The April 2012 through June 2012 Tips explained the meaning of 2, 3 and 4 segment composite position tolerances.  A composite tolerance has one geometric characteristic symbol but multiple segments.  These next 3 Tips will show sample gaging that could be used to inspect those composite tolerances.  I do not want to suggest that gaging is the only way to inspect composite tolerancing.  However, visualizing a gage often helps folks understand a concept.

The upper segment is controlling the location of the holes relative to the datum reference frame.  The second segment is controlling the position of the two holes relative to each other, in other words, coaxiality.  This will keep the holes in-line as if they were a single hole. They can be out of position which includes orientation by as much as 0.4 mm relative to the datum refernce frame.  The lower segment of this position tolerance is used to maintain coaxiality between the two holes.

Ignoring gage tolerance and wear allowance, the size of the gage pin should be the maximum material condition limit of size (Ø15-0.05=Ø14.95) minus the position tolerance of 0. So, it is Ø14.95 mm.

The remaining Tips in this series will show gaging that verifies better control of the orientation of the holes relative to the datum reference frame.