PDA

View Full Version : Distortion When Stringing a Yonex with 2-Point Mounting Mach


chang10is
04-12-2004, 12:18 AM
Short version:
How much racquet distortion is considered normal? I restrung my Yonex SRQ-500 Long on a ATS-SS2, and my racquet's dimensions changed. The length decreased by 1/8" and the width of the head increased by 3/16". I was rather worried, but I let it sit overnight to see if the tension of the crosses would eventually help the racquet go back to the normal dimensions. I measured everything again the next day, and because it hadn't changed, I decide to cut out the strings. For all of you who own racquet stringers with 2-point mounting systems, how many of you have experienced racquet distortion? And how many of you have tried Yonex racquets with the isometric head? Feel free to stop here if you want, but if you want to read on, my applause!

-------------
My attempt at a solution:

I wanted to try to string this racquet w/o any distortion, so I cut out the 4 center mains first, and 1 center cross. I then began a very tedious process of trying to restring the racquet with most of the old strings still there. I'd basically do 2 strings, then take out the old string in the next two pairs of grommets, and then thread the new string in those spots. After finishing 12 mains (and with 4 left to do), the width of the racquet had already grown nearly 1/4", so I undid most of the mains and tightened the crosses, tying knots along the outer edge of the rim for every 2 cross strings so that it would hold tension. I then redid all the mains. Doing the crosses was a pain because the stringbed was so stiff--there was pretty much no room to fan the string as you pulled a cross through the mains. I actually broke the string when I was half-way through the crosses, I think because I burned it when I was pulling a cross. So I had to do it again! I then started over and got through everything successfully. The result: overall length is about 1/32" longer than its unstrung length, and the width is 1/8" narrower. Better than the first run, but WHAT A PAIN. And I'm still not quite happy with the 1/8" difference in width. 1/16" would be a lot more acceptable to me.

chang10is
04-12-2004, 12:24 AM
Details on the measurements I took:

The measurements for the racquet length and head width were the same before I cut out the old strings and afterwards. I compared the empty frame with my other Yonex (same racquet) strung on a Alpha crank machine with 6-point mounting, and the measurements were the same. After mounting the empty frame, I measured the distance between the two mounting posts before stringing. I took measurements of the racquet width and the distance between the mounting posts after every 4-6 strings I did.

I am stringing at around the maximum recommended tension for my racquet (which is actually only 55 lbs). I strung at 54 lbs the first time, and 57 lbs the second time. Even at 57, the tension feels a little too low, probably because the flying clamps are causing me to lose some tension. I am guessing that the actual tension is around 50-52 lbs on my last job, when the drop-weight was set at 57.

Gaines Hillix
04-12-2004, 05:19 AM
chang, that is too much distortion, especially the frame width increase of 3/16". Are you using the frame ratainer/adpaters on the inside of the frame as well as the hold down clamps? Are you making sure that the adapters are snugged up against the frame as you tighten the hold downs? I assume the frame support towers are tight on the bar? If this is all o.k., you might want to consider raising the tension on the crosses a little. I know Yonex recommends a 5% tension drop on the crosses, but if the frame is not returning to its unstrung shape, go ahead and string it to the normal tension.

chang10is
04-12-2004, 01:04 PM
Thanks for replying, Gaines. Yes, the adapters are tightly placed against the frame, and the frame support towers are tight on the bar. The frame support towers move about 2/16" to 3/16" of an inch after doing only the mains, and they move back almost to their original starting position after finishing the crosses (less than 1/16" difference). This leads me to suspect that either the towers or support bar is flexing. The fact that the towers move closer to each other and then back towards their original position means that they are not sliding.

There are only 2 pairs of support adapters that came with my machine, 1 pair of low profile adapters and 1 pair of high profile adapters. The guy who I bought it from said I should put the adapter in between the racquet and hold-down clamps. I first strung a cheap racquet on the machine using the adapters as he suggested, and it seemed to cause a small crack on the frame where the adapter was. So I checked the manual to see if I did everything correctly and found that the manual says the adapters should go under the racquet, not on top. I strung my Yonex next using the correct method, and while there were no cracks, there was significant distortion. That first time I strung the Yonex, I increased the tension of the crosses by a pound, but it wasn't enough to stop the sides from bowing outward.

Gaines Hillix
04-12-2004, 04:36 PM
chang, on a SS II, the adapter goes over the threaded bolt with the radius of the adapter toward the outside of the machine. Use the thickest adapter you can without interferring with the string holes. Then place the racquet on the support pad and adjust the post so that the adapter is snug up against the inside of the frame and lock down the bottom of the post. Do this at both the head and throat of the frame. Then put on the hold down plates and tighten the knob. Check the clearance between the adapter and the frame. There should be no gap. One thing you can do to make sure that the racquet is not slipping is to put some left over cushioned grip material on the hold down plates. Use the kind that has a sticky strip on one side and is cushioned on the other.

chang10is
04-12-2004, 08:51 PM
Gaines, what you said sounds like exactly what the manual says. In my last post, I was just saying that instead of placing the adapter over the threaded bolts *before* mounting the racquet, the person who sold it to me instructed me to place the racquet in position first and then put the adapters in place. This would result in the adapters touching the top part of the frame (looking from the side) instead of the bottom. In other words, the adapter would be on top of the racquet's grommets instead under them. This is different from what the manual says, and I believe it caused a small crack in my racquet on my first attempt (good thing I was using a cheap racquet on my practice run!).

I have done everything you said in the last post (if you get the impression that I haven't, let me know. As far as I know, I'm doing everything correctly.). I've read the instruction manual a couple of times now, and I'm pretty careful to follow everything exactly as it says. I am especially careful to make sure that the frame support posts are as far away from each other as possible so that the racquet is very tight against the adapters. In essence, on the last couple of attempts, I have tried to stretch the racquet during the mounting process to minimize the distortion of the racquet from doing the mains.

christian
04-13-2004, 07:02 AM
You need to string the crosses on yonex raquets from top to bottom.

Gaines Hillix
04-13-2004, 07:44 AM
chang, only thing I can suggest then is that you may need to develop your own set of tension ranges for this racquet on this machine. First, I would decrease the tension on the mains and if there is still distortion, increase it on the crosses to see if that helps. You might also post a question over at ******************.com and see if any of the pro stringers that hang out over there have any other ideas.

cantaloupe
04-13-2004, 08:34 AM
dude don't risk it, just cut it out and restring it,

do the crosses 2 lb lower, do a 2 piece, and start the crosses at the head. IF that still doesn' work the do the 50/50 method, ie string a couple of mains, the a couple of centre crosses and so on. That should stop the frame expanding horizontally,

Yonexes are very fragile frames, and a bad stringjob can really damage the graphite.

good luck

Gaines Hillix
04-13-2004, 10:12 AM
BTW, the 50/50 stringing method only involves the crosses.

chang10is
04-13-2004, 10:36 PM
dude don't risk it, just cut it out and restring it,

do the crosses 2 lb lower, do a 2 piece, and start the crosses at the head. IF that still doesn' work the do the 50/50 method, ie string a couple of mains, the a couple of centre crosses and so on. That should stop the frame expanding horizontally,

Yonexes are very fragile frames, and a bad stringjob can really damage the graphite.

good luck

I like this suggestion, but it seems like I would need 2 additional flying clamps to pull off something like this. Maybe I'm wrong, and there's a special way to do the 50/50 method with only 2 flying clamps?

A big thanks to everyone for replying!

rich s
04-14-2004, 03:42 AM
the 50/50 method for the crosses is the same method by which you pull the mains.

chang10is
04-14-2004, 11:01 AM
the 50/50 method for the crosses is the same method by which you pull the mains.

Rich, if you string a couple mains and then a couple of center crosses, how do you hold both the mains and crosses in place as you move to the next part of your stringing job with only 2 flying clamps?

Gaines Hillix
04-16-2004, 07:24 AM
chang10s, I use 50/50 when I string 2-piece. I do the mains in the normal way and tied off. Then I do the crosses 50/50. I start in the middle and do the top half first, then the bottom half. You only need one starting clamp for this method. Basically, the machine clamp is placed next to the frame on the first string on the bottom half. Then the first string on the top half is tensioned and clamped off. Then the first string on the bottom half is tensioned while releasing the machine clamp. Then the starting clamp or extra flying clamp is placed on that same string. Then the second string on the top half is tensioned and the first machine clamp is moved to that string(the starting clamp is still holding the bottom half string and continues to do so untll the top half is done). When the top half is done, the first bottom string is re-tensioned, the starting clamp is removed and the string is clamped off with the machine clamp on that side. Then the rest of the bottom crosses are weaved and tensioned normally. IMO, it would be a real mess to try to string 50/50 by alternating between the top and bottom side on a machine with dual action swivel clamps, but would be easy to do on a glide bar machine with a clamp base that rotated so the clamps were parallel to the cross strings.