TP Nominals

[[Ma...]]

Howdy, Im having troubles understanding a true position problem. 

Trying to find the true position of a cylinder to another cylinder (datum A) And the nominals aren't lining up. 
Datum A sets my X and Y. Datum B, a plane, sets spatial and Z

When i open up a new position and put the feature in relative to datum A the nominal are zero, and I'm reading a 0.300mm value. However if i use the formula and force the feature nominals to be XY of datum A it reduces down to 0.022mm. I cant understand why this is. Am i fudging numbers or have i been going around this wrong the whole time?

[[Ze...]]

How are you getting your nominal values? Are you extracting features from a CAD model? Are you probing the physical features and creating them that way? Need more information. If you can grab some screen shots of your features, alignment, and how you're measuring them maybe we can figure out what's going on.

In general, extracting features from a CAD model will give you exact nominal values based on the CAD. If you're probing and creating features, then you usually need to go into the features after creation and clean up the nominal values as they usually aren't perfect. That includes feature location and feature vectors.