Projected Tolerance

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  • Projected Tolerance

    I have a blind, compound hole.
    Tolerance is MMC projected 3.5" from surface hole pierces.
    I project the cylinder to a plane 3.5" from surface.
    I get a pierce point on the plane
    What would be the best way to dimension accurately,
    To take advantage of the bonus I should get from the MMC,
    but can not because now, my cylinder projects to a center point.
    PC D-MIS 3.7 MR-2 - XP SP2

  • #2
    In the trueposition window there is a box labeled reference length, this is where you enter your projection length and the demon will do the rest. Lots of luck. HTH

    P.S. pull up the trueposition window and press the F1 key for the help menus, they explain the reference length/projection feature.
    sigpic"Hated by Many, Loved by Few" _ A.B. - Stone brewery

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    • #3
      Will try - Thanks.

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      • #4
        Will it matter which direction you need to project the hole? Does Pcdmis even take projection direction into account?
        sigpic
        Originally posted by AndersI
        I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

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        • #5
          I hope so, I think it does matter.
          As soon as I get on-line I will test by getting true position at zero, +3.5 and -3.5, the error at zero should be reflected in the two projected values.
          The two projected deviations should not be the same (and opposite) unless the hole has a zero deviation at the zero projection - Correct???

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          • #6
            How much variation do you get on the hole as far as size goes?

            If part to part hole variation is not much then try to find average size of hole, calculate MMC bonus (departure from MMC) and add that to your tolerance to plug in.
            PC-DMIS CAD++ 3.7 from 4.2 MR1

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            • #7
              Originally posted by RussL View Post
              I hope so, I think it does matter.
              As soon as I get on-line I will test by getting true position at zero, +3.5 and -3.5, the error at zero should be reflected in the two projected values.
              The two projected deviations should not be the same (and opposite) unless the hole has a zero deviation at the zero projection - Correct???
              I would have to agree, but I have never used 'projected' before. It should NOT matter as to the TP deviation, but only the individual axis (XY or Z).
              sigpic
              Originally posted by AndersI
              I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

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              • #8
                http://www.engineersedge.com/fixed_f...projection.htm

                Try the site - there's a calculator for projected tol zone.
                PC-DMIS CAD++ 3.7 from 4.2 MR1

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                • #9
                  Thanks for all the input.
                  The more I play with true position, the less faith I have in it.
                  I projected in both directions, and at zero, I get the same deviation in all three cases (can not be).
                  I tried a true position at both ends of axis, got the same error which is different from the average (can not be).
                  I have my doubts that many of the features work at all that they have in the true position panel.
                  I will continue to project the centerline of the measured cylinder to the plane,
                  I can then enter this point in Catia, to the model and measure the distance to the theortical centerline per the model.
                  At least I know what I have is correct this way.

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                  • #10
                    Russl,

                    Projecting elements in PCDMIS requires that you have a plane to project to otherwise it will use current workplane - most likely why you're getting same results.

                    You're correct by doing the cyl-pln intersect - try constructing a plane parallel and offset by 7.0 to the plane you're currently using then do another cyl-pln intersect to evaluate other end of cylinder (or projected zone).
                    PC-DMIS CAD++ 3.7 from 4.2 MR1

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