(Topic ID: 257876)

My approach to fixing a broken tooth on a stepper unit gear

By Jahkub

4 years ago



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  • 5 posts
  • 3 Pinsiders participating
  • Latest reply 4 years ago by Jahkub
  • Topic is favorited by 1 Pinsider

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    #1 4 years ago

    I recently found myself fixing a captain fantastic that had a broken tooth on the bonus unit that was preventing the bonus from going past 4k.
    I though I'd share my approach to fixing it, I'm sure others have probably covered this but I wanted add this to the collective knowledge in the hopes that it helps someone else.

    Parts: a small length of ~1/16" spring steel to act as a pin, a drill bit slightly larger than the spring steel, epoxy, a small file, progressive grits of sandpaper.

    Step 1: After removing the gear, drill a hole in the gear for the pin to be glued into. You'll want the pin to act as the vertical part of the missing tooth
    so that it takes the impact of the unit advancing, so the hole position is fairly important, the depth doesn't need to be too deep but the goal is to leave the pin a hair proud of the final height so that it can be filed down.

    Step 2: Mix up some epoxy, (I used metal) glue the pin in place, and then build the sloped part of the tooth with epoxy. Build it up past the final desired height so that it can be filed down. Let cure.

    Step 3: Use a file to do the final shaping of the tooth, use the other teeth as a reference for size and shape.

    Step 4: Polish the epoxy and pin with some fine sandpaper, 200 to 400 to 600 should be plenty but the sky is the limit. You just want a nice smooth surface for the mech to slide on.

    Step 5: Reinstall, give a tiny dab of super lube and test.

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    #4 4 years ago
    Quoted from pinhead52:

    are these gears hard to source?

    I couldn't find any with a quick search but I didn't look too hard.

    #5 4 years ago
    Quoted from wayner:

    The pin is the key-good fix. I take it the stepper is now working reliably and interested upon the 'wear properties' of the epoxy.

    It worked great after many tests. I'm curious too about longevity, I did very slightly polish the corner of the mech that makes contact with the epoxy. I don't think the machine gets a lot of play but time will tell.

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