[FTC]: Set Screws Suck!!!

[nathan_hui]

Make sure the set screws are engaged to the flat of the shafts, and torque the set screws in with the allen key. If that still doesn't work, replace the screw itself (it may be worn, you'll notice it if you look at the tip of the set screw, which would be silver instead of black.)

[JesseK]

File down the tip of the set screw, or replace the set screw with a machine bolt. This spreads the stresses of the set screw out more, making the set screw less likely to slip in the first place.

[Nemo]

We put a dab of red Loctite on some of ours. It helps a bit and you can still get them out (with additional effort) if you want to.

[nathan_hui]

Originally Posted by JesseK

File down the tip of the set screw, or replace the set screw with a machine bolt. This spreads the stresses of the set screw out more, making the set screw less likely to slip in the first place.

Actually, I would not replace the set screw with a machine bolt, primarily because the machine bolt doesn't have a finished end, unlike a set screw, which (most probably) has a machined cup point, which is designed to really grab a shaft. In certain applications, it is advisable to file down the tip of the set screw, but I do not believe that this case is one of them, unless of course you are using a flat tip set screw.

The one time I used a machine bolt (Socket Head Cap Screw, 10-32, 2", Black Oxide Steel) as a set screw, I completely destroyed the tip (the metal in the bolt was too soft).

[JesseK]

Originally Posted by nathan_hui

Actually, I would not replace the set screw with a machine bolt, primarily because the machine bolt doesn't have a finished end, unlike a set screw, which (most probably) has a machined cup point, which is designed to really grab a shaft. In certain applications, it is advisable to file down the tip of the set screw, but I do not believe that this case is one of them, unless of course you are using a flat tip set screw.

The one time I used a machine bolt (Socket Head Cap Screw, 10-32, 2", Black Oxide Steel) as a set screw, I completely destroyed the tip (the metal in the bolt was too soft).

I guess we have different anecdotes then. We've never had a problem with machine bolts as set screws on a flattened face in either FRC or FTC.

We used machine bolts on the inner rail shaft collars of FTC 354's champs-winning robot last year. They worked fine, even with the super high-traction wheels.

[nathan_hui]

hmm. Well, I was placing well over 300 in-lb torque when the machine bolt failed, so that is probably one of the mitigating factors.

[sprocketman92]

Thank you all for your help we have plenty of options to try because of all of you!

[coollog]

Also, try to not use set screws whenever possible and keep axles themselves stationary, but the components (wheels and gears) free to rotate on the axle. So, whenever possible, remove axle hubs and add shaft collars.

[sandiegodan]

+1 on filing the set screws flat on the tips. Things were much more stable once we did this.

If you are filing manually, put a wrench into the setscrew and hold the two together then rub along a stationary file or flat sandpaper. It's easier to keep the file perpendicular to the set screw. I like using a bare grip as it is easy to judge if you are being too aggressive either with pressure or speed or both by the heat you are generating. It should never be uncomfortable to hold.