Does your control support linear compensation?
For backlash, I put in a value of .005 inches, cut a circle with a spring cut, measure the circle and i can see the steps as the axis changes direction. This I subtract from the .005 inches and it should be pretty close. Anytime I see a backlash value exceeding .0035 inches, I know that axis has a problem. Also older machines may have the backlash different between the center of the table where the machine is typically used more vs the ends of the table. A ball screw regrind might be necessary.
Pitch error compensation requires a step gauge or a laser.
George
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)