Tutorial: Easily measuring your string tension

V

vandoc

Guest
MarcR,

Just wanted to thank you for a good job. When my doubles partner misses an easy putaway, I just boink him in the head with the string bed and say I'm practicing my string tension frequency testing :mrgreen: Great job on the program, very easy to use. Just to clarify, for multifilament strings like Wilson NXT, would you use 1.7 g/m?
 

MarcR

New User
@vandoc

I would suggest a value of approx 1.4 g/m . But you can easily
measure the mass-density of the NXT on your own. When you
string your NXT next time on your racket put the string set on
a simple kitchen weighing machine and measure the weight in
grams, then divide this weight by the length of the set (usually
something link 12 m) and you have the mass-density of the NXT.
Maybe even some people in the forum have a set of the NXT
at home and can do this measurement for us right now.

@all readers

If you have some set of string at home, I'd be glad if you could
spent some minutes and calculate the mass-density and post it
here. Especially nylon string are appreciated. Maybe we can built
a database of mass-densities for all kinds of strings then.

mass-density = weight-of-string-set[grams] / length-of-string-set[meters]

Please specify string-length,weight and calculated mass-density.

Marc
 

fastdunn

Legend
I think the frequency-based tension tests are good for reasonable checking
on stringing job quality with an arbitrary string. I think the key advantage is
in the mass/density in the formula which allows you reasonably consistent
calibration value to the reference tension, if the stringing job was consistent.
You can not do this with Stringometer.

However, I can check stringing job quality via Stringometer for my favorite string
that I use repeatedly. Stringometer also let you check individual string's relative
tension while frequency based test can not (it trys to calculate absolute tension
of the whole stringbed).
 

MarcR

New User
Update

Hi,

I just finished a new version of my program. It now features a small database
of mu-values of several string types (Polyester with 1.18 mm diameter ... Polyester with 1.35 diameter,...).

freqmess2.jpg


http://www.tennis-altensteig.de/marc/freqmess-eng.zip

I used the following list of mu values that I calculated via the volume-densities
of the materials (Polyester: 1.39 g/cm³, Nylon: 1.14 g/cm³ ) :

d= 1.18 mm
Nylon : 1.25 g/m
Polyester : 1.52 g/m
Aramid : 1.59 g/m
d= 1.2 mm
Nylon : 1.29 g/m
Polyester : 1.57 g/m
Aramid : 1.64 g/m
d= 1.22 mm
Nylon : 1.33 g/m
Polyester : 1.62 g/m
Aramid : 1.70 g/m
d= 1.25 mm
Nylon : 1.40 g/m
Polyester : 1.71 g/m
Aramid : 1.78 g/m
d= 1.28 mm
Nylon : 1.47 g/m
Polyester : 1.79 g/m
Aramid : 1.87 g/m
d= 1.3 mm
Nylon : 1.51 g/m
Polyester : 1.84 g/m
Aramid : 1.92 g/m
d= 1.33 mm
Nylon : 1.58 g/m
Polyester : 1.93 g/m
Aramid : 2.01 g/m
d= 1.35 mm
Nylon : 1.63 g/m
Polyester : 1.99 g/m
Aramid : 2.08 g/m
d= 1.38 mm
Nylon : 1.71 g/m
Polyester : 2.08 g/m
Aramid : 2.17 g/m
d= 1.4 mm
Nylon : 1.75 g/m
Polyester : 2.14 g/m
Aramid : 2.23 g/m
d= 1.44 mm
Nylon : 1.86 g/m
Polyester : 2.26 g/m
Aramid : 2.36 g/m

Nylon stands for synthetic gut strings.

One can now easily switch between units like (lbs,kg) and (in²,cm²).

More info at http://www.tennis-altensteig.de/freqmess.html

Marc
 

montx

Professional
I wonder what the accuracy is like though it may not be as precise as stringmeter nevertheless an interesting thought that you can do it measuring the frequency. In theory it could probably work, but depending on how well the mic pics up the sound is another point.
 

Gaines Hillix

Hall of Fame
MarcR said:
@vandoc

I would suggest a value of approx 1.4 g/m . But you can easily
measure the mass-density of the NXT on your own. When you
string your NXT next time on your racket put the string set on
a simple kitchen weighing machine and measure the weight in
grams, then divide this weight by the length of the set (usually
something link 12 m) and you have the mass-density of the NXT.
Maybe even some people in the forum have a set of the NXT
at home and can do this measurement for us right now.

@all readers

If you have some set of string at home, I'd be glad if you could
spent some minutes and calculate the mass-density and post it
here. Especially nylon string are appreciated. Maybe we can built
a database of mass-densities for all kinds of strings then.

mass-density = weight-of-string-set[grams] / length-of-string-set[meters]

Please specify string-length,weight and calculated mass-density.

Marc

Marc, kudos for all of the work on this. On the mass density string database thing, that's a good idea. A couple of things to consider with doing this at home is that to be accurate one would really need a scale that would measure to 1g . Also, sets of string can vary in length. It's common for them to vary as much as .3m from what's marked on the package. It would be better to premeasure the string before weighing it. That wouldn't throw the calculation off that far, but still a consideration.
 

fastdunn

Legend
spirit said:
MarcR, Using the string meter doesn't sound much different than this computer generated method. Neither method will match the tension of a freshly strung racquet to be the tension you set the stringer at. Per your original post which I quote here:
.

spirit, only key difference, IMO, is to use the string's weight and density
to calculate the calibration for an arbitrary string.

Stringometer uses an averaged value for this calibration.

So let's say you just have strung up an unknown string.
With a Stringometer reading, it's not clear whether your string job was
good enough or not (it's only averaged stats).

With frequency based method, we have more accurate measure on your
string job quality, IMO, because calibration value depends on the string's
weight and density. Only variable is your string job quality here.

Well, with Stringometer, if you string the same string couple of times
and record its readings, you get pretty good idea about your string job
quality ONLY on that string. You get another different string,
it won't be clear again....
 
Could this technique be used to measure tension loss due to clamp drawback? I have an MS200TT and have wondered how much tension is lost due to not recovering all the drawback due to the grommet friction on the next pull. On some pulls there's roughly 1/32 of an inch that's not recovered.
 

Kevo

Legend
1/32 of an inch isn't anything to worry about. Your strings are going to lose anywhere from 6%-14% of their tension just sitting around after stringing. Just adjust your tension up or down depending on how it plays over time. You have to find a happy medium between playability right after stringing, and playability over the life of the string in your racquet.
 

MarcR

New User
@CheapStrings

Just excite the single string, whose tension you want to measure, and
record the sound via microphone and Freqmess before and after clamping.
There is some tension-loss due to the movement of the clamps, but Kevo
is right the tension-loss due to clamp-movement is negligible compared to
tension-los due to stress-relaxtion of the strings through time.
 

mido

Rookie
MarcR said:
@all readers

If you have some set of string at home, I'd be glad if you could
spent some minutes and calculate the mass-density and post it
here. Especially nylon string are appreciated. Maybe we can built
a database of mass-densities for all kinds of strings then.

mass-density = weight-of-string-set[grams] / length-of-string-set[meters]

Please specify string-length,weight and calculated mass-density.

Marc

Marc, here are some mass-densities. Digital scale with 0.1g accuracy was used.

Poly or poly composite
Signum Pro Poly Plasma 17-1.23 mm: 1.65
Signum Pro Poly Plasma 18-1.18 mm: 1.52
Signum Pro Poly Megaforce 18-1.19 mm: 1.52
Babolat Pro Hurricane 17-1.25 mm: 1.69
Klip K-Boom 17-1.25 mm: 1.64

Synthetic gut, nylon or solid core with multi wrap
LaserFibre Synthetic Gut Classic 16-1.30 mm: 1.59
Signum Pro Ultra Power SF 16L-1.28 mm: 1.58
Prince Synthetic Gut w/Duraflex 16-1.30 mm: 1.51

Multi fiber
Signum Pro Fiber High Tec EXP 16-1.30 mm: 1.56
Tecnifibre X-One Biphase 17-1.24 mm:
Tecnifibre X-One Biphase 16-1.30 mm
Tecnifibre NRG2 16-1.32 mm:
Klip Excellerator 16-1.29 mm: 1.47
Klip Excellerator 17-1.25 mm:
Wilson Sensation 17-1.25 mm: 1.39
 

Rich

New User
If I understand this correctly, it's not uncommon that after stringing with a pull-tension machine the actual tension is about 10 kg lower than the tension that the stringing machine was set on?

As I ususally string my raquets at the medium recommended tension, which is usually 2 kg above minimum recommended tension, this means that the actual tension that I'm playing with is way below minimum recommended tension. Is this correct? So, generally speaking, I should set my stringing machine about 10 kg higher than I always did?

B.t.w., I haven't downloaded your tutorial and program yet, which is what I'm about to do now. Very interesting stuff!

Thanks,
Richard
 

MarcR

New User
Hi Richard,

no do your stringing as usual. You can't prevent the tension loss
of 10 kg and you shouldn't try to compensate the tension loss by
stringing 10 kg higher. Because you will receive a string bed that
nobody can play ( except Thomas Muster :D ), as the tension and
stiffness would be much to high.

The problem with this whole thing is that everyone (including me) thought
that if one strings with a 25 kg pull-tension (reference tension) he will get
a tension of 25 kg on the strings ( but there are only ~15 kg of real tension
on it). So everyone thinks "Hey thats the way 25 kg feel.", when playing the
racket with 15 kg real tension on it. But you definately won't have 25 kg
of real tension on your racket. You want to have 15 kg of real tension, so
you have to string with 25 kg pull-tension (or reference-tension).

That whole tension-loss thing is only important when you want to convert
the real-tension my program measures to the formerly pull-tension (reference tension),
as the normal user is more used to these values. Because thats the
value he adjusts his stringing-machine to.

Greetings,
Marc
 

squashstring

New User
MarcR said:
@CheapStrings

There is some tension-loss due to the movement of the clamps, but Kevo
is right the tension-loss due to clamp-movement is negligible compared to
tension-los due to stress-relaxtion of the strings through time.

MarcR, thanks for the program - very interesting. Maybe Kevo and you have higher-quality stringing machines than me, but I tensioned a string between two clamps and measured a 10% drop in frequency when the pulling force was removed. A 10% drop in frequency gives about 20% drop in tension.

As there is usually only one clamp involved (the other end of the string coming from the grommet hole in the frame), this could be construed as a tension drop of half of 20% (i.e. 10%) due to a single clamp bending towards the centre of the racket. The clamps might not move very much, but even a small movement like 2mm makes a significant difference to the tension.

Some of this lost tension will be recovered when you tension the next string along, but not very much, due to the friction caused by the string passing through two grommet holes as it passes out of and back in to the frame.

On another matter, when calculating the mass density of string, presumably we should weigh the string and then divide this by the stretched length. I just tested some natural gut that I use in my squash racket, and it stretches by 4% when I tension it to 30lbs. Therefore I would get an answer from your program that is 4% too low if I didn't take this into account.

Finally, I have found the easiest way to measure/calculate the area of a racket is to cut out some thick cardboard and then weigh it on a jewellers electronic weighing scales (0.1g accuracy). Then compare this with the weight of a known size of the same cardboard (e.g. 20cm x 20cm). I'm getting answers within a few percent.

Thanks again for sharing the program - very useful. I'm in the middle of converting from stringing on a drop-weight flying-clamp machine to a manual-crank swivel-clamp machine. I've discovered that rackets that I used to string at 29 lbs on the old machine measure as 14.5 lbs. Alarmingly, the first racket I strung on the new machine (also at a nominal 29 lbs) measured to be just 12 lbs. It's rather powerful! I need to check the calibration and compensate for the lack of constant pull - maybe consider prestretching.

Paul
 

MarcR

New User
Hi Paul,

you're right, machines with crank mechanism will leave you with
tension that are a bit lower than tensions you achieve with
constant-pull machines using the same reference-tension.

That trick with the cardboard is very clever :D

You're right, the string elongates when tensioned (Polys elongate by ~ 4% and
Nylons elongate by ~ 9-15%). So strictly one has to divide the mass of the
strings on ones racket by the true length after tensioning. But what would be
a convenient procedure to take the elongation into account (as the elongation
is tension dependent) when calculating the mass-density for strings ? So I
left this error due to elongation in my mass-density values without any try to
compensate for this error.

I will string a racket right now and take this opportunity to measure how much
the frequency decreases after clamping. I will post my results later on.

Thanks for the feedback :)

Greetings Marc
 
Hi MarcR,

Sorry to bother you I can tell your a very intelligent guy into racquet stringing.

I thought I was a very intelligent guy into racquet stringing untill I read this post.

I seem to have got lost along the (5 pages of posts) way.

for a person all lost in a sea of information (ME)

what real use is your programme.

I'm thinking that if it's no use increasing the pull on my machine to take into account
the relaxation of the strings, draw back, & other issues affecting tension.

simply put how where and why should I use it.

when I first started reading your post it all sounded so very good, now with everyone's input(some of whom understand more about string tension than I ever will)

I just cant get hold of it in my mind.

can you explain like " Measuring Your String Tension For Dummies"

regards,

tricky.
 

squashstring

New User
tricky nicky said:
Hi MarcR,

... I can tell your a very intelligent guy into racquet stringing.
I think we all agree with that!

Actually, back in the 80s, I used to be intelligent too; then I had three children and something happened to my brain!:mad: These days, I can just about remember my name - Phil? Pete? Pat? - no, that's gone too!:confused:

tricky nicky said:
simply put how where and why should I use it.
The beauty of this program is that we can (and will) all use it in different ways.

Ever since I started stringing, I have always been uncertain what actual tension I achieved in each stringing job. I knew (because I was using a drop-weight machine that I had calibrated myself) what the pulling tension was, but I could see my flying clamps shifting slightly, and when I started using Tecnifibre and natural gut, I could see the string stretching if I left the pulling tension on for a few seconds.

The first few rackets I strung were for myself, so I experimented with different pulling tensions. I still remember the first racket I strung - the tension was far too high. When I started stringing for others at my squash club, most players hadn't a clue about tensions, and didn't seem to care what tension I used. In fact, the only reason the vast majority of players get their rackets restrung is that they've broken the strings! I think tennis players are a bit more discerning when it comes to strings and tensions, etc. A few of my customers, however, were quite particular, and requested particular tensions, or said, "a bit more than last time", "it's winter, so drop the tension by 2 lbs", etc.

I don't mean to leap in and answer Marc's questions for him, but here is my perspective on the questions you ask.

How?

I use the program on my laptop. The inbuilt microphone picks up too much fan noise, so I use a external headset microphone. As squash rackets don't ring as loudly as tennis rackets, I whack the racket against my head (nothing to damage there)! The heel of my hand is too soft. If you're worried about brain damage, use the handle of another racket - anything hard that doesn't ring.

You need to provide the program with two facts: the area of the string bed, and the mass density of the string. You can get the area from a number of different methods
- the manufacturer's website
- trace the outline (the inside of the frame - the vibrating string mass extends up to the grommets) onto squared paper and counting the squares - count every square with 50% or more of its area inside the outline.
- trace the outline onto thick cardboard with a known or measured weight/area. Cut out the shape and weigh it. As an example, if you're using 120gsm card, and you weigh the cutout shape and it weighs 7.6g, then the area of the racket is 7.6/120 = 0.0633m2, or as Marc's program expects cm2, 633 cm2. If you have a jewellers weighing scales (I have one for setting the tracking weight of my hifi turntable pickup), and you're handy with a scalpel, this method only takes 15s.

The mass density of the string is an indication of how heavy it is. For a given tension, heavy string will vibrate at a lower frequency thatn light string. Marc's program expects the information in grams per metre length. I weighed a 11.4m coil of string, and found that it weighed 17.8g. As 11.4 is the unstretched length, and gut stretches by 4% when tensioned to 30 lbs, I added 4% to the length to get 11.9m. Therefore the mass density is 17.8/11.9 = 1.50g.

Where?
I do all my stringing at home, so that's where I'll be using it. Obviously tournament stringers will be able to use this at tournaments etc.

Why?
I'm sure we'll all come up with different reasons for using this program. Here are mine:

This program has come at a perfect time for me as I am about to change from a drop-weight flying-clamp machine to a crank-arm swivel-clamp machine. The first racket I strung with the new machine ended up with an actual tension that was far too low. Using Marc's program I could verify that the actual tension was 12 lbs instead of 14.5 lbs. This is despite using a pulling tension of 30/28 lbs on each machine! With a bit more investigation, I will be able to work out how to compensate for the lower actual tensions achieved with my new machine. Hopefully, when I start using the new machine to string for my customers, I will be able to achieve near-identical tensions to those I got using the old machine.

If you are lucky enough to string for players who give you their rackets BEFORE the strings are broken, you will now be able to identify the actual tension in the strings. After the stringing job, you will be able to confirm that the new tension is X% higher. You can even provide a service for your customers where you can advise them over the following days/weeks/months what their tension loss is.

Actually, my main reason for being so interested in this program, is that it has given me a much greater understanding of the relationship between the actual tension in the racket and the original pulling tension, stringing method, type of machine, type of clamp etc. This will make me a better stringer (I hope), by helping me to be more consistent.

Sorry to rabbit on, but as you can probably tell, this topic interests me!

Thanks again to Marc for improving our understanding of stringing. This is what the World Wide Web was designed for - I'm sure Tim Berbers-Lee would approve.

Paul
 
Why is that Gaines?

one more question.........if you don't mind answering?

if I'm pulling with the machine set at 58 lbs and I use this programme to discover the actual tension after stringing is say 50 lbs.........

why cant I just increase the pull tension to 66 lbs to compensate.....

and why isnt it that simple........

sorry thats more than one more question.

regards,

tricky.

ps squashstring thanks for taking the time.

regards,

tricky.
 

squashstring

New User
tricky nicky said:
if I'm pulling with the machine set at 58 lbs and I use this programme to discover the actual tension after stringing is say 50 lbs.........

why cant I just increase the pull tension to 66 lbs to compensate.....

... because the tension figures that people alway use (manufacturers, players stringers) is the pulling tension. This is very unsatisfactory as every combination of stringer/machine will achieve a different amount of tension loss and therefore end up with a different actual tension. This is why players who are particular about their string tension will always use the same stringer (who will always use the same machine).

If stringers knew exactly how much tension loss happened during (and shortly after) their stringing job, then they could use actual tension figures and add on the appropriate amount when stringing.

At the moment, good stringers have a rough idea of the relative tension loss during their stringing jobs. They will ask new customers what tension their racket is normally strung at, and try and establish whether a constant pull, or spring and brake machine was used. They will then try to work out (or in some cases just make a wild guess) what pull tension to use to give an actual tension that the customer is happy with. They will then seek out feedback from the customer and record all these details so that the next time they string a racket for this player, they can get it even better.

Marc's program will allow us to measure actual tensions and in Lord Kelvin's words:

"When you can measure what you are speaking about, and express it in numbers, you know something about it.

But when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind."


Paul
 

Gaines Hillix

Hall of Fame
tricky nicky said:
Why is that Gaines?

one more question.........if you don't mind answering?

if I'm pulling with the machine set at 58 lbs and I use this programme to discover the actual tension after stringing is say 50 lbs.........

why cant I just increase the pull tension to 66 lbs to compensate.....

and why isnt it that simple........

sorry thats more than one more question.

regards,

tricky.

ps squashstring thanks for taking the time.

regards,


The RDC will give you total weight, swingweight, frame flex and stringbed stiffness all on the same machine. Squashstring did a good job of answering your second question. The actual tension as measured by an RDC or Marc program is never going to be the same as the set tension on the machine because the machine and stringer combine to lose some of the set tension during stringing. strings loose tension by about 10% in the first 24 hours after they are strung, but every string is not the same. Some lose more or less during and after stringing.
 
ok thanks guys for filling me in.

one more thing, yes or no will suffice.

If I were to string just 1 particular frame with one particular string and I used this test to measure actual tension after stringing and it was say 5 lbs lower than I set my electric machine to pull.

the next time I string that frame with that string if I increase the pull by 5 lbs would I get closer to what I originaly wanted it strung at?


regards,

tricky.
 

Gaines Hillix

Hall of Fame
tricky nicky said:
ok thanks guys for filling me in.

one more thing, yes or no will suffice.

If I were to string just 1 particular frame with one particular string and I used this test to measure actual tension after stringing and it was say 5 lbs lower than I set my electric machine to pull.

the next time I string that frame with that string if I increase the pull by 5 lbs would I get closer to what I originaly wanted it strung at?


regards,

tricky.

No, this method is always going to be lower than the set tension. If you raise it you're going to have a stiffer stringbed than you bargained for.
 
Ok Gaines now I'm getting it.

didnt I read once that the average human brain needs to be told something up to 7 times before it understands?

regards,

tricky.
 

SW Stringer

Semi-Pro
squashstring says: "The beauty of this program is that we can (and will) all use it in different ways . . . Marc's program will allow us to measure actual tensions and in Lord Kelvin's words: . . . "

I've been seriously considering getting a manual crank machine, but I don't know what kind of repeatability one could expect from such a device that is basically patterned after the trigger mechanisms in firearms. I suppose Marc's program would facilitate making that kind of measurement. Is that something you've done already? Just curious.
 

Gaines Hillix

Hall of Fame
SW Stringer....just my 2 cents worth on your last question. I'd believe that would be one of its best uses, i.e. measuring the results from string job to string job to verifiy consistency of what the machine and its stringer are actually producing given the same set of variables(machine, racquet, string, set tension and the person doing the job).
 

SW Stringer

Semi-Pro
Gaines Hillix says: "SW Stringer....just my 2 cents worth on your last question. I'd believe that would be one of its best uses, i.e. measuring the results from string job to string job to verifiy consistency of what the machine and its stringer are actually producing given the same set of variables(machine, racquet, string, set tension and the person doing the job)."



Gaines Hillix . . . On this point I'm in 100% agreement! :D
 

flash9

Semi-Pro
Freqmess Program Testimonial

I have been personally using the Freqmess v0.7 Program to measure the String bed Tension and Stiffness in my racquets for the past year. In fact it was the reason I choose to purchase a stringing machine and to take up stringing myself late last year.

I was disappointed in the tension consistency I was receiving from the tennis stringing I was getting from my local pro shop. I was requesting that my racquets be strung at 68lbs, and the Freqmess Program was reporting back real tension anywhere from as high as 42lbs, to as low as 31lbs right after the racquets were strung! Those of you not familiar with the program if reports back tensions that are 20 to 22lbs below the pull tension. When I asked the stringer about calibrating the stringer he said the Ektelon Model H they had did not require calibration “since it had just been serviced last year”. Obviously, it did since the tension was varying more the 11lbs with every string job. The Freqmess Program was a great tool for me to use to measure the tension loss over time. Once the string bed tension dropped by about 15% or around 12lbs, I would cut out the strings.

Frustrated with the inability to get a consistent string job, I choose to purchase the ALPHA Revo4000, and the WISE 286 Electronic Tension Head and take up stringing myself. We only started late last year (2005) but we are stringing on average 10 racquets a week, and word is spreading fast. My point is that from day one, we have used the Freqmess Program to measure the String bed tension and stiffness of every racquet we have strung. Every time we are between 20 to 23lbs lower then the pull tension just like Marc says in his write up. I had purchased a small digital scale and any string a customer asks me to use, I first weight the string to the 10th of a gram, then measure its total length, and calculate the strings mass-density. I also take a piece of the scrap string after I have strung and set the tension head to 60lbs and clamp the piece of string between the clamps and tension head, then measure the before and after length to get the percentage elongation and have factored this into my string density calculations. I now have values for the following strings.

ALPHA Flexel 16 1.33mm;1.325
ALPHA Gut2000 16 1.33mm;1.424
BABOLAT Attraction 16 1.30mm;1.406
BABOLAT Ballistic 17 1.25mm;1.67
BABOLAT Ballistic 16 1.30mm;1.76
GOSEN Polylon SP 17 1.24mm;1.545
GOSEN OG-Sheep Micro 17 1.22mm;1.278
GOSEN OG-Sheep Micro 16 1.29mm;1.44
GSG Super-Power Gut 16 1.32mm;1.60
HEAD Rip Control 17 1.2mm;1.21
KLIP Armour Pro Gut 16 1.3mm;1.597
PRINCE Lighting XX 17 1.25mm;1.29
PRINCE SynGut DuraFlex 17 1.22mm;1.279
TECHNIFIBRE NRG2 16 1.32mm;1.59
TECHNIFIBRE PolySpin 17 1.275mm;1.77
TECHNIFIBRE Spinfire 17 1.25mm;1.77
TECHNIFIBRE X-One 17 1.24mm;1.375
TECHNIFIBRE X-One 18 1.18mm;1.250
WILSON Enduro Pro 17 1.25mm;1.55
WILSON NXT 17 1.24mm;1.275
WILSON Sensation 17 1.25mm;1.39
WILSON Sensation 16 1.30mm;1.402

I tell all of my customers about the program, but I think only a couple have actually been using it to keep track of their tension loss.

This program also allows us to attempt different setups, yet attempt to keep the string bed stiffness the same with different strings and different tensions. Also, we record the real tension and string bed stiffness in a spreadsheet for each customer. For Hybrids, I have been just taking the average of the two strings mass-density’s, this is not perfect, but the best I can figure out. This process tends to measure pretty close to 20lbs off from the pull tension, and it gives us a baseline, in our strive to provide our customers with consistent string jobs every time.

The most important thing to me with stringing tennis racquets is CONSISTANCY. The reason I purchased the WISE 286 Tension head, was to produce consistent tensioned racquets every time. The Freqmess Program helps provide me with the feedback that we are doing this every time! Thanks Marc!
 

ubel

Professional
Sorry to dig up and old thread, but I really wanted to say thank you to the OP for posting this about a year and a half ago. I string my prostaff 6.0 with a full gosen proform tuff 15l at 63 lbs and after about one and a half weeks it has dropped to 41 lbs. I was really amazed when I got this number, but thinking about it now if I really hit with a racquet strung that high my arm would probably be in consistent pain because of the stiffness.

Also wanted other people to try this out and see if anyone with a similar setup is getting such results :eek:
 

protege

New User
I would like to say thanks to MarcR for this very generous contribution to the greater tennis community.

I've used it just a few minutes ago on a 2-hour old string job at my local sports store. I requested for 56lbs on a K-SixOne Tour using Babolat Superfine Play 17.

I'm quite pleased to discover that my stringer is very accurate because the loss (according to the Excel sheet) was only 0.014124511!

Inputs were as follows:
Head size: 90
Mass-density: 1.33
Pull-tension: 56
Frequency: 723.857

I'll be tracking the tension every 24 hours for 3 days and post my results afterwards.

Again, a big thanks to MarcR and everyone who contributed! :D
 
If anyone has the pdf file, could you upload it to a free hosting service and post it here? The link in the original post isn't working.
 

protege

New User
I've been tracking the tension loss of Bab Superfine Play 17 on my K90 which was freshly strung just last September 14 @ 56lbs.

Here are my results. Please note that the racket was never used throughout the 96 hour observation period.

Time Elapsed (hours) vs Tension Lost (lbs)
1 - 0.14
24 - 3.94
48 - 4.60
72 - 5.16
96 - 5.97

The tension loss stopped at 6lbs but continues to drop a by a few hundredths of a pound.

So effectively, I was playing with a stringbed whose tension was 50lbs. :shock:

If I want to play with 55lbs on my strings, it seems that I need to string it on the same day I play or string it at 61lbs 4 days before I play, or 59lbs the day before, and so on.
 

5263

G.O.A.T.
So effectively, I was playing with a stringbed whose tension was 50lbs. :shock:

If I want to play with 55lbs on my strings, it seems that I need to string it on the same day I play or string it at 61lbs 4 days before I play, or 59lbs the day before, and so on.

Except that after 20 swings it all changes again.

By the way, did your 56 lbs account for the 22 lb initial drop?
thanks,
 

protege

New User
Except that after 20 swings it all changes again.

By the way, did your 56 lbs account for the 22 lb initial drop?
thanks,

Surprisingly, after 6 hours of play, the tension was down a total of about 8lbs. I checked the sweet spot mains and they were notched more than halfway already. I decided it was time to cut them out since I noticed that the balls were sailing a bit long in the last hour of play.

The 22lbs you're referring to is the 10kg offset that you need to add to the program's computed tension. This, however, is a general guide and you have to calculate your set-up's own offset by subtracting the computed tension from the pull tension.
 

Takenobu

Rookie
Hi, I just saw this thread and decided to try it out. Now the only problem is the 2 rackets I have all have been used before. Does this mean i'll never be able to figure out the pull-tension, since I never got a chance to measure them right after I had them all strung?

My KSix-One Tour is strung with Wilson Sensation 16 gauge (I told the shop to string it at 25 kg, one year ago...):

f0: 579 Hz
A: 581 cm2
my: 1,402 (according to a previous poster, flash9)

So I get: 4 * ( 579 * 0,988 )^2 * 581 * 1,402 / 9,81 * 10^7 = 10,87 kg

On my NSix-One Tour which is stung with the same Wilson Sensation 16 gauge (it was strung when I got it) I get:

f0: 634
A: 581 cm2
my: 1,402

And again: 4 * ( 634 * 0,988 )^2 * 581 * 1,402 / 9,81 * 10^7 = 13,03 kg

I never knew the real tension would drop so much from the pull-tension...

I fail to see the point of using pull-tension when i'm not stringing it myself. I'll never know if the stringer did the job properly as I can only measure the real-tension after the stringing? So say I want to change the tension next time and I give him a new measurment based on what I thought was strung, i'll end up with a 3rd result lol? If everyone measured in "real-tension" wouldn't everything be easier? (Maybe except for the stringers, who would have to find out how much the tension would drop)

If we assumed that the current "real-tension" was something I measured just after they'd been strung at 25 kg, and assuming the stringer really string it at 25 kg, would the offset be:

K6.1: 25 - 10,87 = 14,13 kg
N6.1: 25 - 13,03 = 11,97 kg

If that's the case i'll be able to use this method quite well starting the next time I string my racket :)

PS. How about measuring hybrid strings o_O?
 
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000KFACTOR90000

Professional
Some of the links are broken.

Anyone have a working link to the excel chart ?

Anyone have the g/m for alu rough?

thanks marc - love this tool !!
 

stoneage

Rookie
String data page

I have collected the linear density data in this thread, added a few of my own and published them at:

http://appmaker.se/racquettune
(under "strings")

I will try to improve this page and would be grateful for any additional data that you can provide.
 

airman88

Semi-Pro
What mu would you use for poly main, synthetic cross hybrids? Would you average the mu or pluck one string at a time?
 
Goodwork MarcR. I think you should change the name of the app though - "FreqMess" doesn't mean anything to tennis players. An improved GUI would be nice....

Will give that app a go though when I get my android phone. Bargain at 1 euro.

Have anyone been able to compare it with RacquetTune for the iPhone?
 
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