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    Default pre-stretch string

    Does your stringer pre-stretch the string before stringing your racquet? Should s/he?

    belive it or not this has never been discussed on BF before.... i've searched

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    Interesting question from BRL....

    I know some steel beams used in construction are pre-stressed to give a higher strength.. want to know if that also applies to badmintion strings.....

    BRL: How do you come up with that idea anyway?

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    BRL,

    here is a dicussion that has some stuff on pre-stretching.

    http://www.badmintonforum.com/vb/sho...stretch+string

    basically, pre-stretching means that the string won't stretch after tensioning on the racket. good for tension retention. but unfortunately, time-consuming as it requires an extra step. i haven't seen any stringer do it regularly due to the above.

    however, if the stringer use a constant pull machine, most likely a electronic machine, it has the effect of pre-stretching. a crank machine stops pulling too early to "pre"-stretch.

    however, the side effect of all this is that with crank machines, the final tension after stretching is lower than constant pull machine.

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    just my opinion and observation.

    I see some stringers talk about pre-stretching, PT, yada, as a bait to impress and lure new clients. After his first job, he'll stop doing it for that client.

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    The stringers i've used in Toronto all pre-stretch their string so far as I know. I've never paid much attention to it until I got a stringing job done without prestretching the string, and the difference was astonishing. The string was supposed to be at 22 lb but by the time i took the racquet home (without even hitting) it felt more like 18 pounds. My racquets with prestretched string still feel as though it has a higher tension than this after 3 months of play.

    The difference can't be attributed to the string since the unstretched string is bg 70 pro, which doesn't lose tension that easily... at least not much worse than my bg88ti string.

    The stringer i normally get strung at refuses to string unstretched string even when I offered him more money for it... he said it would hurt his reputation or something... (i wasnt paying attention.)

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    not a fair comparison.
    different stringers = different machine and different calibration. (Unless both have highend electronic machines). Also, each stringer who prestretch string dont prestretch in similar method or degree. The best is what works with your reliable stringers that u r accustomed to his/her work

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    Interesting topic, and I never really thought about it before.

    Since I am not using those expensive electronic machine, but just a simple drop weight machine, I am wondering how I am being able to "pre-stretch" the string then?

    Or, maybe an easier alternate method, is just add another 1-2 lb more than my desired tension?

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    LB, if you are using a dropweight, it is a constant pull machine. if you leave the weight settle, you have effectively pre-stretched the string already.

    so you have been doing it all these time without knowing.

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    Just out of curiosity how can you tell if your string has been pre tensioned or not if you don't know what you're looking for?

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    Originally posted by kwun
    LB, if you are using a dropweight, it is a constant pull machine. if you leave the weight settle, you have effectively pre-stretched the string already.

    so you have been doing it all these time without knowing.
    Really... Cool...

    So, guess being slow (stretch more???) on string job is good then. Like my machine even more now.

    This also answered another question for me. There's an experience guy in my club. Once he tested the racket I strung by myself, he thought the tension (22*24) is higher than the ones (claimed to have the same tension) he got on his racket (from another stringer). Since both rackets were freshly strung, but using different string, I was thinking it might just because of the "feeling" is not very accurate. Now, I think his claim does make some sense.
    Last edited by LazyBuddy; 08-05-2003 at 03:25 PM.

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    what we don't know is that what is the proper amount of time for a string to pre-stretch.

    here is how long each type of machine stretches the string:

    in a crank machine, it is around 1-2 seconds (the time take to rotate the crank)

    in a drop weight, i'd say between 10-15 seconds (the time to drop the weight and letting it settle)

    in a electronic machine, i'd say between 5-10 seconds (only from observation of other people using it)

    from experience, i find that that on drop weight, the string stops stretching after 10 or so seconds. so a crank machine definitely is not giving sufficient time. but if the string is tensioned after more than 10 second, does it still stretch?

    maybe somebody can do an experiment, using a drop weight machine, take a piece of string, pull it with the machine, let the weight settle for 10-20 sec. and then leave it overnight and see if the weight drops even more. and then if it does, then adjust the weight to horizontal again, and see if it drops further. it should at one point stop stretching and we will know the "true" time it takes for the string to pre-stretch.....

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    Originally posted by kwun
    in a crank machine, it is around 1-2 seconds (the time take to rotate the crank)
    .....
    so a crank machine definitely is not giving sufficient time.
    I experienced that after stringing a number of rackets, you know when the 'click' comes and the tensioner settles. Even when doing different tensions, the feeling is quite accurate. What i do to get more stretching, is slowing down when approaching the 'click zone' and hold it for a few seconds just before giving the final push to settle. For the middle strings, 10-15 seconds, reducing to the the basic 1-2 second for the pheriperal strings.

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    Now I'm not a stringer but...

    Surely whatever type of machine you string with, every string is pre-stretched (ignore the first string for now).
    Whenever you tension a string, you are stretching the string that is outside of the frame as well as inside the frame. That section of string is then fed through the next holes and tensioned again...and so on...

    How long it is stretched for is another matter.

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    Originally posted by kwun


    in a drop weight, i'd say between 10-15 seconds (the time to drop the weight and letting it settle)

    That long?

    For my own experience, from the time I let the weight settle down by itself, then pick up clamp, and clamp the string, it should not be as long as 15 sec. Or, maybe i should wait a little bit more next time?

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    Originally posted by Neil Nicholls
    Now I'm not a stringer but...

    Surely whatever type of machine you string with, every string is pre-stretched (ignore the first string for now).
    Whenever you tension a string, you are stretching the string that is outside of the frame as well as inside the frame. That section of string is then fed through the next holes and tensioned again...and so on...

    How long it is stretched for is another matter.
    good point there neil.

    It's true that hand crank machine yield the lowest holding time but if one don't rush through the job like a mad man, plus the point made by neil, i think a crank machine would yield result just as good as drop weight and electronic.

    Kwun, as to how long it take to stretch a string? I think it is a log/exp function, it depends on your delta tension that you are happy with.

    Also, the string characteristic is differs on its degree of being stretched. If i'm correct, I believe a prestretched string is closer to the yield point and would loose its elasticity sooner than a non prestretched one sooner.

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    Originally posted by cooler:
    Also, the string characteristic is differs on its degree of being stretched. If i'm correct, I believe a prestretched string is closer to the yield point and would loose its elasticity sooner than a non prestretched one sooner.
    Agree with cooler about losing elasticity thru prestrecthing a string. Prestrecthed string is pushed closer to yield point which means less energy is required to deform the string permanently. A lot of players prefer low tension around 20 pounds would have a longer lasting string since the string is under tension in the elastic range in which a material is not supposed to deform.

    Materials in construction sometimes are prestressed/prestrengthen to avoid change in length. You don't want the roof would bend down because of a new bed placed on top, rite? In our case, prestrengthen string gives us a fix feeling of high tension based on the same concept. The drawback is that the string becomes brittle and does not last long.

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    there are good and bad points to prestretching, it is up to good stringers to know when and how to do it. In this case, more labor doesn't mean better.

    As for prestressed beam and truss in construction, that is to maximizing the strength near its yield point at A PREDETERMINED load or condition, AND to have the beam and truss being straighter AND deform less at loaded condition.

    However, in badminton, performance of a string is judged under DYNAMIC loading, and 99% of stringers no way know how hard their clients are gonna smash their shuttle (ie UNDETERMINED or UNPREDICTABLE LOADS).

    prestretching, PT is not like options for a new car, more is not better. Stringing is more like an art as in cooking and painting, the best result is dependent on putting certain ingredient together the right way.
    Last edited by cooler; 08-06-2003 at 07:31 PM.

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