Hello! I have a moving joint where the screw keeps falling off. My first instinct was "blue threadlocker", but since this is a moving joint, "locking" it isn't an option. Would the threadlocker really lock it, like glue? And if not, will it have any effect at all?

The joint in question is at the steering mechanism of the front wheels of a 3-wheel child scooter, like the one here: https://www.amazon.com/Allek-Scooter...dp/B07S64PYMM/. Very common steering mechanism, also seen in toys, bobby cars, and so on. Pretty annoying, the screw that keeps falling off. Mechanical solutions, such as rings etc, are hardly usable, since there's a tiny nut that comes with the screw and there isn't any room for anything else.

 

We can't say without knowing where you will apply the thread locker. If you only apply it to the threads that will be inside the nut then that is the only thing that will be stuck by the Loctite but if you get it inside the joint or whatever is moving then it can goop it up a bit. Blue Loctite isn't really a glue and it only cures in the absence of oxygen so if you do get some in the moving part it might gum it up but probably wouldn't "glue" it.

 

Many times manufactures will "set" the fastener with a dollop of wax or thread locker on the surface of the screw and the mating part. No chemical will be touching moving parts. You might want to use Loctite Red.

 

I don't see why a bit of threadlocker wouldn't solve your problem of the nut falling off the screw. That's the purpose of it.

Blue threadlock is 'temporary' and can be undone
Red threadlock is 'permanent' and takes significantly more force to undo.

Another option would be to replace the standard nut with a locknut. There's a bit of nylon embedded in the nut to make it much harder to unscrew.

 

I've also made my own thread locking by buggering the threads a bit. Keep the end threads clean so you can start the nut but a few threads in take a punch or nail and lightly smash or ding the threads. When you tighten the nut you will feel it get harder to turn when you get to the damaged threads which will help hold the nut in place and prevent it from loosening.

 

That's called a Nylock and is good choice. But after one or two disassembly's they are not much better than an ordinary lock nut and washer.

 

That's an original idea I've never heard before. Thanks!