Set screw problems

[blackrocks0]

Our team is using chain for our bridge mechanism, and both of the sprockets that we are using have been having set screw problems. I have had to replace 3 set screws (they get stripped),while taking the sprocket on and off their about 7 times. We have drilled into the shafts (putting a dent in them) for the screw to sit in, but one of them still slipped out. What should i do?

[Garten Haeska]

Can you possibly key the shaft at sprocket?

[Kevin Sevcik]

Frankly, you shouldn't use set screws. You should look into getting keyed shaft and keyed sprockets so you don't have to worry about this anymore.

That said, if you absolutely can't get keyed stuff in time, try using Dog Point set screws into an actual hole drilled partly into the shaft instead of just a depression.

Well it looks like you're * takes off glasses * screwed!

Maybe adding loctite, or another adhesive to the screw? Does it work on other sprockets of the same type? I agree with Garten; Cutting it into a key will be really good, though since bag and tag is in about 3 days, you may want to do the quickest thing possible.

[blackrocks0]

We have a mini-regional tomorrow, and i know they have a metal shop there, so maybe i could use the current shaft and make my own key slot.

[Garten Haeska]

We had this same problem with our 4 wheel shooter with 2 set screws now we have 6 set screws with 2 that are pushing down the key. It works very well. Yes it is overkill but anything can happen during a match

[fox46]

If you post a picture of the setup with sizes I could offer some better ideas but here are some options:

-Fast and dirty keyway: Use a dremel to cut a keyway into the shaft, then take a hacksaw, remove the blade, insert into bore, reinstall blade on saw, clamp hub in vice, "cut" keyway into bore with hacksaw. It will take some time and lots of trial fitting before you get it right. Don't force the keyway in but rather keep trimming material until it fits well. Use a set screw to press down on top of the keyway.

-Roll pins: Drill a small hole right through the hub and shaft and hammer in a roll pin AKA spring pin.

-Replace the set screw with a grade 8 bolt sharpened to a point, mill or file a good flat spot on the shaft and have at it with lots of locktite

[Curt Henderson]

You can also try to use two setscrews in the same hole. If you have .25" hub thickness use two .12" long set screws. Drive the first one in hard and drive the second setscrew into the back of the first one. A little blue Loctite on the second setscrew will help as well! Good Luck!