Hello,
I was dealing recently with a precision problem concerning our robots. Problem was, when copying a TP program with user frames from one robot to another, the program always had minor differences although it shouldnt. TCP on both robots are the same and based on CAD and all the programs refer to correctly set user frames so in theory the points should always be the same, but they are not. There are always minor differences approximatelly a FINE give or take. Robots are M710ic-50E R30iB.
Robots are fairly new, 2 years old never had a mechanical or electric failure and they are factory mastered. Never remastered. Running a test on a laser pointer, showed that TCP drifts about 0.5mm during rotation around Z axis. Also, when changing CONFIG of a point from NUT to NDB there is also a drift around 0.5mm on the same point. As I saied earlier the TCP is based on the tool's CAD although I tried reteaching with six point and 4point method but the drifting on rotation still exists. The drifting of the point when changing CONFIG from NUT to NDB suggests a wrong mastery, but, can a fanuc factory master be inaccurate ?