Concentricity doesn't work correctly

[[Ma...]]

Hello, I need to measure the concentricity of one cylinder relative to another, but it doesn't seem to be working correctly. The measured values are completely out of range, and when I visualize the tolerance zone graphically, I can see that the zone is not centered with respect to my reference cylinder — and moreover, it shifts from one stage to another.
I hope I’ve explained myself clearly. I'm attaching two images that will hopefully help better illustrate my issue.
Thanks to anyone willing to provide some clarification.

[[Ch...]]

Please check if the problem is vanished if you use a datum system using the same cylinder as in your screenshot (instead of using the cylinder directly) and setting the standard to geometry. The geometry option in the tolerance effects only the tolerance not additional elements.

If the problem is vanished after doing this then the problem is that your datum cylinder is too unstable to compute a stable datum system from it. According to ISO standard (and this is used in your screenshot for the datum system) a hull cylinder fit is used. Unfortunetely hull cylinder on narrow cylinder can tilt around 90 degrees (this is mathmatically correct but not helpful for the wished inspection)

The first solution is described above, the second one would be to use a stabilization plane, i.e. instead using DS: Cyl B using something like Plane A|Cyl B. Of course your part have to provide such a plane and you have to discuss the inspection change with your customer/designer.

If the problem is not vanished, please contact your local partner to discuss the problem on the given part.

 

Christoph Schult

[[Ma...]]

Thank you very much Cristoph! Your solution works well! Thank you very much!