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Longitudinally locked rotating cylinders

  1. Oct 6, 2009 #1
    I need to make two close fitting cylinders that are longitudinally locked in position but need to rotate against each other. I want to make this in as few parts as possible.

    I was thinking of machining grooves in each cylinder and placing the Teflon ring in the groove of the inner cylinder and pressing the outer cylinder on.

    How secure would this arrangement be?
    Are there any other alternatives?
    Is Teflon the ideal material for the ring?

    Thanks in advance for any help.
  2. jcsd
  3. Oct 6, 2009 #2


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    Science Advisor

    I would need more information on the overall limits or constraints, i.e. speeds, forces, etc... to begin to answer your question.
  4. Oct 6, 2009 #3
    The tubes are fairly small.
    11.2mm ID, 12mm OD for the inner.
    12.05mm ID, 13mm OD for the outer.
    approximately 40mm in length for the inner, 10mm for the outer.

    Force is what a person will apply to rotate the tubes with his fingers The person should be able to turn this easily, but not so easily that everyday bumps and nudges will turn it on (it's a rotating sleeve used to activate a reed switch). Longitudinal slop or play is a definite no-no.

    It has to be able to resist sufficient force that the outer tube will not strip off unless someone puts some effort into it.
  5. Oct 6, 2009 #4
    Sounds like your aim is to either insulate the user ("Teflon rings") or provide some ergonomic benefit by increasing the OD of the control...

    In either case, how about using a 10mm length of vinyl tubing over the 10mm OD control?
  6. Oct 6, 2009 #5
    No that's not what I am doing.
  7. Oct 6, 2009 #6
    What are you doing? Do you have a simple sketch? What is the endgame for this device?

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