String gripper pinching string

MaxSwing

New User
Hello,

My Pros Pro Challenger II has a linear gripper and I have noticed that recently it is pinching the string to the point where it is obviously damaging the string and I have had a couple of racquets where it breaks within a short play - typically if the pinched string ends up on a return. It is worse the higher the tension and unlike other models there doesnt appear to be any ability to control the limits of the gripper. It appears worse on Babolat RPM Blast although other stiffer strings appear less effected.

The pinch appears to be closer to the back of the gripper and initially I thought it might be dirt and have heavily cleaned the jaws with goo gone and then isopropyl alcohol but having retested it is still just as bad.

Is there anything I could do? The limit of travel appears to simply when the jaws can touch the tension bar drum so there is in theory no limit to the gripper. I was maybe thinking of adding some offcuts of other string to 'share' the load maybe.

https://ibb.co/album/rGMvBh

These are a few photos of the gripper and the impact it has on the string, for this one I did pull at much tension as I could on the machine so around 65-70lbs but you can clearly see the indentation, it doesnt look like it slips as there are clear gripping marks. It also appears to only really effect the last couple of centimetres the most. I dont think that the jaws are not closing in a nice parallel manner, I do see some bolts to be able to disassemble but I am really worried about the springs and ball bearings disappearing and I make the situation worse than it already is!

Thanks :)
 

Irvin

Talk Tennis Guru
A linear gripper used the tension in the string to close the gripper plates. So the higher the tension the greater the closing force. The cleaner and better lubricated bearings makes for and even greater gripper plate pressure. When string poly string there is less stretch so the string goes more directly into the gripper. If the string were to go around the drum more there would be greater friction between the drum and string dropping tension on the string between the drum and gripper. Lower tension means less gripping force but on the racket side the tension is constant as long as the bar is level.

  1. Allow string to wrap around drum more by allowing more slack between drum and racket, but make sure the string goes straight through the center of the gripper.
  2. Clean gripper plates but leave the bearings and bearing channel alone unless there is an issue
  3. Don't lubricate bearings or channel
EDIT: The bearings must function to properly grip the string but you Don’t want them moving too smoothly. Unless the gripper plates are binding leave them alone.
 
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Irvin

Talk Tennis Guru
If you have to resort to using a business card to protect the string sell that machine and buy another. Buy once cry once.
 

MaxSwing

New User
Thanks Irvin, I should add I am only doing this as a hobby for myself and a few others at the club. I would love to get a far better machine but she who must be obeyed is being obeyed ;) I am seeing that there probably isnt much I could do but will see if I can continue to get some pulls out of this machine yet.
 

esgee48

G.O.A.T.
Going around the drum before putting string into gripper is a very good solution.

If you have super glue handy, you could try gluing a mechanical stop to limit the amount of travel the plates could move.
 

Lefty5

Hall of Fame
Are you sure the string breakage is a direct result of this pinching? Can you see the break on the pinch? Normally a little crimping or pinching does not affect string this way in my experience.
 

MaxSwing

New User
Yes when inspecting I can see it broke right at the end of the crimp, interestingly I thought originally it was just a fluke but when restringing I noticed the crimp on that particular main lands right on a return and I can only imagine that is the reason.

I have the racquets myself strung without issues but I don't think and if the crimped parts fall on a bend/return so that might be the final nail in the coffin.
 

MaxSwing

New User
Thanks all for input. I should mention this machine isn't one where you wrap the string around the drum, the way the gripper is mounted prevents this 'nicely' however I did test and I can do a wrap which does indeed seem to reduce the pinch.

I however went with a more precise method of adding a block to limit the gripper and this appears to have worked well. Just string a racquet and will hopefully hit with someone over the next couple of days to be sure.

No more pinching!
 

esgee48

G.O.A.T.
Good for you. I wish they just kept the limiter screw design. Was a good design since it kept strings from being crushed or marked.
 
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