What is this shape?

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  • What is this shape?

    I have attached a section view. I am tasked with measuring the radius as seen in the image, the center of which is offset. Is this an I.D. torus? The results aren't seeming to agree with an alternative measurement method, all of which make me wary as it is such a small amount of arc.

    How do you interpret this?


  • #2
    If it's a section of a round part it's a sphere.
    A torus is a doughnut.


    • JacobCheverie
      JacobCheverie commented
      Editing a comment
      Sphere with an offset center? The results are off when measuring as a sphere.

    • UKCMM
      UKCMM commented
      Editing a comment
      It cannot be a sphere as the radius centre is bigger than the bore radius. Just measure as a section radius.

  • #3
    It looks like the drawing isn't proportional (the circle center doesn't look off), what about the CAD model?

    Last edited by AndersI; 10-30-2019, 09:15 AM.
    SW support - Hexagon Metrology Nordic AB


    • JacobCheverie
      JacobCheverie commented
      Editing a comment
      I don't think that the surface is meant to be a circular arc but more of a swept curve...

    • AndersI
      AndersI commented
      Editing a comment
      Well, then it isn't a part of a sphere - surface profile (CAD needed) would be the only thing in that case...

  • #4
    I think there are some other informations on another view...
    Do you have a CAD model ?
    Does the offset is also a radius ?
    In this case, it could be a kind of torus, with the torus radius bigger than the ring radius.


    • #5
      JEFMAN there is only one other view with one unrelated dimension. The center of this radius is offset from the center of the part by a reference length dimension. The center of the radius shifts around the center of the part as the curve is swept out.

      I programmed the part in Calypso and it's automatic feature recognition told me it was a torus. The problem was that the size was out by .0001 when running offline with a model. Now when I run it the size is sometimes too high, sometimes too low.

      When I put in a theoretical circle in the correct location with the correct size, it does not match up with the model.


      • #6
        Maybe you could try to create a .xyz file, with some points like this (I'm not at the cmm, I can't check !) :


        • #7
          it is not a sphere, imagine the shape of a football instead, there is no 3D feature to hit this you would need to probe it as an arc on the part axis which should be possible using the circle auto feature. I do similar stuff on outside diameters that way


          • #8
            looks to me like an after-market upper ball joint cup for a Chevette. There is a sphere, but offset to the bore, and you would flip it 180 degrees to adjust the camber of the tire. But, without seeing a lot more, it's all a guess. IF IT IS a real and true sphere, with the center point offset from the bore, then there is one, and ONLY one setup that will check it and give you the correct answer. But that image just doesn't look like it would allow a real and true sphere to be offset from the bore.
            Originally posted by AndersI
            I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.


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