knuckle calibration A90,B180 for measuring under a part

knuckle calibration A90,B180 for measuring under a part

I was wondering if anyone had a lead on a good writeup for knuckles in UCC server with a 90 degree angle. building it is easy, however I'm struggling with setting up a calibration sphere not vertical to the table. calibrating A0B0 goes well but i'm struggling to set up the other angles for example A90,B180.