PC DMIS Report - Distance question

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  • PC DMIS Report - Distance question

    Hello all

    When reporting a distance in PC DMIS i want to show the measured and acctual coordinate for both points in the axis it was measured.
    I also want the nominal coordinate for the measured points to be 0.

    So lets say I measure (Against CAD) two points on opposite facing planes. I report the distance between the points along Y-axis.. I want the operators to see which point is too far away from nominal value in the axis, (so if its ex. .023 mm or -0.023 mm.

    Has anyone done this? Do I have to change alingment and set my orgin for each point/element that i measure? is there any smarter way?

    Thanks for replies

  • #2
    T-value

    Comment


    • pcdmisstudent
      pcdmisstudent commented
      Editing a comment
      Hello, thanks for the reply.
      I tried the T-value but it doesnt seem to represent the distance very well.
      I measured two points, did the distance between them. Nominal is 13, measured is 12.897.
      I then did the T-value for both measured points and the the points were measured at -0.050 and -0.068.
      12.897 + 0.050 + 0.068 = 13.015, so the values doesnt add up?

      Any idea?

  • #3
    Originally posted by pcdmisstudent
    I tried the T-value but it doesnt seem to represent the distance very well.
    I measured two points, did the distance between them. Nominal is 13, measured is 12.897.
    I then did the T-value for both measured points and the the points were measured at -0.050 and -0.068.
    12.897 + 0.050 + 0.068 = 13.015, so the values doesnt add up?


    T-deviation is: plus=more material, minus=less material. You have less material on both sides, so the calculation should be 13.000-0.050-0.068 = 12.882, which is quite close to your distance. The remaining difference might be caused by using the wrong kind of distance calculation, or your alignment not being square to the surfaces (or the surfaces not parallel to each other). Please remember that distance is a hairy animal, with large teeth…


    dist_reality.PNG
    AndersI
    SW support - Hexagon Metrology Nordic AB

    Comment


    • #4
      T-Value is a 3D deviation (projection of deviations along the surface vector).
      In this case, if the planes are not along Y, T-value should be projected on Y axis.
      I would :
      ASSIGN/DEV_PNT1=DOT(PNT1.XYZ-PNT1.TXYZ,CURRENT_ALIGN.YAXIS)
      ASSIGN/DEV_PNT2=DOT(PNT2.XYZ-PNT2.TXYZ,CURRENT_ALIGN.YAXIS)
      IF ABS(DEV_PNT1)>ABS(DEV_PNT2)
      COMMENT/OPER,(...)
      PNT1 deviation is bigger than PNT2 deviation
      END IF
      ELSE
      COMMENT/OPER,(...)
      PNT2 deviation is bigger than PNT1 deviation
      END ELSE

      Comment


      • #5
        If you want to dimension the point off of the nominal of 13, but want to call 13 "0", then translate your origin 13 in the axis you want, and dimension the point in that new alignment. This is your other option.

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