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what causes this damage?

Discussion in 'Badminton Stringing Techniques & Tools' started by kwun, Feb 22, 2012.

  1. kwun

    kwun Administrator

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    a friend of mine has this damage in his racket, a current gen AT700, near 12 o'clock.

    423063_10150670821911391_751056390_11424854_406615321_n.jpg

    i was told it was strung with a ES5Protech.

    i originally thought if it were done with a clampdown, it maybe the clamps were too tight, but ES5PT is a suspension, so that rules that out.

    any idea what the stringer did wrong?
     
  2. silentheart

    silentheart Regular Member

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    Never seen on like this. Need more info on this. My guess is material fatigue.
    1) is string NBG98?
    2) grommets looks different than my brand new unstrung at700. can you verify the gromment has been replaced before?
     
  3. Fidget

    Fidget Regular Member

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    Brutal grommet extraction sounds a reasonable source of injury.
    Pardon my inexpertise, but is it also possible that a load spreader, at some point during the stringing of the mains, was carrying too much pressure and weakened the inside of the frame? Then the lateral pressure of the tensioning crosses may have applied the coup de grace.
     
  4. Optiblue

    Optiblue Regular Member

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    I'm going to guess that load spreaders were used, but the stringer overtightened the 12 and 6 o'clock mounting points. What tension, how old, and was it like that before it got strung up? I'm predicting a very narrow shaped frame~
     
  5. silentheart

    silentheart Regular Member

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    Sorry to ask stupid questions again.
    1) was that a tie off or starting knot #3 from the left?
    2) String could be ZyMax62 and making the grommets look too big?
    3) The grommets in question are #4 and #7 from the left.
     
  6. yan.v

    yan.v Regular Member

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    The load spreader theory sounds unlikely. I really doubt that the frame would crack that way.

    I would go for 1)Racket inperfection 2)Racket "fatigue" 3)Intense grommet extraction (seriously, they probably did it with a drill)
     
  7. dunmaster

    dunmaster Regular Member

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    never seen this bad of a crack! any picture of the other side of the frame?

    also, from the picture itself, if I see it from an angle, I saw a small "dented line" on the frame around the middle 4 grommets. If this is physically true, not the reflection issue, it would point to a bad mounting and / or load spreader.

    whatever the reason is, it's a big "ouch".
     
  8. Alex82

    Alex82 Regular Member

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    at the moment i don't have a racket to compare, but i think the grommets are to big in diameter. maybe the old grommets on 12 o clock was broken and he changed it with to big grommets...
     
  9. R20190

    R20190 Regular Member

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    Looks to me like an imperfection in the racquet.

    If it were at a shared hole I would have said that someone had been over enthusiastic with an awl causing micro-fractures, exacerbated by tensioning... but as there aren't any shared holes, it looks likely to me that this is an manufacturing fault.
     
  10. Mark A

    Mark A Regular Member

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    Rackets normally crack across the frame, rather than along it, during stringing. Racket imperfection would be my vote as well.
     
  11. silentheart

    silentheart Regular Member

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    That would be my vote it is a new or near new racquet. However, from what I can see, this AT700 has been restrung several time before (my guess is more than 7 times already) If it is a defect, it would have shown very early, may be 2 or 3 restring jobs. I would like to know if ther gromment was ever replaced or turned.
     
  12. R20190

    R20190 Regular Member

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    Not necessarily, it may be because of the cyclic loading and unloading effects of stringing that has gradually exposed a weak area of the racquet. Or perhaps, the stringer made a mistake and did not support the frame well enough on one occasion which revealed the defect.

    Sometimes problems don't show up until much later, as a structural engineer I see a lot of failures occuring when structures are exposed to repeated loads, be it traffic, wind or even temperature effects. Sometimes it is a design flaw, other times it could be a quality or misuse issue... difficult to say in this instance.
     
  13. Valentinas

    Valentinas Regular Member

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    5 prong load spreader and bad mounting.

    Valentinas
     
  14. silentheart

    silentheart Regular Member

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    Agree with your assessments. And yes, paint offent time cover the issue and show up later. However, what you are describing is for a bridge or a structure designed for 10, 20 or more yr of life time. However, yy racquet has 1 year warranty against defect. If you break the string of a specific racquet everyday and restrung every night, sorry, that is a little extreme case. But warranty will still apply given that you do not abuse the racquet and maintain the racquet in a good condition and no clash. To me, it looks more like a tube crack under vertical load to me in this picture. I am not sure if the racquet has always been strung with a ES5ProTech or a suspension mount machine.

    I would like to hear you opinion on this one. In this case of AT700 crack. What is your thought.
     
  15. Valentinas

    Valentinas Regular Member

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    I have similar photo of AT700 taken by myself. Note that cracks are developing between the grommets.

    Valentinas

    crack_at700.jpg
     
  16. silentheart

    silentheart Regular Member

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    There are crack on the 2 left grommet too. WOW. Thanks!
     
  17. yan.v

    yan.v Regular Member

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    Looking at these pictures, I think that it could be possible for the cracks to be caused by a too great tension on the mains. I could really see this as an additional effect from excessive tension (the other being racket deformation). I do think that the rackets would have had to have some kind of imperfection or weakness, considering how rare it is to see such damage.

    What tension are these rackets usually strung at ?
     
  18. Udonming

    Udonming Regular Member

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    NS4500 (4).jpg
    YY NanoSpeed 4500, glad the owner only cut the strings and when I found I couldn't pull the center string then I realized this.
     
  19. Alexccs

    Alexccs Regular Member

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    I agree with yan.v that the possible cause of the crack are the excess tension which the frame did not made to handle those tension. In my collection I have a ISO 800 tour, was great with 26 lbs until I put it to 28 lbs, it crack like Kwun picture.

    ISO-800 tour.jpg
     
    #19 Alexccs, Feb 23, 2012
    Last edited: Feb 23, 2012
  20. silentheart

    silentheart Regular Member

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    Looks like no load spreader was used?
     

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