Hello, we are looking to use a Versaplanetary 1/2" hex shaft and instead of using a lock collar, we want something that is a smaller profile. We were thinking of using a washer and a flat head screw, but this is going on top of a bearing. Does anyone have any other suggestions? Thanks!
Can you post an image that shows what you’re trying to do?
We use washers and a 1/4-20 bolt (I think) into the end of Thunderhex. We tap the hex. As long as you use a washer which is not too big (only covers the rotating part the bearing), it works fine.
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A washer and a screw into a hex shaft to retain a bearing or wheel is just dandy.
Here are some examples from our 2022 robot:
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Use loctite!
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Clip rings are probably the smallest profile, lightest weight solution for retaining hex shafts, but you need access to a lathe to make the grooves. (We move the cutter in until it just touches, then in another 50/1000ths, and it works great.)
But never on Polycarbonate!!!
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I’d really like to see a polycarbonate hex shaft someday 
In all seriousness, loctite is definitely a requirement for the screw and washer method - the screw will actively try and back itself out, and you’ll need to check on it periodically even with Loctite
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I don’t know if you’ve ever heard of MORE Robotics, but if anybody’s done it, they have.
(strongly implied winkyface)
I have seen teams use loctite on a screw going through polycarb and into aluminum shafts. This WILL slowly kill your polycarb. Do not get loctite anywhere near polycarb, use a plastic safe glue or threadlocker if you need to do it.
Hey, whole story here, that claw worked while cracked for several matches afterwards! Then we got the spare swapped in…
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Just say no to Loctite within 3’ of most plastics, so in other words it shouldn’t be used on a robot.
The makers of Loctite recommend the use of super glue in those applications.
I recommend a Nylock bolt, that is what AndyMark supplies to mount motors to the Toughbox mini. You can get 1/4-20 button head Nylock bolts from McMaster.
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Did you give this advice to the people making Falcon motors? .
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Would be ideal to know the exact match when it will fail. Our usual experience is that failures like this occur when they are good and ready. Best not to risk them at all.
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This was our lift setup in 2020. This piece sat on a shelf, for three weeks, with fully tightened screws.
This is what happened one day after we Loctited the screws in place.
At the time we didn’t know about Loctite and Lexan. Loctite dries out the Lexan, causing it to crack.
Live and Learn
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I like using Loctite 248 on a stick. It doesn’t make a mess like liquid threadlockers do.
Threadlocker Paste, Medium Locking Strength, Loctite® 248, 0.32 oz. Stick | McMaster-Carr
Having said that… we rarely loctite bearing retaining screws. They can be torqued plenty tight enough to avoid loosening.
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