True Position Help Datums not perp/parr

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  • True Position Help Datums not perp/parr

    Hello all

    I'm trying to dimension this lovely part and I am running into something I thought might become an issue. This part has 5 Datums called out, A, B, C, D, and E. A is perpendicular to B but share the same Z vector, C is neither parallel or Perpendicular to A or B. C is perpendicular to D and E.
    So first this meant that I had to fudge my alignment to get it to work(A3), so a critique there would be nice. The issue is that the engineer wants the datum D hole called out to [C][B(M)][A], which PCDMIS keeps kicking back because "Secondary is neither parallel nor perpendicular to primary, so tertiary is not allowed.".



    ALIGNMENT/ROTATE,ZPLUS,TO,DCC_CIR_B,ABOUT,XPLUS <---- Fudged part of alignment

    So how would you guys go about dimensioning this?

  • #2
    Level axis is C
    Rotation is to the B cylinder axis line, about C
    Origin X/Y to C
    Origin Z to axis/plane intersect of C to A.

    measure your D hole
    output TP relative to current alignment

    Well, unless there's basic dimensions that guide you otherwise.


    • louisd
      louisd commented
      Editing a comment
      I guess I misinterpreted the napkin. Thought the part components were cylindrical.

    • Loon4ever
      Loon4ever commented
      Editing a comment
      They are, only the top section that's at an angle isn't cylindrical. Boeing Part otherwise id just post the print.

  • #3
    Create a symmetry plane of C.
    Intersect this plane with A.
    Define this constructed line as datum C.
    Align A, rotate to C, origin in A + B.
    Use datum order A, C, B(M) in the evaluation.
    PC-DMIS CAD++ 2o19 R1 SP11


    • #4
      I would say you're not describing the problem as it should... (it's not a criticism, just a way for me to translate my thoughts in english )
      In this case CBA, C is a midplane, B is a circle and A a point.
      There should have some boxed dimensions between the plane A and D and between B and D.
      In V2019, this case sould be treaed as it should, but in previous version, I think you have to change datums like A1 when A is a primary and A2 when it's a secondary (line) and A3 when it's a point .

      If you want to level on A, then you have to rotate on C.

      Just my thoughts...


      • #5
        Nothing during 3 hours, and 3 replies during 3 mn !!!!!


          Editing a comment
          The ketchup effect...

      • #6
        Yeah sadly no basic dimensions with this part, however you guys are awesome and I'll start playing around with your soon as I reprogram everything I just lost because I forgot to save often.


        • louisd
          louisd commented
          Editing a comment
          do yourself a solid and start saving draft iterations. instead of just ctl+s do a file-Save as, then save each one as something like D1, D2, D3 at the end. Make comments to yourself on a notepad what you changed with each draft rev, and you can go back and redo things as often as you'd like.

      • #7
        What ever you come up with, double check that alignment by RECALLING startup instead of a previous alignment. This will tell you 100% if all 6 DOF are locked down. When you are satisfied You can switch that recall back to your main alignment.


        • Loon4ever
          Loon4ever commented
          Editing a comment
          Yep, still had a rotational issue. Thanks for the tip!

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