I have a motor with an an internal parallel keyway and a sprocket with a set screw. The sprocket set screw keeps coming loose allowing the shaft key to slip out. Usually I'd use some blue loctite on the set screw but I'm scared I'll never get the set screw back out as it's a tiny, easily strippable, allen head. Is there a better solution for this particular situation?

2 Answers 2


I'd use the thread locker. If it's too difficult to remove you can apply heat which will soften the thread locker and allow it to be easily removed.

  • Ayup ... sage advice. Aug 8, 2022 at 0:30
  • 1
    And there are other grades of thread locker available, e.g., Loctite 222 (purple) is quite weak. Aug 8, 2022 at 8:11

If space allows, you can replace the socket set screw with a longer socket cap screw. The head of the screw will be exposed and it will have a bigger socket, allowing you to torque the screw properly (so that it won't come loose again) without fear of stripping out the socket.

This would also allow you to use a jam nut on the screw's shaft if necessary, tightened against the hub, to further prevent loosening.

  • Sadly the sprocket recesses slightly into the motor mount bracket. I suppose I could pull the sprocket out slightly but that might mess with the alignment.
    – Tag
    Aug 10, 2022 at 4:45
  • @Tag OK, just a thought: Depending on configuration, you might remove the sprocket and flip it so the hub is on the other side, as long as alignment is not altered. There's also the possibility of motor base adjustment to re-align the sprocket.
    – MTA
    Aug 10, 2022 at 12:10

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