Curve pattern fit rotated about an axial datum feature - how to allow datum shift?

[[Th...]]

This is making my head hurt and it's not even noon.

I have a part with a series of profile segments. These segments are allowed to best-fit as a pattern by rotating around their secondary datum feature, which is a cylindrical bore. Unfortunately, this hasn't improved the profile actuals, so the engineer has proposed adding a positional tolerance with the datum feature at MMB. This is probably a necessary change - the pin that fits in this bore will be made assuming the bore is at MMB, and so parts with bores not at MMB will be able to move - but I have no idea how to apply this. What would it take to get Calypso to handle this properly?

[[Br...]]

I'm confused. So on the current drawing you previously had some features with segmented profile of surface tolerances applied to them, but now they are replacing the tolerances with position tolerances? I guess I would need to see the drawing to fully understand what's going on here.

[[Jo...]]

If this drawing is to be interpreted per ASME Y14.5 then I'm with Brett on this one. Unless those features could otherwise be considered features of size then you can't just change profile to position. If they actually could be features of size and you change the callout to position, realize that the tolerance zone doesn't act the same so there's more to it than simply changing a symbol.

[[Th...]]

The drawing change has gone in a completely different direction, so this is a moot point now, but I'll try to clarify anyway. In 14.5-2009, section 8.8 shows the use of a position tolerance along with an unconstrained profile tolerance. Coupled with the lack of material modifiers in any of the examples given for profile, I took this to mean that I couldn't apply MMB to my B datum feature in the profile, which doesn't seem like it's actually true. I wasn't suggesting that we were replacing profile with position. It was kind of a throwaway suggestion anyway, but because I was typing up my initial post very early on, I may have made it sound like this was definitely the thing we were going to do.

Since I have multiple features with the same DRF, simultaneous requirements applies and I have to allow rotation about the origin as a pattern, so I have to use the curve best fit alignment, copy the features to the new alignment, and so on. From there, I need to be able to allow datum shift as well, depending on the size of the B datum feature, but I can't do that from the curve fit alignment. That's what I can't figure out, getting the rotational fit is trivial, but I don't know how to allow for datum shift as B gets further away from MMB. The only way I know how to get translation in the best fit is by allowing it in the fit alignment, but then the B datum feature becomes completely irrelevant.

I added my best attempt at drawing what I need to be able to do. It's not very good.

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