Why Do You Crank More Than Once?

Discussion in 'Badminton Stringing Techniques & Tools' started by Exert, Jul 4, 2015.

  1. Exert

    Exert Regular Member

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    Hello BC, I was wondering why do people crank more than once on a crank machine? I am not to sure why, But I have been doing it. My friend has been doing one crank so far and has been getting consistent results as well. What is the purpose of pulling more than once? Is it good to pre stretch and still pull the string more than once? Thank you

    -Exert
     
  2. Randomlegend

    Randomlegend Regular Member

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    Well as far as I understand, it's because after the crank locks out from the first pull, the string will stretch or give a bit. Therefore you lose a bit of tension (I have no idea how much in reality, I imagine one of the more experienced stringers might know a bit more on that).

    Pulling a second time ensures the tension on that string is actually what you were aiming for - or at least closer to it - before you clamp and move on.

    If you've pre-stretched the string, you should have got rid of some/most of that give by my reckoning. Logically, to me, pulling a second time would therefore be less important. Again though, one of the more experienced stringers will give you a better answer on that.
     
  3. Mark A

    Mark A Regular Member

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    It's to compensate for sagging (but a doorknob prestretch will do the same and save a lot of time).

    Stretch a piece of chewing gum out and then lock your hands in place - the gum will droop. This happens to strings with a crank machine.
     
  4. Randomlegend

    Randomlegend Regular Member

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    So if you've done a pre-stretch then it's not worth double-pulling, essentially?

    When you do a 'doorknob prestretch' do you just loop it round, wrap the ends round something and pull? How much welly do you give it? Would you lean back on it or is that too much?

    I've had a go but I'm always really wary. I think I probably go too soft on it.
     
  5. Mark A

    Mark A Regular Member

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    IME, no; the doorknob stretch will take everything out that double-pull would. In one tenth of the time.

    Basically, yes. Wrap it around something round, with as big a diameter as possible. You can really go for it - in all my string jobs I have never broken a string by pre-stretching it, and I'm a monster:).
     
  6. emjay

    emjay Regular Member

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  7. Mark A

    Mark A Regular Member

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    The very best way to see the effect is to use a digital scale. Pull it to lock and watch that poundage tumble:D.
     
  8. R20190

    R20190 Regular Member

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    I'm always surprised at how much the strings stretch. I literally wrap it around an old racquet handle and lean all the way back - like I'm waterskiing! lol

    Exert, I only tend to double crank when I think the tension could have been reduced by an obstruction or something loosening. For example at the start when you pull the first two mains against the fixed clamps. Or at the outtermost mains where it is difficult to clamps close to the frame.
     
  9. Randomlegend

    Randomlegend Regular Member

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    Do you guys not worry about over-stretching the string?
     
  10. R20190

    R20190 Regular Member

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    In a way, you actually want to overstretch it - without breaking it of course. Generally most strings stretch about 1 foot (some a bit more) when doubled up around something that doesn't cut into it - a large door nob or a bannister end post.
     
  11. Mark A

    Mark A Regular Member

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    There's no real way to do this unless you break it:). Strings do have an elastic limit, as it were, but you're never going to get near it pulling all 10 m by hand.

    I also waterski with mine... a bit, and I'm a 13-stone blob. Never broken one, and they all go in at 32/33 (with another prestretch from the machine) with no issues.
     
  12. Randomlegend

    Randomlegend Regular Member

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    I've definitely been being too gentle.
     
  13. FeatherBlaster

    FeatherBlaster Regular Member

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    The speed of which you turn the crack also influence the amount of tension loss.

    If you use a digital scale to see the tension loss after lockout, you'll notice a curve that flattens out. IE the tension loss is at it's most at the very beginning.

    I reckon that if you turn your crank fast until lockout, you'll loose more tension, rather than if you turn the crack slowly when getting near the lockout.

    But for all this tension loss and crank turning speed, etc. one thing overshadows everything else: Consistency is the most important thing. It doesn't really matter if you loose 1lb with whatever method you use, if you just make sure that you loose that 1lb consistent - you simply calibrate towards that loss, or adjust your tension setting accordingly.

    So - all in all - make sure to always turn the crank approx. the same speed.

    ----

    Another thing, which I haven't tested yet: I would guess that different strings have different tension loss curves. I'v recently started stringing BG66-Force which is the first .65 Yonex string I've used. Other strings I've been stringing with so far are BG80, BG80P, BG65Ti and some Ashaway strings (.70 and .67).

    I think that the BG66F is more elastic - it feels so. Which is why I would guess that tension loss from a lock-out system compared to a constant pull system is bigger for this string, than it is for the harder thicker strings.

    Any opinions on this?
     
  14. Exert

    Exert Regular Member

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    Regardless of this thread now, I'm pulling the string once rather than 2-3 times & still getting good results and a tight string bed.
     
  15. visor

    visor Regular Member

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    [MENTION=11783]Mark A[/MENTION]

    Lol... waterski?! You're yanking that hard leaning backwards?!

    Btw how much extra length are you getting when you do this prestretch by hand with your various strings?

    When I used to use VS850, I think max I got was 10 inches.
     

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