I worked in engineering for 29 years and have been an educator at a community college for 16 years teaching the Y14.5 standard. Many of my faculty colleagues think the standard is an overkill and adds cost by tightening tolerances and making product verification more difficult.
I am ASME Senior...
To nwrichard:
As a professor in a certified college and ASME GDTP S0667, I caution you against using instructors as basis for standard compliance. I know of many other fellow faculty that teach GD&T incorrectly. They have learned it by teaching themselves.
The tolerance zone would not be...
Concentrically is measured by median points of diametrically opposed elements. The cylindrical tolerance zone would be located by the datum axis. You would need two opposed indicators to measure the median points. As the part is rotated about the simulated axis, the indicators would move back...
Why is the axis primary? Make the flange primary with a control applied (flatness, profile), and the axis secondary. The tolerance zone for the flange would essentially be equivalent.