I have some height-adjustment nuts screwed onto vertical threads to support my print-bed for a 3D printer. They are domed nuts and the aluminium build-plate sits on top of the domes, three holes in the plate align with the domes to hold the plate in place.

How can I protect these nuts from vibration loosening without using thread-locker or similar, so that they remain adjustable?


Double nutting can be an easy option for this.

I was about to describe it myself, but these folks do a great job.

This image, from the article, models the forces that do the job. Take note of the contact surfaces between the threading of the bolt, in the top vs. bottom nut:

force model for double nutting

  • $\begingroup$ In my situation the stem is pointing upwards and there is a domed nut on the top. I guess this means adding a regular nut underneath it and tightening it upwards against it - but without the other surface (the one with the F2 arrows in the diagram) would it still work? $\endgroup$
    – jhabbott
    Jan 21 '15 at 21:57
  • $\begingroup$ I think for your application, as I understand it, the lower nut, which would be tightened against the domed nut, would be referred to as a "jam nut" and should work just fine. The double nutting application referred to in the answer above is similar, but the typical application more like a precursor to today's nylon lock nuts or locking washers. $\endgroup$
    – DLS3141
    Jul 22 '15 at 16:19

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