Six-Point Suspension Vs. Six-Point Internal

* The load spreader is a huge help to lower the stresses at 12 o’clock in the badminton frames on 6p machines. I saw some load spreaders for tennis also at the Orlando symposium.

* Yes you are absolutely right, this is the essential matter to understand. This is the end of the “beam in the wall” in the explanation above.
The worst thing that you can do is to place the bar across the 3 and 9 oclock position this introduces huge stresses between 3 and 12 o”clock.
And therefore it is also of major importance that he outside support are not too close to the 3 o’clock position.

* The maximum stress is much lower when the movement of the frame is gradually divided over the hole length of the racquet between 12 and 3 o’clock. This is the reason that the “old” Ektelon /Neos (4 p inside) supports never cause any problems.

* The bending stress is higher when the bending radius gets smaller.
When you let the racquet move freely with good inside supports the minimum bending radius will be smaller than when you add outside supports. The chance of damaging does not depend upon the movement in milimeters but upon the bending radius.
So on a good inside support the chance of damaging is minimum while the movement at 3 o’clock can be 5 mm.

* The widening at 3 / 9 oclock depends strongly on the way you support the racquet at the inside:
- There would not be any widening if you support the racquet against the inside at every position of a main string. The force of every main string is directly “absorbed” by the in side support. Of course this solution is practically impossible.

- The best practical compromise is to support the racquet at 3 positions.

- The worst solution is only the narrow 12 o’clock support

* The best way to put the cross strings in depends upon the shape of the racquet and also on the support system:
- The widening caused by the main strings is bigger when the width of the string area is bigger. When the string area is elliptic and head and throat have the same width there is no problem.
- The problem arises when the width at the throat and the head is different like on most badminton racquets where the head is narrower than the throat. This causes a “conflict” between the upper and lower part of the frame. The forces of the mains at the head cause less widening at 3 o’clock than the forces on the throat side which causes stress between 2 and 4 o’clock. On the drop-shaped racquets it is the other way around.

- The best way to put in the crosses on badminton racquets:
It is important to lower the stress caused by the mains as soon as you start to put the crosses in. This means that you have to start the crosses at the throat so that the bigger widening there is lowered first.
When the crosses are put in starting at the head the “conflict” between head and throat grows and the stress rises.

- Depending on the support system:
Putting the cross strings in on an inside direct support in the “wrong” way (going from the narrow to the wider part of the string area) is less dangerous than on an indirect support.
The forces on the outside supports on an indirect racquet support are higher on the wider side of the string area. It is important to lower these forces as soon as the cross strings are tensioned. So on such a system it is even more important to go from throat to head on a badminton racquet.

Stringtechno

 

Back the stringing machine truck up . . .

I have been stringing over 30 years as a PROFESSIONAL Racquet Sports Stringer and technician at my own shop and at tournaments. The gobble-de-goo that Stringtechno is professing to be truths are at best unsupported theories, if you can stretch the definition of theory that far. I use machines that only utilize 6 point mounting systems and I, #1 have never broken or cracked a frame and #2 I have never seen a frame distort like the diagrams Stringtechno has used to illustrate his "therory". I would like to ask the following: Stringtechno; What experience do you have stringing badminton or any other racquet sport racquet? What visual evidence do you have or can provide that supports your therory(ies)?

 

pro stringer

Hi Prostringer,

I am not launching these theories to have a theory. We have developed our last racquet support in 1992 based on computer calculation that calculate the stress in the racquet depending on the position of the supports. These calculations do not have anything to do with the size of the racquet only with the shape and the number of strings. So this counts for badminton and tennis.
After we made the calculations we have taken more than 6 months to test the support that we designed based on the calculations.

I am proud to say that our direct racquet support is known as a very reliable system.

Around 2001 one our sales people asked me to design a 6 point outside support because that was easier to sell. After 4 months we stopped working on it because it was impossible to design an indirect (6 point) support that can match our direct support.

So our theory is supported by quite some practical experience.

Stringtechno

 

Stringtechno: Let me see if I understand what you wrote. Are you telling me if stringers use 6 point mounting they will damage any racquet they string? 80%? 50%? 10%? What exactly are you saying? I have never broken a racquet on 6 point while stringing. Never. My customers don’t return with racquets all of a sudden breaking either.

How is it possible for you to take 6 months to design a radical new theory of mounting support based on computer calculations in 1992 when what you came up with is hardly different than what Prince had been making 10 years before that? I can’t believe you never saw the Prince air compressor(p2000) machines from the early 1980’s before you made all your calculations because your mounting is only a hair different. A copy I would guess.

I’m curious to know about this because now that we are in the 21st Century, every major racquet company who also makes high end stringing machines puts 6 point mounting on their machines. Yes! Including Prince with their new P6000. Are you saying that the racquet companies don’t know what’s good for their own bread and butter products? Or is it possible they know they design their racquets to be sufficiently strong to handle whatever stress is put on the racquet from a 6 point mounting. I’ve seen racquet companies caution stringers against stringing a certain racquet on inside supports. I have never seen one that says don’t string on a 6 point support. It would seem to me if there was such a huge problem with 6 point mounting and exploding racquets, the industry would have known about it 25 years ago. By the way, Prince maked tennis, badminton and Squash frames, as does Wilson. I also believe Babolat is into Squash outside the US market.

And while you are formulating your response, please answer my question regarding your stringing experiences.Observing doesn't count!

 

in reply to prostringer's post

Hi Prostringer,

I do not feel good about this personal discussion, I do not think I have to justify my experiences as a stinger and a designer when I try to inform the market about technical matters.

Some remarks:
I think you pull this discussion out of proportion. I am not saying at all that racquets strung on outside supports will be damaged, I am saying that the stress in the racquet material is higher on a 6 point indirect support than on multipoint direct supports.
But as long as the stresses stay below the level that is allowed for the material there is no problem at all, and racquets are very strong nowadays.

But as a mechanical engineer you look for the best possible solution to use on your products and that is why we did the calculations and based our design on these figures.

Designing a support system does not only mean putting the supports in the right position, our system was quite different from the Prince system (which I certainly do know). Our system had a fast clamp system and a T-bar clamping at the throat.
And perhaps I am a slow developer but maybe it is also because of the famous rule in developing: 90 % of the job takes 90 % of the time and the last 10 % also cost 90 %.

I do think that some racquets are not designed well to deal with the stresses during stringing. The big drop shaped racquets had many problems on 6-point machines and I do not think that the low profile bridges that many racquets have at the moment are a good idea , very high stresses occur in that part when the bridge is supported with a support that is too narrow.

I find it quite peculiar that you think that you can develop such a range of stringing machines without learning about stringing continuously.
Anyway I started stringing before we started the Stringway business in 1982.

I hope that I passed this exam.

Stringtechno

 

keeping personal matters out!

I agree completely Oldhand.
I hesitated long before i posted the last one.
So I tried to keep it to technical answers.
On the other hand it is difficult to ignore personal "attacks" when your only intention is to add technical information to the discussion.

Stringtechno

 

at one time, i did consider making a jig for some of the key yonex frame design: cabs, muscle power, armortec, etc but infortunately i was infected by the procrastination sickness

 

Good Compromis

About the mould inside the racquet:
There are very good alternatives that are easier to realize and more universal than making a mould for every racquet.
- A 2p support with rotating supports and the supports 60 mm apart will do a very good job.
- The best compromis is a 3 point support with an adjustable one in the middle.

Because the deformation at the wider throatside of badminton racquets is heigher a 3p at the throatside and a 2 point at the head side would be very good.

When such an option is used on a 6 p indirect support it will lower the pressure on the outside supports enormously.

Stringtechno

 

Some suggestions

Hello Stringtechno

I think that you do have room for improvement in you product

1. At my ML100 the bottom of the two-action fixed clamps is too short. Because of this the middle two mains are not straight when clamped. I think this happens only with badminton rackets and not with tennis ones.

2. When clamping the base of fixed clamp the upper side is moving and sometimes significantly forcing you to re-clamp. I think this is happening because the metal bars of clamping system are narrow and high and have some play. How often do you re-clamp depends on what part of racket you are stringing.

3. Usually it is impossible to clamp the last string on top (hole 7) witha fixe clamp. Frequently second last string is a problem to clamp too. This is happening because the last string are almost blocked with top supporting plate and the ^ shaped top of the fixed clamp are still too fat.

4. Central support on top - the white one with funny shape - are ruining the frame on high tensions. Standart H or 5-finger load spreader cannot be used with it because the central support has shape W and is too fat.

5. I have modified my central support to be able to use H load spreader. But it becomes too long to tighten the last string, so it must be unscrewed and removed every time before tightening 3 last strings on top. Central support will prevent putting the wider flying clamp like HI-QUA.

5. And frame are moving when stringing crosses - this happens always :crying:

Hope this will help to make you product better.

Regards,

Valentinas

 

Improving products

Hello Valentinas,

Thank you for your comments, We are watching the badminton message board closely because we are convinced that we can only improve the details of your products with the help of the users.
And we are also aware that our machines can be improved for use for badminton, our machines were designed primary for tennis.

But we would like to improve any detail with the help of the users.

Some remarks:
1) It is very easy to bring the clamps a little more towards the middle of the racquet. We just move the guiding bars about 5 mm inwards.

2) I am uncertain what happens here. I do not think that the bars are too narrow, it seems more that you have a movement inside your guiding system. Could it be that you have to adjust the clamping force of the guiding system a little heavier?

3) Clamping the last strings on a badminton is an issue that comes up regularly. Of course it is the consequence of the inside support that the movement of the travel of the clamps is restricted. But we changed the front side of the plates which is now machined under an angle.
If the last string can not be reached we advise to use the following trick:
- Skip the string before last and put in the last cross string first (coming from the throat).
- Do not tension the last string.
- Put in the string before the last one and pull the knot tension while pulling tension on both strings together.
- Make your knot.
The last strings are so short that it does not matter when the tension in them is a little lower.

4) The remark concerning the central support is very welcome: I think it might be good to reconsider this design which is already 17 years old.
It is easy for us to supply a special central support that has the shape of a load spreader.
I did some designing.




5) Do you use the V-block at the throat, I do not think that moving around is possible anymore then.

Thanks again we appreciate every constructive remarks and will use those that can help to improve our systems.

Stringtechno

 

Hello Stringtechno

1. Yes, I am planning to do it actually. But I will be happy if it will be possible to get modified shorter stands from stringway-nl.com

2. Ok, I will re-check

3. I agree, but I am using small Yonex strong grip flying clamp to finish las two crosses. Plates mashined at an angle are great .

4. Yes, now it looks like similar design of Yonex ST-250. It is way better now. But I think that three Yonex designs must be considered before making a finas design: Aerodynamic Shape, Box Shape and the Delta Power Frame. H load spreader like this http://shuttle-house.com/PAGE_top_JAPANESE/MAIL_ORDER/category/GOSEN/GOODS/GM02517_b.jpg may be a better option sometimes

5. Yes, I am using the V-block. I have noticed that movement occurs on the modern rackets where the T-joint area is very slim. When stringing the T moves to one side and the handle of the racket to other side.

Almost forgot - some Vistor models with anti-torsion bridge like this http://www.victor-sport.de/badminton_atb.htm can not fit the bottom supports.

Thank you for you answers,

Valentinas

 

I don't know about tennis racquet but in my experience badminton racquets are subject to the greatest stress at the 4-5'o'clock and 7-8 o'clock positions. Using inside supports at the tip and throat of the frame is not as good as using 4 side supports or 6-point supports, with the 6-point machine having two clampdowns at the tip and throat. The greatest stress is not when the mains are completely tensioned using 4 side-supports, insofar as a badminton racquet is concerned. The greatest stress is when you start tensioning the crosses, at very high tension, from the top towards the throat. By design a badminton racquet is "squeezable" on the sides at the top half of the frame. With high tension, tensioning the crosses from the top towards the throat is effectively "squeezing" the frame from the top towards the bottom. Without the 2 bottom side supports, the lower half of the badminton frame will "buldge" and then crack with a sound. This is the most common crack in stringing badminton racquets.
Re cracks at the 12 and 6 o'clock positions on 6-point machines, this happens mainly in 6-point suspension system and is solely the fault of the stringer. In a suspension system the frame should never be stretched by the top and throat supports, because tensioning the mains will cause wear and tear on the inside tip of the frame.
For badminton racquets the key is to prevent the buldging of the lower half of the frame, not from the tensioning of the mains, but from the squeezing of the frame from the crosses that start from the top. Tensioning of the mains on a 4 side support system creates no stress at all on a badminton racquet. As a matter you want the frame to be slightly round after tensioning the mains, provided it is strung on a machine with 4 side supports, so that the "squeeze" hurdle that is to follow when you start the crosses from the top is easily surmountable.

 

Thank you Pete

Hi Pete

I have seen you post before, thank you.
I have considered it carefully and decided not to change the bottom supports plate.

Regards,

Valentinas

 

1) The stands are glued in the main casting with positioning pieces that keep it in place. So you only have to move them inwards a little. I send you a trick in a personal message.

4) We will be happy to design a new center piece that offers the best possible support for badminton racquets. If we do that we will make a number of protos and send them around to experienced SW badminton stringers for testing. We would like to cooperate with you on the board to obtain the best possible shape. We need to know the dimensions of other load spreaders.

This squeezing ending in cracks happened also on oversize drop shaped tennis racquets. Because of the widthe at the top the force on the outside supports was huge and rose even more when the crosses were tensioned from the throat to the head.

I think that it is always better to put the cross strings in from the wider side of the frame towards the narrower side. In this way you lower the conflict between the upper and lower part of the racquet from the first cross string and the forces on the outside supports will go down also from the beginning. When you go from the narrower side of the stringarea to the wider side the "conflict" between the upper and lower part will get worse first with a big chance of damage.

Stringtechno

 

Back the stringer truck up: Part 2

The recent posts are exactly what I’m talking about. Stringway is constantly posting scare tactics with claims of breakage and damage regarding different mounting systems to promote their own when it is ironic that it looks to me like stringers have been complaining about the Stringway mounting on this very site for years. StringWay claims their support is the best in the world and yet they are still trying to come up with something that works. It reminds me of Microsoft. They put a product out without thoroughly testing and let the buyers(in this case stringers) be the lab rats to find the problems and report back what needs to be fixed. Stringway could always do what I know Prince does and I’m sure all the other companies do. Take the next 3 months to string up a 200 or 300 different badminton racquets and discover on their own what most stringers would already know. Thereby avoiding disgruntled stringers with machines that don't suit their needs and a pile of cracked racquets!