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Hooked
02-28-2012, 08:37 AM
In doing my research on proportional stringing, I realized that most of the calculators, including the one on the USRSA site, do not include the string length between the frame and the tensioning head. This will cause you to drop tension too drastically on your outter mains and all of your crosses. When you factor in the total string length and use THOSE values instead, the tension drops from the middle mains is less drastic.

For example using my Volkl C10 Pro and Gamma X-6FC stringing machine:

The center mains are 13.0 inches long and the outter mains are 8.9 inches long. Assuming a reference tension of 60, most calculators will tell me to pull the centers at 60 and the outters at 41 [60*8.9/13.0] the other mains at descending tensions in between.

This gets even worse when you calculate the crosses. The center crosses are 9.5 inches long and the shortest cross is 6.5 inches long. Running the same math, the cross tension starts at 30, increases to 44 at the center and drops back down to 30 at the throat.

Now, if you factor in the string between the frame and the tensioning head (on my X-6FC anyway) the center main string length is 20.1 inches long and the outter main is 16.5 inches long. Using the total string lengths, the calculator tells me to pull the center mains at 60 and the outter mains at ~50 [60*16.5/20.1]. That's a 9 pound delta over the example above!

Doing the same thing on the crosses yields a range from 42 to 54. That's a 12 pound delta at the edges and a 10 pound delta at the center!

Be careful using the calculators when doing a proportional string job and use the TOTAL string length for the string being tensioned, not just the string length inside the head. As the frame rotates around the table, the length of the string inside the frame AND the string from the frame to the head changes affecting the tension. The range of length change from the tensioning head to the frame can vary by more than inch. If racquets were perfectly round, this would not be an issue, but they are oval and the distance to the head varies significantly.

KerryR
02-28-2012, 09:01 AM
Have you found proportional stringing effective? Have you found it worth the effort?

I've found that the lowest tensioned strings sometimes won't hold their (lower) tension-- the elasticity of the tighter strings to their (in)side often overcomes the friction at the turnaround and adds tension to the lower tensioned string. This is most evident on low-tension poly's, to the point that I've given up on it in that application. I used the Tennis Rocket calculator, as well as the 'tuning' methodology, also from the Tennis Rocket site.

Hooked
02-28-2012, 09:25 AM
Have you found proportional stringing effective? Have you found it worth the effort?

I've found that the lowest tensioned strings sometimes won't hold their (lower) tension-- the elasticity of the tighter strings to their (in)side often overcomes the friction at the turnaround and adds tension to the lower tensioned string. This is most evident on low-tension poly's, to the point that I've given up on it in that application. I used the Tennis Rocket calculator, as well as the 'tuning' methodology, also from the Tennis Rocket site.

I'll let you know. I'm about to try it on My C10 Pro and see how I like it. The numbers just seemed a bit silly to me when I used the calculator on USRSA.

The prep work is a chore with all the measuring and calculations and I assume that changing the tension on my drop weight machine will be a PIA too, but if it makes for a noticeably better string job, I'm in. If not, my proportional stringing days will be short.

From everything I read, the strings should hold their relative tension pretty well assuming standard string ports. Prince O port racquets and Babolat Woofer racquets probably don't work as the friction on the turns is lessened. I would assume the same with Polys as they are slippery compared to other types of string. I'm going to mark the strings at the grommets with a sharpie immediately following stringing to see how the strings move after hitting. I'll report back afterwards.

I also built my own proportional calculator in Excel to calculate the tensions and to also look at the reverse - what actual tensions are achieved when you used a fixed reference pull tension. Pretty interesting. On my C10 Pro, to get 60 pounds (actual) in the sweet spot, I need to pull 60/54. That's a bigger delta than I had been using, so if proportional turns out to be more of a time commitment than its worth, I'll at least use the prep work and calculator to figure out what pull tensions I need to use to achieve actual tensions - at least in the center of the racquet.

Irvin
02-28-2012, 09:43 AM
In doing my research on proportional stringing, I realized that most of the calculators, including the one on the USRSA site, do not include the string length between the frame and the tensioning head. This will cause you to drop tension too drastically on your outter mains and all of your crosses...

I don't see how that will make any difference at all. 60 pounds of tension is 60 pounds no matter how long the string is. BUT, if you are going to try out proportional string the bend at the racket WILL make a difference. The greater the angle at the grommet Between the tensioned string and the string from the racket to the tension head the more the friction. The more friction at the bend the less the tension on the tensioned string.

I was going to do a study on that but never did. I did notice the center mains when pulling at 60 pounds were just a little less than 60 pound. When I went out to the second, third, etc it dropped more the farther I went out because the angle is greater. Same will hold true for the cross except you have even more loss because you have the friction of the mains.

Hooked
02-28-2012, 10:58 AM
I don't see how that will make any difference at all. 60 pounds of tension is 60 pounds no matter how long the string is.

String tension and string length vary in direct proportion. Sixty pounds hanging on the end of a 6 inch string will yield a much stiffer string than sixty pounds hanging on the end of a 12 inch string. All the proportional calculators I have found take this into consideration for the string length differences inside the frame. There is less variation in length for the string section between the frame and the head but it is still significant. What may be more significant is that every string is longer when you look at the total length from the far side grommet to the tensioning head.

For example, instead of comparing a 6 inch string to a 12 inch string which will result in a 50% reduction of tension, you are comparing a 12 inch string to an 18 inch string, which will result in a tension reduction of 33%. Big difference.

I understand the issues with tension loss in the grommets, string intersections and angle pulls. My calculator doesn't compensate for those currently but perhaps I will add them based on my findings.

Like I said before, I'm not an advocate of this method. Just a curious stringer looking to try it out to see how he feels about it. Just couldn't get myself to come to grips with some of the tensions the calculators were suggesting. 60 on the center mains and 41 on the outter mains did not feel right to me...

Irvin
02-28-2012, 11:15 AM
If what you are saying is true why in the world would you want to even try proportional stringing? If you hand a 60 pound weight on a 6", 12", or 12' string you will have the same tension on each string. The shorter the string the stiffer the string I will agree. But that is the hold reasoning behind proportional stringing. You want each string to have the same stiffness and not the same tension. As the string gets shorter you want lower tension and longer strings will have higher tensions.

All of that happens naturally when you string a racket the crosses at the top and bottom of the racket have a greater bend at the racket which creates more friction and less tension. Since those strings are shorter it all evens out. Same the for the mains. The farther out you go the greater the angle the more the friction and the less the tension. The farther out you go the shorter the string.

Hooked
02-28-2012, 12:15 PM
All of that happens naturally when you string a racket the crosses at the top and bottom of the racket have a greater bend at the racket which creates more friction and less tension. Since those strings are shorter it all evens out. Same the for the mains. The farther out you go the greater the angle the more the friction and the less the tension. The farther out you go the shorter the string.

I'm not sure that this all happens naturally. I can see a 5-10% variation on some strings relative to others due to natural loss, but not a 10-12 pound delta. Have you checked your theory with a string meter? Would be curious to see what you get.

Irvin
02-29-2012, 02:21 AM
I'm not sure that this all happens naturally. I can see a 5-10% variation on some strings relative to others due to natural loss, but not a 10-12 pound delta. Have you checked your theory with a string meter? Would be curious to see what you get.

No so far it is just my opinion

Irvin
02-29-2012, 03:47 AM
I'm not sure that this all happens naturally. I can see a 5-10% variation on some strings relative to others due to natural loss, but not a 10-12 pound delta. Have you checked your theory with a string meter? Would be curious to see what you get.

Let me qualify why I think this happens. I pull from the level of the string bed and not from below the string bed. If you have 360 rotation and pull from below the level of the string bed then you have a preset angle from the level of the string bed down to the level of the tensioner. Until that angle becomes greater on the outside strings you should have a consistent tension on all strings. Because on my stringer the angle gradually increases from the center out there is a gradual difference in friction and the tension.

Hooked
02-29-2012, 04:31 AM
In reviewing the calculator numbers again, using the string lengths from the tensioning head to the far grommet is more realistic, but still theoretical. It doesn't account for the natural losses and assumes each string is independent. Big assumptions and huge areas for deltas from reality. So I grabbed a recently strung (48 hours ago), but not yet played frame and ran a stringmeter on every string as close to the center as I could. The results were very interesting. The stick is a Yonex RDS001 Mid+ (98 incher) with typical grommets. The mains are Weiss SCP pulled at 60 and the crosses are Weiss B5E at 58 pulled on my X-6FC drop weight machine. Most of the mains are between 50-58 using the string meter. The outtermost two are in the low 30's. The two adjacent to them are at 50. I'm pretty careful with my tie off tension loss but I do NOT currently add tension to my knot string pulls, although I am considering it. Most of the crosses are in the 40's with a few in the high 30's. The bed measures at 53 using Racquet Tune.

Using my proportional calculator in reverse to predict tensions based on the reference pull tension, I am not seeing a marked increase in tension on the shorter strings. They are much closer to each other in reality. There DOES appear to be quite a bit of evening out going on in reality.

Now I'm concerned that if I string proportionally, I'll probably just end up with a softer bed overall which is NOT what I'm looking for. A lot of time and effort for something that I probably won't like.

I think I'm going to stick with traditional stringing and add 10% to my tie off strings to see how that measures and plays over time. When I graph the string results, those string are, by far, the lowest tensioned strings in the bed. I wonder if upping them will help keep tension maintenance up a bit longer or if they will always be significantly lower because they only have strings on one side of them helping to increase tension.

Irvin
02-29-2012, 05:08 AM
I think you are going too deep but your findings stand to reason to me so far. Each string will have about the same tension because of the friction on the cross which will effectively make each string the same length. When you get to the outside string there is no other main outside it and the tie off did lose some tension so it should be lower. The next to the last main is a little looser because the main outside it lost tension due to the knot and some of that bled over to the next inner main. Also because the outer main tends to move outward because there is nothing to stop it there is less friction on the cross which lowers the tension on the inner main.

I just made a video on tension loss and the findings are very interesting (at least to me.) It is going to take me some time to finish up and edit the video and I will post it.

Irvin
02-29-2012, 10:14 AM
Here is a link to the video I made.

http://www.youtube.com/watch?v=SIWDWv1pk88&feature=youtu.be

What I found interesting is how much lower the crosses are tensioned as compared to the mains.

Also if your tensioner is at the level of the stringbed you naturally use proportional stringing and the center mains a crosses are tensioned higher because there is less friction in the center of the racket between the strings and grommets.

KerryR
02-29-2012, 10:32 AM
Cool analysis, Irvin. Thanks for posting that.

Hooked
02-29-2012, 11:03 AM
Here is a link to the video I made.

http://www.youtube.com/watch?v=SIWDWv1pk88&feature=youtu.be



Great stuff. Thanks for posting. Love the tension jig!

All the proportional models I've seen don't factor any of this stuff in.

Ever though of building a model that factors all of these things in to predict actual tension versus reference tension for each string? Might help see if actual tension consistency across the frame makes a difference or not. I'd be happy to put it together if you have the measurements from an entire frame. Or point me in the direction of your tensioning jig and perhaps I'll get one.

Irvin
02-29-2012, 11:57 AM
...Ever though of building a model that factors all of these things in to predict actual tension versus reference tension for each string? Might help see if actual tension consistency across the frame makes a difference or not. I'd be happy to put it together if you have the measurements from an entire frame. Or point me in the direction of your tensioning jig and perhaps I'll get one.

Not so sure that would be a good idea. Many stringing machine do not have self centering mounts which means if the racket is mounted off center as many do you angle will be greater on either the top or the bottom whichever is farther from the pivot point.

To make the jig it is simple. I got a digital luggage scale off the bay and took the big hook off. Then I tie the string to the point where the hook was and used a PVC connector to hold the scale away from the frame. My stringing machine mounts the racket so it floats between the outside supports and it is 1/2" above the arms. I was thinking of using 1/2" plywood under the racket so I could mount the scale to the plywood but never got that far. Then nothing touches the racket.

KerryR
03-01-2012, 06:01 AM
'Tuning' the mains might (?) avoid all these issues; a method discussed on "Tennis Rocket" (if you sign up for the forum). All this means is that you tension the first 2 mains, then each subsequent main is tensioned and strummed until it matches the tone of the first mains, so, as the main shortens, it's tension drops. This is pretty fast and easy.

Problem is, you can't do the crosses the same way.

I've tried this several times, but only ever ended up with a mushy feeling stringbed.

Hooked
03-01-2012, 06:45 AM
'Tuning' the mains might (?) avoid all these issues; a method discussed on "Tennis Rocket" (if you sign up for the forum). All this means is that you tension the first 2 mains, then each subsequent main is tensioned and strummed until it matches the tone of the first mains, so, as the main shortens, it's tension drops. This is pretty fast and easy.

Problem is, you can't do the crosses the same way.

I've tried this several times, but only ever ended up with a mushy feeling stringbed.

I've seen this and it seems to be the most foolproof way to equalize tension on the mains as you say, but I think the bigger issue is that proportional stringing appears to lower the overall bed stiffness significantly that I believe what some people swear by may be more due to a softer stringbed than anything else.

The crosses are the tricky part as they introduce several variables to the tension equation. In looking at the mains tensions of one of my actual string jobs, the mains are very consistent until 8 where tensions drops off pretty steeply. Drop from ~50 to low 30's. The crosses are a little less consistent. Steeper variations from string to string but a similar overall trend with relatively low tension on the tie offs, highest tension near the ends and a dip in tension in the middle. The overall tension of the crosses is ~10 pounds below the mains, despite only being pulled at 2 pound less.

KerryR
03-01-2012, 07:34 AM
That's pretty much what I found with proportional methods-- just a softer string bed. In order to push the average of all mains up, the first 2 mains need a LOT of tension, enough that I'm hesitant to try it.

I find I get easy control of the string job by avoiding the proportional thing, and just work with 'static' ref. tensions to get a string bed stiffness that feels nice and behaves well. I find that low tension full poly accomplishes this.

Hooked
03-01-2012, 07:37 AM
Here is a link to the video I made.

http://www.youtube.com/watch?v=SIWDWv1pk88&feature=youtu.be



Thanks for sharing your stringing knowledge - freely. Great videos up there. I adopted the bead method on weaving crosses. My daughter had a few bead collections collecting dust that I raided and found a couple of good options.

I wanted to clarify something in your tension video above. On the Prince you stated that you were pulling at 65. When you did the hard weave pull in the middle you got 55.5 which is 9.5 pounds off reference. When you did the hard pull near the throat, you got 53.1 which is 11.9 pounds below reference. Assuming the crosses in between, fall in between those values, the crosses will have actual tensions at 9.5-12 pounds below reference. I'm guessing that this is why my cross measurements were trending well below the mains. The average main tension I measured was 50.6 (ref. 60) and the average cross was 41.8 (ref. 58 ). These measurements were taken ~48 hours post stringing, so a large tension loss had already occurred.

Steve Huff
03-01-2012, 07:18 PM
Any part of the string beyond the clamp is irrelevant in the string length measurement when doing proportional stringing. Past the clamp, all the tension is gone as soon as you release the gripper. A more relevant measure of string would be the amount between the clamp and the edge of the frame. If you position your clamps right up against the grommet, you decrease the amount of string that tension was released on. That small length of string will more accurately be the tension of the following string. Either way, it's a minor issue, whereas your end product's playability is the major, comparable (although subjective) factor of concern.

Hooked
03-02-2012, 04:08 AM
Any part of the string beyond the clamp is irrelevant in the string length measurement when doing proportional stringing. Past the clamp, all the tension is gone as soon as you release the gripper. A more relevant measure of string would be the amount between the clamp and the edge of the frame. If you position your clamps right up against the grommet, you decrease the amount of string that tension was released on. That small length of string will more accurately be the tension of the following string. Either way, it's a minor issue, whereas your end product's playability is the major, comparable (although subjective) factor of concern.

This does not make sense. Tension is pulled before clamping. Proportional stringing is all about the string length but most calculators only look at the length inside the frame. That would be great if the grommets isolated the rest of the string in between the frame and the head during tensioning, but they don't. Perhaps a 10-15% isolation due to friction at severe angles, but far from 100%.

Based on looking at the data with the string meter and the video Irvin put together, the whole proportional thing seems to be a good idea in theory but does not translate to reality as there are many other variables that it does NOT account for. Perhaps you can get more even tension by acoustically tuning the mains, but stringing the crosses at lower tensions is going to result in cross tensions far below where most people will find them playable. As I stated before, I think the people that swear by proportional stringing are people that may just be enjoying low or super low tensions IMO.

KerryR
03-02-2012, 05:49 AM
...As I stated before, I think the people that swear by proportional stringing are people that may just be enjoying low or super low tensions IMO.

That's what I think is going on. Those same folks might really enjoy low tension full poly setups...

Irvin
03-02-2012, 06:37 PM
...Perhaps you can get more even tension by acoustically tuning the mains, ...

I am not a big fan of proportional string but I don't think the tuning of the mains will work either. Think about it, when you have only the mains strung the racket is shorter by about 1/4". After stringing the crosses it is back to normal. If you tuned all the mains with not crosses what happens to the 'tune' when the racket stretches back?

Valjean
03-03-2012, 03:50 PM
I am not sure the purpose of proportional stringing is respected enough.

The serious purpose, after all, wasn't to equalize the stringbed simply, but merely to expand the sweetspot for better play--specifically. for enhanced power and control when hitting off-center and toward the edges of the racquet.. This is tested for when you drop a tennis ball on the outer strings, and demonstrated by the higher bounce you get. One play-significant side effect is greater racquet forgiveness, particularly desired in close net play of course....

Steve Huff
03-03-2012, 09:08 PM
Hooked--think about it. Yes, the entire length of string is pulled, but only that which is before the clamp remains at that tension. After the clamp, the string is released, put through the next hole, and pulled at that tension. So, the playable length of the string is estimated to be that inside the frame (where its clamped). You could be pulling the string at 60# from 6 feet away, but it's only the part inside the clamp that makes any difference.

jim e
03-04-2012, 09:58 AM
You want more of a placebo effect with your racquet and game, go here to w w w dot so-stab dot com, and they can relieve you of some $ and promise you the world with their proportional stringing method.

You know I'm sure most of the pros game is in their physical and mental abilities. You really do not hear of pros going through all this, or even know much about stringing in general.

Irvin
03-04-2012, 10:10 AM
^^If it were true Jim I am sure all the qualifiers would be going there.

jim e
03-04-2012, 11:43 AM
^^If it were true Jim I am sure all the qualifiers would be going there.

Thats exactly my point.
Marketers will will make it available to be able to sell you just about anything asked for, no matter what the item or being the truth or not.

Hooked
03-05-2012, 04:14 AM
Hooked--think about it. Yes, the entire length of string is pulled, but only that which is before the clamp remains at that tension. After the clamp, the string is released, put through the next hole, and pulled at that tension. So, the playable length of the string is estimated to be that inside the frame (where its clamped). You could be pulling the string at 60# from 6 feet away, but it's only the part inside the clamp that makes any difference.

The empirical evidence doesn't seem to support the theory though. The theoretical pull tensions are ridiculously low. Too low to be playable unless you enjoy super low tension string beds. I have tried those and they are not for me. Although they are super comfortable and you can get crazy amounts of spin on balls struck at waist height and above, I find them unplayable when hitting low and/or heavy balls from a stronger player.

The conclusion I'm taking away from proportional stringing is that the reason people like it may not be related to the proportional stringing tensions as it is about a much lower overall tension as a result of stringing with this method. Like I stated near the beginning, I do not have a vested interest either way, I'm just trying to understand what is happening in reality, how it affects a string bed and if I will like it in my own sticks.

I plan to string a stick proportionally using the USRSA calculator with a inexpensive SG and measure the tensions with a string meter then try it out.

Valjean
03-05-2012, 09:27 AM
Proportional stringing, though, was first introduced into the lexicon by the USRSA back in the 90s, in an article about Boris Becker's use of same. (For those curious enough to care, the PS employed for Becker's use did not involve the crosses in the lower half of the stringbed.) And unlike racquets and strings today, PS, being a mere stringing method, can be cost-free to the consumer, and even go unpublicized, hence no marketing approach is necessary and called for. How applicable it is for baseline bashers can be debated as well.

For the record too, when a dynamic stringbed tester is used, there is little or no fall-off in the reading when PS has been employed, in my experience.

Hooked
03-06-2012, 02:43 AM
And unlike racquets and strings today, PS, being a mere stringing method, can be cost-free to the consumer...

If I was stringing for money, I would be charging more for proportional stringing. Measuring all the strings and calculating the tensions is time consuming. Changing tensions during the job is not the end of the world, but keeping it all straight through a string job is going to slow you down.

Stringers that do proportional jobs at no extra charge are just absorbing the extra time/cost - at least on that first job on each stick. Not a big deal if you have 1% of your client base that asks for it I guess, but there is a real cost to be considered unless you apply a one size fits all proportional method based on an average size frame. I've seen posts from others that modify the method and simply drop tension at a predetermined rate as they go. Middle 4 mains at reference, next 2 at -1, next 2 at -3 and so on. Not a true proportional job though.

Do stringers that charge their customers for PS charge extra? Do they calculate the tensions for each frame individually or apply a one size fits all model?

Valjean
03-06-2012, 05:56 AM
It isn't as though techniques that are, what, "time-consuming" aren't being applied now, though. Virtually any "trick of the trade" could qualify. What makes them neutral in cost-sensitive terms is that they are habit, part of what a given stringer does, and has to.

I go by what head size, string, string pattern and game the player has. There are so few of those it's easy. Minor adjustments can be made in each case, if that's called for.

Hooked
03-07-2012, 01:14 AM
OK. I strung my Prince OG Oversize proportionally. Shouldn't knock it until I try it - right? Some observations:

Measuring and recording the string lengths is the biggest time sink. Once you have that though you never need to do it again. Changing tensions as I went wasn't too bad. Slowed me down a bit, but I was stringing with synth gut so I picked up some time there. Been a while since I strung with SG. Forgot how easy it was to string.

Immediately after it was strung, I measured the full bed with racquetTune. My reference tension was 65, the overall bed measured 55. Then I used my string meter to measure every string as close to the middle as I could. In comparison to a standard string job:

The proportional job was more consistent across the mains. Excluding the two outermost mains (7 and 8 ), the proportional job ranged from 55-60 pounds. A recently strung regular racquet had a range of 12 pounds (55-67), showing a marked increase in tension at the 5th/6th mains on both sides. So a significantly tighter tolerance across the mains on the proportional job, but at a lower point. The standard stick was strung at 58 and the proportional at 65.

The proportional job was also more even in the crosses with tension rising in a straight line from head to throat. There was no marked tension increases at the top and bottom that I see in standard string jobs.

The proportional job tension delta between the mains and crosses averaged 20.1 pounds! The mains average 53.6 pounds and the crosses 33.5. The crosses were ~50% below reference tension! On a standard string job I see a delta between mains and crosses more in the 10 pound range so this appears to be the most significant difference between proportional and standard jobs from a pure tension standpoint.

I marked the string at every grommet with a sharpie to see how it creeps after playing. I hit the courts tomorrow and will report back on how it feels.

Irvin
03-07-2012, 03:05 AM
...Measuring and recording the string lengths is the biggest time sink. Once you have that though you never need to do it again...

Why not use the tennis rocket calculator it is a lot easier?

http://tennisrocket.us/Stringing.aspx

Hooked
03-07-2012, 04:26 AM
Why not use the tennis rocket calculator it is a lot easier?

http://tennisrocket.us/Stringing.aspx

It is a lot easier and I would probably use it if I was stringing proportionally for others. I did a spot check on my POG OS and tennisrocket varies by up to 3 pounds from the actuals I got by using the measured lengths. Probably close enough for most but I wanted to be spot on for this play test.

If I feel the bed is too soft, I'm going to try re-stringing with the crosses at a reference 10 pounds higher than the mains. That should raise the crosses to be about 10 pound less than the mains on average - more like a standard string job.

Hooked
03-08-2012, 04:35 PM
OK. Played the POG OS with the proportional job. Have to admit I was impressed. Partially because I had low expectations going in but I was pleasantly surprised that it had good control and was very comfortable. A touch too much power for me but once I dialed back my swing speed a few notches, I settled into it nicely. This may be the best full synth gut job I have played to date. The strings also didn't move. There are a few sharpie marks that moved maybe half a millimeter in from the grommet but most of the marks are still right at the grommet.

Time for the next test. Going to A-B Tecni X1B/BC on two identical, matched frames. One PS85 will be proportional at 65/75 reference tensions and the other will be standard stringing at 58/55 (my current favorite setup). Both should measure in the high 50's on the full bed.

Hooked
03-16-2012, 12:23 PM
OK. I was able to hit with my matched PS85s last night. Both were strung with Tecni X1B 17 Red mains and Tecni BC 17 crosses.

Racquet B was strung at 56 on the mains and 53 on the crosses. Immediately after stringing I measured the string bed using racquetTune. It registered 53.0. Then I measured every string using a string meter. I measured each string as close to the middle of its length at least 3 times to make sure I was getting a consistent reading. The mains measured; 32,48,53,54,54,56,54,54,53,54,58,58,57,57,50,37. The crosses measured; 28,38,38,35,38,36,39,37,39,40,42,44,44,44,44,44,42 ,32. The average of the mains was 52. The average of the crosses was 39. A ~13 pound delta.

Racquet A was strung proportionally using 60 as the reference tension for the mains and 75 for the crosses. I decided to up the crosses radically to minimize the delta between the mains and crosses I experienced when using the same reference tension for both on my first proportional string job on a different frame (POG OS). Immediately after stringing I measured the string bed using racquetTune. It registered 54.9. Then I measured every string using a string meter. The mains measured; 27,42,52,56,58,59,61,60,59,60,60,57,57,54,42,31. The crosses measured; 26,34,35,38,40,39,42,42,42,42,46,45,45,46,44,40,37 ,28. The average of the mains was 52. The average of the crosses was 40. A ~13 pound delta.

For completeness, both frames were measured for weight, balance and swingweight. Weight and balance were identical at 362 grams and 12 3/8” (9 points HL). SW on A was 330 and B was 332. As close to an apples to apples comparison of two different string techniques that I can do.

Then I hit the court with a hitting partner for 90 minutes trading the two frames between us every 15 minutes or so. We weren’t playing a match, just hitting all sorts of shots to feel out the deltas in the string. We didn’t discuss our opinions while hitting but it was pretty apparent which frame was more consistent. When we finished, we shared our thought and our conclusions were essentially the same. The racquet with the modified proportional string job (A) was significantly more comfortable and more forgiving of off center shots. The standard string job much less so. The difference became quite pronounced whenever the pace ramped up and we had less time to set up. We also felt the standard job became increasingly difficult to find the sweet spot as we approached the 90 minute mark and our arms and legs began fatiguing from a pretty aggressive hitting session.

My take away on proportional stringing so far is that in its pure form, the crosses end up being too loose for my game. See my post above for my thoughts after stringing and using my POG OS. However, by upping the cross reference tension to compensate for this, I got noticeable better results without the springiness I got with a standard job. I also noticed that when I looked at the actual tensions of the sticks on a graph, the proportional stick was much more consistent left to right and top to bottom. The main curve was almost ideal. The cross curve was a gently rising slope from top to bottom. The curves on the standard string job were noticeably more lumpy with significant rises in tension as you approached the frame edges. I have decided to use this method on my string jobs for the time being. I use the reference tension to calculate the main pull tensions and increase the cross reference tension by ~25% and use that higher figure to calculate the pull tensions for the crosses. I end up with a string bed that has a similar overall tension as a standard job at the reference tension but with a much more consistent feel across a wider area of the string bed.

Irvin
03-16-2012, 12:27 PM
Here is what I get out of all you said. The proportionally strung racket was strung at tensions that resulted in lower (feeling) tension and you and your friend like the softer string bed best.

EDIT: Do you know yet if you can string one of the rackets conventionally at lower tensions and get a string bed similar to the proportional racket?

Steve Huff
03-16-2012, 09:58 PM
Hooked--I agree with you that maybe it's just the lower average tension that appeals to some players. I've tried it, and it felt as if I had just lowered the overall tension some. I couldn't tell any difference in control either. Maybe we're hitting on the same thing, just in 2 different ways.

Hooked
03-17-2012, 04:14 AM
Here is what I get out of all you said. The proportionally strung racket was strung at tensions that resulted in lower (feeling) tension and you and your friend like the softer string bed best.

EDIT: Do you know yet if you can string one of the rackets conventionally at lower tensions and get a string bed similar to the proportional racket?

I don't think I was very clear. The two racquets felt the same in terms of ball depth when hitting the ball well. Good spin and baseline depth on both. When striking the ball in the sweet spot, they felt essentially the same. The difference didn't start to be noticeable until you hit off center. On the proportional string, the off center hits felt more comfortable and resulted in noticeably fewer errors. These 85's are demanding racquets to play. Things start out great, but after an hour of playing aggressively it becomes increasingly difficult to find the sweet spot with that 85 inch head. These racquets also hit a really heavy ball so you need to set up early and get around on the ball to strike cleanly - consistently. When forced to strike the ball on the run you sometimes don't have that luxury so we both found the proportional string to be more forgiving during those times.

Hooked
03-17-2012, 04:27 AM
Hooked--I agree with you that maybe it's just the lower average tension that appeals to some players. I've tried it, and it felt as if I had just lowered the overall tension some. I couldn't tell any difference in control either. Maybe we're hitting on the same thing, just in 2 different ways.

I found that to be the case when I did a by-the-book proportional string job. Lower overall tension but I also noticed that the string bed felt more consistent in a wider area even though I felt I had too much power. I like to generate power from my swing, not my string. That's when I decided to try upping the cross tension radically to see how it would play. Even when using 75 as a reference on the PS85 crosses, the maximum pull tension on the longest crosses was 55 pounds, which happens to be closer to where I pull my crosses when doing a regular string job. This gave me the overall tension feel I like (55-58 ) with the more forgiving string bed the proportional job provides. I think that by using a proportional technique but manipulating the reference cross tension I've landed on a stringing technique that gives me the best playing string bed I have used to date. I'm going to try it out on my Diablo next which is my match stick and see how it goes. I'll use 60 and 73-75 on that one too. According to the calculations, that will put the middle crosses at 56-58.

Hooked
03-19-2012, 03:39 AM
Anyone else using a proportional method but altering the reference tensions? Curious if anyone else is on this island.

Hooked
03-21-2012, 02:44 AM
Bueller? Bueller?

Feeling a little like Tom Hanks in Cast Away. Maybe I'll stencil a face on one of my Wilson sticks and name him...Wilson;)

Steve Huff
03-22-2012, 03:41 PM
So, are you changing the reference tension for the crosses only? Wasn't sure quite what you meant.

Hooked
03-23-2012, 03:14 AM
So, are you changing the reference tension for the crosses only? Wasn't sure quite what you meant.

Yes. On a recent string job, I used 60 on the mains and 72 on the crosses. Although it sounds odd to say it that way, the longest crosses are pulled at 56 pounds. The longest mains are pulled at 60. The result feels like a standard string job using 60/56 as your tensions give or take a few pounds, but the string bed feels more consistent than a standard string job.

Here are the actual pull tensions used in the example above:

Mains: 38,45,50,54,56,58,59,60,60,59,58,56,54,50,45,38
Crosses: 33,40,44,48,50,52,54,55,55,56,56,55,55,54,52,50,48 ,44,40,33

And the actual measured (using a String Meter) tensions after pulling:

Mains: 32,46,53,57,57,60,60,59,59,59,59,57,57,53,49,32
Crosses: 27,38,39,38,37,38,41,40,45,43,44,44,43,47,42,46,38 ,41,38,28

The mains are more consistent over a wider width with the 10 inner mains all within 3 pounds of each other. This is more consistent than what I measured using a standard string job. The crosses are also more consistent than a standard string job but there is a wider variation than what I find on the mains.

When I strung another stick using a by-the-book proportional string job, the average cross tension was 20 pounds below the average main tension. And it played too soft. By upping the cross tension in the calculator, the crosses now average ~13 pounds less than the mains which is closer to the delta I see when measuring a standard string job.

So I am getting a more consistent string bed without making it too soft that it becomes a rocket launcher. The sticks I have strung with this modified proportional method play great and have a wide sweet spot. I find it makes my smaller head racquets a significantly more forgiving, particularly when you play past the 60 minute mark.

Steve Huff
03-23-2012, 07:07 PM
I guess you're factoring in the tension loss due to friction. You still lost me. I thought you pulled tension at 72# on the crosses, but your chart of actual tension pulled is only 56 (and decreasing). Not quite sure what you meant.

travlerajm
03-23-2012, 07:58 PM
I'm intrigued by this thread.

But one thing I'm dubious about is how well the differential tensioning can hold without eqilibrating a bit.

Hooked: did you go and remeasure the individual string tensions of your PS85s after hitting? I know you used the felt markings, but I'm not sure how that correlates with tension. I'm curious about how much equilibration there is, and whether the frames will gradually play more alike over time?

I might have to give it a try soon.

Hooked
03-24-2012, 03:35 AM
I guess you're factoring in the tension loss due to friction. You still lost me. I thought you pulled tension at 72# on the crosses, but your chart of actual tension pulled is only 56 (and decreasing). Not quite sure what you meant.

When you enter the tension in the calculator it multiplies it by the length of the string divided by the longest strong (1L & 1R mains). In other words, when you use a proportional calculator, it will always spit out results that have cross tensions that never achieve reference tension. If the longest main is 10" and the longest cross is 8", the highest pull tension on the crosses will be 80% of that value. So if you have a reference cross tension of 60, the longest cross will be pulled at 48. However, by upping the cross tension only in the calculator, you will increase the cross tensions overall and minimize the delta between the mains and crosses (and not end up with such a soft string bed). The good news is that you still get the consistent feel across the string bed that proportional stringing provides.

I have come to the conclusion that the true benefit of proportional stringing is not to get equal stiffness on all of the strings. That does not appear to be practical as there are many variables that make that ideal impossible to achieve on the crosses. As someone who enjoys tensions in the high 50's, a true proportional job was too soft for me, but I did appreciate the advantage it provided in a more even playing string bed. So I am now using this hybrid approach where I use a proportional calculator, but up the cross tension ~20% to get the pull tensions higher, where I find them more playable.

Hooked
03-24-2012, 03:50 AM
Hooked: did you go and remeasure the individual string tensions of your PS85s after hitting? I know you used the felt markings, but I'm not sure how that correlates with tension. I'm curious about how much equilibration there is, and whether the frames will gradually play more alike over time?

Good idea. I haven't but will. I would be curious to see how the string beds age too and if they end up in a similar place or maintain their differences until the end. Still a bit surprised at the difference we felt. Now my hitting partner is requesting I string all his sticks this way. Just made more work for myself.

Steve Huff
03-29-2012, 06:41 PM
Gotcha. Interesting. I agree that there's a lot of tension loss due to friction which would correlate with your findings. I'd be interested in your findings when you used different strings (different materials, different TEXTURES, etc). Lots of work, interesting results though.

Hooked
03-30-2012, 04:08 AM
Gotcha. Interesting. I agree that there's a lot of tension loss due to friction which would correlate with your findings. I'd be interested in your findings when you used different strings (different materials, different TEXTURES, etc). Lots of work, interesting results though.

I've been keeping a spreadsheet of all my findings. It a bit tedious to do all the measuring and document it all, but it is very helpful to review the data and see what is actually going on. The main benefit to proportional appears to be the near ideal mains tension across the bed. Certainly more consistent than regular stringing which tends to put too much tension on mains 3-5 on both sides. The crosses too tend to be more consistent when strung proportionally but still way down overall from the mains. My modified method seems to end up ~2 pounds below a standard job comparing identical frames and strings. I might try a string job just doing the mains proportionally and the crosses regular to see how it compares.

As a side note, I really dislike the really soft multis like; Tecni NRG2, XR1 and Bab XCel. They drop tension so quickly. String them at 60 and they come off the machine in the mid 50's and become rocket launchers with a few hours of hitting. Think I'm done playing around with them. Back to Tecni X1B.

stoneage
03-31-2012, 08:39 AM
I have come to the conclusion that the true benefit of proportional stringing is not to get equal stiffness on all of the strings. That does not appear to be practical as there are many variables that make that ideal impossible to achieve on the crosses.

A correct observation! The idea of having equal stiffness on all strings is not based on what the string bed in racquet looks like and how the strings behave. The outer strings are shorter and stiffer, but they are deflected less and contribute less to the string bed stiffness. And you right in that the problems is much more complex.

stoneage
03-31-2012, 08:52 AM
I used my stringBed tool to calculate the differences and similarities between a string bed with radically varying tension and one with the same tension everywhere. If I let the mains vary from 12 - 26 kg and the crosses from 8- 26 kg I got the same string bed stiffness ("feel") as in racquet with 22 kg. But the latter was 15% stiffer at an off center hit. More about this calculation in the 4th post here:
http://tt.tennis-warehouse.com/showthread.php?p=643793

/Sten

_________________________________________________
racquetTune (http://racquetTune.com), stringBed (http://www.appmaker.se/stringBed) and swingTool (http://www.appmaker.se/swingTool) racquet apps for the iPhone/iPad.

travlerajm
04-06-2012, 05:51 PM
Just strung up my BLX Pro Tour with 1.10 18g kevlar mains at 45 lbs, and Silverstring 17g 1.20 crosses at:

Top 4: 35 lbs
Next 5: 44 lbs
Bottom 11: 50 lbs

I did the crosses with 3 separate tie-offs to eliminate tension equlibration (doesn't really take much extra time or effort to do this).

The intent is to offset the power gradient from top to bottom.

Bouncing the ball on my stringbed, I can really tell the difference. The top of the stringbed feels just as lively as the bottom, without the harsh feeling near the top. I'll hit with it tonight and report back.

travlerajm
04-06-2012, 11:15 PM
Just strung up my BLX Pro Tour with 1.10 18g kevlar mains at 45 lbs, and Silverstring 17g 1.20 crosses at:

Top 4: 35 lbs
Next 5: 44 lbs
Bottom 11: 50 lbs

I did the crosses with 3 separate tie-offs to eliminate tension equlibration (doesn't really take much extra time or effort to do this).

The intent is to offset the power gradient from top to bottom.

Bouncing the ball on my stringbed, I can really tell the difference. The top of the stringbed feels just as lively as the bottom, without the harsh feeling near the top. I'll hit with it tonight and report back.

Update: WOW!

This was the most amazing, most versatile stringbed I've ever hit with.

The amount of spin was borderline ridiculous, with the rpm so high it looked like the ball was going to explode. after half an hour of wall hitting, the ball looked like the fuzz had been through 3 days of match play. But the rebound angle didn't seem to vary much with the swingpath like it does with other spin-friendly stringbeds I've used in the past. The control on volleys and slices was still there. I think using this extreme tension gradient in the crosses is the way to go. I doubt that I'll ever string my crosses with one piece of string again.

I did notice after I hit with it that the 4 crosses at the top were actually a bit tighter than when it came off the stringer, even though these were done as a separate piece ( the shape of the racquet was noticeably slightly wider near the top than near the bottom, as it looks like the frame shape had adjusted in response to the differential tension). In any case, the result was very satisfying.

Hooked
04-07-2012, 07:37 AM
I used my stringBed tool to calculate the differences and similarities between a string bed with radically varying tension and one with the same tension everywhere. If I let the mains vary from 12 - 26 kg and the crosses from 8- 26 kg I got the same string bed stiffness ("feel") as in racquet with 22 kg. But the latter was 15% stiffer at an off center hit.

Hi Sten,

Big fan of your apps. Thank you for making them. I use raquetTune and swingTool all of the time. They have taken a lot of the guesswork in my pursuit to find/customize the perfect racquet for my game.

My experience is mirroring your stringBed tool findings. Now that I'm measuring every string after every string job and plotting the results I'm seeing the differences and similarities between standard stringing and the modified proportional stringing method I've been using recently.

When I chart the string tensions of the mains strung in a traditional method, the chart profile looks like a soft "M" with the center mains down a bit relative to the shoulder mains. The crosses look similar but the second bump on the "M" (the one closer to the throat) is noticeably higher. I'm guessing this is due to the increased string bed tension as you near the end of the string job and perhaps less frame narrowing at that point. I'm assuming most of the frame narrowing occurs when the center crosses are pulled which may drop the tension in the top crosses a bit.

I'm going to try a 50/50 string job with my modified method to see if it is more consistent on the crosses from top to bottom. I think this is why the mains look nearly ideal when I string them with my modified method.

Hooked
04-07-2012, 07:48 AM
Just strung up my BLX Pro Tour with 1.10 18g kevlar mains at 45 lbs, and Silverstring 17g 1.20 crosses at:

Top 4: 35 lbs
Next 5: 44 lbs
Bottom 11: 50 lbs

I did the crosses with 3 separate tie-offs to eliminate tension equlibration (doesn't really take much extra time or effort to do this).

The intent is to offset the power gradient from top to bottom.

Bouncing the ball on my stringbed, I can really tell the difference. The top of the stringbed feels just as lively as the bottom, without the harsh feeling near the top. I'll hit with it tonight and report back.

You may also want to try stringing the top ones higher than the bottom ones to see what you think. My measurements show that a top-to-bottom cross stringing yields noticeably higher actual tensions at the bottom compared to the top. Maybe +5 (1 & 2), +4 (3 & 4), +3 (5 & 6), +2 (7 & 8 ) and +1 (9 & 10). The bottom half should more or less take care of itself.

Guessing that the actual tensions in your string job have a delta that is greater than the pull tensions due to the tendency of bottom crosses being higher - at least on a top-to-bottom cross stringing pattern. That is what I'm seeing.

travlerajm
04-07-2012, 08:36 AM
You may also want to try stringing the top ones higher than the bottom ones to see what you think. My measurements show that a top-to-bottom cross stringing yields noticeably higher actual tensions at the bottom compared to the top. Maybe +5 (1 & 2), +4 (3 & 4), +3 (5 & 6), +2 (7 & 8 ) and +1 (9 & 10). The bottom half should more or less take care of itself.

Guessing that the actual tensions in your string job have a delta that is greater than the pull tensions due to the tendency of bottom crosses being higher - at least on a top-to-bottom cross stringing pattern. That is what I'm seeing.

Maybe you didn't understand my intention?

I was not trying to equalize stringbed stiffness. I was trying to make the stringbed stiffness near the bottom (where apparent coefficient of resitution is ~3x that of the top) much stiffer than the stiffness near the top. That way there would be less of a power gradient.

Take a look at the racquet sweetspot power maps on the TW University site to see the gradient I'm referrring to.

Hooked
04-07-2012, 09:19 AM
Maybe you didn't understand my intention?

I was not trying to equalize stringbed stiffness. I was trying to make the stringbed stiffness near the bottom (where apparent coefficient of resitution is ~3x that of the top) much stiffer than the stiffness near the top. That way there would be less of a power gradient.

Take a look at the racquet sweetspot power maps on the TW University site to see the gradient I'm referrring to.

I did misunderstand what you were going for. I was assuming you were trying to achieve even bed stiffness.

Steve Huff
04-07-2012, 03:45 PM
Hooked, look at the Pro Supex MP 3 Uniflex racket. What are your impressions of it? Just curious.

Hooked
04-08-2012, 03:14 AM
Hooked, look at the Pro Supex MP 3 Uniflex racket. What are your impressions of it? Just curious.

I just looked at it. That's one way to help ensure more consistent string tension. I think it will be difficult for people to get past the looks though. Wonder how it plays and how it is selling. What are you thoughts?

Wilson's Perimeter Weighting System (PWS) also serves to make the center crosses more consistent in length on racquets equipped with it. Not as broad as the Pro Supex design, but with a less severe look. My BLX 6.1 Team has the center 6 (8-13) crosses at approximately the same length (9.25 inches). On my PS85's the PWS makes the PWS crosses a touch shorter then the crosses immediately adjacent to the PWS bump.

The Yonex Isometric racquets are a touch squarish looking. Their designers were going for this affect too, but in a more market acceptable look.

Hooked
04-08-2012, 03:21 AM
Well I did the modified proportional with a 50/50 technique on the crosses. The cross tensions did not even out as I was hoping. I still get more tension in the lower half than the top. Perhaps the handle keeps that side from deforming compared to the top and will always have more tension than the top. I might try adding tension to the top half to compensate and see what happens.

As aside note, 50/50 stringing is a total PIA especially when you add in the unique tensions for each cross. Going back and forth took a lot longer than normal as I kept having to double check the cross number and pull tension to make sure I wasn't making errors. I'm glad this method did not provide more consistent tensions. I don't think I ever want to string crosses 50/50 again.

travlerajm
04-08-2012, 08:16 AM
Well I did the modified proportional with a 50/50 technique on the crosses. The cross tensions did not even out as I was hoping. I still get more tension in the lower half than the top. Perhaps the handle keeps that side from deforming compared to the top and will always have more tension than the top. I might try adding tension to the top half to compensate and see what happens.

As aside note, 50/50 stringing is a total PIA especially when you add in the unique tensions for each cross. Going back and forth took a lot longer than normal as I kept having to double check the cross number and pull tension to make sure I wasn't making errors. I'm glad this method did not provide more consistent tensions. I don't think I ever want to string crosses 50/50 again.

Hooked,
I'm not sure I understand the point of trying to get equal tension in all of the crosses. Isn't the whole idea of "proportional"string to get a more uniform ball response across the stringbed? In order to get a uniform ball response, the tension in the lower half of the stringbed needs to be much stiffer than at the top. I've tried it and it works amazingly well.

Hooked
04-09-2012, 12:16 PM
Hooked,
I'm not sure I understand the point of trying to get equal tension in all of the crosses. Isn't the whole idea of "proportional"string to get a more uniform ball response across the stringbed? In order to get a uniform ball response, the tension in the lower half of the stringbed needs to be much stiffer than at the top. I've tried it and it works amazingly well.

Yes. The ultimate goal is to get uniform ball response. The proportional methods don't account for the top versus bottom half crosses. I will try your method for crosses and see how it plays. How did you arrive at the values you selected for the pulling tensions?

I notice that tensions increase naturally from top to bottom in standard, proportional and my modified proportional stringing methods. I can't explain it but I'm guessing it is due to the added rigidity of the throat being connected on that side helping it to maintain its shape/size more than the top. Keep in mind I'm using a 6-point mounting system (and the racquets are always centered on the table), so frame deformation should be minimized and tensions deltas on the outermost pulls roughly equal. Even still, there is definitely a marked increase in tension near the throat side every time even when stringing the crosses 50-50.