Questions to GammaTech. With high end Gamma machines :
1) Does the string angle make any difference. I mean the angle at which the string comes from racket to the tension head ?
2) What should be the expected accuracy of properly calibrated machine, is there any overshoot and how much tension loss triggers re-pull
3) Is re-pull any different from initial pull thinking of overshoot
4) Do string stretch properties affect overshoot ?
The best way to answer your question is….yes. Just about everything will have an influence on the accuracy of calibration, and pulling tension in general on any stringing machine. If all the moons are lined up perfectly you will always have a straight line from the calibrator to the gripper, and be on the same plane, and then to have the same conditions being exactly the same as when you are stringing the frame. In addition you would have the same string on the calibrator as what you are using to string the racquet with. The temperature would be the same and the humidity as well. Technically any of those attributes will have some effect on what happens when you pull tension on a string.
The difference in angel makes a difference in accuracy and could be around .5 pound depending on the type of string, angel, etc. However the roller guide on the gripper does help to offset the angel by creating a consistent entry into the gripper. The difference in re-pull from initial pull, overshoot and stretch properties can also vary by .5 pound.
There are so many attributes that are a bit out of our control when stringing. The best thing to do is, as many suggest, is to be as consistent as possible when checking calibration, calibrating, and most importantly when stringing.