Our team has been having some troubles with our screws falling out as we drive. Every time they fall out, we tighten all of them, but the same problem happens again and again. We’ve heard whispers and rumors about using the screws with the blue dots on them, but we’re not sure if it would be worth replacing all the screws for an uncertainty. Is this the way to go, or is there another way? Thanks.
Not too sure what going wrong here, but if your screws are coming loose, i suggest using threadlock or nylocks. It’s probably better to use nylocks so you can at least take it off easily.
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@NorthShore, what type of nuts are you using?
Are you using keps-nuts (pictured below) or regular nuts (without the spiky collar)?
For different places on the robot there are different mounting options that work the best.
If you are attaching two aluminium pieces together, then properly tightened keps-nuts are the best option.
If you are attaching plastic bearing block to a metal frame then it is best to use nylocks:
And, if you are using standoffs, instead of nuts, then it is best to insert plastic spacers between the metal and standoff that could compress:
In my experience, using thread-locker only makes sense when the joint is experiencing constant twisting loads. Then use only blue (medium strength), because once you apply red (max strength) thread locker, you could only undo it with a heat gun.
Screws with pre-applied thread locker (blue dots) are usually much more expensive and it is cheaper to apply it yourself. But, once again, most of the times nylocks are all you need.
Additional info could be found here: Standoffs Coming Loose
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pro tip - use a standoff on an L key to tighten, you get more mechanical advantage and you wont spend as much on expensive tools.
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I like to use nylon washers for the same reason listed above with the spacers.
Not gonna lie, I clicked on this half-thinking people were trying to get me banned…
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My nickname at MIT at one point was screw loose, because I did not have good build quality…
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Thats exactly what I was thinking
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Okay. The fans(?) get what the fans(?) want.
It’s a general rule of thumb to have at least 2 threads sticking out past the nylock to ensure maximum performance. The nylon needs to grip the Screw well.
If out of nylocks, I sometimes cheat and use a keps nut backed by a metal shaft collar. Sounds janky, but I’ve never had an issue. I even forewent the keps nut on a rubber band holder I needed to open and close frequently.
On that note, Vex’s new nut retainers may seem like a good idea, but I maintain that the screw itself might just work its way Loose, rather than the nut spinning off.
I’ve actually never used nylock on standoffs, but it does seem like a good solution when the teflon spacer/washer thing doesn’t work.
Maybe @loose_scews has some thoughts on the issue?
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That’s true, but it will bend the threads on the standoff.
We were told that we should use wrench to tighten nuts and not the screwdriver to tighten screws, because we kept stripping them.
So my team bought a good 11/32 wrench at home depot and we now almost don’t lose parts on the field.
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We have not had issues with bent threads with this technique.
Definitely use wrench.
This technique is good for when you have to tighten screws in difficult places.
You should also seat the tool properly in the screw head to prevent stripping.
We are using keps nuts
Then that’s your problem
If you have no access to nylocks, I might try to double up on the keps nuts. I’ve used a shaft collar on the screw to hold a keps nut in place before, but then you run the risk of damaging the threads. (Never happened to me)
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Nylock Nuts OP.
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