constant pull vs crank

Discussion in 'Stringing Techniques / Stringing Machines' started by rscottdds, May 15, 2008.

  1. rscottdds

    rscottdds Rookie

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    Are constant pull machines better than cranks as far as racquet playability is concerned? I know consistency is the name of the game, and if you can string a racquet the same every time it doesn't mater what kind of a machine you use. However it would seem easier to get a consistent string bed with a constant pull machine. Is this true? And if so does it really matter? Can the above average player tell the difference as far as playability is concerned if you indeed get a more consistent string bed?
    -Robert
     
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  2. YULitle

    YULitle Hall of Fame

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    Consistency comes from the stringer first and foremost.
     
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  3. rscottdds

    rscottdds Rookie

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    And I realize this. However I have a very accurate measuring devise and when I pull with a lockout machine, I can get differences with each pull. I assume with a CP machine these differences would be minimized. Does this translate to a difference on the court for a college level player and above? I'm wondering if it is worth it to change to a CP machine (ie buy something like a wise)
    -Robert
     
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  4. YULitle

    YULitle Hall of Fame

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    Care to document those differences? It would help me get an idea of what you are expecting from an electric-CP as far as consistency goes. Accuracy is in the eye of the beholder afterall.
     
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  5. MAX PLY

    MAX PLY Hall of Fame

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    Interesting. I have two calibration devices--one the "normal" cylindrical and a Prince digital--they are both generally spot on and I have not incurred the phenomonon you describe on my Neos. What sort of string are you using in the calibrator? Are you testing at different distances from the clamped device?
     
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  6. wumanchu23

    wumanchu23 New User

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    I hear the term "calibrate" alot when it comes to crank machines. I think someone said it takes very little time, and they don't calibrate it unless they moved the machine or felt like theres a need to do it. I'm kind of new to this, what tools are required when it comes to calibration. Does the machine have to be brought to a shop?
     
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  7. YULitle

    YULitle Hall of Fame

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    It just takes a calibrator (which tests the tension actually being pulled) and the appropriate hex wrenches (or other tools) required by the machine. Most machines can be calibrated at home.
     
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  8. MAX PLY

    MAX PLY Hall of Fame

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    Basically you will need a tension calibrator (available from TW) and what ever tools are required to adjust your crank mechanism (should detail in your machine manual). The details vary from machine to machine but essentially the calibrator has string on each end. One end goes in your clamps (the tray will need to be stationary (i.e., brake on)) the other end fits in your tension head (just like pulling tension while stringing a racquet). You want to verify that the calibrator and your reference tension are in synch--if not, adjust your tension head appropriately. You should be able to do this yourself. Hopefully, your machine manual details the specifics for your machine. Good luck.
     
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  9. fastdunn

    fastdunn Legend

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    in strining process, there are many variables you want to try to be consistent about.
    constant pull just keep one variable(pretty important one) at constant.
    you still need to make other variables constant, like the time between pulling and clamping off.
     
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  10. SW Stringer

    SW Stringer Semi-Pro

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    Published accuracy on the Wise is plus or minus half a pound, on the Babolat's its plus minus 100 grams. However it's been noted on the GSS site that many of the electric/electronic tension heads overshoot by quite a bit (up to 5 lbs), but the Bab's appear to be critically damped and don't overshoot by much. If your electronic measuring device can't capture peak pulling tension then you may not even see it - I don't think even the $40 fish scale that GSS sells can "capture" quick transients. That (transient capture) requires a fast acting lab grade transducer/controller. And certainly the spring based tension checkers are neither accurate (compared to the resolution of the digital units) nor able to show transients. But YU is correct, accuracy is in the heholder's eye.
     
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  11. YULitle

    YULitle Hall of Fame

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    I wanted to slarify what SW Stringer said, when the Babolats overshoots the tension, it settles back on the correct tension immediately after.
     
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  12. barry

    barry Hall of Fame

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    So what is the difference between overshoot and pre-stretch? On my machine, when pre-set is on, the tension goes to the percent of pre-stretch + tension, then settle back to the tension. If you turn pre-stretch off, then it pulls and holds the desired tension.
    On my drop weight machine, it pulls and holds the desired tension. The crank varies by as much as 5 pounds, depending how fast you turn the crank. If you crank it slowly, it is within 1 to 2 pounds of the tension.

    Drop weights are by far the most accurate tensioner.
     
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  13. YULitle

    YULitle Hall of Fame

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    The difference, I would guess, is intention. The overshooting of tension is not a desired trait, for some stringers.
     
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  14. SW Stringer

    SW Stringer Semi-Pro

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    I agree, dw's are the most accurate and if used gently will NEVER overshoot. On the electric/electronic CP's every time it repulls it will overshoot some or alot (depending on the model) so if you're clamping off when it's at 5 lbs overtension - that's what you get - so how do you know what the tension is when you clamp off? Ans. you don't - it could be anywhere from REF Tension minus the repull hysteresis to the REF tension plus the overshoot - and that could be a 5.5 pound or more range. Again the repull trigger point and overshoot amount depend on the machine and the manufacturer - and most likely not even published. The user has no say in this matter. At least with the DW's and cranks the user is in direct control of the clamp-off tension.
     
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  15. rjkardo

    rjkardo Rookie

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    To answer your first question... no.

    2nd question... No. And it does not matter anyway.

    Last question...No.

    Rodjk #613
     
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  16. abllee2198

    abllee2198 Rookie

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    rscottdds: The best answer is, "It depends." It depends on the constant pull, it depends on the crank, and most of all it depends on the stringer.

    So if you'd like to be more specific, then perhaps you will get a better answer. So, which crank and which constant pull?

    Albert
     
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  17. fastdunn

    fastdunn Legend

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    I agree dropweight is just about the most accurate in terms of tension itself but sometimes I do single pull, sometimes double or even triple pull where main inconsistency of drop weight stems from, IMHO.
     
    Last edited: May 19, 2008
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  18. rscottdds

    rscottdds Rookie

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    Oops, I forgot I even posted this question :). The crank is on a Gamma 5003 and the CP I was talking about was the Wise. When I use the lock-out and the digital scale I can pull a few lbs different on each pull, and it drops by a quarter or half a pound every few seconds until it levels out.

    I've seen video of a digital scale on a Wise and it pulls then stays very consistent (ie the tension doesn't drop). So my questions were if this tension difference really matters and if so would getting a Wise help? I understand that if I use a lock-out and it locks out at a certain value then starts to drop by a consistent amount, then if I clamp at the same time after lockout every time then I should get a consistent result. It would just seem that if you take away as many variables as possible that you would get better results.

    Wow, I just reread what I wrote. Hope it’s understandable :)

    -Robert
     
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  19. LttlElvis

    LttlElvis Professional

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    Robert,

    I am not sure if I am answering your questions but I think I have about as close a situation to what you want. I have a Gamma 6004 and a Wise. I can tell the difference in the sound of the string bed and feel of my racquets when I use a crank. I used to tend to have a favorite racquet.

    When I switched to the Wise, the sound of the string bed and feel of my racquets are identical. No more favorite racquets, and I just use them on a daily rotation to get even wear ( I use gut). By the way, I am a dentist too, so I am very anal about every little thing. The best thing about the Wise is the consistency.
     
    Last edited: May 19, 2008
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  20. jim e

    jim e Hall of Fame

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    Hi LittlElvis: I use a constant pull machine as well,(not the wise), just to have more consistancy in the process.Three of my racquets are all gut, and feel the same,(4th gets changed a little to try out different strings).BTW I am a dentist too.(Ohio State, 1980).I am not a string breaker,and got a great # of hours out of 1 racquet, now like you I rotate between them so they all feel the same.Seems that consistancy is the name of the game, and although it is said you can get consistant results with both, I believe it is easier accomplished with a constant pull.
     
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  21. rscottdds

    rscottdds Rookie

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    Thanks guys. That's the exact kind of information I was looking for. Maybe it's the dentist in me looking for perfection (UOP 83) but it just seems that a constant pull machine would lead to a higher degree of consistancy.
    -Robert
     
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  22. ryohazuki222

    ryohazuki222 Semi-Pro

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    can anyone chime in on the effects of tension maintenance between these two scenarios? A friend of mine keeps telling me that the tension drops so fast on my stringjobs because im not stringing with a constant pull machine. If I strung a racket on my revo 4k crank and then the exact same way on a revo 4k wise with constant pull.... will the tension maintenance of the string job vary at all? ... how so?
     
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  23. Mansewerz

    Mansewerz Legend

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    Do electric machines need to be calibrated?
     
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  24. dancraig

    dancraig Hall of Fame

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    The constant pull feature will take some of the "creep" out of the string. This will help with tension maintenance. A pre-stretch will have a similar effect on tension stability.
     
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  25. jim e

    jim e Hall of Fame

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    My machine is electronic digital electronic processer, when I placed a calibrator on it, it was right on. They can be adjusted as they have potentiometers to adjust for it, but I heard that they don't need adjusting much, as they are self calibrating, the tension head moves twice on start up, setting up machine, which self calibrates.
     
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  26. SW Stringer

    SW Stringer Semi-Pro

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    You can regain consistency by keeping the "time under tension" a constant between single, double, and triple pull situations. Depending on the frame I can usually do 60% to 80% single pulls, the rest doubles. On my single pulls I wait an extra couple of internal counts before clamping off to equalize the time under tension with the longer double pulls. What I'm trying to do is equalize the amount of stretch per pull so that the ending string diameters are the same between single and double pulls.

    The essence of the difference between the CP machines and Lockout is the ending diameter of the string. Both tension the string to the reference tension but the CP's keep pulling until you clamp off and you end up with a thinner string at reference tension. Net result is a higher SBS number. Which is better? Neither, just different. A good stringer should be able to produce a given SBS number for a particular racquet regardless of the machine type.
     
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  27. LttlElvis

    LttlElvis Professional

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    rscottdds,

    Where are you located? If you are in the Houston area, you are welcome to borrow my Wise on your machine. Try it on a couple of racquets and you will immediately hear the same stringbed sound on identical racquets. (BTW, San Antonio '91)
     
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  28. rscottdds

    rscottdds Rookie

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    Thanks for the offer but I'm in California. I'm thinking we'll be rooting for different basketball teams these next few weeks :).

    Did you lose 360 rotation with the Wise? And did you need an adaptor to fit it on the Gamma, and if so what does the adaptor do?

    -Robert
     
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  29. kmartin

    kmartin New User

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    I emailed **********.com that same question about the 360 rotation. Herb emailed the following response:

    "We designed the 2086 so that it does NOT allow for a complete 360 degee rotation.
    And it doesnt seem to bother anyone.
    We want the gripper and the string bed to be totally level so that there is no
    angle in pulling string (up or down)"
     
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  30. Zhou

    Zhou Hall of Fame

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    I believe you would lose 360 if you added a wise and the adaptor raises the height of the Wise to pull linearly.

    If I remember right, all Gammas require adaptors.

    Ha, he beat me to it by less than 1 minute.
     
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  31. YULitle

    YULitle Hall of Fame

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    This is unavoidable with a non-adjustable tension head. The string plane is at different heights, relative to a static tension head, depending on the cross-sectional width of the racquet.
     
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  32. fastdunn

    fastdunn Legend

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    I personally feel like dropweight gives me somewhat pre-stretched feel and crank machine gives me tad hollow feel.

    No scientific data to support it. :) I just feel like it. It could be all in my mind. No major concern. Both produce very playable string-bed.

    This is after I add a few pounds (on crank) to the reference tension I use for drop-weight.
     
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  33. LttlElvis

    LttlElvis Professional

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    Robert,

    No. I did not lose 360 rotation with the Wise. The Gamma has an extra long track so I mounted it far from the table to where the gripper just clears the racquet handle.

    You do need an adaptor ($45). It raises the Wise unit about 3 inches. I see no way around not having it. It would pull in too much of a downward angle. All the other cranks must be made to similar heights to the racquets. I guess Gamma cranks are made a little taller, thus a lower track.

    Do a search. I posted pics of my machine and adaptor.

    Spurs over Lakers 4 - 2.

    On a dental note: Cerec machines suck. I would have had more satisfaction buying a brand new Porsche 911 S, and driving it off a cliff.
     
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  34. rscottdds

    rscottdds Rookie

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    I would have to respectively disagree ............. on the Spurs over Lakers that is :)
    -Robert
     
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  35. kmartin

    kmartin New User

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    That makes the Gamma's a little more appealing. What model do you have? Any idea if all their cranks have longer tension arms like yours?
     
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  36. jim e

    jim e Hall of Fame

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    Nice to know that. I work with one of my brothers, and he was going to look into a cerec to see if it would really be a payback, after saving on lab bills. Thanks for input! Jim
     
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  37. LttlElvis

    LttlElvis Professional

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    Robert and Jim,

    Yeah, I think I am one of the few to speak openly about my experience with it. Patterson acted like I was the only person who was ever dissatisfied with it. Email me sometime and we can discuss in detail. LttlElvis@aol.com

    Back to pics of my machine with a Wise:

    http://tt.tennis-warehouse.com/showthread.php?t=198939
     
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  38. rscottdds

    rscottdds Rookie

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    Thanks for the picts. It's nice to know you can still have 360 rotation if you want it.
    -Robert
    PS Good thing for me the Lakers had Kobe last night
     
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  39. LttlElvis

    LttlElvis Professional

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    Robert,

    No problem on the pics. I'll post pics of game 6 when the Spurs win the series over the Lakers.
     
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  40. rscottdds

    rscottdds Rookie

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    You're supposed to use a :) when saying something in jest.
    -Robert
     
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  41. ryohazuki222

    ryohazuki222 Semi-Pro

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    quoting myself....

    anyone have any input?
     
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  42. TenniseaWilliams

    TenniseaWilliams Professional

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    There longer the string is kept at reference tension during stringing, the flatter the tension drop curve over time will be. Depending upon string type, the curve is noticeably steeper in the first 10-30 seconds, is still fairly steep until about the 10 minute mark, then flattens out. The majority of the non-impact elongation occurs in the first 30 hours.

    The curve is also similarly effected by pre-stretching. Note that most poly strings are adversely effected by pre-stretch, so the constant pull may not be "better" than a lockout, but will show less tension loss over time proportional to the amount of time left on the tensioning head before clamping.
     
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  43. barry

    barry Hall of Fame

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    Something to think about. Doesn’t the clamp act as a lockout once the referenced tension is reached? So is there really such a thing as constant pull or is it all marketing term.
     
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  44. MAX PLY

    MAX PLY Hall of Fame

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    You are right about the clamp. However, lockout and constant pull are different--the "constant pull" machine will continue to make adjustments during that two seconds or so it takes to clamp the string--a measurable but perhaps not meaningful difference. As had been said many times on this forum, the key is consistency, irrespective of the type of machine used. And, after all , all we are discussing here is a reference tension. I personally use a Neos (a lockout) and string my racquets at the same reference tension, the same way (e.g., keeping the distance between the tension head and the frame approx. the same from pull to pull and from job to job, weave the same way, pretty much the same time between lockout and clamping, etc.). Stringing the same racquets on a constant pull may require a small adjustment in reference tension (to match what the Neos produces in my example) but again the key is consistency.

    Is there a difference? Yes. Is it a marketing term? Yes (but that is not meant to be pejorative) Should it make a difference in the final string job? In the hands of a qualified stringer, No.
     
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  45. TenniseaWilliams

    TenniseaWilliams Professional

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    I agree that if it was possible to clamp immediately after tensioning, there would be no difference between a lockout and a constant pull. But I feel there is a significant difference, good or bad. the USRSA recommends an adjustment of almost 10% pulling tension to get the same approximate results between the two machines. And there is a difference in final tension and string diameter on a constant pull clamping at 2 seconds vs 10 seconds.

    I like Max Ply's notion of keeping the distance between the frame and tension head consistent, but I think the lockout machine mitigates most of the "time to clamp" issue, which can make it very consistent. A good analogy might be an automatic transmission vs a manual.

    I like having the control the constant pull gives me, although the potential for inconsistency seems higher. Natural gut and other strings that tend to display high initial elongation I leave tensioning longer before I clamp; poly I try to clamp as quickly as I think I can do consistently.
     
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