Open a picture in Paint, Maximize the program to fit the whole screen. Reduce the picture or enlarge the picture to about a quarter of the size. Save it as a JPG. Upload it on here Large or Fullsize
So here is the part loaded against the primary datum "D" (clamped to the left block) and against the secondary datum "A" (loaded against angle plate in rear) Then I have a 1-2-3 block resting on tertiary datum "B".
Notice the measurement on the height gage. I was worried about my measurement, because if the corner has an edge break on it, it wont be to the theoretical sharp corner.
Hopefully this makes more sense?
This pic shows where the demon is measuring datum "B" from.
Your pictures still suck, anyway, but your tertiary datum is just to lock that last axis from moving, if that's a plane at an angle where do you stop your last axis. Primary and secondary have 2 functions. The tertiary has one function. stop the last axis. It can't rotate or level, that is locked down by Primary and Secondary. That's why I still think it's DBA.
I gather your datums are planes. If this is so then DMIS calculates from the center of the Plane, not the 'intersection' of the planes; like is stated in Y14.5 fig 4.4.
yes, all three datums are planes. That's what I was thinking that it was using the centroid of the plane and not the intersection. So million dollar question is why does PC-DMIS do it incorrectly per ASME Y14.5?