1)Why would you include bonus on a thread? Unless the print calls the position out to the minor diameter and you line scan/max inscribe the hole (and even that is a bad idea) you should never allow bonus of a threaded feature because the pitch is where the position should be calculated, and I highly doubt you're constructing the pitch diameter.
2) What's your tolerance of your Datum B? Did you enter in a tolerance for it in your nominals tab? You're allowing over 11mm worth of Datum bonus which would lead to a perfect number (probably) every time.
The person who made the drawing didn’t consider that you’ll need a fully qualified datum system, if you have a tolerance zone that's clocked in a certain direction. In this case, the two position callouts have tolerance zones that are not cylindrical, but rather defined by two parallel planes. With just A and B, PC-DMIS doesn’t know the orientation of those planes and therefore can’t calculate a result.
Also, as Singularity stated, it is imperative that you don’t use MMC on the thread, because there is usually no way you could measure the pitch diameter of an M6 thread.
Thank you everybody. So, what could be a workaround? I'm a little lost here to be completely honest. I understand the thing with the thread, I actually am measuring a circle on the head of a bolt which is mounted on the part and that bolt fits into the threaded hole of my holding fixture. I build a projected circle from the measured circle onto the plane on which the part sits and that's the circle I'm measuring position on. Tbh I can't find anything on PC-Dmis to fix this result so I don't know if it's a bad design (?)
Hirxm I really can't help 100% without more information. Although, I know prints are confidential. I need to know what type of features Datums A and B are and how they are related to each other. I also need to know how many true position or profile callouts have the same Datum Reference Frame (AB with modifier) because if there are more positions/profiles, then they should be checked simultaneously. I also need to know if the datum size tolerance was added to the nominal size in the nominal tab to ensure PC-Dmis calculates bonus correctly. I'm assuming that AB does not constrain all 6 degrees of freedom but which degrees of freedom are left?
It's obviously Datum B that is the issue. You're getting way more bonus than you're allowed (assuming). Maybe a napkin sketch or some code can help us, help you.
