[To...] Posted January 25, 2023 Share Posted January 25, 2023 Customer claims that when checking perpendicularity of a plane to a cylinder on their Zeiss, the results do not corelate with other form measuring equipment. They have implemented using the constraint setting as shown in the picture below and the results match. Does anyone know specifically what is happening or how they are affecting the data with this setting? On a side note, they have experimented with adjusting the height of the +Z clearance plane and have seen the results change. My BS detector reached DEFCON 1 on this one...lolScreenshot 2023-01-25 075522.jpg Link to comment https://qualityforum.zeiss.com/topic/8820-constraint/ Share on other sites More sharing options...
[Da...] Posted January 25, 2023 Share Posted January 25, 2023 Please sign in to view this quote. Sure actual result will be 0.000000, all correlates well :) Link to comment https://qualityforum.zeiss.com/topic/8820-constraint/#findComment-39862 Share on other sites More sharing options...
[To...] Posted January 25, 2023 Author Share Posted January 25, 2023 Please sign in to view this quote. Actually the current data changes from .00069" to .00004" when applying the constraint. Link to comment https://qualityforum.zeiss.com/topic/8820-constraint/#findComment-39864 Share on other sites More sharing options...
[Je...] Posted January 25, 2023 Share Posted January 25, 2023 Please sign in to view this quote. . So, they are constraining the datum feature to the controlled feature within a characteristic that evaluates the controlled feature to the same datum feature. A house divided against itself cannot stand 🤣 They should remove that constraint. If the cylindrical datum feature needs constraint of its axis, usually due to its depth being less than twice its diameter, they should choose a different constraining feature other than the feature being evaluated. . . Link to comment https://qualityforum.zeiss.com/topic/8820-constraint/#findComment-39866 Share on other sites More sharing options...
[Ri...] Posted January 25, 2023 Share Posted January 25, 2023 Projection error is most likely the culprit. But if they are unsure how to properly measure and evaluate this simple of a measurement on a CMM, I'm not certain I trust them on a Form Tester. Link to comment https://qualityforum.zeiss.com/topic/8820-constraint/#findComment-39868 Share on other sites More sharing options...
[Ri...] Posted January 25, 2023 Share Posted January 25, 2023 What they are doing is about the same as swapping features for which one is the Datum. This falls under the category of "Short Unstable Datum or Feature", this doesn't imply that the feature or part has moved, it is about each features A1 and A2 values and projection. Link to comment https://qualityforum.zeiss.com/topic/8820-constraint/#findComment-39870 Share on other sites More sharing options...
[Je...] Posted January 25, 2023 Share Posted January 25, 2023 Well, thats BS. Your result will be nearly the same like as flatnes (if you use a Gauß-Plane for constrain), or exactly the same (if you use LSQ-Plane for constrain). Link to comment https://qualityforum.zeiss.com/topic/8820-constraint/#findComment-39872 Share on other sites More sharing options...
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