So one of our team members apparently used too much loc-tite on the motor screws on our catapult and now there are 10 motor screws VERY firmly stuck into the motors.
My question is, how easily can these be removed if they can not actually be turned physically?
Maybe heating up the screw to weaken the loc-tite?
Are the screw heads stripped? If not, get a longer 5/64" Allen wrench and see if you can break them loose. You might strip them but it’s worth a try.
If they are stripped or you strip them with the longer Allen wrench, there are a few techniques you can try.
Use a pair of vise grips/pliers to grip the sides of the screw head. This is pretty difficult but once you get a good grip you can usually break them loose.
As a last resort, use a Dremel to cut away at the screw head just enough to let it pass through the hole in the metal. After you get the motor off you can use a pair of pliers or vise grips to get the rest of the screw out.
Yeah the motors are attaching the motor to a C-Channel so I’m not sure how the vice will work, I may have to just dremel it off if that doesn’t work.
As long as the 5 motors stay intact
Alternatively, you can use a Dremel to cut a slot, and then use a flathead screwdriver.
Thanks,
Nick H. (8000)
Ended up using an allen key in a drill on high-torque then for some just removed the screw head with an angle grinder then used a vice to unscrew it
What happens is that the loc-tite not only gets stuck in the motor screw, it basically melts the plastic of the bearing flat, fusing the screw in place.
The melting plastic is a huge reason to not use loctite on the robots. The special screws with the locker on the screw are fine, but the blue and red loctite is not a good idea. If you must go that way, use Loctite “222” the purple liquid. It’s designed for smaller screws like are found in motor mounts and will come apart.
You can also use a lock washer (hint, take a keps nut apart) on the screw.
Using cap head screws can help with motor mounting to the robot helps so you can get some good elbow grease tightening on the motor screw. 6-32 ones plus a washer for the motor mounts. You then need a different hex wrench as it is no longer 5/64 or 3/32. You lose some clearance so it may not be viable for tight spaces.
We have also had better luck with cap head screws on the motor covers too. Those tiny phillips head screws are prone to stripping. M2 for the front/back covers. 10mm for normal 16mm for IME covers
All on this page. You can find better prices on the 6-32 screws elsewhere.
I was actually talking about these: Central Welding Supply
When you clamp down with them, they lock. This makes it easy to turn stripped screws if you can manage to lock the pliers on the screw head.
Also, I think the key with Loctite is moderation. If you just use a little bit, the screw will still be fairly easy to get out. I’ve found that the VEX screws with Loctite don’t hold very well compared to screws with Loctite that you applied.
Yeah, we had to loctite the screwws at the last minute as the constant use of the motors keeps working the screws out.
I will try the keps nut idea
use new 6-32 screw with the red threadlocker on them, put a metal washer underneath the screw head and a dab of loctite super glue on the threads. Never shakes loose, but still possible to unscrew.
Just an alternate point of view, we have used red and blue loctite for years without any issues. Granted, we usually take apart assemblies before the loctite has even had a chance to set XD
Umm, they both cure in ~12 hours, if your disassemble time is less than that not sure why you are using loc-tite. In theory the blue will come apart with extra force. I’ve never used red on VEX but on other projects the red doesn’t come apart without an insane amount of force or some heat.
Usually we think we have settled on something, and then decide to change it later.
We use it VERY sparingly so maybe that’s it, but we use exclusively the red.
I also have had the red be very hard to unscrew in other applications. Probably just we use so little.
All you need to do is learn to use mechanical advantage instead of loctite. If you use the short end of the allen key in the screw and the long end to turn, you can tighten motor screws and keps nuts so tight they need a wrench to get off, and not strip the screws. I had about 30-40 screws on my robot tightened this way for almost 3 months on a heavy flywheel, and only one or two came loose, and that was because they had stripped heads and couldn’t be tightened enough. You could also try using this to get loctite off.
