Alignment rotation between 4 surface points

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  • Alignment rotation between 4 surface points

    I'm fairly certain I know the answer to this question before I ask it, but this is what I've been left with.

    I've got a part with a shape similar to this illustration. What's a good way to handle rotation between those four Datum 2 points?

    The scenario is that I've been given no other option and I've tried to insist that this isn't how rotation works.

    As always, thanks in advance.

  • #2
    Do an iterative alignment. It will work like a dream.
    Originally posted by AndersI
    I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.


    • #3
      The 4 "Datum 2" points can also be used to create 2 mid points, which can then be rotated to (or constructed as a line and rotated to).

      Best fit would work well.

      Iterative would be my go to normally.
      "This is my word... and as such is beyond contestation."


      • #4
        Currently, that was my unspoken compromise, Vinni.

        I wanted to be sure I wasn't overlooking something simpler, or better before plowing forward.

        I'm sure someone is going to argue if I tell them anything is out of specification and I don't like to leave 'well maybe it's the alignment' wiggle room for them to argue and waste time.

        Thanks for the feedback.

        Iterative rotating to all 4 points are giving me a 'Reached Maximum Iterations: Points still exceed tolerance value.' however. I've got Target Rad set to 0.5 and Fixture Tol set to 0.2

        I'll switch back to 2 mid points.


        • VinniUSMC
          VinniUSMC commented
          Editing a comment
          MUlissi Also, I would point out too that if the datum structure is 1|2|3, then 2 is rotation and translation up/down (in the top view), and 3 is only let/right translation.

          If it is 1|3|2, then 3 is translation in both, and datum 2 is only rotation.

      • #5
        What VinniUSMC said.

        Or you could do a two lines (that are pointing in the same direction) and then do a midline.


        • VinniUSMC
          VinniUSMC commented
          Editing a comment
          In a perfect world, that would be ok, but this is PC-DMIS., so I would recommend against this.

        • LaserJay
          LaserJay commented
          Editing a comment
          I use it all the time with no issue, but I am pretty OCD with my alignments so usually my points will be in the exact same location on both sides of the part

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