True Position with MMC Not Applying Datum Bonus

[[Ka...]]

Hello everyone,
I’m having an issue with my Zeiss Contura G2 when evaluating true position with MMC, and I’m hoping someone can help me understand what I might be missing.

The drawing calls out true position with MMC. In Calypso, I applied MMC to the datums in the true position characteristic. However, when I generate the report, it looks like the CMM is only calculating the MMC bonus from the measured feature itself, and not from the primary or tertiary datums.

I’ve attached screenshots for reference.
Does anyone know why this is happening or what setting I may be overlooking?

Thanks in advance for any help.

 

[[To...]]

MMC on datum features does not give you additional tolerance on the position.  On datum features, MMC is really MMB and only allows for the datum feature to shift in order to help it fit, like jiggling a part onto hard fixture.  

[[Pa...]]

Tom is absolutely correct.  In addition, where the requirement is simultaneous for multiple features, MMB provides datum shift but all features use the same shift (magnitude and direction).  This fits nicely with Tom's "jiggling the fixture" comment.  

Unlike MMC, MMB does not produce a number that can just be "added" to the position tolerance.