I have a bore that is Datum B. It has a perpendicularity callout to Datum A, which is a flat surface. So, I have to measure it as a cylinder. I have another bore that has a circular runout callout to AB. So do I have to measure B again as a circle? Because I would have to assign that as another datum to build the feature control frame. But if I just use B as a cylinder, then wouldn't it be measuring total runout and give me a different result than circular runout?
In that case, I have another similar part. It wants the circular runout of Datum A (flat surface) to Datum B (inner bore). Do I still measure Datum B as a cylinder? Because it always reports way out of tolerance if I measure the circular runout of A to B. But if I measure B as a circle, then the circular runout of A to B looks good. If I measure total runout of A to B as a cylinder, it's always exactly the same as if I measure circular runout of A to B. In this case, there are no other callouts on the print that would require me to measure B as a cylinder.
In that case, I have another similar part. It wants the circular runout of Datum A (flat surface) to Datum B (inner bore). Do I still measure Datum B as a cylinder? Because it always reports way out of tolerance if I measure the circular runout of A to B. But if I measure B as a circle, then the circular runout of A to B looks good. If I measure total runout of A to B as a cylinder, it's always exactly the same as if I measure circular runout of A to B. In this case, there are no other callouts on the print that would require me to measure B as a cylinder.
