True position reports zero for Z location on threaded holes

[[Th...]]

I’m measuring the true position of two threaded holes using the legacy true position with datum B primary and A secondary. The Y results vary, but the reported Z location is measuring zero. Nominal location being zero.

When I switch from a diametral Y/Z tolerance zone to a polar zone, Z variation appears but the drawing does not specify a projected tolerance so I don’t want that. I also changed a feature’s nominal Z from 0 to 0.100 as a test, and its actual Z then reported 0.1000.

Anyone know why this is happening? Given the datum structure, rotation is free so is Calypso forcing the feature to the perfect zero? If so, is this ok to leave like this?

Note: I’ve also tried using a bore pattern and freeing the rotation.  When I do there is variation in both Y and Z but of course TP results significantly increase since there is now another variable to include in the error. 

[[Ma...]]

Hi,

can you describe what feature you used for threads?
What are those datums B and A.
How your TP callout looks like?

Drawn sketch would help also.

[[Jo...]]

you openend two threads for the same topic?