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ac3111
12-03-2009, 05:50 PM
It could fit in the other equipment board but since it is about stringing tension I think it is more appropriate to post here.

I would like to get a cheap but accurate and reliable device that can measure the string tension after the racquet is strung so I can monitor the progress of tension loss on my strings...

The Gamma String Tension Tester (http://www.tennis-warehouse.com/descpage-STTEST.html) has an exceptional good price but is it accurate enough? I saw some electronic devices like the Gamma ATS ERT 300 Tenniscomputer (http://www.tennis-warehouse.com/descpage-ERT300.html). The tenniscomputer says it measures the stringbed stiffnesess (dynamic tension). Does this mean it measures the elasticity of the stringbed? Is it worth it to get it compared to what it offers with the plain String tension tester?

Thanks.

raygo
12-03-2009, 06:30 PM
If you test the racquet right after stringing and establish that baseline/reference tension, the Gamma is a very practical way to track your tension loss. It's been accurate enough for me to know when to restring.

Unless you determine the 'starting' numbers, I don't find it useful to arbitrarily measure tension/stringbed stiffness. I can't justify the cost of an ERT, regardless of how hyper-accurate it is.

FWIW, the Physics of Tennis book by Lindsay and Cross compared stringbed stiffness measurements by Stringmeter and ERT, and the Stringmeter turned out to be extremely accurate. They didn't test the Gamma, which operates on the same principle, so it may be worth it to spend the extra bucks on the Stringmeter.

ac3111
12-03-2009, 06:33 PM
Well I am interested to check the tension loss not just right after the stringing but after 10hours if play, then 15 etc...

raygo
12-03-2009, 06:41 PM
Correct, the Gamma will do just fine.

SW Stringer
12-03-2009, 11:51 PM
If you test the racquet right after stringing and establish that baseline/reference tension, the Gamma is a very practical way to track your tension loss. It's been accurate enough for me to know when to restring.

Unless you determine the 'starting' numbers, I don't find it useful to arbitrarily measure tension/stringbed stiffness. I can't justify the cost of an ERT, regardless of how hyper-accurate it is.

FWIW, the Physics of Tennis book by Lindsay and Cross compared stringbed stiffness measurements by Stringmeter and ERT, and the Stringmeter turned out to be extremely accurate. They didn't test the Gamma, which operates on the same principle, so it may be worth it to spend the extra bucks on the Stringmeter.

Also FWIW, in the lab, Lindsay and Cross and Crawford used the frequency method as their baseline when they did their comparisons of tension measuring devices. There is a free program available for download at stringforum dot net and it's called freqmess. Check it out. It's much more sensitive than the ERT devices and it's FREE.

origmarm
12-04-2009, 12:40 AM
For what you seem to require the Gamma should be a good low cost solution. I've had one for several years and it does just that. I measure the STI value just after stringing and then at regular intervals to determine tension loss, this allows me to gauge when to restring. It also allows me to determine how consistent my stringing is i.e. I should have the same starting value after every job

The ERT is the better machine and has some additional features but for what you describe the Gamma is really all you need.

Valjean
12-04-2009, 02:59 AM
....I would like to get a cheap but accurate and reliable device that can measure the string tension after the racquet is strung so I can monitor the progress of tension loss on my strings....
I have relied on a combination of the Stringmeter and this little device-- http://eagnas.com/maxgen1/etest.html --for years; they backstop one another, but measure different things. Particularly helpful is the dwell time measurement the latter can give you, since, in some cases (notably Gamma's TNT series), tension can remain high when the string is actually "dead" for play itself.

Otherwise, the Mini ST performs the same dynamic measurement of the total stringbed that, say, an ERT does, except you provide the stimulus manually instead.

Gamma used to sell one.

ac3111
12-04-2009, 03:43 AM
Honest to be I'd be interested in something that could warn me about the elasticity or the loss of it. Some would say that your arm and elbow will tell that. Well I want the machine to tell it before my elbow or arm, wrist tell me. And I say this because when you play everyday the arm, wrist, elbow adjusts to the gradual loss of elasticity.
I started playing with polys. I string them at 53lbs. I am not a stringbreaker but I like to string low and even a 1.15 poly (PL II) I don't know how but makes the stringbed feel so controled even when the ball hits outside the sweetspot.
Maybe it's the big tension loss that widens the sweetspot? I don't know.
With each racquet/string combination I perform a small test. I hit the ball numerous times towards the ground and I try to hit all the sides of the stringbed...
Even when the balls hits strings and bit of frame still the control is amazing...
But I am worried that even the low strung very soft co-polys as ProLine II or CyberBlue 1.25 may cause in the future any arm issues. So I want the device to indicate when I should change strings on the ground of elasticity loss...

raygo
12-04-2009, 04:33 AM
Also FWIW, in the lab, Lindsay and Cross and Crawford used the frequency method as their baseline when they did their comparisons of tension measuring devices. There is a free program available for download at stringforum dot net and it's called freqmess. Check it out. It's much more sensitive than the ERT devices and it's FREE.

I've been curious about this, actually. It's on my "to do" list if I ever get a mic. Thanks for the reminder.

origmarm
12-04-2009, 04:47 AM
Honest to be I'd be interested in something that could warn me about the elasticity or the loss of it. Some would say that your arm and elbow will tell that. Well I want the machine to tell it before my elbow or arm, wrist tell me. And I say this because when you play everyday the arm, wrist, elbow adjusts to the gradual loss of elasticity.
I started playing with polys. I string them at 53lbs. I am not a stringbreaker but I like to string low and even a 1.15 poly (PL II) I don't know how but makes the stringbed feel so controled even when the ball hits outside the sweetspot.
Maybe it's the big tension loss that widens the sweetspot? I don't know.
With each racquet/string combination I perform a small test. I hit the ball numerous times towards the ground and I try to hit all the sides of the stringbed...
Even when the balls hits strings and bit of frame still the control is amazing...
But I am worried that even the low strung very soft co-polys as ProLine II or CyberBlue 1.25 may cause in the future any arm issues. So I want the device to indicate when I should change strings on the ground of elasticity loss...

Indeed this is something a simple string deflection device is not going to measure. I think it's a fair assumption though that for the majority (though not all) strings that the tension loss is a reliable indicator of elasticity loss. Certainly for poly I believe this to be the case.

When I played copoly, in my case SPPP (I've stopped for now), I noticed a significant difference in comfort when playing during the last session before my meter would read significant tension loss. For me it wasn't linear i.e. it would read say 40 then 38, 37, 37, 36 and then suddenly 30 and I would know it was done.

DrpShot!
12-04-2009, 08:35 AM
Stringmeter works well for me for this, although with NRG I usually shred or break it before I need to worry too much about the tension, although sometimes in that 2nd or 3rd racket that's been sitting around awhile its nice to know how it compares to what you were used to in your main racket.

Lefty5
12-04-2009, 09:35 AM
I have both the Gamma Tester and the Stringmeter, when you use them both on the same racket the Gamma one seems really sketchy, I get inconsistent and inexplicable readings. The stringmeter is solid and consistent. If not for my facination with the differences between them, i would have thrown the gamma one in the garbage... maybe tomorrow.

ac3111
12-04-2009, 09:46 AM
Buth of the devices are Gamma. The Tester I guess measures only tension and manually while the Gamma TennisComputer is electronic...

Valjean
12-04-2009, 10:51 AM
Honest to be I'd be interested in something that could warn me about the elasticity or the loss of it. Some would say that your arm and elbow will tell that. Well I want the machine to tell it before my elbow or arm, wrist tell me. And I say this because when you play everyday the arm, wrist, elbow adjusts to the gradual loss of elasticity....
This is what the Mini ST's dwell time measurement has in view as well; the dwell time rises when the elasticity diminishes.

ac3111
12-04-2009, 12:26 PM
You mean the TT-001 Tension tester (Tension meter).
I see it is designed in Germany. Where in Europe could find one?

edman9898
12-04-2009, 07:09 PM
Good thread, wouldn't mind getting one myself!

jwbarrientos
12-18-2009, 02:20 PM
Sorry for my ignorance, but how this tension tester works? I mean how you use to measure the tension?

volusiano
12-18-2009, 03:04 PM
Sorry for my ignorance, but how this tension tester works? I mean how you use to measure the tension?

Do you mean the manual one or the electronic one? With the manual one you physically twist the main string and see how much force you have to twist it to line up the main to the arrows on the meter. The higher the tension, the harder you'll have to twist the string, resulting in a higher number.

With the electronic one, the device is clamped on the string bed and will generate a vibration and measure the harmonic frequency from the vibration and calculate the tension from this. So it's less stress on the string because you don't have to physically twist the string to get a reading.

For cheap natural guts that are more fragile like Global or Gaucho where there's a lot of reports on string breakage while in the bag, there's also a report of string breakage while using the manual tension tester on it (due to the twisting). So I wouldn't recommend using it on those kinds of guts. The electronic meter should be safer on those guts.

Valjean
12-18-2009, 06:25 PM
Except: The unit of measurement for an electronic tester cannot be lbs. or kg., and the result is not a tension measurement too.

volusiano
12-18-2009, 07:22 PM
Except: The unit of measurement for an electronic tester cannot be lbs. or kg., and the result is not a tension measurement too.

This implies that the electronic tester is not as good or direct as the manual tester because its unit of measurement is not in lbs or kg, but this is misleading.

The manual tester may be labeled in lbs or kg, but it does not represent the actual tension pulled during stringing as people think. At best, it may be the force required to twist the string-under-test to lign up with the arrows, that's all. So if you expect it to show 55 lbs after you've done a 55 lbs string job, you'll be in for a big surprise because you'll get a very inaccurate lower reading. It can easily be 10-20 lbs off what you'd expect.

So all you can do from it is to record the data on a regular basis and compare the data points relative to each other to track relative tension loss. This is in fact what the manual tells you to do.

So whether the tester has the the unit is in lbs or kg is a moot point. There's simply no way to take a measurement that represents directly the tension pulled while stringing after the fact. The best measurement you can do after the fact is to see how stiff the stringbed is by applying a force on it and see how far the stringbed deflects due to this force. This is call dynamic tension (DT) and is usually in kp/cm (how many kp it takes to deflect the stringbed 1cm).

You can do it in the literal way by coming up with a device that can push down on a stringbed and measure the deflection. But it would be a very expensive and not very portable device. I think Babolat has made such a device.

But a cheaper way is to vibrate the stringbed and electronically measure the harmonic frequency the stringbed gives out due to this vibration, and feed this data into a series of scientific equations/calculations to determine the equivalent DT value. This is exactly what the electronic tester like the ERT300 or Eagnas does.

So either way, you won't get direct tension-on-the-string measurements with either method and will have to record a bunch of measurements in order to track relative tension loss.

But if people want to debate which unit of measurement is more meaningful in a tension tester, I would contest that the DT value in kp/cm (the force required to deflect the stringbed by 1 cm) from the ERT300 or Eagnas is more meaningful than the lbs or kg value of a manual tension tester like the Gamma Tension Tester or the Stringmeter.

Valjean
12-19-2009, 06:50 AM
....With the electronic one, the device is clamped on the string bed and will generate a vibration and measure the harmonic frequency from the vibration and calculate the tension from this.....
When I do nothing more than clarify something important in what you've said--it's in the USRSA's recent tome, The Physics and Technology of Tennis too--I don't expect to be guilty of something myself. I've "implied" nothing between the two; in fact, I rely on both types, which do different things well.

Valjean
12-19-2009, 06:52 AM
10 characters

volusiano
12-19-2009, 10:00 AM
When I do nothing more than clarify something important in what you've said--it's in the USRSA's recent tome, The Physics and Technology of Tennis too--I don't expect to be guilty of something myself. I've "implied" nothing between the two; in fact, I rely on both types, which do different things well.

Hey Valjean, if I misunderstood you and you've now clarified that you didn't mean to imply anything other than to point out some more of the differences between the 2 types, then I apologize! Sometimes I can read too much into things.:)

thebuffman
12-29-2009, 02:39 PM
thanks for this post. i just purchased the stingmeter.