Originally Posted by Lakers4Life
That's true, but in the case of O-ports it does not follow the intended line of the cross, but the path of least resistance. There is no grommet to keep it on it's intended path.
I can understand what you are saying as far as the string having 0 lbs tension when it is pulled perpendicular out of the grommet. That's basically 90 degrees or more. How often does that happen in stringing? When stringing O-port rackets, I will usually try to set the brake where the string is barely touching th side of the O-port. I try to reduce the angle as much as possible.
If you use your brake the cross string will follow the intended line of the cross straight across the racket out the port and into the gripper. There is no bend anywhere except for the slight bend (the smile) from the opposing force of alternate mains.
Now if that cross were equally distant from the pivot point of the turntable as the entry point into the gripper of the string there would be a 90 degree bend going into the gripper and it would be impossible to tension the string without moving the tensioner farther away from the pivot point (or moving the pivot point of the turn table away from the tension) which is impossible. If the angle of the string going into the gripper is 90 degrees to the direction of pull there is no tension, if the string goes into the gripper without having an angle the tension on the string is the same as the pull of the tensioner. If there is any angle it seems to me the tension on the string is not reference tension and that is what happens when you use a brake.