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Legacy dimension - profile of a surface

First of all, I am aware this topic has been covered, but my google-fu failed to find a solution for my current conundrum.

All that follows is relative to PC-DMIS 2012

Part setup:
Datum A: Cylinder along Z, locking X, Y and two rotational DoF
Datum B: Plane perpendicular to A, locking Z
Datum C: Plane perpendicular to B at 5.5 basic from A's axis, locking the last rotational DoF

Callout:
Profile of a surface of datum C relative to datum A

The issue:
While this is pretty straightforward to do with exact dimensions, the report template at my current workplace plays nicely only with legacy dimensions.
The result of legacy profile of a surface (form and position, LSQ best fit) while aligned to ABC are different (worse) than exact above.
To my understanding this is to be expected as legacy "form and location" fits to the current alignment, which is restricting 6 DoF instead of just 4 as Datum A alone would.
If this is the case, is there any way to use legacy with the callout that I have?
Parents
  • To do it properly with legacy you would need to replicate the datum reference frame with the alignment. Since the datum reference frame only uses datum A your alignment would need to level the datum A cylinder to Z and origin X & Y. You would then need to do a 2D bestfit in the Z workplane allowing rotation only on your datum C plane. You can then dimension profile, form & location of your datum C feature to the active alignment and should get the same result as XactMeasure. If the result is different then check you are using the same fit as XactMeasure is using for it's bestfit calculation (shown on the Nominals tab of the XactMeasure dialog - it should be vector min max to comply with ASME Y14.5).
  • Your best fit alignment needs to be 2D no translation - it needs to allow rotation around Z but you don't want it to move the origin.
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