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Using a datum feature set (4 holes in this case)

Hello,

I'm new to this and I came across a part (for the first time) that has datum feature A as a plane and B as 4 holes. Other features on the part have to be positioned within .015" with respect to -A-B-. How do I use the 4 holes as a datum in XACT measure? Can I use the plane (primary) and 4 holes (secondary) to find the location of the other features?

Another thing I cant comprehend is that datum B (the 4 holes) are toleranced with a positional tolerance of .005 to datum A. (With no basic dimensions on the print). From my understanding, when holes are toleranced with a Position tolerance to a planar feature, its controlling the orientation to the planar datum (in this case). What about location of these holes? What am I missing here guys (besides years of GDT and cmm experience). I read an article (not sure when it was published) that focused on datum feature sets of holes and it didnt have a positive note for CMMs being able to measure a feature set's position.

I hope this makes some sense. I will try and post a print once I figure out how to properly create a post.
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