Is your robot absolute accurate?
No, it's not.
I'll check with a program anyways, as suggested by SkyeFire.
OK, I tested a big linear movement along world "Y" :
I setup a program where the robot moves between 2 points : one at Y= +2500, and one at Y= -2500.
I managed to set my laser so that the cross is in the same location on my paper targer at both points, and I looked at the position of the cross at mid-distance between the 2 points.
I measure a downward sag of 1.5 mm and a horizontal displacement of 0.5mm in X+.
Does that show a bad calibration ?
I guess I ought to find an EMD somewhere to straighten this out... can this be rented ?