stapletonj
Hall of Fame
harrumph harrumph, as emperor of the old geezer chapter of talk tennis, I must protest this this relegation of Weed and granny stick users to the ash heap of history!
**Stringway – information – Questions – answers**
- Thread starter Stringway Official
- Start date
onehandbh
G.O.A.T.
If the current trend continues, one day soon, 115 square inch racquets will be labeled as midplus.
I do not understand why would you want to string badminton racquet on machine that is not suitable? My cheap machine has two positions and two shapes for side supports, one for badminton other for tennis racquet; what is exactly the issue and how is it related to external/internal support?
You do realize that there might be other engineers here, therefore information better be somewhat substantiated in the way it can be independently checked. Otherwise it resembles a promotional material no matter where and by whom it is posted. In a scientific community they learn to challenge claims made by even Nobel prize winners, and for a good reason so.
At that time you designed your support, even modeling a simple bending rod was a significant challenge (and to some degree it is even today, depending on one's abilities and access to resources). So yes, it has to be doubted, especially if one does not even disclose the model assumptions.
It may very well be correct, or depend too much on racquet shape, or model could be too simplified to apply to modern racquets.
Sorry, but there is no stress without deformation. You should not post such absurd claims.
I can understand that you may be implying specifically "no bending deformation", but that ONLY means that racquet shape has worked as intended and resolved applied forces into compressive stress as per design. This is why they use carbon fiber. Compressive stress is still causing deformation which is small, harmless and you do not see it with naked eye. One should use strain gauges to detect such deformations.
AGAIN, what a straight beam has to do with tennis racquet. We have discussed it before, but you keep coming back with this questionable analogy.@villis
Just have a look at this “beam in the wall theory” .
The question is: What support is best for the beam?
I understand that you will doubt this explanation also.
You may know that in order to avoid the need for support of straight beams, people have invented Arches as early as 2nd millennium BC, if we can trust Wikipedia. Now have a look at tennis racquet and see that it somehow more resembles arch rather than a straight beam. But you choose to discuss straight beam, apparently because arch would not support your claims, as easily.
Stringway Official
Semi-Pro
@villis
The analogy between the beam and the racquet is that the support in point A does the same as an outside support: They both create stress which is not there with a support close to the load.
IOW The stress in the racquet is caused because the force of the outside support has to be transferred to the position of the mains.
Biggest proof of this effect (shown in the graph) were the “support beams” which supported the racquet between 3 and 9 o’clock.
They disappeared quicker than they came because racquets broke on the machine.
No, it does not. There is a significant difference between arch and straight beam.
WHERE the graph shows that? At 220mm which should be close to 3 and 9, your graph shows stress at ~half of that for 2 point support.
What racquets broke on which machine? As I mentioned before, I have strung wooden racquets with only supporting them at 3 and 9 (without machine), and never broke one. Plus, outline on the paper was not showing any deformation that I could notice. What did I do wrong?
fritzhimself
Hall of Fame
I agree.
Already had cracked racquets that have looked pretty bad.
Wanted to destroy the absolutely when stringing - I also did not succeed with 39 kg - but that was not a Stirngway machine.
Stringway Official
Semi-Pro
Apart from the fact if the racquet broke or not, it is very unlogic to support the racquet between 3 and 9 o’clock. The “worst moment” for a racquet occurs when all main strings are strung.
2 point mountings work so well when they have stiff tables because they support the racquet in the direction of the high load of the main strings.
onehandbh
G.O.A.T.
Wow. My wood racquets wood have warped or broke. What tension did you string them at?
By the way, a couple years ago I restrung my 100+ year old racquet on my stringway ml90 and it survived without warping. I used VS gut at 27 lbs.
Stringway Official
Semi-Pro
@onehandbh
We tested the prototype of our turntable in 1984 with a big wooden Racquet at 66 lbs because tensions were very high then. The support had 3 points at the head and a banana at the throat. No problems at all.
Of course, installing temporary support in place of some cross strings that are not yet there is totally unlogic.
So unlogic that engineers massively build those arch things like this:
Those, of course not real engineers.
Does it not look a bit like tennis racquet with mains only? Nop, racquet is more similar to a beam sticking out of the wall, THAT is logic.
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Racquet ProKennex Q5 295, 16x20. Dimensions head L = 327mm, W = 246mm.
Tension 30kg (~66 pounds). Only mains strung on my cheap 6-point machine, L = 324mm (shortening 3mm, a bit better than ML100 in RacquetQuest testing at 60 pounds).
After releasing the inside (12'and 6') supports, L = 322mm W = 252mm. Now racquet is supported only by outside supports, it is shorter ~5mm which is comparable to that of ML100. Racquet is shortened due to widening, local deformations (I compared shape with other racquet that was widened by just pulling at 12' and 6' without any supports at all). Apparently outside supports are not that strong to completely hold the racquet shape without inside supports.
After removing outside supports, racquet is now completely unsupported (with mains ONLY strung at 30kg), L = 320mm W=256mm.
My understanding is that the main thing to worry about is minimum deformation NOT some mythical stresses without deformation, and none of the options (inside or outside supports) really solve this. I have tried additional support for the towers on my machine (shortening of the racquet then is ~1mm) and there is a huge difference, subjectively it feels like at least ~2kg tension increase, but a bit difficult to string crosses. It is difficult to judge if the tension distribution is more even, but probably it is.
As a conclusion, I do not see any need to protect a modern racquet more than any of the existing modern systems do. What we need though, is less change of racquet shape for the reason of maintaining stable tension, not to protect racquet.
For the internal support, I would sure choose a 5 point support over 2 point (just to "feel" better, not to really protect racquet), however it is obvious that even 5-point system would significantly benefit from added outside supports in order to somewhat unload the inside support and minimize frame deformation (again, to increase stringing quality not protect the racquet that does not really need more protection).
Tension 30kg (~66 pounds). Only mains strung on my cheap 6-point machine, L = 324mm (shortening 3mm, a bit better than ML100 in RacquetQuest testing at 60 pounds).
After releasing the inside (12'and 6') supports, L = 322mm W = 252mm. Now racquet is supported only by outside supports, it is shorter ~5mm which is comparable to that of ML100. Racquet is shortened due to widening, local deformations (I compared shape with other racquet that was widened by just pulling at 12' and 6' without any supports at all). Apparently outside supports are not that strong to completely hold the racquet shape without inside supports.
After removing outside supports, racquet is now completely unsupported (with mains ONLY strung at 30kg), L = 320mm W=256mm.
My understanding is that the main thing to worry about is minimum deformation NOT some mythical stresses without deformation, and none of the options (inside or outside supports) really solve this. I have tried additional support for the towers on my machine (shortening of the racquet then is ~1mm) and there is a huge difference, subjectively it feels like at least ~2kg tension increase, but a bit difficult to string crosses. It is difficult to judge if the tension distribution is more even, but probably it is.
As a conclusion, I do not see any need to protect a modern racquet more than any of the existing modern systems do. What we need though, is less change of racquet shape for the reason of maintaining stable tension, not to protect racquet.
For the internal support, I would sure choose a 5 point support over 2 point (just to "feel" better, not to really protect racquet), however it is obvious that even 5-point system would significantly benefit from added outside supports in order to somewhat unload the inside support and minimize frame deformation (again, to increase stringing quality not protect the racquet that does not really need more protection).
Stringway Official
Semi-Pro
Dear @villis
I really appreciate your “out of the box approach” of this subject.
BUT:
In mechanical designing the stress is the major value to calculate.
Stress is the force per square millimeter.
When this value is too high the part (or racquet) cracks.
The designer has to choose a bigger part or stronger material.
As illustrated with the beam in the wall there can be displacement without stress. The bending stress with the outside support is caused by the fact that the force of the outside support has to be transferred to the position of the main strings.
Your test proves very nice that indirect supports are less efficient.
Perfect support
To make the 3 point support more perfect outside supports are not the answer.
An easy solution would be to make the 3 supports wider.
The perfect support has a direct support at every position of a main string, the racquet would not feel anything.
We think that our 3 point system with wide supports is the best possible solution for racquets with different shapes.
Stringway Official
Semi-Pro
@trev1015
Just an idea about your problem:
I see that your machine offers 2 positions for the outside supports.
In what position did you use it for badminton?
The closer you come to the 3 and 9 o’çlock position the higher the stress around 2 o’clock.
The higher the tensions the more critical this is of course.
Maybe you can post a picture with a mounted badminton frame?
OK very well, so why you did not continue to describe relation of stress with deformation? I assume you know how stress in material is usually measured, by strain gauges, measuring strain (deformation) in material and calculating stress knowing the material’s elastic properties? Do we have anything to hide?
This happens not when "value" is too high, but when the elastic properties of the material are exceeded. In any case, there is NO stress without deformation.
Arch (and tennis racquet) is specifically designed to solve this problem of a straight beam.
Anyway, in your out-of-place example of the beam in the wall, of course there is stress in the beam in any of 3 drawings where force is applied to the beam, it is just different type of stress and in different locations of the beam. Look up at your own definition of stress and note that force applied to the beam cannot simply disappear without causing stress (or acceleration if beam would be not supported at all).
Look here:
I do not see any internal support supporting force of main strings, DO YOU? I specially posted the photo of bridge arch which is exactly the same design principle.
Best possible solution is that which ensures minimum racquet deformation during stringing.
Your support requires stringer frame that does not bend (as falsely advertised on your website) because all force of main strings is supported by the frame, but your frame does bend, at least according to RacquetQuest review. If it had that frame that does not bend, it would be much closer to ideal support.
Traditional 6-point support transfers part of the force to the racquet (and racquet is specifically designed to withstand this force). It means, main string force is supported partially by racquet frame, not only by supports.
Result is less deformation at 1/3 of the price. If you ask me, that's a smart design.
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I had the supports in the same spots as the picture posted. I see what you mean, moving the supports closer to the 2 o'clock position would have given more support in the area where the crack occurred.@trev1015
Just an idea about your problem:
I see that your machine offers 2 positions for the outside supports.
In what position did you use it for badminton?
The closer you come to the 3 and 9 o’çlock position the higher the stress around 2 o’clock.
The higher the tensions the more critical this is of course.
Maybe you can post a picture with a mounted badminton frame?
Stringway Official
Semi-Pro
Yes between 1 and 2 o’clock is better than between 2 and 3 o’clock because that generates bending stress between 1 and 2 o’clock.
Furthermore it is very important that you start the crosses from the bottom so that you start lowering the forces on the outside supports on the wide side of the frame first.
The forces on the outside supports at the wide side of the frame are much higher than on the narrow side of the frame of course.
Most badminton racquets have a guidance graphic on where the outside supports should be. Most people including stringer don't know it's there!
Also badminton racquets are way softer than you think. Use a load spreader & mount them far looser than a tennis racquet.
Please watch this video by renown badminton stringer Halim.
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onehandbh
G.O.A.T.
Another thing to take into consideration is that the strength and properties of the material can degrade over time with repeated stress with a magnitude that is below the maximum elastic limits.
I see this in construction projects as well. I personal preference is to err on the conservative side by having more latitude when it comes to boundary conditions when it comes to software and also construction projects.
Great video very helpful, thank you
Stringway Official
Semi-Pro
I agree.
But there is one thing I do not understand:
The stringer tells about the importance of the load spreader.
Why does he only use it at the head and not at the throat while the pressure on the frame is the same on head and throat?
Irvin
Talk Tennis Guru
The 12 support does not have a support pad on it as the 6 support does. When the center main is first pulled it is nearly in a straight line and there is little side pull on the frame. As the 2nd main is pulled there is more side pull and because there is no support pad the top inside edge against metal would surely be marred.
The badminton supports that came with my machine (700-ES) do not have support pads on the 6 or 12 supports but did come with load spreaders. If I were to string a badminton racket I would use load spreaders at the head and the throat. The tennis 6 and 12 supports do have support pads.
Stringway Official
Semi-Pro
Starting clamp idea.
We get questions about a starting clamp regularly and up till now our reply was:
Take our double flying clamp which offers double the friction with the same clamping force.
The question is: Why not make a single starting clamp when that is easy to do.
The pictures show the clamp. Of course it is less bulky and lighter than the double flying clamp.
It has the same clamping power as our fixed clamp because it is nearly the same.
We get questions about a starting clamp regularly and up till now our reply was:
Take our double flying clamp which offers double the friction with the same clamping force.
The question is: Why not make a single starting clamp when that is easy to do.
The pictures show the clamp. Of course it is less bulky and lighter than the double flying clamp.
It has the same clamping power as our fixed clamp because it is nearly the same.
Irvin
Talk Tennis Guru
Not a bad idea if you’re clamping a cross inside the frame. If you’re clamping a string outside the frame it‘s not so good because it could damage or compress a longer section of the string which may end up in a grommet turn or knot.Starting clamp idea.
We get questions about a starting clamp regularly and up till now our reply was:
Take our double flying clamp which offers double the friction with the same clamping force.
The question is: Why not make a single starting clamp when that is easy to do.
The pictures show the clamp. Of course it is less bulky and lighter than the double flying clamp.
It has the same clamping power as our fixed clamp because it is nearly the same.
Stringway Official
Semi-Pro
Hi @Irvin
I think that the danger of compression is much smaller because the string is clamped over 50 mm lenght when the string is against the pegs.
Smaller clamps need much more pressure to hold the string at the same tension.
Quick question - unfortunately I scratched a clients racket today when pulling the first mains from the the throat. The tension head has a pretty sharp leading edge which was pulled against the racket frame just above the grip. Does this leading edge need to be so sharp? Can I file it down so it’s not so scratchy? Many thanks, John
Stringway Official
Semi-Pro
Hi @Jbmgh
What machine do you use?
Is the table stop in place?
Can you post a picture.
Or send it to my mail stringway.fred@gmail.com.
What machine do you use?
Is the table stop in place?
Can you post a picture.
Or send it to my mail stringway.fred@gmail.com.
Stringway Official
Semi-Pro
Thanks for the good conversation John, problem solved.
One bit of information especially for users who bought a second hand machine.
All Stringway machines which do not have the Concorde system originally had the table stop. This stop makes it impossible to hit the tension head with the grip of the racquet.
Stringway Official
Semi-Pro
30/3 DIFFERENCE IN “SPRING TENSIONERS”
It seems that there is some misunderstanding about “spring tensioners” with some people therefore some information:
- A lock out tensioner has a spring as reference for the applied tension. When the spring reaches the adjusted compression, the tensioning system locks. When the string still stretches the tension goes down as shown in this graph. The amount of loss of tension depends on the elongation and “stretch-speed” of the string.
The Stringway “spring driven” machines (MS140 and MS200) use the spring as “drive system”: The stringer charges the spring with tension and the spring pulls tension when the foot pedal or lever is released.
The advantages of a spring drive are:
- Very cheap.
- Very reliable.
Many very old MS200’s before 2000 are still in use without any spring exchange.
- Can not overshoot the tension.
This is very important when stiff monos are used.
- Very consistent as shown in this video of the MS140 tension system.
- Perfectly constant pull as shown in this graph
In comparison, this is the graph of a quite good electronic machine with a stretchy mono,
It seems that there is some misunderstanding about “spring tensioners” with some people therefore some information:
- A lock out tensioner has a spring as reference for the applied tension. When the spring reaches the adjusted compression, the tensioning system locks. When the string still stretches the tension goes down as shown in this graph. The amount of loss of tension depends on the elongation and “stretch-speed” of the string.
The Stringway “spring driven” machines (MS140 and MS200) use the spring as “drive system”: The stringer charges the spring with tension and the spring pulls tension when the foot pedal or lever is released.
The advantages of a spring drive are:
- Very cheap.
- Very reliable.
Many very old MS200’s before 2000 are still in use without any spring exchange.
- Can not overshoot the tension.
This is very important when stiff monos are used.
- Very consistent as shown in this video of the MS140 tension system.
- Perfectly constant pull as shown in this graph
In comparison, this is the graph of a quite good electronic machine with a stretchy mono,
OK, but I am afraid that after reading these excerpts from Stringway promotional material, "some people" may understand even less than before.
Is machine that produce these 2.5kg tension changes really "quite good"? I do not see such jumps with my Wise head..
In the video, tension head moves like 10mm, why not full range? In an honest experiment, one not fully familiar with the design might suspect that spring will not provide same force at different extensions, would it not be useful to show how well it is compensated for?
Why stretchy string (and possibly longer piece of string) for electronic tensioner and different, possibly shorter string for spring tensioner?
How useful such measurements outside the racquet frame really are, given that inside the racquet tension will drop differently than outside of the frame? In such case, jerky pull from "quite good" tensioner may even provide more stable tension inside the frame compared to gentle and really constant pull by the spring..
Stringway Official
Semi-Pro
@jbmhg excuse me for the slow reply.
We do not have a document about overhauling the T98 system, but we can advise you if you have questions.
What problems do you have?
Btw The 92 system is 6 years older than the 98.
We only offer the T92 system for the last 10 years because it is better in every way.
Thanks for getting back to me Fred.
I do like the look of the t92 system but I don’t think my turntable has the right casting to upgrade unfortunately.
The issue I’m having with the T98s is that when I clamp the base after clamping to the string there is quite a lot of movement (in unpredictable directions) pulling the string away from the tensioned line, which leads to me unclamping and readjusting before I can move on.
I wonder if there is a way to take out some of the play without making them harder to slide on the rails.
Many thanks,
John
I do like the look of the t92 system but I don’t think my turntable has the right casting to upgrade unfortunately.
The issue I’m having with the T98s is that when I clamp the base after clamping to the string there is quite a lot of movement (in unpredictable directions) pulling the string away from the tensioned line, which leads to me unclamping and readjusting before I can move on.
I wonder if there is a way to take out some of the play without making them harder to slide on the rails.
Many thanks,
John
Stringway Official
Semi-Pro
@jmgbh
Hi John,
Maybe you can find out where the movement comes from there are 2 options:
- The system slides over the guiding rails, but in that case the string is not pulled sideways?
- The system rotates over the friction disc.
I assume that the second case is more likely.
You can roughen the disc with rough sanding paper or fix a new disc we still have these.
This document describes how to take the system apart.
http://www.stringway-nl.com/pdf/T98-replacing-pullrod-ecc-shaft.pdf
These pictures show the indications:
Stringway Official
Semi-Pro
Another important point with the T98 system is the adjustment of the clamping force.
The system clamps stably only when the lever is switched to the end position and beyond the vertical position.
It is important to adjust the clamping force with the handle in that position.
The system clamps stably only when the lever is switched to the end position and beyond the vertical position.
It is important to adjust the clamping force with the handle in that position.
I think what’s happening is that it needs to be loose to slide on the bars, but when it is this loose, it leans a little before the base clamp is tightened. I feel like I need to reduce the friction on the bars so it can slide freely whilst tightened up more. Hope that makes sense.
In any case I’ll take it apart, give it a clean etc and see if it improves.
John
In any case I’ll take it apart, give it a clean etc and see if it improves.
John
Stringway Official
Semi-Pro
That is because the tie rod is in the recess of the eccentric shaft.
You have to turn the shaft so that the recess is at the bottom.
When tapping out you have to push the pull rod slightly upwards,
Stringway Official
Semi-Pro
Send me an email with your address and I will send you the quote including shipping.
stringway.fred@gmail.com
Stringway Official
Semi-Pro
RUCANOR HISTORY
Someone sent us this Rucanor system made in 1988 for an overhaul. But he did not put it in a box and UPS lost the rest of the machine.
This is the missing part which they never found.
A sad end for a loyal system.
Someone sent us this Rucanor system made in 1988 for an overhaul. But he did not put it in a box and UPS lost the rest of the machine.
This is the missing part which they never found.
A sad end for a loyal system.
Stringway Official
Semi-Pro
The funny thing about the Rucanor tension system was that it could be used in combination with our first stiffness tester.
Stringway Official
Semi-Pro
So that the information about our stiffness testers is complete, here are a few more pictures
The principle of the 1989 system was the same as of the Stringlab 2. It measured the force needed for a certain deflection of the string bed.
The spring + the linear potentiometer worked as a force transducer.
The stringlab 1 worked like the ERT system, it generated a vibration of the string bed and calculated the SBS (DT value) based on the measured frequency. We thought it was too inaccurate because of the indirect principle
The Stringlab 2 also does a direct measurement of the stiffness, and uses an actual force transducer
The principle of the 1989 system was the same as of the Stringlab 2. It measured the force needed for a certain deflection of the string bed.
The spring + the linear potentiometer worked as a force transducer.
The stringlab 1 worked like the ERT system, it generated a vibration of the string bed and calculated the SBS (DT value) based on the measured frequency. We thought it was too inaccurate because of the indirect principle
The Stringlab 2 also does a direct measurement of the stiffness, and uses an actual force transducer
Stringway Official
Semi-Pro
HYBRIDE STRINGING IS TRICKY
Because we have done the elongation test of many strings we get questions about combining strings for hybrid stringing very now and then.
In our opinion hybrid stringing is mechanically quite tricky. It is important that both strings do their part of the job. When one string looses tension quicker than the other the string on the higher tension delivers most of the power.
To choose the best combination of strings we advise to choose strings with the same elongation figures. Our list with tested strings shows these figures ( see next picture).
Because we have done the elongation test of many strings we get questions about combining strings for hybrid stringing very now and then.
In our opinion hybrid stringing is mechanically quite tricky. It is important that both strings do their part of the job. When one string looses tension quicker than the other the string on the higher tension delivers most of the power.
To choose the best combination of strings we advise to choose strings with the same elongation figures. Our list with tested strings shows these figures ( see next picture).
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How does this make sense?
If elongation figures "shows what the player feels on ball impact...", then what is the point of such "hybrid" over single string? Purpose of hybrid was to gain some benefits from both soft and stiff strings, no? Or does it now turn out using gut/poly hybrid is wrong?
Stringway Official
Semi-Pro
Yes this is very strue.
But when you compare strings the sbs has to be the same because that is what the player feels most.
