Tru-Pos Locators UNJF thread

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  • Tru-Pos Locators UNJF thread

    Need to measure some threaded holes 1/4-28 UNJF.
    Anyone know where I can find plugs for this thread to check location?
    Lately, it occurs to me
    What a long, strange trip it's been.

    2017 R1 (Offline programming)

  • #2
    Does it help ?
    http://www.practicalmachinist.com/vb...hreads-236892/

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    • #3
      I know about J threads.
      What I am looking for is true-position plugs for 14-28 UNJF.
      Lately, it occurs to me
      What a long, strange trip it's been.

      2017 R1 (Offline programming)

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      • #4
        Originally posted by DungT
        Good luck finding one that big.
        grin....I meant 1/4-28
        Lately, it occurs to me
        What a long, strange trip it's been.

        2017 R1 (Offline programming)

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        • #5
          If all you need is location, why not just put the pitch (.0357) into your circle probing parameters?
          Play stupid games, win stupid prizes.

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          • #6
            Originally posted by thenev View Post
            If all you need is location, why not just put the pitch (.0357) into your circle probing parameters?
            +1 & for good measure probe another circle 0.005" higher than the 1st circle in Z (assuming Z+ WP) then another 0.005" lower than the 1st one.
            Poleaxe

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            • #7
              Originally posted by DungT
              http://store.measurenow.com/true-pos...lugs-p463.aspx
              We bought a set 6-32 to 9/16-18 more than 15 years ago, still have it. The manufacturer claimed that the plug itself is true and square better than .0001”. I don’t believe them but there is no way for me to verify it.
              Yeah, I have found several sources for UNF threads. What I need is UNJF thread.
              I didn't see them at that source.
              Lately, it occurs to me
              What a long, strange trip it's been.

              2017 R1 (Offline programming)

              Comment


              • #8
                Originally posted by thenev View Post
                If all you need is location, why not just put the pitch (.0357) into your circle probing parameters?
                Originally posted by Poleaxe View Post
                +1 & for good measure probe another circle 0.005" higher than the 1st circle in Z (assuming Z+ WP) then another 0.005" lower than the 1st one.
                That is what I will probably end up doing.
                I would rather be probing on a smooth surface rather than on jaggy threads. We will be using a thread mill (and for this thread that is new to us) and the TP tolerance is kinda tight at .008".
                Lately, it occurs to me
                What a long, strange trip it's been.

                2017 R1 (Offline programming)

                Comment


                • #9
                  Originally posted by John Riggins View Post
                  That is what I will probably end up doing.
                  I would rather be probing on a smooth surface rather than on jaggy threads. We will be using a thread mill (and for this thread that is new to us) and the TP tolerance is kinda tight at .008".

                  Yeah, the center will stay the same, but if the TP has a MMC callout, you'll need an accurate diameter. I've used cylinder probes to measure TP @ MMC of threads in the past with great results.
                  Play stupid games, win stupid prizes.

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                  • #10
                    Not to get off topic, but... I have an ME here who has been telling me for some time now that, from a practical standpoint, TP on a threaded hole is meaningless. I've never actually disagreed with him, but I do like to argue. Of course, print requirements are print requirements.
                    Probitas laudatur, et alget.


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                    Hang on to your butts!

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                    • #11
                      In a perfect world, they would thread the part AFTER inspection on CMM. Let the arguments begin on inspection of threaded holes with respect to location. I have valid arguments disproving EVERY method, including the use of location plugs.

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                      • #12
                        threads like these (pun INTENDED) rarely reach a happy consensus..............

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                        • #13
                          If you're really serious about threaded hole locators for this, check out this link: http://www.ring-plug-thread-gages.co...tion-solid.htm They can probably quote it for you.

                          Good luck.

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                          • #14
                            Originally posted by thenev View Post
                            Yeah, the center will stay the same, but if the TP has a MMC callout, you'll need an accurate diameter. I've used cylinder probes to measure TP @ MMC of threads in the past with great results.
                            You mean you got results that said they were ok.
                            cylinder probes cannot be calibrated by pcdmis.
                            if you cant calibrate it you cant use it.
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                            • #15
                              Originally posted by pwhitsa View Post
                              You mean you got results that said they were ok.
                              cylinder probes cannot be calibrated by pcdmis.
                              if you cant calibrate it you cant use it.

                              Well, that may be the case. We have no problems calibrating our 2mm cylinder probe. We also back up our results with manual methods (gage pins, micrometers, etc.) and the measurements are always the same.

                              Could you please provide some information that says cylinder probes can't be calibrated?
                              Last edited by thenev; 08-28-2013, 10:22 AM.
                              Play stupid games, win stupid prizes.

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