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  • Tap tool supplier for (1.3125" - 32 UNS-2A) thread.

    Discussion in 'Machining' started by JohnS, Mar 13, 2012.

    1. JohnS

      JohnS Member

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      A friend needs to form a '1.3125" - 32 UNS-2A' thread in a plastic prototype part but is having difficulty finding a supplier of a suitable tap tool. Any ideas?

      I welcome any suggestions.

      Thanks, John S
       
      Last edited: Mar 13, 2012
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    3. JohnS

      JohnS Member

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      Just checked the part type ... not plastic, the tap needs to be formed in an aluminium housing.

      John S
       
    4. Dana

      Dana Well-Known Member

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      Are you certain it's 1.3125 and not .3125? The finest thread size I see for 1-5/16 is 27 pitch, but 5/16-32 is an available size. You might have to single point it... what is it for?

      The most complete source I know of (in the US at least) is MSC.
       
    5. JohnS

      JohnS Member

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      Hello Dana, Many thanks for your reply.

      I've checked with with my friend and the thread spec is indeed 1.3125" - 32 UNS-2A (21/16 or 1&5/16 inch nominal size).
      The thread details come from a spec drawing for an optical lens part. A matching thread is required in the aluminium housing for lens mounting purposes. I guess the "UNS" designation is used because "32" is a non-standard thread pitch.

      John S
       
    6. s7silver

      s7silver New Member

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      Why not just cut the thread on a lathe instead of using a tap? Any reasonably good machine shop should be able to do this.
       
    7. Dana

      Dana Well-Known Member

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      Optical thread, that makes sense. Yes, the UNS means standard form but non standard pitch. You will probably have to single point it with a lathe, but as s7silver said it's easy to do.
       
    8. Karl

      Karl New Member

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      A competent machinist with a CNC machine can thread mill any weirdo size and pitch thread. A tap is most likely more expensive (if attainable in that config) than a quicky thread mill job. Good luck.
       
    9. Randall Wink

      Randall Wink Member

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      If this is indeed a one-off, you can turn the thread on a steel bar, cut reliefes along the axis and heat treat the bar to make a "home made" tap that will cut a couple of threads.
       

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