Straightness Question

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  • Straightness Question

    I have a plate with a Ø 34.912 / 34.937 and is 40mm thick
    The bore is in the Z+ axis

    There is a Line Element Straightness call out of 0.0076 whichthe engineer wants checked at 4 places evenly spaced around the bore.

    So I scan 4 lines equally spaced around the bore and reportout the straightness of all four 3D constructed lines

    Now my QE doesn’t want to see four different straightness’s,he wants just one showing the worst case of all four.

    Can anyone show me some code using either assigned values, arrays,generic features or some way to combine these four and have one showing worstcase.

    Thanks for your help
    sigpic

    B&S ADVANTAGE 12-22-10, EXCEL 9-15-9, ETC.
    PCDMIS 4.1, 3.5mr2,

  • #2
    ASSIGN/V1=MAX[ARRAY[STRA1.MEAS,STRA2.MEAS,STRA3.MEAS,STRA4.MEAS]]

    Then create a generic circle with diameter nominal 0 and actual V1.

    Typing off the top of my head, might need slight modification of the assignment.
    "This is my word... and as such is beyond contestation."

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    • #3
      Average off all 4 ? Wouldn't worst case of all 4 averaged be equal to or "better" than the worstcase of a single line ? Maybe try individual circles, evenly spaced from top to bottom. Create cast points on each circle. Create line from cast points. Dimension straightness of that line ? Maybe PERP check to face of part also ?

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      • #4
        Also, exactly what is your straightness FCF pointing to? It means different things if it is pointing to the surface or if it is attached to the diameter with a diameter symbol in the FCF.
        "This is my word... and as such is beyond contestation."

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        • #5
          Originally posted by VONDY View Post
          I have a plate with a Ø 34.912 / 34.937 and is 40mm thick
          The bore is in the Z+ axis

          There is a Line Element Straightness call out of 0.0076 whichthe engineer wants checked at 4 places evenly spaced around the bore.

          So I scan 4 lines equally spaced around the bore and reportout the straightness of all four 3D constructed lines

          Now my QE doesn’t want to see four different straightness’s,he wants just one showing the worst case of all four.

          Can anyone show me some code using either assigned values, arrays,generic features or some way to combine these four and have one showing worstcase.

          Thanks for your help
          Is the callout Straightness of the bore or of something else, or are there 4 bores?. Not getting why there are four lines constructed.
          If it is for the surface around the bore Flatness would seem to be more in order.
          sigpic

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          • #6
            "Line Element Straightness" means that it does not have the diametrical symbol with it, it is pointing to the surface of the bore. The engineer agreed to take just 4 scans straight up and down of the bore at 0º, 90º, 180º, & 270º.
            I have no issues with this. What I want is to report out only the worst case of the 4 straightness dimensions I have now.
            I am trying out Vinni's suggestion but I don't have a part in hand to check result. I am hoping the engineers don't see that it is reporting out a diameter and want an explanation on why I am reporting out a diameter instead of straightnesss
            sigpic

            B&S ADVANTAGE 12-22-10, EXCEL 9-15-9, ETC.
            PCDMIS 4.1, 3.5mr2,

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            • #7
              Why not use Cylindricity and report the measured, max & min values, then show the deviations graphically. You know if your not aligned to the cylinder your scans will be off C/L.
              3.7mr3CAD++ / 2011mr1CAD++/2012mr1CAD++/QUINDOS7

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