Debate: 2 vs 6 Point

[Mansewerz]

I've measured headwidth on my SP swing and the width increases with just the mains. When I put the crosses in (I put em in 2 lbs tighter just in case), the headsize when back to normal.

[mellofelow]

Originally Posted by Bud

The bow is not a very good analogy.

And why not? It's only a bit of a stretch... LOL pun intended! Please elaborate... don't just refute my analogy without a scientific explanation.

Honestly, considering you're using an X-2, I think you're so focused on the task at hand and failed to recognize this phenomenon.

IMHO, after 20+ yrs of stringing on Ektelon, the 6pt mounting system is the single most significant innovation in recent years (in string machines).

I do agree though that the racquet head will return to shape when cross strings are installed. Again that's because the law of physics is applied when pressure is applied (almost) equally from 360 degrees. Here's an analogy again. Remember in early shool we tried to break an egg in the palm of our hand? Impossible because the force is being applied from all around. In a racquet with the main installed, it's like breaking the egg with 2 fingers.

[Bud]

Originally Posted by Mansewerz

I've measured headwidth on my SP swing and the width increases with just the mains. When I put the crosses in (I put em in 2 lbs tighter just in case), the headsize when back to normal.

How much of a width increase did you note with just mains strung?

[Bud]

Originally Posted by mellofelow

And why not? It's only a bit of a stretch... LOL pun intended! Please elaborate... don't just refute my analogy without a scientific explanation.

With a bow, the forces are completely different... and you're dealing with 2 very flexible pieces of wood or fiberglass connected solely by a string. A bow is not mounted when strung nor is it braced in multiple locations due to different forces acting in different ways. Apart from that, they are identical!

Honestly, considering you're using an X-2, I think you're so focused on the task at hand and failed to recognize this phenomenon.

Perhaps, that's why I stated I'd focus directly on it when I string my next racquet, take pics and measurements. I'll let you know the outcome. To this point, i've not noticed significant deformation after stringing many racquets.

IMHO, after 20+ yrs of stringing on Ektelon, the 6pt mounting system is the single most significant innovation in recent years (in string machines).

I do agree though that the racquet head will return to shape when cross strings are installed. Again that's because the law of physics is applied when pressure is applied (almost) equally from 360 degrees. Here's an analogy again. Remember in early shool we tried to break an egg in the palm of our hand? Impossible because the force is being applied from all around. In a racquet with the main installed, it's like breaking the egg with 2 fingers.

So, being that I've strung many racquets on a 2-point system, from wood to brand new kfactor and everything in between and never had any issues with structural damage... why is a 6-point mount such an innovation in your opinion?

[Mansewerz]

Originally Posted by Bud

How much of a width increase did you note with just mains strung?

I believe it was about 1 inch, give or take a quarter inch. I don't remember the exact measurements, but it did get wider. After the crosses, it was fine again.

[Bud]

A HEAD Radical OS tennis racquet was strung on a Gamma X-2 with a 2-point mounting system (with included plastic collars) in order to measure racquet deformation at various points along the racquet head. This was performed to document and understand the effects/forces of a two-point mounting system on a tennis racquet head. A moderately flexible, oversize racquet was used to accentuate any potential deformation.

Equipment:

Racquet: Head Radical OS (Bumblebee) - Made in Austria
Headsize: 107 sq. in. (9-3 measurement - ~11.0")
Stiffness: 58-60
String: Babolat Tonic Gut 15 mains at 60#, Isospeed Baseline 17L crosses at 50#

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Measurements:

Two diagonals were measured (5 to 11 o'clock and 4 to 10 o'clock) and a measurement was taken from 3 to 9 o'clock. In addition, the inside and outside of the racquet frame, from approximately 1 to 5 o'clock and 7 to 11 o'clock, was traced on a piece of cardboard. Measurements and tracings beyond these points were not possible due to interference from the racquet mounting system.

Method:

Measured distances, traced frame on cardboard and took pictures (from overhead) when racquet mounted under no tension.
Measured distances, traced frame on cardboard and took pictures (from overhead) when racquet mounted under 60# tension on mains only.

Results:

Deformation from 5 to 11 was negligible (near the throat, the racquet head deformed slightly inward approximately 0.05").
Deformation from 4 to 10 was approximately 0.20" (0.10" each side) - outward.
Deformation from 3 to 9 was approximately 0.50" (0.25" each side) - outward.

Conclusion:

Racquet head deformation is small (~4.5% using 9 to 3 measurement) and barely noticeable (to me) on a moderately flexible, oversize racquet when mounted on a Gamma X-2 stringing machine using the 2-point mounting system and plastic collars.

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Will post pictures, ASAP.

[Mansewerz]

Is this just with mains measured? Also, you may not notice it as much with a frame that is already pretty round. But half an inch wider could be like .25" shorter.

[Bud]

Originally Posted by Mansewerz

Is this just with mains measured? Also, you may not notice it as much with a frame that is already pretty round. But half an inch wider could be like .25" shorter.

This is strictly with the mains strung and while the racquet is still secured to the stringing machine. That is what the experiment was for. It was to detect the bulging that occurred from 9 to 11 / 1 to 3. Were were determining the amount of stress/deformation on the racquet head with a two-point mounting system.

It won't be any shorter... the racquet head is constrained at 12 and 6. The only way it would/could be shorter is if the posts started collapsing/bending inward... or the turntable started collapsing upward... both of those scenarios could possibly affect the 'roundness' while the racquet is still on the stringing machine.

[Mansewerz]

Originally Posted by Bud

This is strictly with the mains strung and while the racquet is still secured to the stringing machine. That is what the experiment was for. It was to detect the bulging that occurred from 9 to 11 / 1 to 3. Were were determining the amount of stress/deformation on the racquet head with a two-point mounting system.

It won't be any shorter... the racquet head is constrained at 12 and 6. The only way it would/could be shorter is if the posts started collapsing/bending inward... or the turntable started collapsing upward... both of those scenarios could possibly affect the 'roundness' while the racquet is still on the stringing machine.

It has happened before on a stringing machine such as the x-2.

My RDX 500 MP shortened by 1/16th of an inch. Neglible, but still there.

[Bud]

Originally Posted by Mansewerz

It has happened before on a stringing machine such as the x-2.

My RDX 500 MP shortened by 1/16th of an inch. Neglible, but still there.

While still secured in the machine? or after you pulled it off and measured it fully strung?

How did you measure a difference of .06" with the mounting system in the way?

[Mansewerz]

Took it off the machine. Can't accurately measure when it's mounted. It was fully strung (I'm not hoping to crack a frame by having just the mains in!)

[Bud]

Originally Posted by Mansewerz

Took it off the machine. Can't accurately measure when it's mounted. It was fully strung (I'm not hoping to crack a frame by having just the mains in!)

Yeah, we're talking about the racquet... still secure in the machine... with the mains strung only.

If your mains are strung significantly higher than the crosses (or if they are a different material like poly or kevlar), it's possible the racquet head is shorter.

[mellofelow]

Originally Posted by Bud

why is a 6-point mount such an innovation in your opinion?

I don't claim to be a historian but modern era of stringing machine pretty much started by Ektelon. 30 years ago it was a solid hunk of steel, 2 pt mount, gliding bars and crank tensioner. Think about the evolution of machines since then, what has changed? Pneumatic tensioner, electronic tensioner, swivel base clamps, floating clamps... etc. No matter which tensioner is used, as long as they're calibrated to the exact tension and the string is clamped within a second or two... there are no differences in the result. As for the clamps, regardless which type, as long as there are no movement under tension, again... no differences.

So what is it then? Since you already confirmed the great debate about head shape deformation under load on 2 pt mounts, the only variable from any of the discussion obviously is that the 6 pt mounting system greatly enhances the frigidity of racquet head shape during stringing. That, my friend... is the only innovation that has improved and prolonged the life of your precious racquet in the last few decades. Anything else is mere luxury.

[Mansewerz]

Originally Posted by Bud

Yeah, we're talking about the racquet... still secure in the machine... with the mains strung only.

If your mains are strung significantly higher than the crosses (or if they are a different material like poly or kevlar), it's possible the racquet head is shorter.

Yea, but 1/16th of an inch is pretty much nothing. It's nothing to worry about. .1" is acceptable (from what Gamma Tech aka Bret told me)

[Bud]

Originally Posted by mellofelow

So what is it then? Since you already confirmed the great debate about head shape deformation under load on 2 pt mounts, the only variable from any of the discussion obviously is that the 6 pt mounting system greatly enhances the frigidity of racquet head shape during stringing. That, my friend... is the only innovation that has improved and prolonged the life of your precious racquet in the last few decades. Anything else is mere luxury.

I confirmed that any deformation is barely noticeable, if at all... on a large-headed very flexible racquet (which is a worse case scenario and why I chose the racquet to test). Deformation on a mid/mid+ or smaller headed racquet will be even less significant.

In your diagram, you have the area at 11 oclock going inward. That wasn't the case. There is some slight outward deformation that starts between the 10 and 11 o'clock region and increases until 9 o'clock. The deformation goes outward, not inward.

The only evidence of inward deformation was near 5 o'clock where the bridge, head and neck meet. That area (approximately 1.5" along the curve that transitions into the neck) deformed inward very slghtly (about .06").

So, basically, your diagram is incorrect. All 3 arrows should be pointing outward. The neck, below the bridge deforms slightly inward (.06").

Now, I'm going to research the 6-point mounting system and which forces it's designed to minimize. From what I can surmise, you assumed those forces were pointed inward and the 6-point was preventing the racquet head from collapsing inward. That's not the case.

[mellofelow]

Originally Posted by Bud

So, basically, your diagram is incorrect. All 3 arrows should be pointing outward. The neck, below the bridge deforms slightly inward (.06").

Now, I'm going to research the 6-point mounting system and which forces it's designed to minimize. From what I can surmise, you assumed those forces were pointed inward and the 6-point was preventing the racquet head from collapsing inward. That's not the case.

How the heck is a piece of oval graphite/composite positioned stationary at 2 points expand all around from 11 to 8 positions? It's not a WART! The volume increase at 9 must be displaced by somewhere else. Furthermore, a frame in the hands of more seasoned player, the 2 areas that get abused the most are 10 & 2. This is where you jam the racquet into the pavement on half volleys and/or drag the frame for 2 to 3 feet in full speed and full stretch. Therefore, you should do all you can to prevent anymore stress to those vulnerable points during stringing. My point is that the 6 pt mount provides that insurance over the 2 pt.

I'm done with this nonsense. I have both Ektelon (2pt) & Eagnas 910 (6pt) in my garage so I'm not speaking in theory.

Anyone else thinks I have my head in the sand, feel free to speak up.

[Bud]

Originally Posted by mellofelow

How the heck is a piece of oval graphite/composite positioned stationary at 2 points expand all around from 11 to 8 positions? It's not a WART! The volume increase at 9 must be displaced by somewhere else. Furthermore, a frame in the hands of more seasoned player, the 2 areas that get abused the most are 10 & 2. This is where you jam the racquet into the pavement on half volleys and/or drag the frame for 2 to 3 feet in full speed and full stretch. Therefore, you should do all you can to prevent anymore stress to those vulnerable points during stringing. My point is that the 6 pt mount provides that insurance over the 2 pt.

I'm done with this nonsense. I have both Ektelon (2pt) & Eagnas 910 (6pt) in my garage so I'm not speaking in theory.

Anyone else thinks I have my head in the sand, feel free to speak up.

Hey guy, didn't mean to upset your applecart. If you think about it, though, it does make sense.

Here is what happens: the forces from the tensioned mains pull inward... but, since the racquet is constrained from collapsing inward (from the mounts at 12/6 o'clock), it must bulge. It bulges the greatest at 9/3 o'clock (where no mounts constrain the racquet) and tapers off right before the mounting system (at 12/6)

Looking at a 6-point mounting system, I notice the mount prevents the racquet head from bulging outward... which is consistent with what I discovered. This is also the reason that some think the 6-point mounting system may be more detrimental to the racquet than the two-point system. The 6-point system doesn't allow the racquet head to expand/bulge (assuming the mounts are tight and touching the frame)... and thus puts a large amount of force on the racquet head directly at the additional mounting locations (10/2).

[Bud]

I'm also assuming, based on my experiment that there are no stringing machines on the market with outside mounting at 12/6 and 9/3... since that would not allow the racquet to bulge at all in the area that experiences the most deformation (9/3)... and would probably end up snapping the racquet at 10/2.

[Bud]

Originally Posted by Mansewerz

Yea, but 1/16th of an inch is pretty much nothing. It's nothing to worry about. .1" is acceptable (from what Gamma Tech aka Bret told me)

As I said, we're NOT talking about racquets that are fully strung and off the machine. This is about the stresses on the racquet head while the racquet is STILL IN THE MACHINE with the mains strung ONLY.

You keep referring to the racquet after it's strung and off the machine.

[mellofelow]

Originally Posted by Bud

Looking at a 6-point mounting system, I notice the mount prevents the racquet head from bulging outward... which is consistent with what I discovered. This is also the reason that some think the 6-point mounting system may be more detrimental to the racquet than the two-point system. The 6-point system doesn't allow the racquet head to expand/bulge (assuming the mounts are tight and touching the frame)... and thus puts a large amount of force on the racquet head directly at the additional mounting locations (10/2).

Bud, bud, bud... that statement was a Dud. The only thing it make any sense was you contradicting yourself.

Originally Posted by Bud

I'm also assuming, based on my experiment that there are no stringing machines on the market with mounting at 12/6 and 9/3... since that would not allow the racquet to bulge at all in the area that experiences the most deformation (9/3)... and would probably end up snapping the racquet at 10/2.

Wrong again!! Here again is the machine I used in the junior days. It's a piece of #^%$ work &%)! but got the job done nicely. And no!!! It would NOT break the racquet at 10/2. The effect is absolutely opposite. Having firm support at 9/3 creates the strongest structural design known on earth... AKA.. the Roman arch.


http://en.wikipedia.org/wiki/Arch

It's an open forum... but I really question your expertise to advise others in this subject.