Profile Constraint.

[[Cl...]]

I have a cylindrical part (imagine a tall thin wine glass). The stem is the datum (-A-) and the inside glass (bowl) has a surface profile callout back to -A-. The datum and bowl run along the Y axis. Do I create a Best Fit inside the FFS allowing only rotation around the Y axis, create an alignment (WP_Free Form Surface1) referencing that inside my Datum -A- secondary alignment?

[[Ma...]]

If from drawing can be determined, that only datum for callout is "profile" axis, then you can use translation in axis too.

Any sketch describing drawing would help with solution.

[[Cl...]]

Unchecked activates? See PDF

[[Ma...]]

OK so in this case make an alignment where will be as main this A cylinder.
Then your FF will have this alignment - then you can check only rotation in Y and translation in Y - nothing more.
Checked is allowed.

Because of A gives you an axis, so you can only rotate ( depending on shape it will or not give you better number ) and movement along its axis.

[[Cl...]]

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Got it. Thanks Martin! In my 20+ years I have never had to use this.

[[Cl...]]

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Ok, so I check only what I want to rotate & translate (Y). Then do I click "Create Alignment" button?

[[Ma...]]

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Yes. For FF it's the only way, but i would rather use curves and align from many curves ( if you create FF with scanning path, then you can recall points with recalculation into curve ( remember to delete actuals before recalculation ).
On curves you can choose points which will go into calculation, aka mask points.