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Discussion in 'Badminton String' started by Blitzzards, May 18, 2011.
What do you mean with "point of movement" in that context?
If it moves, it breaks. If you put enough pressure on the frame, it moves. No matter how well the racket is supported, it happens.
Still not sure if I'm following you. So you mean that if you just set the tension high enough, every racket will detach from the supports and move on the machine, correct? Or do you mean that the frame is bending and distorting during the job?
And for both options, I don't see why it should any effect regarding the sinking grommets. The load that is applied on the hole edges will be the same in the end. It's a different story if we talk about damaging in frame in general.
Bending and distorting during the job, which is pretty unavoidable. There are good reasons we don't just leave rackets half strung.
Sinking holes is a product of the frame losing integrity right? It's just another instance of failure. In my opinion, sinking holes is in the same boat as the frame cracking. The material is unable to cope with that strain.
My point is, that no matter if you string at 24 or 34lbs of tension, if the tension is high enough to distort the frame in any capacity, it's high enough to compromise the integrity of the frame. Some frames will take significantly longer to become compromised, others will compromise sooner - like those with sinking grommets (sinking tends to occur before a breakage occurs in any case).
Indeed. Remembered buying an armortec 700 offensive many years back... Strung it to 33lbs despite being adviced not to by sunrise and the frame just cracked like an egg shell when I made a miss hit while using it for the first time... ..should just use a tennis racket instead for playing
IMO none of this directly. First of all we need to talk about the racket which is not 100% identical even if the same model has the same weight, head weight and balance point, the material distribution must not be equal. This could be the first reason why some rackets sink and some not, even it is the same model. I refer here that I have/had 6 JS10 in total and was 3 unlucky, 3 times lucky. This racket is not a good example because there where different versions made over time, even if the paint job was the same. I run add the moment 2 JS10 OC which have much tighter holes, compared to my previous ones. I noticed it on the grommet service of the mint rackets.
I thought about a few "theories" which are just my thoughts and I don't have any bullet proof evidences here.
1. compact frames tend more often to sink
The distance between the holes is shorter so the part between the holes is shorter. To imagine what I mean I would use the letter "H". The middle stroke is the part between the holes and the open space at the top and bottom of the letter is the hole. I know that this is just a small difference but it could be affect the sturdiness of frames.
2. uneven distribution of material
We had all a point where you noticed that the material is more distributed towards the head or towards the T and so on when we swung a racket. Another of my theories is that the thickness of the material of the middle stroke of the "H" and around is not always equal. This could also be a reason if a racket sinks or not and could be explain beside different sources and quality of the graphite and errors during the molding process, why same models sink and some not.
1. Thickness of the string
That a thin string add more pressure on a smaller area than a thick string could also be factor if a racket sinks or not. I remember the time when I got a racket from a friend who bought a racket from a 3rd tier racket brand strung with Aerosonic at 24lbs. The racket was not strung by me, it was the 1st job and the racket was new. Never the less, the racket showed early signs of sinking.
While I had a long term theory about the thickness and material of the grommets and thought it was the main culprit for sinking, I'm not as sure about this like in the past. While I have seen even new rackets on the first job showing slightly issues of sinking, the grommets was not totally cut by the the string and grooves of grommets are there, but the grommet was more flushed into the hole. I think that the fitting of the grommet plays a bigger role/ the drilled hole of the frame. If the grommet don't fit tight inside the holes are bigger than usual which also results in less material between the holes.
3. The head shape
I do measurements of my racket when they come off the machine. I measure the length/width of the head and also at last shared on top and bottom. Additional I have often an empty frame of the same model as reference and in terms of stringing im very spot on in keeping the shape with my 0.5kg on cross. That I don't hit it 100% is impossible by the differences at each spot are less than 1mm.
4. tensions loss
According to the head shape topic I observed the shape over longer time on my rackets. It changes slightly. Nothing drastically, but it if a jobs stays longer in the frame the head often gets slightly narrow and longer. My explaination is that the mains are longer than the cross and the length of the mains during the loss gets more longer than the cross in difference. I have no scientific background for it, I don't included friction and length of each segment, pulled angles and the exact tension of each segment, it is just an observation that the shape changes a tiny bit and can cause a tiny imbalance of the whole system which lead the stress in some parts. This is the reason why I suggested before use a high tension job just for 2 weeks to pevent this small changing of the shape which I have seen on my own rackets years ago.
5. tension ratio in combination of the frame
While all stringers here dicussed this topic here several times in over 10 years here, I think this could also be a culprit why some rackets sink and not. The frame profile of each racket is different can more stable/less stable than a different one. Even some parts of frames change the profile. I'm talking here about boxy frames, hybrid frames and so on. That a boxy frame is more stable might be nothing new, so maintaining the bringing such a racket out of shape could be more difficult than an aero frame. Again, I don't have no scientific background for that, but observed that some frames move more on the machine/while others not. So maybe the perfect ratio of not only related to the machine and it's supports, it could also be related to the frames.
It's easy to imagine that any structure and profile collapse at a specific load is only made for useful zone. That stringing a racket at high tensions means that the material has to withstands more forces of different vectors in the head/system. That this will wear anything down faster is simple. I use to give my rackets a time of unstrung rest. Don't get me wrong that I await anything or a recovery. But they have a shorter time of stress and will don't wear down as fast as resting them with th full load of a strung frame. It might sound strange, but a high tension racket should be played and break/cut after 2 weeks instead of resting several month in a bag, because the time of stress in the head will be longer.
In total I think that nothing is made for forever. Even rackets. And if you wear your favorite pair of shoes and walk alot in them, wearing and washing you T-shirts hotter than noted and so on, even rackets are not made to last 5 years and more. It depends on the usage and every thing which you use often tear down and have some wear and tear.
I have the impression that I was trapped in the past to await a longer lifetime/more sturdiness of rackets like others here. Nothing lasts forever and if I push it to the limit and slightly over any lifetime becomes really short. If any racket lives 5 years at 30lbs without issues, it would be great, but alot companies would struggle with racket sales and can close their doors. It's also simple economics that anything must be broken in time x.
I think I wrote here a lot of ideas behind the sinking holes instead of reasons which I can backup with scientific formulas. Feel free to comment to my thoughts. They are theories, nothing set in stone.
Very good points @ucantseeme. One thing that has not been mentioned was tensioning speed. I think there can be additional stress on the frame if you let your dropweight "drop"/"bounce", crank to fast or if the electric tension head is set to be very fast.
The tensioning speed is definitely something to consider because if it's too fast then the tension just before it stops (whether it's a drop weight or electronic) would be higher than the desired tension. This is why when my racquets are strung the stringer slows the speed down each time towards the end of the pull.
Tbh I just thought about ECP machines which apply the tension with a smooth curve more evenly, but I think that jerky tensioning with a dropweight or crank can punch the grommet with an abruptly change of force into the hole or do a jigsaw movement on the hole? I think you mean something like that? If this happen often, I think this can also result in sinking.
Your mentioning of speed bring a different aspect on the list as well which is machine prestretch. I don't string with prestretch often because a lot of my clients don't like the feel. Especially at higher tension, beside harming the racket, it will make strings dead and dull, but each pull put also more strain on the racket for a short time. Maybe this short time is enough to go over the limit of the material strength and can do nano defects and speed up the wear?
The more I think about it, the more it makes sense that the pulling process can really make a difference in how much load is applied on the grommets. The pulling curve of an ECP is totally different to a drop weight since the pulling sequence of a drop weight normally takes about half the time compared to an ECP (at least that was the case when I still had the drop weight...). And in most cases, the pulling speed won't be smoothly reduced once you get close to the set tension - in a lot of cases you will see a bit of bouncing which should, in theory have a comparable effect than using machine pre-stretch.
And let's not underestimate the effect of those 10% extra load. It's a short period of time but it might be right to push the frame integrity just of the edge to cause the denting.
As a stringer, you don't have much influence on most of the other things you've mentioned. But I'll definitely consider to decrease the speed setting on my WISE.
I run mine at 2 instead of 3 since the mid of last year because I ditched the PS. Don't effect the time of my stringing much, because I'm not a high speed stringer or after any records, but I didn't experienced any improvement in regards of sinking on new rackets at higher tension.
I still think that it's a more racket related thing when I take into account my observations over years of my own rackets. This would also explain the randomly sinking issue on same models with same stringer and would also explain why certain model sink all over the world at different machines with different stringers. And if even somebody like Paul spotted this, I think the sloppy stringer myth is busted here or what do you think?
My personal opinion is that any manufacturer of badminton rackets, should take the stringing process into account for their product development, otherwise the product is faulty for its usage. I see clearly a manufacturer issue instead of a machine issue, because I also experienced that some rackets are totally fine and I don't mean heavy beasts like my 47g head weight Armortec in my closet. Maybe this is the reason why he don't have any Yonex High End at 30 compared to other brands. They are more careful what the can promise.
It depends how you use the drop weight.
First choice is have the bar up, gripper level
Grip the string and drop the bar back
Second choice is have the bar down, gripper level
Grip the string, then lift the bar to above 80 degrees (so it's just above 90), let it drop, rinse and repeat
The latter is much gentler on the string.
In any case, when you drop the bar (and this is for any other stringers), I recommend you keep two fingers under the bar at the tip just to ease it down a little more gently.
8xp. Regardless, shouldn’t be an issue still since the warranty period (at least here) is 3 months or so. (3 or 6 I don’t quite remember exactly)
You are right! What a shame and stupid me, I also opened the DUO8XP thread here. I take my words back. Warranty differ for each country is not always a smooth process, so if it's avoidable I would do that. Furthermore the companies have always "the clash and abuse"-backdoor.
Indeed which is why I found it even more funny. You created the thread itself.
It most certainly isn’t a very pleasant experience for everyone unless you have an open & shut case to present and / or know someone that works there.
But the 8XP is not available here, so he can't be always on my mind.
The world of importing is heavenly.
Resident of a country ignored by sunrise.
We see knockoff Yonex racquets in our shop every month. Most of the racquets purchased on Alibaba cannot handle 30lbs tension. We have had knockoffs break on our Gamma 8800 at < 25 lbs. My only quibble with an otherwise excellent contribution.