This is probably very well explained but I'm lacking the terminology knowledge and that's keeping me from finding the information I need.

I have a frame to which I need to attach a weight carrying arm. The arm will need to rotate vertically (1 degree of freedom) but will not be doing complete turns thus a bearing is overkill. The arm has a rectangular profile which is hollow inside, so I was planning to weld 2 small pieces of sheet metal to the frame that will form a bracket inside of which the arm will fit then drill a hole and put a bolt through but I'm afraid that due to the vertical rocking motion the bolt will quickly come loose.

What would be the proper solution in this case?


Long story short : In any moving part you need to use a bearing, however there are many, many types of bearings. The main two types are : https://en.wikipedia.org/wiki/Plain_bearing https://en.wikipedia.org/wiki/Ball_bearing

Also important is the direction of the bearing : https://en.wikipedia.org/wiki/Thrust_bearing

If you google on 'buy bearing' you can find them in all shapes and sizes on any technical supplier website.

Anyway if you insist on using the good old 'this is a bolt and can be used as a bearing' technique just use two nuts. One nut as obvious the other as a counter nut tightened to the first one.

Good luck!

  • $\begingroup$ It's probably a common misconception to think of a ball bearing whenever people speak of bearings, I just learned that bushings (plain bearings) are in fact bearings! $\endgroup$
    – php_nub_qq
    Sep 20 '19 at 13:00

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