Position without DRF/Datums

Hey all,
Wondering how to best measure and report a pattern position without datums. (See Dim labeled 11 on attached print view). The three holes are properly dimensioned to each other with basics and are the primary datum so the GD&T checks out but I'm not sure how to do it properly on PCDMIS. I've used a constructed feature set for that Datum A made from three cylinders, and it seems to be the centerpoint between the three, but I cannot report position with GeoTol as it says datums are required. Do I have to use Legacy? And can MMC be applied in Legacy? Thanks in advance for any advice!

Attached Files

PositionQuestion.pdf

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Schlag over 3 years ago

I would say to get an orientation you are going to have to make a line from A to B , then rotate to that, then do a basic rotation of 120°. This will then " square " it back up to the print. Yes you can use MMC in legacy. The 3 holes for A will just be best fit alignment using those 3 holes.
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Schlag over 3 years ago in reply to Schlag

You would have to do surface hits for them. Idealy I guess they should be cylinders. Circles are 2D and this is a 3d callout. How thick is it ? Im guessing the face should be A and the bolt pattern B but I didnt draw it. Its so rare an engineer or drafter pay attention to this.
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Schlag over 3 years ago in reply to Schlag

You would have to do surface hits for them. Idealy I guess they should be cylinders. Circles are 2D and this is a 3d callout. How thick is it ? Im guessing the face should be A and the bolt pattern B but I didnt draw it. Its so rare an engineer or drafter pay attention to this.
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