For the dropweight, crank stringing machine

Discussion in 'Stringing Techniques / Stringing Machines' started by Ray_cn, Jun 20, 2012.

  1. Ray_cn

    Ray_cn New User

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    Maybe i get the point now. After the time, don't need re-horizon. I agree with that, if it is elongated not to much "hardly noticible". e.g. less than 10degree almost same. 60*cos(8)=59.4. And I agree with that it really depend on the stringer's good experience.

    Maybe I should discuss how to use a machine to get a accurate tension, not which one is more accurate, because the striger's experience is most important:oops:

     
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  2. Ray_cn

    Ray_cn New User

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    I didn't found any detail operation procedures for crank and dp from that pdf.

    That make me confused. If it has the operation procedures, others could repeat the operations. As you said, maybe the dp do the "re-horizon", but the crank didn't do the "re-pull". For manual machine, the operation procedures are very important.

    I learned some from these two sentences. The time control is just same as SwankPeRFection said. I think it is good experience. And the speed is just many electronic machines's function. So I think pulling slowly in crank is a method too. I do some learning start from these points.
    "Strings need between 3 and 10 seconds time to stretch when they are tensioned"
    "looses tension depending on the type of string and on the speed of
    pulling"

    Now I learned that
    Temperature and humidity, Tension, Time(same as speed) are important for elongation. (Stress relaxation,still learning). And confirmed in these discussion.

    I heard a story about famous tennis player put the racket into a plastic bag to maintain the humidity. But not sure it is real or not. If it is real, so that is string's hydroscopic property. Maybe it is a very old method when using catgut, not polyester fiber.


     
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  3. Ray_cn

    Ray_cn New User

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    Here, maybe he do the additional "re-horizon" operation after seconds. So for crank, it should do "re-pull" too. I think that is fair.

    And still don't know how.
    "tension is the same for every angle of the lever"
    [​IMG]
     
    #53
  4. Ray_cn

    Ray_cn New User

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    Maybe "Constant Pull" concept come from "Speed" control in electronic machine.

    I think if pulling with not constant tension, it can't be called "constant pull".

    So it is not a property of the dropweight, except it has "the quality that the tension is the same for every angle of the lever."

    Most dropweight is not constant pull because the tension is different with every angle although different is not noticable at small angle change, crank is not too.

    So to avoid the string elongation, dropweight and crank even the electronic should be operated with some good experience follow these. discussiong of you all.
     
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  5. SwankPeRFection

    SwankPeRFection Hall of Fame

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    Constant pull is constant pull Ray! If you tension a string with a tensioning head and then cut the string while the tensioning is still active, if the head of that tensioner then move/pulls away, the machine is a constant pull. Tying a rock to a rope and dangaling it IS constant pull. Pulling on a rope through a doorway and maintaining tension on it is constant pull because if I cut that rope, you'll fall backwards because you're still pulling on it. However, if I was to close a door on that rope so that the rope is stuck in the doorjam and causes it not to move anymore when you pull it, if I cut it, you won't move because you're still supported by the tension between you/rope/door, nothing beyond the door plane of reference matters anymore, so the cut on the other side of the door doesn't affect you. In this case, the closed door variable made this example/system no longer a constant pull.
     
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  6. Irvin

    Irvin G.O.A.T.

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    If there weren't two opposite pulling forces pulling on a string there would be no tension in the string.
     
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  7. Ray_cn

    Ray_cn New User

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    We always using "constant" as a never changed parameter.e.g. Constant Pi=3.1415926, or set some parameter as constant, Constant a=60. That mean the a is 60, and will never changed.

    Maybe my english is not good to distinguish the "constant" and "continually", just thought the constant pull must be continually pulled by a constant tension, as shown in that pdf. If only continually pull, that is just pull, but don't care the pulling tension, no matter increasing or decreasing.

    And pulling with a constant speed and a constant tension is better to control the elongation.

    Learned from sstchur "string relax at the same rate every time", that remind me if the relax rate is same for different tension( or just assume it is same), then pulling at different tension will get different relax time. So using a constant tension and constant speed for a constant relax rate, this is easy to control the relax time. If the tension is decreasing especially cos(a) not a linar decreasing, it will be complex, not easy to control the speed or the relax time.

    I think i understand the example you list. I think we are both agree if a string tensioned by a crank, then release the lock, the tension head will go toward to the racket, whether the string elongated or not, because the tension head is always pulling by the string.

    I think you just thought if cut the string, the crank will not go toward the racket because of the lock. We just thought the tension head only has a lock, no spring. Actually the lock is just pulling the string. If the lock is soft as a fishing rod, holding it then cut the fishing line, the rod will swing. The lock is same too, but the swing of the lock is hard to notice.

    And from the chart i drawed above, the spring is pulling, same as the gravity. Dropweight and crank are same lever system. One is tension by gravity and one is tensioned by gravity.

    Only if the spring loosing to the stopper, then the lock is still pulling. If the weight arm drop to the table, then what pulling? not the table, it is the ratchet inside the gripper.

    That's why i confused with that the "constant pull" only is in dropweight, not in crank.
    1. dropweight not pulling at a constant tension, the tension is descreasing.
    2. both dropweight and crank are always pulling the string.
    3. crank is pulling at a decreasing tension too by spring or the lock,
    4. from princple, they are same lever system, only the tension method is not same, and has stopper or not.

    All happend on dropweight should be happened on crank too.

    The different is the dropweight is easy to detect the elongation and descreased tension. but crank is not easy.

    I think we thought the dropweight has "constant pull" as electronic because we saw the weight arm is still dropping by gravity. But didn't notice the tension is descreaing although the descreasing is too small maybe not noticable. And crank's head is locked, but didn't notice the spring-arm-gripper-string is still working although it is hard to notice the elongation and tension lost. The ratchet and the lock will pulling if the weight arm drop to the stopper or -90degree, or the spring stopped by stopper.

    So I think we should forget the "constant pull" concept in dropweight, just let it be a electronic property "pulling string at a constant speed with a constant tension".

    The string elongation could be controlled by good experience stringer for dropweight or crank. e.g. waiting a time , re-horizon, re-pull, slowly pulling or more experience i learned from here.

     
    #57
  8. barry

    barry Hall of Fame

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    Intersting video on subject.

    http://www.youtube.com/watch?v=3aYI5DXQxSA

    He even measures the difference, and proves 2 pulls on a crank does equal constant pull.

    Also when you clamp off the string, CP is off, the clamp becomes the lockout.
     
    #58
  9. Ray_cn

    Ray_cn New User

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    Sorry, if the weight arm drop at -90 degree, it is 0, no pulling tension. If the degree is caused by the string elongation, the string current tension is 0 too. It will never happened, just a example for the confused concept "Constant pull" in dropweight.
     
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  10. diredesire

    diredesire Super Moderator

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    Thread cleaned. No need to call names/make things personal. Debate/discussion is encouraged in machines/techniques, but we generally keep it extremely civil here ;)
     
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  11. Woolybugger

    Woolybugger Rookie

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    industrial espionage,... just saying.....
     
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  12. fortun8son

    fortun8son Hall of Fame

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    An electronic machine, even at it's slowest setting, pulls way faster than one can do on a crank.
    I believe that if one pulls slowly(at least 3 sec) on a crank, it will equal what the auto tensioner does.
    Pulling twice on a crank will ensure a more CP tension, but is maybe not absolutely needed.
    The graph shows a 1sec pull.
     
    Last edited: Jun 29, 2012
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  13. Irvin

    Irvin G.O.A.T.

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    Surely you do not believe that.

    EDIT: There is a big difference between how fast you CAN turn the crank and how fast you SHOULD turn the crank.
     
    Last edited: Jun 29, 2012
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  14. diredesire

    diredesire Super Moderator

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    Definitely. I wonder how many low quality, terrible-speed electric tensioners fortun8son has used, too ;)
     
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  15. Irvin

    Irvin G.O.A.T.

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    I don't think there are many high speed electronic machines that string this fast.

    http://www.youtube.com/watch?v=xy8D72FqBV8

    But you could argue that you could hit the button and run in the next string while the tensioner is doing its work. Then move the clamp and tension the next while you are pulling the next string. I have tried this and it does not work for me because the turntable is held in one position when strings are tensioned. It may work for some though.

    EDIT: 'diredesire' I like posting right before or after you makes everyone wonder who copied who. LOL
     
    Last edited: Jun 29, 2012
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  16. fortun8son

    fortun8son Hall of Fame

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    I guess I did not express myself clearly.
    What I meant was that you can hand pull very slowly and allow the string to stretch gently before the lockout engages to minimize the tension loss after lockout.
    A slow electronic setting is still rather quick.
    Does that make sense, or am I still delusional? :)
     
    Last edited: Jun 29, 2012
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  17. Irvin

    Irvin G.O.A.T.

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    I would agree that pulling slowly would minimize tension loss but how do you repeat each pull? I would rather do a normal pull and pull again after say 10 seconds that is easier to replicate.
     
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  18. BigGriff

    BigGriff Semi-Pro

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    OK, so after all of this I have come to the conclusion that cranks, CP, and drop weight machines will have deviations in tension based on the settings. I wonder if there is a formula for the various inconsistencies in string. I am sure elongation will throughout the same piece of string.

    I good stringer will try his best to eliminate those factors as much as possible. As one poster said I wouldn't some of these mathematics and engineering wiz kids in here stringing my sticks.

    Reducing elongation and ruining a strings playability goes hand in hand. It is a fine line between the two.
     
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  19. diredesire

    diredesire Super Moderator

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    Actually I don't think a "good" stringer has to account for deviations. This is probably a slightly controversial statement if taken out of context of the stringing ecosystem as a whole. What we agree on is that there are differences based on "settings" (machine, pull speed, etc). Sure, no problem. The mantra you hear experienced stringers harp on over and over is simply: consistency. If you have two stringers that do their thing consistently, one on a crank, one on a CP, you'll have some sort of "offset" in "tension" (SBS and string bed feel are separate discussions).

    If you have consistency, the player can make simple adjustments to move between stringers.

    The discussion here is trending to be more about best methods to match a crank vs. CP, but I don't personally give a second pull when stringing on a crank. This isn't because I'm lazy, it's because I don't intend to replicate CP. There are several players who prefer the "feel" of a lockout bed, and I don't think it's as simple as the age-old rule of thumb of 10% +/-.

    However, if I were stringing on a crank, and I was trying to replicate a CP bed (on request), I'd probably spend more energy doing so (with methods mentioned above).

    ;) You and me both, buddy.

    I've tried cutting time by prelacing, etc as well. I actually think it reduces the consistency, at least for me, as the time I spend with the tensioner pulling varies depending on how much i'm struggling with the lacing.
     
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