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  1. #18
    Regular Member milton's Avatar
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    Ok thanks for the video. What about the outer main when you have skilled two holes so the gap is too big for a flying clamp? Do you pull two at once then? Thanks

  2. #19
    Administrator kwun's Avatar
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    Quote Originally Posted by milton View Post
    Ok thanks for the video. What about the outer main when you have skilled two holes so the gap is too big for a flying clamp? Do you pull two at once then? Thanks
    Yonex flying clamp is ok.

    check this video, around 5:15 or so.


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    Quote Originally Posted by milton View Post
    Ok thanks for the video. What about the outer main when you have skilled two holes so the gap is too big for a flying clamp? Do you pull two at once then? Thanks
    I usually do one pull for the last two mains with an extra 2 lbs.

    Also, if you have flying clamps and don't wan to clamp outside the frame, just get a piece of cardboard, cut a small slit in it for the string to fit, and put it between the clamp and frame. Works really well for me.

    I've experimented with clamping outside the bottom of the frame where sometimes the grommet sticks out a little bit. Haven't had any issues with that either.

  4. #21
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    I had a short discussion at the weekend with a stringer which string on some small tournaments around here. He pulls two strings at a time (with a Pro's Pro Pilot) and he says, that he has tested this and this would not be noticeable. I remember how Kwun measured this a year ago, so I have copied his technique (sorry Kwun ) and tested this yesterday evening, this is the result:

    Pull on one string at the mains with prestretch (20%) enabled:
    Name:  IMG_0185.jpg
Views: 310
Size:  35.9 KB

    Pull on two strings at the mains with prestretch (20%) enabled:
    Name:  IMG_0186.jpg
Views: 316
Size:  46.9 KB

    Pull on two strings at the mains without prestretch but constantpull:
    Name:  IMG_0187.jpg
Views: 315
Size:  48.2 KB

    Pull on one string at the crosses with prestretch (20%) enabled:
    Name:  IMG_0189.jpg
Views: 352
Size:  74.3 KB

    Pull on one string at the crosses without prestretch but constantpull:
    Name:  IMG_0190.jpg
Views: 322
Size:  79.5 KB

    Pull on two strings at the crosses with prestretch (20%) enabled:
    Name:  IMG_0192.jpg
Views: 311
Size:  51.8 KB

    Pull on two strings at the crosses without prestretch but constantpull:
    Name:  IMG_0191.jpg
Views: 311
Size:  53.1 KB


    Every time I have pulled with 9kg (~19,84 lbs).

    Also i measured two finished string jobs with the ERT 300 (this is a small tool to measure the "dynamic tension" of tennis rackets). Normally the ERT 300 works for badminton rackets too...

    First i strung this racket with pull on every main with 9 kg (~20 lbs) and prestretch 20%. On the crosses I've pulled two strings at the same time with 9,6 kg (~21 lbs) and prestretch 20 %.
    The result of the ERT300 is 38.
    (My heard was bleeding while i strung this racket with pulling two strings at a time...)

    Second i strung the same racket with the same string with pull on every main with 9 kg (~20 lbs) and prestretch 20%. On the crosses I've pulled every strings with 9,6 kg (~21 lbs) and prestretch 20 %.
    The result of the ERT300 is 44.

    The procedure with pull pulling two strings at a time is more than 15% lesser than the normal one.
    The ERT300 is not optimal for badminton rackets, but i think its a good reference value...

  5. #22
    Regular Member Mark A's Avatar
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    ^It's more noticeable with crosses because a double pull doubles the cross friction, which is far higher than grommet-borne friction.

    Losing 0.3 lb on a main isn't exactly the end of the world, but I wouldn't be satisfied with it.

    P.S. I'd be very interested to see a hand prestretch vs. ECP prestretch result for a "normal" string job...

  6. #23
    Administrator kwun's Avatar
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    awesome work Alex!!

    15% loss is quite a bit. if we do a 20lbs job, instead of 20lbs we will end up with 17.

    two more observation:

    - the loss on cross and main is different. what it means then is that it will change the main/cross ratio. and as we know, main/cross ratio has a very big influence on the playability of the stringjob
    - pre-stretching reduces the effect. which is interesting as it means it is forcefully overcoming the friction before settling down on the actual tension. make sense, but it also might mean we are not getting the pre-stretch'ing which is one of the factor contributing to the reduce ERT reading.

  7. #24
    Regular Member Blitzzards's Avatar
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    Quote Originally Posted by kwun View Post
    Quote Originally Posted by Alex82 View Post
    I had a short discussion at the weekend with a stringer which string on some small tournaments around here. He pulls two strings at a time (with a Pro's Pro Pilot) and he says, that he has tested this and this would not be noticeable.
    Every time I have pulled with 9kg (~19,84 lbs).

    Also i measured two finished string jobs with the ERT 300 (this is a small tool to measure the "dynamic tension" of tennis rackets). Normally the ERT 300 works for badminton rackets too...

    First i strung this racket with pull on every main with 9 kg (~20 lbs) and prestretch 20%. On the crosses I've pulled two strings at the same time with 9,6 kg (~21 lbs) and prestretch 20 %.
    The result of the ERT300 is 38.
    (My heard was bleeding while i strung this racket with pulling two strings at a time...)

    Second i strung the same racket with the same string with pull on every main with 9 kg (~20 lbs) and prestretch 20%. On the crosses I've pulled every strings with 9,6 kg (~21 lbs) and prestretch 20 %.
    The result of the ERT300 is 44.

    The procedure with pull pulling two strings at a time is more than 15% lesser than the normal one.
    The ERT300 is not optimal for badminton rackets, but i think its a good reference value...
    I am thinkingawesome work Alex!!

    15% loss is quite a bit. if we do a 20lbs job, instead of 20lbs we will end up with 17.

    two more observation:

    - the loss on cross and main is different. what it means then is that it will change the main/cross ratio. and as we know, main/cross ratio has a very big influence on the playability of the stringjob
    - pre-stretching reduces the effect. which is interesting as it means it is forcefully overcoming the friction before settling down on the actual tension. make sense, but it also might mean we are not getting the pre-stretch'ing which is one of the factor contributing to the reduce ERT reading.
    It looks like this would justify the "add 10% to cross strings" practice. Seems that by doing uniform tension on both main and cross strings, the cross strings will also end up with slightly less tightness thus making the tension "not scientifically uniform" anymore.

    However, a better way might be to just string the mains at the desired tension, and then the cross strings with pre-stretch on (not sure if 10% is enough or we really have to go all the way to 20%).

  8. #25
    Administrator kwun's Avatar
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    Quote Originally Posted by Blitzzards View Post
    It looks like this would justify the "add 10% to cross strings" practice. Seems that by doing uniform tension on both main and cross strings, the cross strings will also end up with slightly less tightness thus making the tension "not scientifically uniform" anymore.

    However, a better way might be to just string the mains at the desired tension, and then the cross strings with pre-stretch on (not sure if 10% is enough or we really have to go all the way to 20%).
    still not quite the same.

    as the result, while have similar tension on average, will have interleaving strings, one at higher than norm, the other one at lower than norm.

  9. #26
    Regular Member Blitzzards's Avatar
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    Quote Originally Posted by kwun View Post
    still not quite the same.

    as the result, while have similar tension on average, will have interleaving strings, one at higher than norm, the other one at lower than norm.
    That is true, but shall we not let "feel" be the best judge of all?

    I myself have been doing uniform tension, but at the same time having the "centre cross strings" (i.e. between bottom 5 and top 4/5) pre-stretched to 10% when stringing. Thus far this new tensioning practice of mine is giving me a little different "spark" in string feel compared to strictly uniform tension and uniform tension with all strings pre-stretched to 10%.
    Last edited by Blitzzards; 04-08-2013 at 02:13 PM.

  10. #27
    Administrator kwun's Avatar
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    Quote Originally Posted by Blitzzards View Post
    That is true, but shall we not let "feel" be the best judge of all?

    I myself have been doing uniform tension, but at the same time having the "centre cross strings" (i.e. between bottom 5 and top 4/5) pre-stretched to 10% when stringing. Thus far this new tensioning practice of mine is giving me a little different "spark" in string feel compared to strictly uniform tension and uniform tension with all strings pre-stretched to 10%.
    I do similarly for center strings (i add 10% tension instead of turning off pre-stretch)

    but that's quite different than alternate strings. i guess we need to try it out to see how it feels.

  11. #28
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    Quote Originally Posted by Alex82 View Post
    I had a short discussion at the weekend with a stringer which string on some small tournaments around here. He pulls two strings at a time (with a Pro's Pro Pilot) and he says, that he has tested this and this would not be noticeable. I remember how Kwun measured this a year ago, so I have copied his technique (sorry Kwun ) and tested this yesterday evening, this is the result:

    Name:  IMG_0185.jpg
Views: 310
Size:  35.9 KB

    Name:  IMG_0189.jpg
Views: 352
Size:  74.3 KB
    @Alex82 & @kwun
    I noticed that when you measured the tension on your electronic calibrators you have what looks like a PVC tubing tied on one end. Is this acting as a substitute to clamping the other end of the calibration unit?

    I'm also assuming that you just went to your local hardware store to buy the tube and hand cut it yourself? Can you give me the specific tube type if possible?

    Thanks. I find it rather ingenious.

  12. #29
    Administrator kwun's Avatar
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    Mine is a PVC tube from the hardware store. 2.5" outside diameter. 5" long. I used a hole saw to cut a hole as the string side opening.
    Attached Images Attached Images      

  13. #30
    Administrator kwun's Avatar
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    The tape is for protecting the frame. I used a few a layer of masking tape.

  14. #31
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    Quote Originally Posted by Alex82 View Post
    Pull on two strings at the mains with prestretch (20%) enabled:
    Name:  IMG_0186.jpg
Views: 316
Size:  46.9 KB

    Pull on two strings at the mains without prestretch but constantpull:
    Name:  IMG_0187.jpg
Views: 315
Size:  48.2 KB

    Pull on one string at the crosses with prestretch (20%) enabled:
    Name:  IMG_0189.jpg
Views: 352
Size:  74.3 KB

    Pull on one string at the crosses without prestretch but constantpull:
    Name:  IMG_0190.jpg
Views: 322
Size:  79.5 KB
    From this experiment, it seems that the final tension is higher if you use the prestretch function. From my other post http://www.badmintoncentral.com/foru...chine-with-ECP, I was trying to find out if the actual pulling tension from prestretch function is actually higher than constant pull tension.

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