Simultaneous Evaluation Bug?

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  • Simultaneous Evaluation Bug?

    PC-DMIS 2016 SP10. I know that the simultaneous evaluation can be a bit buggy at times, but I'd like to know if there is a reason why, especially in this particular case.

    I have a primary planar datum A normal along Z+. Secondary outer cylindrical datum B referenced at MMB with axis along Z. In the DRF [A|B(M)], rotation about Z is unconstrained and translation about X and Y are partially constrained due to the MMB condition.

    I have an inner width along Y and an inner cylinder with axis along Z. Both of these features are assigned a position tolerance to [A|B(M)]. When I evaluate them independently, everything is great as can be seen in the following image.


    XACT1.jpg


    When I attempt to evaluate these simultaneously, Xact decides to take advantage of the unconstrained Z rotation and rotate by almost 90 degrees, causing my slot position to go crazy as can be seen in the following image.



    XACT2.jpg


    Why is this happening? Is it because the width is a constructed feature? If a bug, can I somehow constrain Z rotation without adding a tertiary datum while still allowing for X and Y translation?



    EDIT: I can make this work as expected if I lie to Xact and tell it that the planar tolerance zone for the width is along the direction of the cylinder axis (Z). Is this valid? It seems to be computing just fine, but I don't like the idea of telling PC-DMIS that the tolerance zone is along Z when the feature is along Y.
    Attached Files
    Last edited by JacobCheverie; 12-04-2020, 09:12 AM.
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