New GD&T orientation

[[Ja...]]

I’m still having trouble with bolt circles in the new GD&T. For items 6 & 26, the new engine will let me select -A- and -B-, but I can only select -C- after I’ve basically made a simple circle using the bolt holes (it’s not going to clock to a best fit). When I select common datum, all of the features disappear except for -A- & -B-. Is there any way to do this staying completely in the new engine, or am I stuck trying to adapt part of the old way?

[[Iv...]]

To use the Common Datum option, the feature must be plane or cylinder. Try creating the Datum C holes as cylinders instead of circles. 

[[Ja...]]

Thanks. That did the trick. However I'm not understanding the logic Zeiss used requiring cylinders rather than circles.

[[Iv...]]

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 Completely agree and happy to help! The common datum is a great addition, but there are some current limitations that I'm hoping will be addressed in the near future.

I had a similar part, but instead of holes, the bolt pattern was symmetry planes. Despite the common datum option allowing planes, it was unhappy about the symmetry planes and did not compute an answer. I had to use the legacy method for this. 

[[Ri...]]

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 I haven't ran into a particular case of common symmetry planes, but a workaround you could do would be to create the position of each symmetry plane (to say your A B DRF), set it to a SIMREQ, then go to Resources - Utilities - GDT Best-Fit - Select one of the Positions, now you can use that Alignment as your A B C alignment. 

I've done this for complicated DRFs, and it works wonders. 🙂

[[Iv...]]

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 Love that! Thank you so much for that tip. I'm eagerly waiting for the next opportunity I get to try that out 🤓

[[Ch...]]

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same here. Another thing I did with the old GDT was make a theoretical 3d line for the best fit bolt pattern (or pattern of features) that is nominal 0 to the best fit, then in position characteristic report to A|B + Theo line -C- for example .. same difference. Ive used both ways.