Different tensions with poly makes no difference

Discussion in 'Strings' started by DonDiego, Apr 12, 2013.

  1. BreakPoint

    BreakPoint Bionic Poster

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    OK, let's think of it this way. Assuming you guys are correct, let's say you want a tension of 50lbs.

    We'll start with a poly string. You set the dropweight at 50lbs and start the arm at horizontal. You wrap the poly string around the gripper with no slack and allow the weight to drop. The weight doesn't budge (does not drop at all). So the tension on the string is supposedly at 50lbs. already, right?

    Now do exactly the same thing with an elastic multi. You start the arm at horizontal. In the split second after you allow the weight to drop, the tension should already be at 50lbs since the arm started at horizontal and there was no slack in the string, right? Then the weight drops well below horizontal all the while pulling on the string and applying more tension. You rachet the gripper well above horizontal and allow the weight to drop again, all the while pulling on the string more and applying even more tension. Since the weight dropped below horizontal again, you rachet the gripper once more and repeat. This time the weight settles at horizontal on its own after pulling on the string even more and applying even more tension. So if the tension on the string was at 50lbs initially since the arm started at horizontal, the tension now after several rachets and all the additional pulling on the string which applies more tension, the resultant tension should be much higher than 50lbs., right? More like 70lbs.?

    So if the physics dictate that starting the arm at horizontal already applies 50lbs. of tension to the string, why does that only work for polys and not for multis?
     
    #51
  2. jgrushing

    jgrushing Rookie

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    Okay, I give up after this. In the poly example, 50 lbs. of tension is being applied and the string is not stretching or elongating. With a multi with the arm at horizontal, 50 lbs. of tension is being exerted and is stretching the string. As the arm falls below (or above) horizontal, less than the target tension is being applied. You adjust the slack to get the arm back to horizontal, at which time the target tension is achieved. With strings with high elasticity, this may take a couple of adjustments as the string elongates. With poly, which is not elastic as all, the bar probably won't move at all if the correct amount of slack is allowed.

    On of your mistakes here is to think that the bar going beyond horizontal means more tension is being applied. Actually, short of or beyond horizontal is less than the target tension. I would suggest studying the sticky thread on the physics of dropweight stringers.
     
    #52
  3. danotje

    danotje Rookie

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    #53
  4. BreakPoint

    BreakPoint Bionic Poster

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    I understand the physics behind dropweight stringers, but it still doesn't make intuitive sense with the difference between stringing a poly versus a multi.

    According to the discussion above, both a poly and a multi start at a tension of 50lbs. if given no slack and the arm starts at horizontal. But with a multi, as you physically pull on the string more (by the weight dropping below horizontal), the tension drops below 50lbs.? So the tighter you pull the string, the more the tension drops?
     
    #54
  5. jgrushing

    jgrushing Rookie

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    No you don't understand drop weights. The rotation of the gripper or cam has nothing to do with how much or little tension is being applied. The target tension is being applied when the bar is resting at horizontal. If resting above or below horizontal, less than the target is being applied. Going past horizontal is not, I repeat not, pulling more tension. Going past horizontal means that there was either too much slack or that the string is stretching.
     
    #55
  6. tlm

    tlm Legend

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    I agree this is pretty basic stuff when it comes to stringing with a drop weight machine. Even with poly I usually have to make a couple of adjustments to get the bar level, But not near as much as multi's or nat. gut.

    I don't understand what BP is trying to say here. I do know that when stringing kevlar there is no stretch, you have to be careful to have enough slack otherwise the bar will not drop near level.
     
    #56
  7. BMWprestigem3

    BMWprestigem3 New User

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    I strung my racquets at 48 lbs and then tried 46 lbs. At 46 lbs I didn't like the feeling, I had to much pop. Then I tried 48 lbs on the mains and 46 lbs on the crosses (my current setup) and I love it.

    So to answer the question, I felt the difference from 48 lbs to 46 lbs.

    Usually you string poly at low tension so not to hurt your harm. I tried poly from 55 to 46 and my arm never felt sore. But at 50 lbs and up it was used with natural gut, which is must liking why my arm never hurt.
     
    Last edited: Apr 15, 2013
    #57
  8. Muppet

    Muppet Hall of Fame

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    The multi doesn't start at 50 lbs. Multis need to stretch a lot more to reach the desired tension. It's easier to tension poly on the first try because it doesn't stretch much. It's not the initial tension of the string that counts. It's the final tension with the arm at vertical. That's what counts. That the arm is at vertical. If you're a lucky guesser, maybe you can get the bar to rest at horizontal on the first pull, but probably not with multi. Forget about the amount of slack or the initial position of the tensioning arm. For correct tension, all that counts is the arm is resting horizonally when it comes to rest. Multi takes more effort to come to rest than poly.

    I hope that's enough, but probably not.
     
    #58
  9. MikeHitsHard93

    MikeHitsHard93 Hall of Fame

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    Exactly my experience. The last string job I did was cyclone and it was way too stiff to go even past the halfway mark. So, I just held it there after stretching it a bit and it ended up at like 50 lbs after I was done. I'm just wondering how you guys measure your string beforehand in order to compensate for the starting at horizontal.

    BP, basically if the arm is above horizontal or below horizontal, it is closer to the racket and that's why less tension is being applied. Being at horizontal makes the string basically farther away from the point of contact on the racket. If you wanted to string at say, 30 lbs, you would have to have much less slack.

    I hope that's what they're trying to say anyway, because that's what I got out of it
     
    Last edited: Apr 16, 2013
    #59
  10. spinovic

    spinovic Hall of Fame

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    I've had no trouble stringing polys.

    You do what is necessary to get the drop weight horizontal. It really is that simple. If it is horizontal immediately, on the first try, that's great. If you don't have enough slack and have to release tension and re-tension, that's not a problem. If there's too much, crank it back and drop it again.

    The biggest difference, for me, when stringing polys are the knots. Their stiffness makes manipulating the strings and tying knots a little more difficult than a synthetic gut. My experience anyway.
     
    #60
  11. MikeHitsHard93

    MikeHitsHard93 Hall of Fame

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    For me, it's weaving and getting them through some tight spots where the mains and crosses are very close
     
    #61
  12. anubis

    anubis Hall of Fame

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    If you don't know how to string poly with a drop weight then you probably shouldn't be stringing poly to begin with. You're likely to cause more damage to your racquet.

    If poly is too difficult for you to string, then keep stringing with syn gut until you figure it out. It's definitely harder to string poly with a drop weight, it takes finesse, trial/error and a very in-depth understanding of all the idiosyncrasies of your machine. Once syn gut is crazy easy and you've string both stiff strings and soft strings, then perhaps try poly again.

    As to tensions, My wrist can't handle poly over 52 lbs, so that's where I keep it. Whether or not it plays perfectly for me, I wouldn't know, as I've never tried high-tension poly.

    i string multis between 54 and 56 lbs, and poly @ 50 currently. I get way more control and spin with poly than I do multi. If i'm lazy and don't quite have an as aggressive enough WW finish to my forehand, with poly the ball usually lands in. If I'm on multi, I have to do this crazy WW finish otherwise the ball sails long.

    In other words, with multi, it's not applying hardly any spin on the ball -- I have to do all the work. With poly, it's sort of meeting me half way.

    FWIW, i've tried poly @ 40 lbs and it was just way too low. No control, no spin, total trampoline.
     
    #62
  13. MikeHitsHard93

    MikeHitsHard93 Hall of Fame

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    ...I'm not gonna string poly just because I don't know everything about it. I won't learn unless I try it. Idgaf if I do a little damage to my racket because its in kinda bad shape anyway. And you're not the all-knowing guru of the stringing world so please don't act like it... I appreciate criticism but not THAT much.
     
    #63
  14. roman40

    roman40 Rookie

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    My first string jobs were with poly, using a drop weight machine. It took me a while to figure out all the details, but the actual stringing was straightforward and easy. I don't know what all the fuss is about. It's not any harder than stringing syn-gut or multi. Obvious no-no is pushing on the weight arm from top, just hold it on the bottom and get it into a horizontal position (however you have to do it, given your machine, pretty easy if you have a ratcheting arm).
     
    #64
  15. tlm

    tlm Legend

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    Poly is not difficult to string with, actually it is faster because you don't have to keep ratcheting the arm to get the string to stretch out like you have to with multi's.
     
    #65
  16. spinovic

    spinovic Hall of Fame

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    And because the stringbed gets tighter with every string you tension, weaving gets tougher and tougher as you near the finish line. I wouldn't say I've had trouble, but my fingertips are a little sore afterwards.

    Definitely a big difference between the first cross and 14th cross.

    I did a little better with my knots when I strung the cyclone, but it seemed a little softer than the Gamma Poly Z.

    Thus far, I've strung Gamma TNT 2 in a 16x20 pattern, Gamma Poly Z in an 18x20 pattern and Volkl Cyclone in a 16x19. I would say the TNT was definitely easier for the knots, but there wasn't a huge difference in weaving process to me. Also, the Cyclone was a 2-piece job, the other two were one-piece.
     
    Last edited: Apr 16, 2013
    #66
  17. Muppet

    Muppet Hall of Fame

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    Stringing poly is sooo hard on my fingers. I used to have to bandage them up, after having trouble with slits, tears, and sawing through the skin. Then I found a pair of soccer (American football) goalie gloves that I use, especially on shaped poly strings. Comparing to synthetic gut (especially Spiral Flex) the sg is pliable, weaves very easily, and doesn't hurt my fingers.

    But if you want to use poly, I'd jump right in and learn through experience. If you have a less valuable frame, I'd practice with that one. Also, what's great for practice is an inexpensive reel of Forten Nylon. But I found that the black color bleeds onto my clamps and gripper and I had to clean the machine every time. Get natural.
     
    #67
  18. Big_Dangerous

    Big_Dangerous Legend

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    Yeah weaving takes forever. And then my last cross tie off is always in a pretty right spot.
     
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