Set screws keep coming loose on stepper motor coupler.

Discussion in 'Off-Topic' started by spinnaker, Jan 31, 2016.

  1. spinnaker

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    If you do not already know, I purchased one of those cheap Chinese CNC engravers ro experiment with engraving PCBs.

    On one of the stepper motors, the set screw in the coupler from motor ro shaft keeps coming loose. I need to tighten it every few runs. I thought about some locktite to fix it but I am worried I won't be able to get the screw back out if need be. The screws are pretty tiny.

    Any ideas on the best way to fix this?
     
  2. jpanhalt

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    Loctite is color coded. There is a very firm, green version that requires heat to remove. I suspect any of the red versions will work for you. "Permanent" is only relative and depends on the fastener size. I would have no problem using a red permanent version in your application. Worse comes to worse, you can use heat to remove the set screw.

    John
     
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  3. tracecom

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    You might try some dabbing some fingernail polish (color optional) on the screw after it's seated.
     
  4. #12

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    Blue is the soft thread locker.
    I used some red on a guitar jack and I had to use a grinder to cut it off.:mad:
     
  5. Lestraveled

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    The set screw might be out of tolerance. (Chinese grade). You might try replacing it.

    As far as Loctite, I would use Blue.
     
  6. jpanhalt

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    As an additional aid, if the shaft is round, you might consider filing a flat on it or drilling an indent where the screw sets into it.

    John
     
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  7. spinnaker

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    OK locktite or nail polish?

    I thought about nail polish put where the screw sits it might be a little difficult to scrap off. Though I suppose I can get a screw driver in there.
     
  8. spinnaker

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    Was going to ask that too. It is round.

    Another thought I had was to put a dab of nail polish on the shaft where I intend to put the set screws. Let it dry first of course.
     
  9. #12

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    Too brittle. No grab.
    It works for an outside coat, or a thread lock, but it won't work for a point controller.
    It scrapes off easy because it is too brittle.
     
  10. tracecom

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    Acetone on a Q-tip.
     
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  11. spinnaker

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    So would you suggest filing the shaft a bit then?
     
  12. spinnaker

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    True. Maybe I will do both then.
     
  13. #12

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    Yes. A flat on the shaft has saved many a drill bit for me.
    But you might use a grinder. Tool steel (drill bits) can be difficult to file.
    If you're on a motor shaft, that's, "mild steel". A file will work.
     
  14. MaxHeadRoom

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    You can also get Allen set screws with a pointed end they grip better than the flat ended style.
    Max.
     
  15. Lestraveled

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    @spinnaker
    I always did think you had a screw loose.:D
     
  16. shteii01

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    Prepare to get pie in the face.
     
  17. kubeek

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    Better loose screw than loose wire ;)
     
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  18. spinnaker

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    That is what these are.


    Actually just look at them again . They are mode flat. Where do I get the ones with the point? How would I know what size to use?

    What are they actually called?
     
    Last edited: Jan 31, 2016
  19. spinnaker

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  20. cmartinez

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    The only way to loosen a bolt that's been locked with red loctite is to heat the part with a small torch.
    I like using the type used for cooking desserts, like creme bruilé
     
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