Mains, Pulling tension two at a time!

To avoid all of the various mains starting techniques I thought I would have play around with pulling the main strings together.
I'm sure you will be horrified by this idea
but it was interesting to try and seems to work ok!

 
If you look carefully I'm pulling twice the length giving me 2:1 advantage.
The piab shows 100lb with 55lb set on the wise, the 5lb is the friction through the shackle!
This gives me 50lb on each string.
 

alexmcnab

Rookie
Andy, looks very interesting, just needs to be able to string the crosses as well, and build a robot to operate it!
 
Thanks, crosses would be good, but not possible with current setup!
It's just for the first 6-8 mains ( the important ones! )
Don't think I will be using it just yet, I just enjoy playing around with ideas!
Andy.
 

Irvin

Talk Tennis Guru
If you look carefully I'm pulling twice the length giving me 2:1 advantage.
The piab shows 100lb with 55lb set on the wise, the 5lb is the friction through the shackle!
This gives me 50lb on each string.
Length of string does not change the tension on the string. It (longer string) will change (Make DT lower) the dynamic tension but not tension. Tension in the string is equal to the force applied to the ends. If you pull 2 string you will have half the Wise tension applied to each string.
 
Sorry Irvin, the video wasn't to clear.
The wise is moving twice the length of string from the machine through the shackle back to the anchor.
Basically 2cm moved to every 1cm after the floating grip.
This doubles the pull, my piab ( load cell )
shows double what the wise is pulling.
There's just abit of friction through the shackle so 55lb = 100lb
It's interesting because it pulls both sides of the frame together symmetrically which can
only be a good thing.
As I said before, I doubt I will be using this setup, I just like trying things!
To much spare time!
Thanks
Andy
 

afeller

New User
I love such "trying things". That means, that some people think about the process itself. And not just doing what others say.
What @Goat Stringer uses is the pulley principle (https://en.wikipedia.org/wiki/Pulley). Great idea!

My concerns are:
  • Your fix point must be higher, because the Wise don't like any force in another direction than straight. In that case the force going a little bit downwards. The Wise mechanics are very fragile (for the "older" models I know).
  • You pull with a "force" of 100 lb on the racket instead of 50. So the mounting point of the machine AND racket on the 12 o'clock position must hold 100 lb instead of 50. Maybe not a problem for some rackets, but some rackets are much weaker than we want...
 
Thanks, good advice. I can extend the anchor up to improve the direction of the pull. I just have to make sure the floating clamp doesn't touch the racket as it moves.

I thought about the 12 o'clock point on the racket and wasn't sure, normally if you load one side with 50lb and then the other you must end up pulling 100lb on the frame but not evenly because it's not a double pull.

I have a few old rackets to play with that I don't mind damaging but I don't want to hurt my wise! so will definitely move the anchor!
Thanks
Andy.
 

Irvin

Talk Tennis Guru
@Goat Stringer don't worry about your Wise, if it is set to 55 lbs that is the most tension you will have on it. What did you mount the end of the string to for the anchor?

EDIT: I’d be more worried about the frame than the Wise.
 
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afeller

New User
I thought about the 12 o'clock point on the racket and wasn't sure, normally if you load one side with 50lb and then the other you must end up pulling 100lb on the frame but not evenly because it's not a double pull.
Not really. In this case you pull the racket with 100 lb against the 12 o'clock fix point on the machine. If you're pulling normally only 55 lbs.
 
The anchor is a 150mm length of M10 studding with an eye on the end clamped to the rail, it's independent to the wise.

I think the wise is designed to sit higher not allowing 360° movement.

I raised my turntable by adding a bearing on the main shaft, very easy fix.

I think the angle of the pull which is slightly down is probably better than up, as this is how wise designed it to work.
 
Not really. In this case you pull the racket with 100 lb against the 12 o'clock fix point on the machine. If you're pulling normally only 55 lbs.
I'm still not sure, as when you pull the second main at 50lb there's already 50lb on the first main = 100lb at 12 o'clock?
 

Irvin

Talk Tennis Guru
Probably. But I can't tell anything from the vid. It just looks like double pulling to me. wise pulls on a metal thing that has 2 strings attached. How is that different than putting the strings directly to the wise?
He has a linear gripper connected to a U bolt. The two strings from the racket (1 in your case) go into The linear gripper. Then there’s a loop OG string anchored to the from of the wise (it looks like,) loops around the U bolt, and into the wise. Tension on racket side of linear is almost doubled with the pulley leverage. A pulley in place of the U bolt would have been more efficient.

EDIT: You will also be pulling from a lower point because of the anchor putting more downward stress on the racket.
 

Shroud

G.O.A.T.
He has a linear gripper connected to a U bolt. The two strings from the racket (1 in your case) go into The linear gripper. Then there’s a loop OG string anchored to the from of the wise (it looks like,) loops around the U bolt, and into the wise. Tension on racket side of linear is almost doubled with the pulley leverage. A pulley in place of the U bolt would have been more efficient.

EDIT: You will also be pulling from a lower point because of the anchor putting more downward stress on the racket.
sorry I dont see it. The description doesn't follow either. What is "loop OG string anchored to the from the wise" mean?

It just looks like 2 strings to a central point and the wise pulls that. how is it being doubled
 

MathieuR

Professional
It just looks like 2 strings to a central point and the wise pulls that. how is it being doubled
Freeze the frame at 15sec in the second film.
The two strings are in a clampdevice. On this device the u-bolt. On the rail a fixed point where the "pull-string" is attached. This loops through the u-bolt, to the wise.
 
Apologies for the confusion, the video and forum is all new to me, I don't normally have any involvement with online social media!
Anyway here's another video showing the idea hopefully abit clearer.
 
The shackle is at least 8 times the width of the string made of smooth stainless steel.
Since increasing the anchor height 1cm I now have barely any friction, I'm getting double the pull.
A small block would have been nice but the distance is limited between the grip and the wise, I may have run out of room!
 

Irvin

Talk Tennis Guru
sorry I dont see it. The description doesn't follow either. What is "loop OG string anchored to the from the wise" mean?

It just looks like 2 strings to a central point and the wise pulls that. how is it being doubled
Just look at picture of video in post 21. There is a bar from LO tension arm Where a loop “of” string is connected (not OG.) that string goes through the U bolt and to the wise gripper. Once the string is taught every 2 cm of Wise gripper pull pull the U bolt 1 cm closer giving you a 2x advantage (minus friction.) Assuming you put a string string in the gripper with the U bolt and set tension to 60 your reference tension is doubled to 120. There is 60 lbs on pull on the vertical bar and 60 lbs on the wise minus the friction of the string going around the U bolt.
 

Shroud

G.O.A.T.
Thanks everyone. Clearly it works even though I can't figure out why it does. Sometimes I just can't seem to get things. Its rare, but when it happens its like world class inability to understand.

So lets do this. If I take a string and wrap it around a pole and pull its half the force to each string. How his this any different? In Irvins example, 30lbs to each side of the loop at the Ubolt coming from the wise. What is making it 120??
 

Irvin

Talk Tennis Guru
So lets do this. If I take a string and wrap it around a pole and pull its half the force to each string. How his this any different? In Irvins example, 30lbs to each side of the loop at the Ubolt coming from the wise. What is making it 120??
Here’s an example. The man pulls the same as the weight and the pulley pulls at 2x the weight.


If the weight is replaced with some fixed like the vertical bar on the tension arm the what ever the man pull is doubled. The man would be the Wise and the pulley is connected to the string you tension. If you want 120 lbs set wise to 60.
 
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It's basically a ratio, a lift is a good analogy, everyone you add a block you gain more advantage.
The worrying thing is I'm starting to think this is a good idea!
Maybe I should share some of my ball machine mods!
 

Wes

Professional
@Goat Stringer,
I've been following along... waiting to see what the "endgame" here is supposed to be.

Is it your hope that you'll be able to implement this method so that you can cut the time it takes you to install your mains in half (since you clearly can't do this for the crosses)?
So, let's say it normally takes you 8 minutes to do 16 mains. Are you thinking that, by using this, you'll be able to do those 16 mains in just 4 minutes?

If that's the goal, personally I don't think it's going to happen.

Now, if the goal is to achieve tensions above the Wise's limit of 86lbs. (@Shroud), that's another story.

So, what exactly is the "endgame"?
In other words, what problem are you solving?
 
It's not about time, it probably would slow things down.
I have no interest in stringing above 60lb
For me it's all about creating an even, balanced symmetrical pull that will balance string tension and avoid unnecessary use of starting clamps.
Balancing the stress evenly on the frame, making sure the first 6-8 mains are perfect.
Trying to create a simple technique that everyone can use.
Although I think if this is a good idea why hasn't it been built into the tension head already? or has it.
I don't have experience of other machines, can they pull 120lb?
 

Shroud

G.O.A.T.
It's not about time, it probably would slow things down.
I have no interest in stringing above 60lb
For me it's all about creating an even, balanced symmetrical pull that will balance string tension and avoid unnecessary use of starting clamps.
Balancing the stress evenly on the frame, making sure the first 6-8 mains are perfect.
Trying to create a simple technique that everyone can use.
Although I think if this is a good idea why hasn't it been built into the tension head already? or has it.
I don't have experience of other machines, can they pull 120lb?
How could everyone use it? Don't you need a bunch of things that most people wont have?
 
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Wes

Professional
It's not about time, it probably would slow things down.
I concur.
For me it's all about creating an even, balanced symmetrical pull that will balance string tension and avoid unnecessary use of starting clamps.
Balancing the stress evenly on the frame, making sure the first 6-8 mains are perfect.
Trying to create a simple technique that everyone can use.
There are already methods that can accomplish that (even if you don't have, or choose not to use, a starting clamp).
I'm all for thinking "outside the box". It just seems, so far, that this is a solution to a problem that didn't really exist.

Also, I'd argue that getting only 1 main ahead, on each side, does balance the stress evenly.
Suppose you had 4 mains completed (2 on each side) - then did the 3rd on the left - then (a mere few seconds later) did the 3rd on the right - you don't think the frame is balanced?
 
I have not seen another method that can hold full tension on both strings with no clamps used in the process.

I think once the first 6 or 8 mains are done ( depending on the throat ) switching back to single pull would not unbalance the frame.

I imagine the first 6-8 strings are the most important with them being longer spans and taking more stress.

I will have to string a few rackets and see how my 15yr old gets on with them.

He will tell me straight away if there not good enough, he's already serving at 116mph and hitting 85mph one handed backhands!
I just enjoy playing around with things!
always got something in bits trying to improve it
Problem is when you have finished and there's bits left over
 

Irvin

Talk Tennis Guru
How could everyone use it? Don't you need a bunch of things that most people wont have?
I’m sure it could be made simpler. But the real question is will the machine, racket, string, clamps, and bases handle the extra tension you will be able to pull? I’m sure you have more drawback, wear, and tear on your clamps and bases at 86# than normal. What going to happen if you bump the tension up 50%?
 
Interesting, the clamps seem to hold better as there tightened together and have the same load ( 50lb on each clamp ) which balances them nicely.
The only real stress point I can see is where the string goes around the racket as it's one pull instead of two, but again balanced.
Normally when you pull your second main and release the clamp the load must increase to roughly double on the racket ( 50&50=100)

The only real reason I could see for not doing this is if the string breaks it would put more shock load on the tension head, but as it's 2:1 that's not the case.
Image if the tension head was pulling 120lb and the string broke!!!

I still can't find a good reason not to use this method and think it improves the stringing.

When it all goes horribly wrong I will let you know and you can all have a good laugh!
 

zinzan8

Rookie
I am no mechanical engineer, and am unfamiliar with some of the terms like piab and load cells, but a couple questions/comments anyways:
* are you asking more from the linear gripper than it was designed to handle? Is the force on the gripper double the usual?
* in regards to the two concurrent 50 lb pulls on the space between the 1st two mains, is this something you could ask @Babolat Official about, or one of the other racquet reps? Maybe they can find out if this is something that shouldn’t matter, would void warranties, or should be avoided for whatever reasons?
 
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The gripper is the only part of the set up that actually has double the load ( 2x50 )
It is more than capable of handling it.
At work we proof test lifting equipment,
10x load for man lifting.
I could test it to destruction, but I know the strings would break along time before that gripper fails.
The most controversial part of all this must be the stress as you say at top of the racket.

How about using a seesaw as an example.
Is it better to load one side then the other
or both at the same time?

I have just strung and tried out my old longbody prince and it feels great, best
string job it's every had!

It's a pleasure tightening the two base clamps together knowing there perfectly balanced.
 

Shroud

G.O.A.T.
Ok I don't get it but havent' really read too much to figure it out. Basically I have ditched the heavy high swingweight sticks where more tension would be welcomed for a 100g lighter stick with an estimated sw of 340-350 instead of the 400+ I was using. So no need for more than what the wise can do.
 

Irvin

Talk Tennis Guru
are you asking more from the linear gripper than it was designed to handle? Is the force on the gripper double the usual?
The gripper is the only part of the set up that actually has double the load ( 2x50 )
It is more than capable of handling it.
Unless I’m mistaken there are 2 linear grippers in this setup. There is a linear gripper on the Wise and another linear gripper the U bolt is connected that pull the string from the racket. The Wise gripper has normal tension which is 50% less with the diablo and the other that pulls the strings from the racket has 100 more tension than what is set on the Wise. So the second linear gripper has 4x the pressure of the wise which could easily damage the string.
 
It's two times on the gripper that floats,
100 instead of 50.
If you look at the string after the pull there
are no marks.
I think this is because a linear gripper is clever, it only grabs as much as it needs to over a longer surface area making it much better than a starting clamp or base clamp which rely on the user, squash or slip, it's a tricky adjustment.
100lb across two pieces of string through the gripper is less pressure than 50lb on a starting clamp with one piece of string due
to the surface area and the way it clamps.
Anyone fancy doing the math?
 
Just had a quick look, the linear gripper is 75mm long so 75x2 strings = 150mm X 1.3mm = 195mm2
Starting clamp 20mm x 1 string X 1.3mm
= 26mm2
Roughly 6 times more surface area through the linear gripper but only twice the load
must mean three times less pressure on the string!
It's also alot kinder due to the way it works.
 

Irvin

Talk Tennis Guru
Roughly 6 times more surface area through the linear gripper but only twice the load
must mean three times less pressure on the string!
Complete surface area does not count only the portion that contacts the string.

EDIT: pressure = force / area the smaller the area and the greater the force the higher the pressure.
 
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Very good point, but still over 6 times more length.
I suppose if you think about it the pressure on one string in the linear gripper at 50lb is the same as the pressure on two strings at 100lb
Twice the load, but twice the surface area.
Much kinder than a starting clamp!
 
One thing it could do if eventually incorporated into the machine itself is increase the life of the load cell (pulling only half the load has surely got to stress it less).
 
Interesting, I could set the wise at 25lb and pull one string at 50lb.
I just downloaded tennis tension which works very well.
My prince reads 54 that I strung at 50
Double pulling the first 8 mains.
My lads yonex reads 44 that was strung at 48 a week ago normally.
I'm definitely getting less tension loss
double pulling due to the clamping technique.
 

Irvin

Talk Tennis Guru
Very good point, but still over 6 times more length.
I suppose if you think about it the pressure on one string in the linear gripper at 50lb is the same as the pressure on two strings at 100lb
Twice the load, but twice the surface area.
Much kinder than a starting clamp!
6 times more length? How do you get that? The string from the racket does not go around the diablo which drops the tension between the diablo and gripper by 50%. Your still doubling the pressure on the 2 string you’re pulling.

Much kinder than a starting clamp? If it ain’t broke don’t fix it.
 
I was comparing the linear clamp to a starting clamp, not the wise.
I think a major cause of string breakage is from starting clamps weakening the string at the start of the mains when stringing.
So it is broke! and this is a fix as you know
longer need to use one.
This has only really showed up as a problem since using 18 gauge, it must be more sensitive to be crushed by starting clamps.
I'm enjoying using this technique and the stringing is better quality!
As I said before, when it all goes wrong I will let you know so you can have a good laugh!
 

Wes

Professional
I think a major cause of string breakage is from starting clamps weakening the string at the start of the mains when stringing.

This has only really showed up as a problem since using 18 gauge, it must be more sensitive to be crushed by starting clamps.
I suspect there are other factors at play here.
Even more likely, there's more than one factor working against you (synergistic effect).

First of all, exactly what is this 18g string you keep speaking of breaking at the point where a starting clamp was placed?
Something really soft, like X-One Biphase?

Second, exactly what starting clamp have you been using?
Maybe you've been using one that is very strong (which applies more force to the string).

Third, exactly where do you have the string reside within the starting clamp?
Near the tip? In the middle (near the eyelets)? At the bottom (near the hinge)?
 
It's Volkl V-Torque tour 18
I have spaced the clamp away from the frame, and moved it slightly away from the grommets, we discussed this in another thread a couple of days ago.
I always strung hybrid and the soft multi always broke in the middle of a cross.
Since going full poly, looks like the main is the
weak point.
I have only had this happen with this string.
 

Irvin

Talk Tennis Guru
I was comparing the linear clamp to a starting clamp, not the wise.
I think a major cause of string breakage is from starting clamps weakening the string at the start of the mains when stringing.
I can’t remember ever having a string break at a point where I used a starting clamp. I have damaged string with a bad clamp but I replaced the string before I finished the racket. If a starting clamp is damaging a string you either have a poor quality clamp or you’re using it wrong.
 
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