New to stringing - help with proper tensioning/racquet crack

[BrockOz]

Stringing Equipment: Gamma X2
Rackets: Wilson Pro Staff 97L CV V13, Wilson Pro Staff 97L V14
Strings: Technifiber NRG2 16

Hi,

I am very new to stringing (about 10 stringing jobs or so). I have started with stringing Wilson NXT Comfort on the mains and ALU Power 16 on the crosses on tensions around 55/50. I didn't have much problem doing this however I wanted to switch to full bed of multi to see if it helps with my elbow pain, which it did! I did a few stringing with Wilson NXT and NRG2 full bed (tension around 55). Then I wanted to try whether I can increase the tension to 60lbs and further, because I felt like the tighter the strings the more comfort I felt.

That's where my problem started. I strung my V13 racket with 62lbs of tension on mains when it cracket on the side near the edge of the bump. See the pic1 on this racket. The crack happened about 10 holes in (I was doing 2 on each side and alternating left/right). This attempt was with the NRG2.

I figured there might be many reasons for it, the reasons I speculated were:

1- Racket was about 5 year old, a lot of stringing during that time. Perhaps its time was up.
2- 62lbs maybe a bit too much, I should keep in under 60lbs.
3- I was doing two holes on one side before moving to the other side, perhaps that caused some imbalance.
4- Maybe racket was too tightly clamped down.
5- Perhaps I was a bit too harsh with the drop weight.
6- I thought stringing top to bottom could reduce stress on the racket.

So in order to eliminate all these possiblities, I got a V14 of the same prostaff, same specs. I kept the strings same, decreased the tension to 60lbs, string gently/top-to-bottom and very gently/slowly with the drop weight.

Needless to say, this time around about the same hole, the new racket cracked near the very same bump (see pic2).

I asked around a little bit to experienced stringers and they said they don't use drop weights for this reason. However I have also met with players who use drop weights without breaking their rackets. So I am looking for the root cause of this issue and most likely cause/causes of this problem. I really don't want to invest more in the stringer only to break another racket.

Any help/experience with this issue is much appreciated. Thank you

(pic1) https://ibb.co/ngVhr3r
(pic2) https://ibb.co/ZKW5Rzk

 

[esgee48]

The crack occurred near the PWS bump? In looking at your pictures, I could see the crack at the side of the frame. I assume you are still doing the mains? And that you are at the 5th main from the central mains. If so, check how you are mounting the frame. The frame needs to be in contact at 6/12 with the standards. If not, the frame will collapse inward putting outward pressure at 3/9. Edit: Make sure the towers are fully secured.

 

[Irvin]

I’ve never had any issues with my X-STRINGER, but I’ve only strung about 50 rackets with it since I bought it? Some things to check:

1. Make sur the racket towers are securely attached to bar and the head and throat are touching the spacers on the post.
2. Place the cap plate with cap plate pad on post and secure finger tight.
3. When tensioning allow the weight bar to lower slowly do not drop or push it.

 

[stapletonj]

I string my Yonex at this tension all the time. 2 point mounting? sounds like a loose mounting to me. I assume you have done the same sticks on the same frame the same way at lower tension before and no problems.
I strongly suspect they were all mounted with too much slop. Probably a weak point developed and when you upped the tension there was enough stress to create a crack.
Do what Irvin says and also hand check the tension on the post screws to be sure they didnt loosen in the stringing process.

 

[BrockOz]

Thanks for the replies. Yes the crack is near the PWS bump in both rackets. I had the racket mounted 2-point, 6-12. However I am not quite certain whether I had the mounting points in the right place, or the mounting setup is correct. I took a couple of pictures of the mounting point. The cap plate is hand tightened, but not overly tight. I can see the racket somewhat bending when drop weight is on.

The mounting point is about 1 inch away from the frame, it sits inside edge. Am I using these pieces right? I remember looking up the instructions and in a few videos the setup looked like this. Anything you can notice in the mounting? Thanks

(top mount) https://ibb.co/wJ0BfSw
(bottom mount) https://ibb.co/Wv8KNds

 

[esgee48]

The inside edge of the frame should be in firm contact with the edge of those oval pieces. It was hard to determine if the tip was mounted correctly but the throat is not mounted correctly. Too loose according to my eyesight.

BTW if you have taller ovals, use them. They’re better for box beams.

 

[Warren S]

That's a pretty significant crack in both rackets. I would suspect some movement in the towers or some torque being applied when tension is applied. I would also find a way to check for proper tension calibration. good luck in your troubleshooting.

 

[stapletonj]

2 point mounting, design is "towers" do not touch the frame, but the frame has contact with pieces that hold it in place with raised curved pieces.

Recipe for disaster.

diff. sticks have different curvatures, etc for the throat area and even somewhat for the head area.
Consequently, you would almost need a different set of mounts for every single racket. Ugh. OK, I am probably overstating this problem some.

Even if the pieces provided enough of a point of contact, you would (will) need to be super super careful in cranking down the tension on the mounts to :

A. make SURE the frame can't slip, at all.
B. not crack the frame at the head and throat.

 

[BrockOz]

Thanks for all the recommendations. Upon further looking into the mounting I noticed there have been several things I fixed that improved the mounting stability. I will write those down in case someone is looking into the same problem.

1- First of all, here is the instructions manual: https://www.gamma-europe.com/mediafiles/Sonstiges/Gamma X-2.pdf. I read this halfway, and filled in the rest of the information through Youtube videos. This is not a good idea, since YT videos might or might not be describing the technique correctly. I recommend reading this a couple of times over before going over to YT.

2- There are 2 Racquet Support Adapters. Here is the text from the manual:

"The GAMMA X-2 is supplied with two styles of Racquet Support Adapters. A thick profile adapter for wide body racquets and a thin profile adapter for conventional racquet frames. The Adapters are also tapered, use the highest side of the adapter that does not interfere with the string grommet holes.

It is extremely important both plastic adapters are in contact with the frame to prevent racquet damage."

I have been using these adapters the wrong way. When I mount Pro Staff with the thin adapter in the bottom, the racket slips and drops down after stringing tension is applied, which crates movement during stringing. I believe this is the main reason why my racket broke.

3- Make sure all the screws are thightened firmly. This includes all the M5 bolts that hold the racket, the drop weight, as well as the bottom little set screw that holds the racket mount. In my case, the set screw in the bottom was definitely loose, and probably one or more of the M5 bolts were not tightened fully as well.

If all of them are tightened properly, the racket doesn't move at all. In fact, if you tighten the bottom screw quite well, it gets hard even to rotate the racket.

I fixed all of these and the mount now feels a lot different and more stable. I will try this new setup to see if the crack happens again.

Thanks everyone for the help.

 

[Standupnfall]

I see you mentioning drop weight as if you think you should drop it. I always guide it down and let the weight do its work without dropping it. Just wanted to make sure there.

I am glad you are working through your issues but it is uncommon to break 2 racquets in the same spot unless you are doing something very wrong. Even more uncommon if one racquet was brand new.

 

[Radicalized]

Here's a video of the official Gamma tech assembling the machine and mounting the racquet. From there, string as normal following instructions for using floating clamps. And as noted previously, it's a "let it down slowly weight," meaning don't ever actually drop it or press down on it. Make sure the weight is set to the correct reference tension on the correct scale.