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  1. #18
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    Quote Originally Posted by yan.v View Post
    I've never heard of pre-stretch NOT being used from people that have it on their machine.

    Only exceptions seem to be for very high tensions where manual pre-stretch is used.
    I don't know about your stringer but my two favourite stringers do not turn on prestretch function on the machine when stringing strings like ZM62 and BG80. Only when doing BG65 and VS850.

  2. #19
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    The basis for our project is that we can measure both SBS and shaft-stiffness of the racquets.
    With the help of these tools we want to find out more about the combination of playability and accurate values.




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    Does any of you already use a stiffness tester for badminton?

    Does any of you already have ideas about the best combination of shaft-stiffness and SBS?

    The amazing thing with a badminton racquet is the huge difference between sbs and staftstiffness. The sbs goes up to 30 kg/cm while the shaft is less than 1 kg/cm.

    This means mechanically that a badminton player plays much more with the flexibility of the shaft with than with the deflection of the stringbed.

    So one of the questions is: how much sens does it make to string at these high values?

    My colleague is working on a computer model so that we can simulate the badminton stroke at different speeds and see what happens.

  3. #20
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    I don't know about your stringer but my two favourite stringers do not turn on prestretch function on the machine when stringing strings like ZM62 and BG80. Only when doing BG65 and VS850.
    It seems to me that the prestretch function is only felt by the player when the SBS or stringing tension is not too high.

    At what tension are your racquets strung?

    The higher the stiffness the smaller the deflection of the stringbed, and the smaller the difference that a player feels between prestretch and no prestretch.

    Our advise system advises a string in a certain class (S1 to S4) at a certain sbs.
    This means that stretchy strings (comfort string S1) are never advised for high tensions.

    In our opinion it is not a good idea to string a stretchy string at high tensions.

    We test badminton strings at regular bases so forum members like to know figures badminton strings you can let us know.

  4. #21
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    I'm my stringer :P

    I usually leave prestretch on for every string, but set it higher for BG65 and VS850. Even BG80 loses tension so by leaving prestretch on (with only 10% prestretch, it doesn't lose all of it's elasticity), it helps minimizing the tension loss while retaining playability.

  5. #22
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    Hi guys,

    We would appreciate to get some more info from you about this:

    - Do you think that it makes sense to check the string bed of badminton racquets, or is this less important than in tennis?

    - At what loss of tension does a badminton player want a restring?
    Tennis players 20 % loss of tension does not feel good anymore for most players.

    - Is there any other testing method that is used except listing to the sound of the string bed after hitting it?

    Thanks for supporting our “project”.

  6. #23
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    Afaik, stringbed frequency is the only method we have available.

    http://www.badmintoncentral.com/foru...string-tension

    So your method uses a pressure sensing device?

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    I used to leave the string pulling on my drop weight until I finish weaving the next hole(around 10-15 secs or maybe even 20 depending on shared holes), now ive been just pulling and grabbing my clamp i would clamp the string right away(1-3 secs of pulling). I found that my old method made the string bed TOO stiff as when i play i dont "feel" the bird anymore. its just too stiff. The new method i believe is better because I "feel" the bird once again and the playability is much more satisfying. I pull 30/32 lbs. we dont want the strings to lose its elasticity.

  8. #25
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    @heroclass
    Just out curiosity, at that tension you're playing plastic or feather?

  9. #26
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    feather shuttles

  10. #27
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    ^ I have a feeling that your first method is giving you a more accurate and more stable tension. In other words, with your second method, there's more significant tension loss after stringing thru remaining elongation and you're actually playing with perhaps 28/30 lbs.

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    That's what I thought too however I had two arcsaber 10 and each strung differently with same strings with my old method as well as new method. Both resulted in Same tension after playing

  12. #29
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    ^ How'd you know same tension? Same stringbed frequency?

  13. #30
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    Yes. I hear the frequency with my ear. Of course that is not the most accurate way in measuring, however the differences is so minimum that not even the human ear cant pick up.

  14. #31
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    So probably then your method 1 has over pulled the string beyond its elastic limit. Is the tension retention better on method 1 since there's not much elongation remaining?

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    Did he mention if he also pre-stretched before hand?

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    So your method uses a pressure sensing device?
    Our system measures deflects the stringbed (or racquet with the stiffness test) over a fixed distance and measures the force that is needed for this deflection.


    I used to leave the string pulling on my drop weight until I finish weaving the next hole(around 10-15 secs or maybe even 20 depending on shared holes), now ive been just pulling and grabbing my clamp i would clamp the string right away(1-3 secs of pulling).
    IMO this is a very good and accurate way of stringing. I think that it is better to lower the tension than switching to method 2.


    The new method i believe is better because I "feel" the bird once again and the playability is much more satisfying. I pull 30/32 lbs. we dont want the strings to lose its elasticity.
    If you hit the total elongation occurs in the string, so remaining + elastic. The elastic elongation recovers, part of the remaining does not recover ((depending on the time) so the tension in the string goes down.

    So you never lose you the actual elasticity.


    ^ I have a feeling that your first method is giving you a more accurate and more stable tension. In other words, with your second method, there's more significant tension loss after stringing thru remaining elongation and you're actually playing with perhaps 28/30 lbs.
    I certainly agree on that.

  17. #34
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    I think this is quite an interesting way to look at it. To my knowledge there're several factors that influence the 'feel' of your stringjob:
    1) the racket it is strung in, stiffness of the frame and stringing pattern
    2) stringtension
    3) stringingpattern and stringing practise (type of machine, way it is strung)
    4) type of string (stretchy or stiff, thick of thin)

    Now, for a lot of people it's not practical to go over all these variables to get a racket strung well. So in this sense, introducing a new variable "SBS" that combines all these factors int one simple and understandable number would be quite a good idea. (Much like a Von Mises yield criterion in engineering).
    However, the question to be asked is then: does an indention-test cover all these different factors?

    I usually play with bg80 (0.68mm) or an apacs string of 0.67mm at 31lbs. Now theoretically I could string bg65 or 65titanium (0.70mm) at at tension higher than 31lbs to get the same "SBS". These thicker stretchier string would be just as stiff.
    However, no matter how high I string 65 or 65ti, they still feel different, even if the SBS would be the same (I tried 31-34lbs).
    So how can SBS be used to solve this problem?

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