i'm curious, have you ever used thread-locking fluid?
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@Felthry

Is this a thing for screws?

@Tathar yes, a sort of glue for high-vibration environments

i'm a little surprised how many people don't know what it is! if you've ever been taking something apart and saw a blue or red streak on the head of a screw, that's probably residue from thread-locking fluid (i think an intentional mark to indicate "yes we remembered to put the thread lock on this bolt")
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@Felthry

I don't remember one being on the head, but I know bolted joints can have some blue stuff (wouldn't really call it a fluid) on the bolt thread. I knew it had to do with keeping mechanical stresses on the bolt low enough to prevent the shaft from snapping, because it couldn't shift around in the nut.

@Tathar yeah that's thread-locking fluid

it's not fluid after it cures, but it's about the viscosity of water when you apply it to the bolt
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@Felthry

The bolts on my chair had it applied from the factory, so apparently you don't have to apply it at the time of assembly?

@Tathar you generally do? you can put it on a bolt that's already screwed in and it'll seep into the threads a bit too, i think they make a different formulation for that kind of application

but i'm pretty sure it's mostly applied before screwing the screw and bolt together
-F