string slipping into drop weight string holder

stapletonj

Professional
Hi guys!

I am still futzing around with the Gamma II dropweight with the circular type tensioner.

Although I havent noticed any severe problems after 2 or 3 string jobs, I did notice one annoying potential (or actual?) problem.

when wrapping the string around the "wheel" and feeding it through the tensioner "gap", I am noticing that the spring loaded part of the "wheel" is a little wobbly/wiggly.

When applying tension, often (not every time, but at least 30%), the string will slip off the movable gripper part of the wheel and slip into the housing, necessitating another crank of the wheel (clickety click)
and redropping the weight.

After the weight gets to horizontal and I clamp off and pull the weight back up, the string will often stay stuck in the gap behind the movable part of the gripper wheel.
A light tug or two usually frees it, and I dont see any real gouging on the string to my naked eye. nonetheless, I get the feeling it is gouging the string as well as slowing me up on my string jobs considerably.

MY questions:

is this normal?
Is it an adjustment issue?
am I doing something basically wrong in how I wrap the string?
(1 or 2 loops around the outside and then through the "gap", them give the wheel a squeeze to be sure the moving part of the gripper wheel has bitten down on the string before dropping the weight.)
Is something worn out and needs replaced?

As always, the collective wisdom of this board is appreciated!
 

kabrac

Semi-Pro
Hi guys!

I am still futzing around with the Gamma II dropweight with the circular type tensioner.

Although I havent noticed any severe problems after 2 or 3 string jobs, I did notice one annoying potential (or actual?) problem.

when wrapping the string around the "wheel" and feeding it through the tensioner "gap", I am noticing that the spring loaded part of the "wheel" is a little wobbly/wiggly.

When applying tension, often (not every time, but at least 30%), the string will slip off the movable gripper part of the wheel and slip into the housing, necessitating another crank of the wheel (clickety click)
and redropping the weight.

After the weight gets to horizontal and I clamp off and pull the weight back up, the string will often stay stuck in the gap behind the movable part of the gripper wheel.
A light tug or two usually frees it, and I dont see any real gouging on the string to my naked eye. nonetheless, I get the feeling it is gouging the string as well as slowing me up on my string jobs considerably.

MY questions:

is this normal?
Is it an adjustment issue?
am I doing something basically wrong in how I wrap the string?
(1 or 2 loops around the outside and then through the "gap", them give the wheel a squeeze to be sure the moving part of the gripper wheel has bitten down on the string before dropping the weight.)
Is something worn out and needs replaced?

As always, the collective wisdom of this board is appreciated!
This shouldn't happen at all. Did you. It this machine new and assemble it? YouTube has lots of videos on how to use this machine. I have owned one for 4 years and nothing has ever given me any problems. Or go to Gamma website and download the manual.

Only make 1 loop over the gripper, then bring it around in a clockwise motion and feed the string into the jaw.

Hold the clutch with your left hand, and lower the weight with your right. Repeat if necessary to get at the set tension/and bar horizontal.
 
Sounds to me like it’s not assembled properly. Unless I’m misinterpreting what you’re saying, there shouldn’t be a gap for the string to slip into.

I first looked at this thread because I feel like my string has been slipping between the gripper teeth. Another issue I guess.

Does yours look like this?




Sent from my iPhone using Tapatalk
 

Irvin

Talk Tennis Guru
@stapletonj @travlerajm another issue you could be experiencing is the top of the drum goes down when tensioning to grip the string. This opens a small space between the black part of the drum and the Blue top of the gripper. If the string is placed around the drum near the black section it is possible it may slide under that black part. Try to keep you string in a straight line from the drum to the grommet and make sure it is up against the lip of the blue part of the drum.

EDIT: I can provide pictures if that isn’t clear. Just let me know.
 

stapletonj

Professional
Irvin has it exactly. bought the machine used. the gripper appears to have a little wiggle in it. could the springs in there be worn out? is this a user fixable issue?

PS - not sure how to up load pics? Do I have to create some kind of onlune drop box account?
 

Irvin

Talk Tennis Guru
Irvin has it exactly. bought the machine used. the gripper appears to have a little wiggle in it. could the springs in there be worn out? is this a user fixable issue?

PS - not sure how to up load pics? Do I have to create some kind of onlune drop box account?
I doubt your springs are worn out it is just a matter of getting the string away from the black knob and against the outside lip of the blue part. To post pictures you must use a hosting service like tinypic. You cut and paste the link to the pic in your thread and you’re good to go. You must have reached a certain number of post on TT to post pics though.
 

Irvin

Talk Tennis Guru
Here is another problem I have encountered. When starting your mains especially at the head on the first pull on the 1st main the handle of the racket is in the way so you can’t lift the DW. If you turn the racket you increase the angle of deflection on the string so you increase friction and lower tension. If you turn it the wrong way you will also get the string resting on the black part of the knob and it could get pinched in there. To avoid those issues I don’t start on the first center mains but instead I start my mains using the 1st and 2nd mains on the left side of the racket.
 

RayPS97

New User
Here is another problem I have encountered.
.​
.​
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If you turn it the wrong way you will also get the string resting on the black part of the knob and it could get pinched in there. To avoid those issues I don’t start on the first center mains but instead I start my mains using the 1st and 2nd mains on the left side of the racket.



For OP and just paraphrasing @Irvin 's bolded section of his reply. Imagine a plane/plate defined between the black section(left side of pic) and blue section extending perpendicular to the page. You want to rotate the racquet so that the grommet( with the string) is on the right side of this plane.
 



For OP and just paraphrasing @Irvin 's bolded section of his reply. Imagine a plane/plate defined between the black section(left side of pic) and blue section extending perpendicular to the page. You want to rotate the racquet so that the grommet( with the string) is on the right side of this plane.
In the picture above, there is no gap between the outer surface of blue part and the inner surface of the black part. But that is because there is no string stretched around the blue parts, which compress the blue part, moving it inward to create the gap.

On the suggestion to rotate the racquet, isn’t the position of the racquet a variable determined by which grommet it is? To rotate the racquet means pushing against the tension force of the drop weight - I suppose it only requires about 10 lbs of force or so due to mechanical advantage, but it seems like that would be awkward?
 

Irvin

Talk Tennis Guru
In the picture above, there is no gap between the outer surface of blue part and the inner surface of the black part. But that is because there is no string stretched around the blue parts, which compress the blue part, moving it inward to create the gap.

On the suggestion to rotate the racquet, isn’t the position of the racquet a variable determined by which grommet it is? To rotate the racquet means pushing against the tension force of the drop weight - I suppose it only requires about 10 lbs of force or so due to mechanical advantage, but it seems like that would be awkward?
I figured that was going to be confusing I’ll make a video tomorrow to explain.
 

RayPS97

New User
Video: "Starting mains on a Gamma DW with flying clamps"
Just excellent...you should have been the copy editor on the Gamma instruction manual. By chance, I started stringing the "right side" strings and kept the routine but thought that I would just have to live with the tennis grip and tension head bar colliding issue. Thanks for adding a bump in my confidence on those days when I was not meant to be stringing ;)
 

Irvin

Talk Tennis Guru
Not to derail, but over the last few months I've had trouble posting pics. Do you know what the number of posts required is?
You have more than enough posts to post pics. Just get a public link to the picture you want and paste the link in you post.
 
I came home this weekend and strung up a frame yesterday. The string using into gap issue happened on almost every cross. Its clear that the blue plastic load bearing part (or red part on my machine) is poorly designed. When pressure is applied to the bearing surface to compress the spring inward (radially), the spring compresses unevenly so that the side of the part closest to the black part has a smaller radius. That is, the bearing surface slants toward the black part, inevitably causing the string to slip into the gap.

It should be easy to modify this part by either adding an inner lip to prevent the string from sliding toward the gap, or sanding down the part of the bearing surface that is farthest from the gap, so that the string naturally slides toward the outer lip rather than the toward the gap.
 

swizzy

Hall of Fame
i have used mine now for 7 years, for me a few friends and my girls and boys varsity teams..quite a few rackets in that time. still functions like new. any mechanism can be faulty and yours must be.
 

RayPS97

New User
I came home this weekend and strung up a frame yesterday. The string using into gap issue happened on almost every cross. Its clear that the blue plastic load bearing part (or red part on my machine) is poorly designed. When pressure is applied to the bearing surface to compress the spring inward (radially), the spring compresses unevenly so that the side of the part closest to the black part has a smaller radius. That is, the bearing surface slants toward the black part, inevitably causing the string to slip into the gap.

It should be easy to modify this part by either adding an inner lip to prevent the string from sliding toward the gap, or sanding down the part of the bearing surface that is farthest from the gap, so that the string naturally slides toward the outer lip rather than the toward the gap.
I grant you the design is not perfect and appreciate you delving into the inner workings of the X-2. There is a lip on the blue side where Gamma want you to direct the string/grommet but they (the company) are short on explanation in their User Manual. Mayber your idea of a inner lip will be on the X-3 ;)

Except for my first (and only) instance of the string falling into the "gap", I have not had any problems provided you pay attention to the one small detail of keeping the grommet on "blue" side of the divide define by the gap. Irvin goes one further and suggests proactive steps to keeping more of the tension on the string and avoiding collisions with the racquet handle. The part that I am confused is why it happens on the cross for you...this has only occurred for me on the mains when I was trying to avoid the grip. The crosses are much more straight forward...what am I missing ???
 

1HBHfanatic

Hall of Fame
you have to tighten the gripper bolts from time to time!
my klipermate had similar issue of sorts (after several years and several hundred rackets), in my case the gripper bolt broke in half, and it became loose;
its a moving part after all, it will come loose from wear and tear
 

stapletonj

Professional
by gripper bolt do you mean the hex bolt that is attached to the moving part of the "cam"? BTW - it is red not blue on mine, i must have an older model.
 

Irvin

Talk Tennis Guru
by gripper bolt do you mean the hex bolt that is attached to the moving part of the "cam"? BTW - it is red not blue on mine, i must have an older model.
The top part of the gripper slides in and out to tighten on the string. There is a bolt that cen be tightened on the face of the gripper. If it is too tight the gripper won’t slide properly. It is the top bolt when the gripper is on top.
 
This happens to me also.
The string absolutely gets damaged when it scrapes into the gap

Excellent video by Irvin.
I do what he did at 2:23
I push the racket towards 11'oclock so the string rests on the blue ridge away from the gap.
With my fingers, I also push the string away from the gap while tensioning. This helps a bit.

I might upgrade to a crank machine to eliminate this supremely annoying hassle.

 
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you have to tighten the gripper bolts from time to time!
This can help a little bit. Tighten the gripper bolt as much as you can, then back it off so there is slack to move.
You need some slack so the gripper can move in the first place.

But, it is clearly a design flaw .
When the gripper closes the gap to grab the string, the new gap opens above.
 

loosegroove

Hall of Fame
So have we concluded that it's a faulty gripper assembly? In the 10+ years I had my X2, I've never had the string slip into a gap between the jaws and the black housing.
 
The physics is clear.
As you tighten the slack, the string has no where to go except into the gap.
It's truly a garbage design.

These drop weight toys destroy strings even before you take the first swing.
 
Irvin,
In your video, why do you keep the drop weight in the down position? (Loop string, raise weight, lower weight)
Why not keep it raised first, loop the string, and then lower it down?
 
Irvin,
In your video, why do you keep the drop weight in the down position? (Loop string, raise weight, lower weight)
Why not keep it raised first, loop the string, and then lower it down?
I wondered the same thing. Seem like you make a lot more work for yourself over the course of a string job doing that. My guess is that he wants 360 rotation, but I wouldn't trade having to lift the weight twice as many times just for 360 rotation.
 

Irvin

Talk Tennis Guru
Irvin,
In your video, why do you keep the drop weight in the down position? (Loop string, raise weight, lower weight)
Why not keep it raised first, loop the string, and then lower it down?
2 reasons 1) if you leave the arm up you lose 360 rotation, and 2) if the arm is up and the string is so stiff your arm won’t drop to level you never get reference tension.
 
What do you mean by 360 rotation?
You can't ever rotate more than about 90 degrees.
I do see that if you start vertical, you need to rotate a little bit to get the string to catch,
so you lose some of the range of motion. Is that what you mean?
With your method, you can use the entire 90 degrees to pull the already secured strings.
 

Gamma Tech

Professional
The problem of the string getting behind the rotational gripper is most likely caused by one of two things.

1. The gripper jaw may need adjusted. The small (half moon shaped) gripper moves down when the drop weight/bar is lowered. The movable gripper jaw should be loose so that it can easily pivot up and down. However it should not be so loose that it wiggles and allows a gap between it and the rotational drum where string can get caught. This sounds like what the original poster experienced. Adjust the gripper jaw by tightening the one hex head cap screw. To do this properly press the gripper jaw down against the lower gripper jaw and tighten the screw. Lift your finger and the two gripper jaws will be held together. Then turn the screw counter clockwise very slowly until the small half moon shaped gripper jaw pops up, then stop. When you press the gripper jaw down and remove your finger it should come right back up.

2. There might be something stuck behind the gripper jaw. It is amazing how often string debris can get into the strangest places. Something may have worked its way behind the gripper jaw and is hanging it up. If adjusting the gripper jaw, as described above, did not take care of the problem you can remove the four screws and take off the rotational gripper to inspect for debris, broken spring, etc. If you are a bit nervous about removing the gripper, just let me know.
 
Unfortunately, neither scenario apply to my stringer.
1) My small gripper is not loose. I tightened it all the way, so it could not move, and then backed it off so it could do the spring action.
2) This makes zero sense, but is a moot point. Nothing is stuck behind the jaw. Something behind the large jaw has absolutely nothing to do with the string falling into the gap created by the smaller jaw.

It's just a terrible design, plain and simple.
 
That's not a bad idea. You'd have to groove it around the entire circle. And then sand it smooth.
Alternatively, what about gluing a section of rubber tubing around, giving the string a "tunnel" encasement to sit inside, so it can't slip off the side ?
Or, the opposite of a groove. Glue some kind of "curb" around the perimeter of the channel, so the string can't cross over it, and fall into the gap?

The more I think about it, the more disgraceful this jackass design is.
 

stapletonj

Professional
Alternatively, what about gluing a section of rubber tubing around, giving the string a "tunnel" encasement to sit inside, so it can't slip off the side ? "

Good idea except that you woulld have to thread the string through every.single.time. ugh. Of course if you threaded it as a part of the process of pulling the string through the frame while you still had the end of the string in your hand, it would not be so bad.
 
That's not a bad idea. You'd have to groove it around the entire circle. And then sand it smooth.
Alternatively, what about gluing a section of rubber tubing around, giving the string a "tunnel" encasement to sit inside, so it can't slip off the side ?
Or, the opposite of a groove. Glue some kind of "curb" around the perimeter of the channel, so the string can't cross over it, and fall into the gap?

The more I think about it, the more disgraceful this jackass design is.
If I had to string more often, I’d get serious about modifying my gripper in one of these ways to fix the design flaw.

I agree that this is crummy engineering.
 
I’m thinking a dremel might be risky because I don’t know how deep the plastic is. Might be safer to glue a separate strip of pre-grooved plastic on to the bearing surface. I don’t know what type of plastic it is, but you could first test if it can be solvent welded or superglued somewhere else on the machine (on a less critical part).
 

Herb

Semi-Pro
sounds to me like the screw is to loose. Just allow the upper jaw to move up and down, but not tilt. Tighten the screw and let us know if it works.
 

esgee48

Legend
That was what Gamma Tech suggested. The complaint is that this is not a good fix being a recurring issue or one that does not fix the issue.
 
It's not from the screw being loose.
It's just how the thing is engineered.
Garbage. Shocking no one has improved this failed 50 year old technology
 

esgee48

Legend
1. The gripper jaw may need adjusted. The small (half moon shaped) gripper moves down when the drop weight/bar is lowered. The movable gripper jaw should be loose so that it can easily pivot up and down. However it should not be so loose that it wiggles and allows a gap between it and the rotational drum where string can get caught. This sounds like what the original poster experienced. Adjust the gripper jaw by tightening the one hex head cap screw. To do this properly press the gripper jaw down against the lower gripper jaw and tighten the screw. Lift your finger and the two gripper jaws will be held together. Then turn the screw counter clockwise very slowly until the small half moon shaped gripper jaw pops up, then stop. When you press the gripper jaw down and remove your finger it should come right back up.
@stapletonj , did you do this? I suspect that your upper cam is not adjusted properly if it leans downwards and pressure creates the gap. I would say [1] do the adjustment [2] try it with a string pulling tension and if the gap appears, tighten or loosen the bolt some more. Trial and error this until the gap is minimal. I am talking about making 1/8 turns counter clockwise or clockwise. Once you are satisfied with the movement of the cam, mark the position of the screw and the cam by drawing a line across both using a sharpie.
 
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stapletonj

Professional
I tightened it. but the gap is still there. I am taking a loooongg time to do a string job because I am being uber careful not to get the string anywhere near that precipice of doom known only as "the string eater"....

one other thing I noted is that the blue "cams" look slightly different on the bottom than my red ones......

also a question for gammatech, is it possible to buy an "upgrade kit" for this stringer that would convert from a cam pull to a linear gripper?
 
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