High Strength Gear Shaft Inserts

I just bought a whole bunch of high strength gears and when putting in the shaft inserts it seems like some of the gears have the hole where the shaft insert goes a little bigger, so that the shaft insert just falls out. Does anyone have any bright ideas on how to get those shaft inserts to stay when they are loose? My students keep losing them…

medium strength (blue) Locktite. https://www.amazon.com/Loctite-37418-Strength-Threadlocker-6-milliliter/dp/B000FIXQXK

Awesome, I can’t believe I didn’t think of that! Thank you!

Is it legal to use Loctite for this application? My understanding of rule R15(b)i was that it could only be used for “mechanical fasteners”. Otherwise you could just use Loctitie as glue for all sorts of applications. Has anyone ever clarified this in Official Q&A?

That exact same blip of R15(b) says it can be used for securing hardware only. Keeping the HS insert in place is in the same vein as keeping a nut from falling off a screw. In theory you should be using spacers and shaft collars to make sure it stays within the gear, but they aren’t holding 2 random parts together, just keeping an insert in place.

I’ll go ahead and put it in Q&A, because I have always interpreted “hardware” there to mean screws and nuts (mechanical fasteners) only. I sure hope you guys are right though, as it is so much more useful in applications like the one being discussed here.

Let us know if you ask in the Q&A and what you find out?

The answer was no, it is not legal to use Loctite threadlock to secure inserts for gears and wheels in VRC.

So you end up having to clamp a shaft collar to each side of the gear or wheel to keep the insert in place, or fill the shaft with nylon spacers to trap the insert into place. Using drive shaft lock-bars on each side of the gear would both hold the insert in place and reduce play/slop in the system.

It sounds like their product is out of spec on one side or the other. It is not functioning as intended. Contact VEX.

Another rule that cannot be policed.

Exactly, it annoys me when they make things like this illegal. There’s no harm that I can think of in allowing people to use loctite for this and it’s impossible to enforce it.

The way i read it, they were making the decisions based on material properties, which i consider to be reasonable. If they know that loc-tite and their plastic do not get along, and can cause mechanical failure, then that is a pretty solid reason to say “don’t do that”. It is less of a thing to police and more of a thing to point at if you wreck your materials and then complain to them.

yeah, making it illegal is sort of a useless gesture, but it’s certainly not something i would attempt based on the results they provided.

I would love to, except it was about 1/3 of the gears and wheels I purchased that have this problem. My guess is that it is considered allowable tolerance. I really wish they could fix this. Once it is on the robot, it is not really a problem. Its only a problem when the parts aren’t attached to the robot. I guess it is a matter of just getting middle schoolers to pay attention when they are carrying the parts around, which is a lot like herding legless cats.

I would sincerely hope that most people follow the rules no matter what they are.