We have a gantry Fanuc that removes parts from an injection molding machine. Its a used robot and the markings for mastering it are mostly missing.
Here is the problem: It won't move in a linear motion in the world cord system. If you move in the Z(+/-) it wants to rotate on joint 6 while moving up or down. So we have to put in extra points to compensate. Also when you move in the X(+/) it wants to bend at joint 5 while moving. It just can't hold the EOAT in a linear path.
Our theories so far are that some of the mastering marks are 90 degrees out from the originals, or that the servo motors in some of the joints are incorrect for that model of robot and they receive pulse encoder data differently.
Any help would be appreciated. Its getting irritating to set up nipper cuts with a nonlinear robot.