***Stringway Machine Users Club***

Discussion in 'Stringing Techniques / Stringing Machines' started by 10SDad, Apr 19, 2013.

  1. OccasionalStringer

    OccasionalStringer New User

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    If the tension head makes angle A with the vertical line and string coming to tensioner makes angle Bh with horizontal then the length of lever which the string uses create rotational torque around pivot point is b * cos (A - Bh) * Tf

    When the string comes exactly perpendicular to tension head Torque is directly b* Tf , where Tf is string tension (=pulling force)

    When the tension head is at angle A relative to vertical and string comes perpendicular to the tension head the equation to calculate Bh (=string angle to horizontal line )

    (90-A) + 90 + Bh =180

    Which gives

    Bh = 180 - (90-A) -90 = A

    If you now use this value in b*Cos(A-Bh) * Tf, you get b * Cos (A - A ) * Tf = b * cos (0) * Tf = b * Tf as it should be
     
  2. TennisCJC

    TennisCJC Legend

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    I am not even going to read the posts with the heavy math as I would not understand them. For me, I get the bar close to parallel give or take a bit and the tension is damn good. Also, I have 2 action clamps and the pull back is not an issue as the next pull tends to correct any pull back. All in all, I think the quality of string job on these machines is as good or better than the local tennis shop that uses the $5K electronic space age machine.

    If you are considering buying 1 of these machines, you don't need to worry about accuracy as it is damn good and pull back is not a worry either. The next pull takes out any pull back slack. If anything, these machines tend to string a bit crisp due to the true constant pull.
     
  3. volusiano

    volusiano Hall of Fame

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    Is it possible if you could post some drawing to help explain this math? Especially where where Bh is exactly as defined by you relative to everything else.

    A picture is worth a thousand words, so without the picture, it's almost impossible to follow what you're trying to explain here.

    Similar to why it's hard for me and Jacklondon00 to understand Fred Trimmer's explanations when he used just words-> no way to visualize what he's talking about.

    Thanks.
     
    Last edited: Feb 4, 2015
  4. duffman

    duffman Rookie

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    I for one have always felt that my racquets were spot on when stringing on my stringway ml 100. I also verify with using racquet tune.

    I do have a question about the clamps however. One of my double action clamps is feeling loose at the base. When I engage the lever it takes very little resistance. Is there a way to tighten this up at the base?
     
  5. OccasionalStringer

    OccasionalStringer New User

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    I tore my right shoulder rotator cuff quite badly last summer (playing tennis of course) and had just a month ago rotator cuff reconstruction surgery. My right hand is still in a sling for 3 more weeks and thus non functional (hope I can get back to tennis and golf late summer this year)

    But using my left hand I was able to outline this simple drawing. Takes a lot of time with left hand but I have plenty of time to kill right now.



    [​IMG]
     
  6. Irvin

    Irvin G.O.A.T.

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    The turntable on the Concorde models doesn't spin level. The handle is up in the air so the when you pull tension from the bottom of the racket the string is angled downward to the gripper and when you're pulled from the top the string is angled upward to the gripper. So unless you install and remove you book each time you string a main the tension will be off on every other string. When you're stringing the crosses the angle (of the string going into the gripper) slowly increases downward from the top to the bottom of the racket.

    But I don't have a Stringway am I incorrect?
     
  7. lew750

    lew750 Rookie

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    It would be interesting if someone were to test the tension loss using the Concord System compared to pulling over the frame without it.
     
  8. OccasionalStringer

    OccasionalStringer New User

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    I do not have concorde in ML100 but it tilts the racket only when the racket handle is towards tension head.

    Looking at the picture of the concorde the string seems to come at about - 8 degree angle from low to high. This angle is slightly affected by the angle of the tension head but not that much.

    So we if we assume that tension head is otherwise perfect (=perpendicular to weight bar) then when the bar is at level (A=0) the error factor caused by this angle is cos(0)/cos ( 8 ) = 1,0098 i.e pulling tension is 1 % higher.

    When the bar angle is 20 degrees then the error factor is cos(20)/cos(20 - ( -8 )) = cos( 20 ) / cos ( 28 ) ) = 1,064 i.e. pulling tension is 6,4 % over intended reference but on the other hand this fights against the grommet friction.

    I do not think that there is that much benefit concernig pulling accuracy from concorde. If you take the string going over the throat there is some friction loss but on the other hand going over the throat changes string angle the way that it increases pull tension which compensates the friction losses. It might even overcompensate the friction losses.


    The other benefit of the concorde is of course 360 turntable rotation but I do not know how handy it is due to tilt when the racket handle points to to the tension head.
     
  9. Irvin

    Irvin G.O.A.T.

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    I'm not so sure that is true I would think the handle is always up and not just tilted when the racket is toward the tensioner. I'd like to hear from someone who does have a Concorde version.
     
  10. OccasionalStringer

    OccasionalStringer New User

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    For example here

    https://www.youtube.com/watch?v=Hatj4ByunNk

    at about 5 min
     
  11. 10SDad

    10SDad Rookie

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    Yes, there is. Here is a pic and instructions from the manual.
    [​IMG]

    "The clamping force of the guiding system can be adjusted with the nut (fig.17).
    VERY IMPORTANT:
    - The clamping force on the rail should only be adjusted with the handle in the VERTICAL end position.
    - During use the handle should always reach the vertical end position to be stable."

    Just make sure the handle is in its complete locked position before making your adjustments.
     
    Last edited: Feb 5, 2015
  12. Jacklondon00

    Jacklondon00 New User

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    Here is a much more elegant solution to the problem.

    http://youtu.be/UgFO7NCjGt8


    However, since I am so good at adjusting the slack in the string that the lever falls very close to horizontal almost every time (thanks to my old M50), I am not really sure I am going to use this, but we will see.
     
    Last edited: Feb 5, 2015
  13. Jacklondon00

    Jacklondon00 New User

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    The concode system lifts only on the side of the racquet handle, so that's not an issue.

    However, your comments made me examine a few other things, and one of them was the position of the racquet on the platform, if the racquet head is not centered, that means that the side closer to the tension head was going to have a higher angle than the side that is further from the tension head. After making sure that both support towers were the same distance from the tension head, this was no longer an issue. However, I did notice that even when the machine and the racquet is centered, the center crosses enter the tension head from a slightly lower angle than the top/bottom crosses, which improves the accuracy of the machine a little.

    Still, with this new setup I am getting less than 1/2 pound variance on the extremes, and exactly the same tension when the lever is a reasonable distance above/below horizontal.
     
    Last edited: Feb 5, 2015
  14. volusiano

    volusiano Hall of Fame

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    This is very professional looking Jack! Very nice.

    Since you already went through the trouble making it, might as well use it even if you're good at keeping the lever horizontal.
     
  15. volusiano

    volusiano Hall of Fame

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    Sorry to hear about your surgery, and thanks for drawing out the pic with your left hand.

    I notice that in this pic, you drew the lever bar not quite perpendicular to the line "b". Where is the angle Bf we talked about earlier that's supposed to be the manufacturing deviation that makes it not perfectly perpendicular? Is it in here somewhere?

    Also, I cannot follow your equation (90-A) + 90 + Bh =180 from this drawing. Can you highlight these components from this equation on the drawing?

    I can see in your drawing how Bh manifest itself in many places nicely. A picture is worth a thousand words indeed.

    The math you discussed has been spread over several posts so it's all disjointed. Can you put together all the maths in one place from top to bottom using this drawing as a reference to help consolidate your explanation? Thanks!
     
  16. OccasionalStringer

    OccasionalStringer New User

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    The drawing was only to illustrate effect of string angle to horizontal (Bh). I was thinking that showing also Bf makes the drawing messy and Bf is included in angle A in my first drawing

    But I updated the drawing a bit to show Bf and also some other varibles. Not to make drawing too messy I used angle A' to denote tension head angle to vertical. So the updated drawing:

    [​IMG]


    For consolidation we have now the following variables:

    • W = Force the weight is rotating tension head counterclockwise (CCW)
    • Tf = String Tension = Force the string is resisting CCW rotation caused by the weight
    • a = Distance of the weight from the Tension head pivot point
    • b = Tension head length i.e. distance from pivot point to string gripping point
    • A = Weight bar angle to horizontal
    • A' =Tension head angle to vertical
    • Bf =Tension head angle deviation from 90 degrees to weight bar
    • Bh =String angle to horizontal
    • C =String angle to tension head
    • Ef =Error factor


    Now when the system is in balance (=tension head is not rotating) rotational torque caused by weight CCW equals the torque generated by the string CW.

    Torque is defined as the cross product of the lever-arm distance vector and the force vector, which tends to produce rotation.

    So the balance equation is

    W * a * cos(A) = Tf * b * cos (A' - Bh) (1)

    Due to manufacturing tolerance A' depends on Bf:

    A' = A + Bf (2)

    Substituting A' with equation (2) in balance equation (1) gives

    W * a * cos (A) = Tf * b * cos ( A + Bf - Bh) (3)

    Now solving Tf from equation (3) gives

    Tf = ( cos(A)/cos(A+Bf-Bh) ) * W * ( a / b ) (4)

    So string tension tension is a function of string angle A and we can intoroduce error factor Ef

    Ef = cos(A) / cos( A + Bf - Bh ) (5)

    Which gives us a function for string tension Tf at angle A

    Tf(A) = Ef(A) * W * ( a/b ) (6)

    Where,

    Ef(A) = cos(A) / cos( A + Bf - Bh ) (7)

    Note!: Because the the tension head rotates string angle Bh depends somewhat on tension head angle A and also racket grommet hole position relative to the tension head pivot point. Knowing all the measurements it possible to explicitly calculate Bh at every tension angle A but the variation here is quite small when the string comes directly from grommet hole to tension head.


    This was to check that formula with Bh gives correct torque when the string comes perpendicular to tension head (b)

    So, first
    1. Angle of straight line is 180 degrees
    2. Sum of all 3 angles in a triangle is also 180 degrees

    So with these facts and with angle C in the drawing we can write (look at below the topmost horizontal dashed line)

    (90-A') + C + Bh = 180 ( 8 )

    90-A' is the angle the tension head (b) makes with the horizontal line and we get it from the triangle defined by b, horizontal line and vertical line. When string comes perpendicular to tension head C=90 degrees and we have thus

    (90-A') + 90 + Bh = 180

    And solving for Bh gives

    Bh = A'
     
  17. volusiano

    volusiano Hall of Fame

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    Hey OccasionalStringer, thanks for updating the drawing to introduce Bf, C and Ef. I follow everything you're saying now and agree 100% with your math! Again, excellent translation of Bh from the horizontal deviation into showing how it affects A' and rolls into the math and plays the part in the error factor Ef. I could not visualize how Bh gets factored in but you could and you drew it out for all of us to see, nice!

    So using all this as a reference, let's go back and talk about why JackLondon00 was seeing a deviation/discrepancy when his stringer is at normal, and how, by raising the one end of his stringer, is able to alleviate this deviation/discrepancy.

    I think you already made that conclusion but I just want to confirm my understanding. Basically what you're saying is that he originally has a manufacturing variation Bf (causing his lever to not be perfectly perpendicular to the tension head's gripper), so when he raises the one end of his stringer, it incidentally introduces the angle Bh into the picture. And if he raises it just enough to make Bh=Bf, then they'll cancel each other out and correct the error coefficient Ef back to 1, resulting in correct tension pulled at almost any angle on the lever bar. Is that right?

    And it's duly noted on your comment about how Bh depends on a combination of angle A and the position of the grommet which dictates the angle of the string from the grommet to the gripper. Yeah, we can probably go through some more math to show how Bh will vary as a function of A, But like you said, the position of the grommet may dictate how this angle Bh will vary with A and probably will keep the variation of Bh small enough that in the end, JackLondon's experimental solution will still be successfully accurate for the most part.

    Thanks again for being able to recognize this and explain it with your drawing and math for all of us to see!
     
    Last edited: Feb 6, 2015
  18. lew750

    lew750 Rookie

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    I see it! I see it! Wait, what do I see?
     
  19. duffman

    duffman Rookie

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    Has anyone had a problem with the the gripper not automatically sensing the string when pulling tension? When I string stiffer polys I need to push the black knob down to get the tension head to pull. It's weird that it only does it with polys. Sometimes if I give the string some slack it will still automatically pull the tension but it's hit and miss. I've gotten used to pushing the lever down so it doesn't slow me down at all. Just a little annoyed my ml100 isn't working perfectly like it usually does.
     
  20. OccasionalStringer

    OccasionalStringer New User

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    Made this drawing of tilting the machine:
    [​IMG]

    When the machine is tilted by angle T then the weight bar is at angle A+T to horzontal and string at angle T to horizontal if at level before the tilt.

    Error factor after tilt is then

    Ef = cos(A+T)/cos(A+Bf-T)

    To have error factor 1 we must have

    A+T = A+Bf-T

    Solving T from this equation gives

    T=Bf/2

    So you need to tilt the machine by half of the manufacturing variation
     
  21. 10SDad

    10SDad Rookie

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    In light of the number of postings regarding various user tests, hypotheses, and mathematical formulas regarding the foundational theory of Stringway dropweight machines, I’d like to bring some closure to this discussion through my own summary/opinion, and with additional information provided by Stringway.

    1) The Stringway tensioning system is engineered according to mathematical theory. In application, there are always variables that are introduced that impact exact tension outcomes, whether that is standard manufacturing tolerances, or the occurrence of angles and/or friction.

    2) Stringway has informed me that every system is adjusted individually. Up until last year, “Angle A” was adjusted with dimension” D” of the hole in the upper jaw and checked on a test plate.
    [​IMG]

    Starting last year Stringway is using a new test rig, which measures the tension at different angles in order to determine the correct position of the hole in the upper jaw.
    [​IMG]

    3) The OP’s first test demonstrates that other than at the most extreme arm angles, the differences in tension of a particular pull (using 60 lbs. of reference tension) were 1 lb. to 1.5 lbs., equating to a 1.6%-2.5% deviation. In my opinion, that is very nominal and falls well into the acceptable range. Considering the percentage of deviation that would occur on a standard dropweight machine at similar arm angles, the Stringway meets its objective.

    4) When measuring accuracy, it’s important to keep any testing of machine deviations in perspective with other potentially contributing elements. I use a device to measure SBS, and have found there are other factors that can influence final results.

    For example:
    - The use of synthetic gut can generate a 10% to 20% higher SBS than monofilaments in the same frame at the same reference tension.
    - Clamping off quickly can impact proper string elongation, causing a loss in SBS.
    - Something as simple as straightening the cross strings while tensioning can make a difference in final SBS.

    5) Several posters have indicated they have not specifically tested the tension on their machines, yet can regularly achieve the same SBS. This demonstrates that the machine can produce consistent results when an individual follows their established routine and methodology. And the final result is really what matters to your customer.

    Bottom line in my book:
    - Stringways are extremely accurate through their range of motion.
    - Factors beyond machine capabilities alone influence final results.
    - Stringways enable the Stringer to achieve consistent, predictable results for his/her customer.
    - Consistent, predictable results are the goal.
     
  22. 10SDad

    10SDad Rookie

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    Poly/Mono can slip through if the surfaces of your stringclamps have smoothed over time or have been coated with residue from various strings. If you have never cleaned those surfaces, here are options:

    1) Try this one first. Disassemble the top clamp from the bottom and use denatured alcohol to fully clean the surfaces. I recommend denatured alcohol over mineral spirits, which has petroleum distillates that also leave a coating.
    2) If that doesn't work, you can fold a piece of fine emery cloth around something that is thin/flat (ruler, file, etc.) and gently grind/sand the inner surfaces of the clamps in a motion perpendicular to the direction the string will be pulled in. You may need to brace them gently in a vice. Again, clean with denatured alcohol. I recommend on this one you do a little bit, test, do more if needed, etc. You don't want to sand too much.
    3) Test the friction on the tension head when it opens/closes by opening the jaw, pulling it backwards, and letting it go. It should spring back quickly to the closed position.

    Let us know if any of these work.
     
  23. OccasionalStringer

    OccasionalStringer New User

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    Just wondering how that rig is used for individual adjustmet of the upper jaw hole?

    I would think that in order use the rig for tension test the upper jaw must already have a hole in it and once drilled it is not possible to change position of the hole.

    If the tension variation is outside acceptable range in the test do they use a new jaw or have some other adjustment measures?
     
  24. volusiano

    volusiano Hall of Fame

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    A more elementary question for my understanding is what does the dimension D as drawn in that picture have anything to do with the math at all?

    And how does angle A get adjusted with dimension D? And for what purpose? It's such a vague statement ("angle A is adjusted with dimension D") that it doesn't mean anything without further elaboration.
     
  25. 10SDad

    10SDad Rookie

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    Here is the answer from Stringway as I received it:

    "We have 5 test jaws with the hole in different positions (different dimensions D). The new tension head is put in the jig, with one of the jaws. When we see the deviation with that jaw we know which jaw (of the 5) is right for the system. We test the head with that jaw. And if it is ok he drills the hole in a new jaw at the same position."
     
  26. 10SDad

    10SDad Rookie

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    Here is Stringway's additional elaboration:

    "The bigger the dimension D , the smaller the angle A. The pull rod has be lifted further to reach the hole in the upper jaw. Like how it rotates when you open the string clamp to put a string in."
     
  27. duffman

    duffman Rookie

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    Are you referring to the clamps or the actual gripper that is attached to the tension head? My problem is when I pull the string tight and then tension it the little black knob doesn't automatically disengage and I have to manually press it down to let the weight drop. If I give some slack in the string before tensioning it still works fine. This is only with poly. Gut, synthetic gut, and multis I can pull the string tight and the weight still drops automatically.
     
  28. 10SDad

    10SDad Rookie

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    Yes, the tension head/gripper is what I was referring to. How old is your machine? Has it been used a lot? May be a maintenance issue.

    From Stringway:
    <--------------------
    There are 3 things which can cause this on older machines that are used often:
    1) The pin in the upper jaw is bent.
    2) The lower pin in the pullrod is bent or worn.
    3) The tension head does not move freely because of friction.

    Because the release still works when the poly is not pulled tight, it is likely that there is too much friction.
    -------------------->

    It would be my guess that the reason the non-polys are working when pulled tight is that they have additional elasticity, which is acting in a similar fashion to putting some slack into the poly before dropping the tension arm.

    Stringway has provided a guide for doing maintenance on the tension head. Note: The guide indicates it is for a foot-pedal model, however the methodology is applicable to drop-weights as well.

    http://www.stringway-nl.com/pdf/MS200-repairing.pdf

    If you have further specific questions, you may want to consider contacting Stringway directly.
     
  29. volusiano

    volusiano Hall of Fame

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    OK, so it sounds like they want to adjust the dimension D (by picking the right upper test jaw with the right pin hole position) to change the angle A to reach a targeted reference tension.

    That's more information but it's still not the complete picture. What is the original objective and what are the test parameters of their setup? Are they trying to get angle A to be 90 degrees to the horizontal line?

    A complete test objective statement with detailed test conditions and perhaps some supporting math would be nice. Did Stringway give you any of this info? Or is it just little bits and pieces like what you have so far?
     
  30. volusiano

    volusiano Hall of Fame

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    I have the MS200 DX so this information is great to have for reference.

    Do you have any other pdf docs of this nature from Stringway you can share with us? Thanks!
     
  31. 10SDad

    10SDad Rookie

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    Stringway is building an Information Center on its website to provide users with more resources and information. If you go to their US website: http://www.stringway-nl.com/USA/ and click on the "Information Centre" button/link in the center of the homepage, you can access what they have thus far. The PDF I referenced can be found under the "Technical Info" section. My understanding is that this is a work-in-process.
     
  32. duffman

    duffman Rookie

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    Thanks 10sdad! My machine is getting up there in years. I'd say it's about 7-8 years old now. I string about 2-4 racquets a week. A few more when the weather warms up. Pretty much just string for myself and people that I know that want a really good string job for a decent price. I'll have to check out the tension head this weekend.
     
  33. 10SDad

    10SDad Rookie

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    From Stringway:
    <----------
    - With the test rig unit we test exactly what the tension head should do, deliver the same tension in different angles.
    - The system should generate 10.0 kg.
    - The tensions with the lever upwards above and downwards below the horizontal are measured.
    - When these tensions are 10 kg for all angles of the lever that position of the hole in the upper jaw is the right one.
    - The hole is drilled at that position in new upper jaw for that tension head.
    - The theory is exactly the same as already discussed.
    ---------->

    I appreciate all of the feedback that has been provided regarding the testing and mathematical calculations. There are some very intelligent and dedicated people here. With all due respect, however, I believe we are now heading down a “rabbit trail” of pursuing information for information’s sake, and making it more complicated than it needs to be. The practical benefits of drilling down any further into the trigonometry of the machine, testing methodologies, and impact on results have effectively been exhausted. While it would be "nice" to have this info (as stated above), it is not necessary. The discovery of exactly how mathematically accurate stringing machines are can be an interesting discussion, but it’s at the point where that would be better pursued in an entirely new thread on TW dedicated to that topic rather than continuing to fill page after page with that micro level of discussion here. I’m not trying to limit discussion of Stringway..as this forum is intended specifically for the education of current or potential customers through shared experiences…but continued analysis of this particular topic provides no further practical value in the overall picture of usage. Can we agree to call this one done?
     
  34. lew750

    lew750 Rookie

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    Since Jacklondon00's original post about the subject, it has been an interesting but overly complicated discussion that distracts from the main point made by Jacklondon00 and confirmed by others: In practice, Stringway machines do not pull the same tension regardless of drop weight bar angle. I would be interested in hearing from someone whose Stringway does pull the same tension or hearing about a simple (other than the book-under-the-legs) fix or that Stringway had discovered and corrected a manufacturing defect; otherwise, I agree this line of discussion has pretty much played out.
     
  35. volusiano

    volusiano Hall of Fame

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    Not sure why you think we're pursuing information just for information's sake at this point.

    The discussion with showing the math on why JackLondon00's solution works is a different discussion that was already done with. I know it was a drawn-out discussion and I can understand why you feel like we've beaten that horse to death already.

    But the discussion on the subject of calibration is a different and new discussion that you brought up. We're only asking for details because the initial information given was sketchy, so the natural reaction was simply to ask for more details to understand better what they are trying to calibrate and how. It's not just for information's sake.

    Some people only care to know that Stringway does do calibration but they don't care to know what Stringway calibrate or how they do it. And that's fine. If you had said "I heard Stringway told me that they do do calibration, but I don't know what or how they do it." then that would have been the end of the discussion. It's the sketchy info initially given that prompted further questions, that's all. At any rate, sure, we can stop the discussion on calibration here. It looks like you've shared with us all the info you have already anyway.

    I just want to make a final comment that it looks like this calibration step which Stringway does would not have solved the deviation that JackLondon saw on his machine. This calibration, as explained by Stringway, ensures that the tension is true at any angle, which is already observed on JackLondon's machine, as demonstrated after his "fix". But it doesn't address and apparently does not "fix" the issue of his lever bar not being 100% perpendicular to the gripper due to manufacturing tolerances.

    Having said that, I completely agree with many folks who already said here that manufacturing tolerances is a fact of life and unavoidable. I'm not trying to nickpick on manufacturing tolerances. And it's been proven that even with manufacturing tolerances, Stringway machines still give better results at any angles compared to other drop weight machines.
     
    Last edited: Feb 12, 2015
  36. 10SDad

    10SDad Rookie

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    I can appreciate your point, volusiano. You've brought some great insights to this discussion. My relaying of this information was in response to several references/questions regarding calibration that are posted throughout the discussion. A main one being Jacklondon's in post 261: "Still, if I was Stringway I would be more sensitive to the quality control/calibration of that mechanism." I just thought it was important to let everyone know that Stringway is making continued efforts to ensure quality control and factory calibration of components on new machines.
     
  37. Jacklondon00

    Jacklondon00 New User

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    Wow, I came back to this thread after a busy week to find a lot of interesting info.

    In particular, the "calibration" procedure outlined by 10SDad was very interesting. In a previous email Fred said that they don't calibrate their machines:

    "It has nothing to do with the calibration of the machine.
    There is no individual calibration of our systems it is the same since we make it in 1984."

    His statement above surprised me, but it makes perfect sense now, because it's not calibrating, it's still the manufacturing stage of the process. So once they know where to drill the hole based on their testing, they manufacture that part to specification.

    I do think we have basically got to the bottom of this and pretty much exhausted the topic. We figured out why my machine is off and why my "fix" works (thanks to the gentleman geniuses Volusiano and OccasionalStringer.) Although looking at my tension head, the distance in question, actually looks to be noticeably less than 90 on my machine.

    So it seems like Stringway is compensating for the manufacturing tolerances by customizing the top of the gripper for every machine, which Fred never told me about. I think that's great, and this is what I would have expected. This should reduce the variance.

    I just wanted to note that my machine does not give me 10 kg at every angle. When within reasonable distance from horizontal, I am getting a variance of 500g (250g each way) and 800g on the extremes. So I assume my machine was either not made within the last year, or someone was not rigorous enough with their whole drilling position, 500g on 10 kg is 5% variance.

    So looks like even with this calibration/manufacturing process, it's still difficult to get the hole in a perfect place for the machine to be perfect at every angle. I can live with that explanation. Moreover, it seems that Stringway is working hard to try and mitigate the variance as much as possible via their new method.
     
  38. onehandbh

    onehandbh Hall of Fame

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    Test of Stringway ML90 auto dropweight

    I finally got around to testing my ML90. Using the large metal cylinder I set the tension to 54 lbs.

    I used a Gamma Tension Calibrator to measure the tension.
    String used was Volkl Cyclone 17g.

    Did the three tests:
    1) Tension arm above level (as high as I could get it)
    2) Tension arm level (parallel to table)
    3) Tension arm below level (as close to table as possible without touching)

    The results:

    https://www.youtube.com/watch?v=0t3Am5wns1Y
     
  39. Gut4Tennis

    Gut4Tennis Hall of Fame

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    awesome!!!!!!!!!!!!!
     
  40. Power Player

    Power Player Talk Tennis Guru

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    Nice work. Makes me feel a little better about tensioning gut and syn gut, since that usually drops a little below level.
     
  41. 10SDad

    10SDad Rookie

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    Thanks for your efforts on this, onehandbh. I grabbed a screen capture from your video. I think this says it all.

    [​IMG]
     
  42. Aretium

    Aretium Professional

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    Is the stringway the fastest machine out there?
     
  43. eagle

    eagle Hall of Fame

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  44. onehandbh

    onehandbh Hall of Fame

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    IMO, it's probably not the fastest machine, but it's pretty easy to use.

    - Lots of space in the turntable area to weave strings.
    - Easy to adjust the two towers and secure the racquet.
    - LOVE the flying clamps! They don't have a sandpaper-like texture, but somehow they grip the strings very well -- even slick poly strings.


    I think in terms of sheer speed I could string faster with my Gamma XST crank stringer b/c I could just crank super fast and move on to the next string. Of course this resulted in less accurate string jobs b/c I didn't allow the string to finish stretching. Plus I could never know how slow to crank it b/c I couldn't tell when it finished stretching.

    With the ML90, I just lower the arm and don't worry about angle that much, and the tension is pretty consistent and I know it keeps pulling the string to reach the target tension and keep it there.
     
  45. eelhc

    eelhc Hall of Fame

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    If you still have this setup... Could you also recoed the calibrator tension for tge center mains pulled over the throat for machines without the concorde option? Curious to see if there is significant tension drop.
     
  46. onehandbh

    onehandbh Hall of Fame

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    which test would you like? center main over throat vs ??
     
  47. eelhc

    eelhc Hall of Fame

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    vs the tests you've already run. I suspect the tension will be consistent vs the angle of the weight but the calibrator will read slightly lower due to the added friction from the string resting on the throat of the racquet.
     
  48. 10SDad

    10SDad Rookie

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  49. 10SDad

    10SDad Rookie

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    Need immediate help: tension ruler

    Fellow Stringway Club members, I need some immediate assistance. I'm out of town at college matches for my son and need to string some racquets for him for tomorrow. I just realized I left my tension ruler at home and am unable to set tension without it.

    Could someone PLEASE measure the distance in inches and or cm from the center of the anchor hole to both the 53# and 57# locations on the ruler? I can run out and get a ruler from the store tonight, but I need the inches or cm equivalent to set the weight in the proper positions. I do mains at 57 and crosses at 53.

    Would really, really appreciate if someone is willing to take these measurements and post back ASAP.

    Thanks so much.

    10SDad
     
    Last edited: Mar 20, 2015
  50. Rysty

    Rysty Rookie

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    Hi, those are 47 cm and 43,5 cm.
     

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