and shaft as well?

Anywhere it’s working it’s way lose…

Pick up a version of Lock Tite that isn’t permanent, might have to unscrew it some day.


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You may want to consider using Purple Low-Strength Permatex 24024 or Henkel Loctite 222 for small fasteners.

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Thanks for the suggestion on loctite. It did work a bit longer than without it but eventually the rod came lose from the stepper coupling again. It’s always that same rod.

It almost seems like it’s shorter than it should be as when I try to push it back into the coupling it barely reaches and the screws do manage to grab it but just a little bit. Is there anything to do in that case?