I have holes that I could only create as single point circles (they are 4-40 threaded holes) that have a true position call out. I created a position dimension and matched the feature control frame to the drawing (using 3 datums) but PC-DMIS reports failure that is far out of tolerance. When I looked at each of the basic dimensions I found that the y and z basic dimensions are close to nominal but the x dimension is far out of nominal. With the datum structure i put in and the CAD model, PC-DMIS designated the x axis going into/out of the part which is not relevant to the callout. How do I get PC-DMIS to calculate the position solely on the y and z planes?
If I understand the OP correctly, he is measuring the hole as a point because it's so small, perhaps with a Romer or manual CMM. If that's the case, I don't know if perp to C/L will work.
