Boundary Type True Position

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  • Boundary Type True Position

    I'm a bit behind...will someone please point me in the right direction to report boundary type true position? I've used profile to report deviation in the past but I want a more better method...:-\
    Boundary TP Callout.png
    10
    Legacy
    30.00%
    3
    XactMeasure
    40.00%
    4
    Profile
    50.00%
    5
    Manual Calculations
    0%
    0

  • #2
    Wow, the check box vote is sweet.
    Its the little things in life.

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    • #3
      Profile is probably your most bestest, correctest method, because Boundary is technically a unilateral tolerance. Boundary is represented physically by a pin that is at (MMC minus TP tolerance) size. So, if you can analog scan that slot, you'd be better off that way.

      Otherwise, your next bestest choice is (probably) XactMeasure. Although, since there's only MMC on the feature, legacy TP would be just fine.

      What's missing in a TP calculation is whether or not there is boundary violation.
      Last edited by VinniUSMC; 06-13-2018, 03:07 PM.
      "This is my word... and as such is beyond contestation."

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      • #4
        I agree with Vinni. Profile would be best but its asking for position. I would use XactMeasure if i had to program.

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        • #5
          Ya, it get's hairy marry when the slot length and width have different position tolerance. Then I'm asking "How do I account for that?"

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          • VinniUSMC
            VinniUSMC commented
            Editing a comment
            Yes, that does make things... interesting. I generally ignore it while running parts on the CMM and treat it like a normal Position. The fixture will take up the slack.

        • #6
          Alright kids...True Position or Profile for this one? Note 1 is a die break / die roll comment. Datum Z is a plane, B is a line, and C is a point.

          boundary_TP.JPG

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          • #7
            When I need to report the true position of the width of a slot with MMC I measure 2 points to report the width of the slot then create a generic circle and plug in the width of the slot for the diameter of the generic circle (ex. loccir.nom, loccir.meas) then report the true position of the generic circle.

            Not sure if this is what your looking for but if it is let me know and I'll post the code from the program

            Comment


            • bfire85
              bfire85 commented
              Editing a comment
              I am not sure if you were replying to mine or not, but I use that method quite a bit. As for my post above, there are many features of size that make up the slot. It is not an ordinary slot. Plus, there is an all around callout on the features as well. After discussions with our team and research, they 9X slots would be created as a set with a bunch of points and measured as one single pattern.

            • VinniUSMC
              VinniUSMC commented
              Editing a comment
              I think that's the right way to do it. Even though the feature is technically a feature of size, profile is more appropriate. PC-DMIS can dimension TP of a set of points, but the size (when MMC is applicable, is definitely questionable).

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