How accurate is your eCP

How accurate is your eCP when it keeps the ref.tension constant when the string is stretching.

  • - ± 5 % of set ref.tension

    Votes: 1 7.7%

  • - ± 2% of set ref.tension

    Votes: 1 7.7%

  • - ± 1% of set ref.tension

    Votes: 0 0.0%

  • - ± 0.1% of set ref.tension

    Votes: 2 15.4%

  • I don't care. I set my tension and work consistent.

    Votes: 9 69.2%
  • Total voters
    13
MathieuR

MathieuR

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It has been "touched" in several discussions: how accurate is your eCP, what is the variation in "real" tension in the string when you clamp. (I mean "real" tension, not what the machine indicates (allthough that is also interesting to know).
And to make it easy: only mains. Tension in crosses is more complicated)

And I asked for "%", as 1# on a ref.tension of 50# is 2%, but on 35# it is 3%.
And I am specifically interested in the values in the first 10 seconds, cause there is the biggest part of the "stretch" that needs to be corrected.
 
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Me and Trip and a lengthy pirvate message discussion about this.....I'm farely knew to stringing and I was having to set my reference tension to 62/60 on my Pure Aero 2023 (100") to get a DT of 34 measured with an ERT300

Now when i string my 305s at 55/53 reference tension i get a final DT of 36

So in my very little experience I think that head size, string pattern, and type of string play a big part in final string bed tension
 
Jpipes8787 said:
So in my very little experience I think that head size, string pattern, and type of string play a big part in final string bed tension
Click to expand...
I think you are 100% right, but that is not what I wanted to know .

I want to know: when you tension 1 (one) string at eg 50#, between what values is the stringtension when you clamp.
 
Your eCP’s accuracy is usually around ±1-2% of the set tension when keeping reference tension constant despite string stretch. ±5% is too loose, and ±0.1% is unrealistic. If you work consistently with your set tension, that’s fine for most cases.
 
± 0.1# when I calibrate it. The calibration device is a digital luggage scale that has also been calibrated with known volumes of water. The rest is up to the stringer.
 
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Your question/poll is somewhat confounding because you've asked for a percentage, rather than just asking for the difference/variance (in pounds/kilos) from the reference tension set on the machine.
Therefore, it makes it difficult for those reading your query to determine just what figure you're actually after.

I set my machine to 50.0lbs
Using my digital scale, the reading was 49.87lbs.

So, that's a difference of 0.13 pounds.
However, you didn't ask for that. You want us to then convert that difference (of pounds/kilos) into a percentage, right? :unsure:
If that's the case, then I think the answer that you're wanting, as a percentage, is 0.25% (50.0lbs. - 0.25% = 49.875lbs.)

So, I'm not really sure which of your poll choices applies here.

I think many readers are going to merely report their variance in terms of difference (in pounds/kilos), rather than realizing that you're wanting them to convert that number into a percentage.
You should probably clarify what numbers it is, exactly, that you're really after.

Whenever one can, one should make things as clear as possible for the reader.
 
esgee48 said:
± 0.1# when I calibrate it
Click to expand...
When you calibrate you use a piece of string which is "stretched"; no, or hardly correction needed to keep the tension at ref.tension.

I am interested what happens in "real" stringing, when you stretch the tensioned string.
 
How soon after the racquet off the machine you’d want this result/number and how do you suggest to measure it and with what device?
lol
 
esm said:
How soon after the racquet off the machine you’d want this result/number and how do you suggest to measure it and with what device?
lol
Click to expand...
I would like to see results if you tension one piece of string, "without a racket".
Just the same what you would do when you calibrate your tensioner. (But now using a fresh, stretchy piece of string)
 
MathieuR said:
So, you vote for "I don't care. I set my tension and work consistent "
Click to expand...
Ultimately, isn’t this all that matters? With any new customer, there’s going to be a difference, even if their old stringer used the exact same machine.

It’s one of my biggest pet peeves in the String & Racquet sections here…people claiming “50 lbs is waaayyy too tight for that racquet/string combination”, not having any clue how the frame was strung.
 
MathieuR said:
I would like to see results if you tension one piece of string, "without a racket".
Just the same what you would do when you calibrate your tensioner. (But now using a fresh, stretchy piece of string)
Click to expand...
lol. What is the point of this?
Do you think the end result of this “test” will translate to the actual stringing job when you unmount the racquet from a stringer?
Too many variables. Other than proper/regular calibrations, consistency is the key.
 
In the real world, when I am putting new strings into a frame:
I pull until the tension settles, e.g. no more adjustments and and I count to 5 before clamping. (None of that Quick Clamp)
I move my crosses when I pull them, up/down/up to remove as much interstring friction as possible. Then I wait before clamping.
I don't prestretch.
If the client ask for a ref tension, that's what they get generally within 0.2-0.5# after 12 hours. Use RT with own measured SF. The SF DB is useless.
General first comment for new clients is 'It's too tight!'
2nd string job or subsequent ones are 'close enough' to what they want. (Note all the details in my String DB)
If they change strings, we have a discussion before proceeding unless they say I want X #.
Rinse and repeat.

I am consistent because when I do multiple frames with same string at the same time, they end up with same final tension when they come off and after 12 hours.
 
MathieuR said:
I would like to see results if you tension one piece of string, "without a racket".
Just the same what you would do when you calibrate your tensioner. (But now using a fresh, stretchy piece of string)
Click to expand...
So far I haven't understood what our string specialist from Holland wants to do with the data. :unsure:
Perhaps he wants to switch to an eCP because his previous machine may have died of old age?

I thought to myself, if I'm going to collect data, I might as well make videos of it.
The first string shown is an Isospeed Black Fire in 1.25, stretched umpteen times, which has certainly been hanging in the measuring device for 2-3 years and could possibly serve as a reference.

Then comes the String Kong Banana Bite in 1.25mm,
the Solinco Hyper G in 1.20mm,
the Head Lynx Tour in 1.20mm,
the Babolat VS Touch in 1.30mm and finally the
Head Velocity MLT in 1.25mm.

I am very happy with my machine, which I have been using since December 2017, and I think that the measurement data is also very accurate.
So far I have never had to calibrate the TE 3300, but maybe it always does that when you switch it on.

Have fun watching it.
Best regards to the Netherlands.






https://youtube.com/shorts/IZ-fjh8MgVc
 
@fritzhimself , Thank for taking the query (very) serious.
Don't worry, my Stringway is build like a tank, and I will die before it dies on me.

What I noticed:
- the beep is almost instantaneous (0.5sec?)
- I thought "beep" means ref.tension reached, for most stringers the signal to clamp the string.
- after the beep the difference between lowest and highest value measured was 0.58/0.45/0.35/0.5/0.7 kg = 2.5/2/1.5/2.2/3% of the ref.tension.
(This is the max. difference in tension between the individual mains tensioned).

All this has apparently little influence on the endresult as was to be expected.

But I am glad you took time and trouble to demonstrate that also a very accurate eCP has a bandwidth. (but gives a consistent result!)
 
Well, yes - but I still don't know what you want to prove (aim) with that?
The short beep is due to the fact that I have already placed the string to be measured close to the linear gripper.
I did this with all the strings to show a uniform measurement pattern.

In fact, you only wanted to know about one string. I presented you with different results to show the variety of strings.
A good result also requires a stable turntable and good clamps.
In order to measure a good result, the brake (if present) must also be fixed to the table.
The wobbling of the turntable prevents accurate measurements.

The entire tensioning process is very dynamic and consists largely of losses - a good 30% less tensioning weight arrives at the finished frame than is actually set.
In order to evaluate good tensioning, the SBS is also used to measure this. Then there are thousands of strings from soft to hard and round to angular and twisted.
What does the whole thing look like in a frame to be strung?
The friction on the cross strings is also a significant factor that you have left out.

So tell me - “What is the whole procedure for?”
 
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fritzhimself said:
Well, yes - but I still don't know what you want to prove (aim) with that?
The short beep is due to the fact that I have already placed the string to be measured close to the linear gripper.
I did this with all the strings to show a uniform measurement pattern.

In fact, you only wanted to know about one string. I presented you with different results to show the variety of strings.
A good result also requires a stable turntable and good clamps.
In order to measure a good result, the brake (if present) must also be fixed to the table.
The wobbling of the turntable prevents accurate measurements.

The entire tensioning process is very dynamic and consists largely of losses - a good 30% less tensioning weight arrives at the finished frame than is actually set.
In order to evaluate good tensioning, the SBS is also used to measure this. Then there are thousands of strings from soft to hard and round to angular and twisted.
What does the whole thing look like in a frame to be strung?
The friction on the cross strings is also a significant factor that you have left out.

So tell me - “What is the whole procedure for?”
Click to expand...
lol. So, how long is a piece of string? Asking for a friend……
 
MathieuR said:
There was a discussion a while ago. @Kentse refused a MS140, cause it had 2% difference between pulls. In that thread people were asked what the accuracy/pull-repeatability was of their eCP's. No reaction there.
That triggered my curiosity.
Click to expand...
All right, but discussing with the clueless is not always easy. :unsure:
 
esgee48 said:
± 0.1# when I calibrate it. The calibration device is a digital luggage scale that has also been calibrated with known volumes of water. The rest is up to the stringer.
Click to expand...
What do u use to hold that known volume of water with? And how much does that container weigh and how accurate is that?
 
Used a 5 gal container. Weighed separately several times. Used water in which I measured the temp. (Chemistry handbook will give mass at temp) Then it a question of volume which I use glass 4 cup measure. Convoluted calculations. Poured in X amt. Weigh it and calcs agree with scale, it was good to go. Did it at 30# and 50#. Scale was accurate to 0.1-0.2#. Now can use scale on stringer to calibrate. Took me longer to get water calc than actual machine calibration. Could have use regular spring calibrator, but knew it was not linear enough. I pulled with both calibrator tied end to end and devices had slightly different tensions. [Don't do this unless you are OCD and have a lot of time to fiddle.:eek::happydevil: ]
 
It will be informative only if you keep certain variables fixed like how the calibrator is supposed to be mounted. And in ideal case everyone use the same digital calibrator. And use the same string, 1 that won’t stretch because when u talk about during stretch then u r introducing fact that different strings stretch at different rates and that causes the ecps to repull at different rates. And Also imo ecps pulling at different speed settings will give u a different maximum variation range. And also the amount of time you wait before taking the measurement from the digital scale display. The longer u wait the more stable and accurate that reading is. On my machine for example I’d have to wait around 5 to 10s before the reading is stabilized enough. So if one is to take a reading earlier you will see a bigger variance. On the other hand while you can wait longer b4 taking a reading, during actual stringing I’m sure most stringers aren’t standing there and waiting for more than 5s before clamping off. So in practice there r other variables for sure. IMO if your result Ert300 reading end up lower even though the machine is calibrated. Then it makes sense to calibrate the eCP to pull a little higher.
 
esgee48 said:
Used a 5 gal container. Weighed separately several times. Used water in which I measured the temp. (Chemistry handbook will give mass at temp) Then it a question of volume which I use glass 4 cup measure. Convoluted calculations. Poured in X amt. Weigh it and calcs agree with scale, it was good to go. Did it at 30# and 50#. Scale was accurate to 0.1-0.2#. Now can use scale on stringer to calibrate. Took me longer to get water calc than actual machine calibration. Could have use regular spring calibrator, but knew it was not linear enough. I pulled with both calibrator tied end to end and devices had slightly different tensions. [Don't do this unless you are OCD and have a lot of time to fiddle.:eek::happydevil: ]
Click to expand...
Good to know thanks. And to add to the OPs question different digital scales can read differently from my comparisons and some are more sensitive that they fluctuate more than others. And the digital ones r more precise than the Gamma spring calibrator for sure but not sure about accuracy. Compared to digital ones my Gamma spring calibrator will give me a slightly lower measurement which will calibrate out to a higher tension. These r all variables.
 
You don't know my history which is posted thru out TTW. I use tied prestretched 15G 4G. They have been stretched for years. I always pull at slowest setting. I was a chemical engineer and I been chided by others for waiting for equilibrium. Everything you mentioned above has been noted. ERT300 used vibration frequency to estimate DT. I do not believe its accuracy since it does not know length of strings and pattern. A mechanical RDC is probably more accurate if calibrated. Consistent repeatable tension gives a consistent DT so I use tension.
 
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No idea.

I'm too busy not worrying about it and no one i know worries over it either.

I'm guessing it's more accurate than i am. We do ok. Just be consistent.
 
I thought the frequency ert300 measures should be affected by string length and pattern. But then again it definitely doesn’t account for the head size that’s why it needs a lookup card that provides 3 possible values based on different head size ranges
 
malagabee said:
I thought the frequency ert300 measures should be affected by string length and pattern. But then again it definitely doesn’t account for the head size that’s why it needs a lookup card that provides 3 possible values based on different head size ranges
Click to expand...
I don't think you've ever held an ERT in your hands - have you?
At least that's what it says in the operating instructions:

After the stringing process, the tension of an individual string can no longer be measured directly.
The string bed stiffness DT is measured precisely by electronic simulation of the ball impact.
The corresponding string tension kp (lbs.) can be read at the DT-disc as an average value.

The effective resulting DT-value may deviate slightly.
This is not unusual and is subject to string material, racquet design, string pattern and stringing technique etc.
The experienced stringer will adjust the tension on his stringing machine accordingly.
Check periodically the machine pull tension.
Do not forget: Within the first 2 to 4 hours after stringing, there is often a remarkable tension loss of 2...4 DT, called the stabilization losses.
 
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fritzhimself said:
I don't think you've ever held an ERT in your hands - have you?
At least that's what it says in the operating instructions:

After the stringing process, the tension of an individual string can no longer be measured directly.
The string bed stiffness DT is measured precisely by electronic simulation of the ball impact.
The corresponding string tension kp (lbs.) can be read at the DT-disc as an average value.

The effective resulting DT-value may deviate slightly.
This is not unusual and is subject to string material, racquet design, string pattern and stringing technique etc.
The experienced stringer will adjust the tension on his stringing machine accordingly.
Check periodically the machine pull tension.
Do not forget: Within the first 2 to 4 hours after stringing, there is often a remarkable tension loss of 2...4 DT, called the stabilization losses.
Click to expand...
Did you type all these out?
Lol
 
fritzhimself said:
I don't think you've ever held an ERT in your hands - have you?
At least that's what it says in the operating instructions:

After the stringing process, the tension of an individual string can no longer be measured directly.
The string bed stiffness DT is measured precisely by electronic simulation of the ball impact.
The corresponding string tension kp (lbs.) can be read at the DT-disc as an average value.

The effective resulting DT-value may deviate slightly.
This is not unusual and is subject to string material, racquet design, string pattern and stringing technique etc.
The experienced stringer will adjust the tension on his stringing machine accordingly.
Check periodically the machine pull tension.
Do not forget: Within the first 2 to 4 hours after stringing, there is often a remarkable tension loss of 2...4 DT, called the stabilization losses.
Click to expand...
No I have not. Maybe some day. So it does electronics simulation of ball impact measuring resonant frequency from the string bed. I’d think the string pattern has an effect on the DT but I don’t get how different sized racquets can produce the same dynamic tension with different reference tensions. I guess it’s not able to determine the difference and needs a manual conversion/offset.,,, it’s interesting though
 
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malagabee said:
I’d think the string pattern has an effect on the DT but I don’t get how different sized racquets can produce the same dynamic tension with different reference tensions.
Click to expand...
It doesn't either.
This strange table that comes with the ERT can only be used as a guide, as you can't really measure a tensioned and interwoven string.
You have to string an OS racket harder than a mid to get the same DT. This table is intended to explain this.
I have an RDC, a Quick RA and the ERT and can already say that with a uniform string type the measured SBS is measured quite well.
With hybrid, they all get hung up on frequency-based measurements.
The ERT only measures any numbers for poly/multi or poly/gut.
But you can at least measure the loss of tension linearly, even if it's not the real DT.
 
MathieuR said:
It has been "touched" in several discussions: how accurate is your eCP, what is the variation in "real" tension in the string when you clamp. (I mean "real" tension, not what the machine indicates (allthough that is also interesting to know).
And to make it easy: only mains. Tension in crosses is more complicated)

And I asked for "%", as 1# on a ref.tension of 50# is 2%, but on 35# it is 3%.
And I am specifically interested in the values in the first 10 seconds, cause there is the biggest part of the "stretch" that needs to be corrected.
Click to expand...
Unless you put a load cell in series with a main string you will never know. And each main string, different strings, rackets, and grommets have different resistance to tension.

Tension should not be checked in a racket it should be checked on a straight string with a load cell in series with it, where there are no friction point impeding the tension.
 
Irvin said:
Tension should not be checked in a racket it should be checked on a straight string with a load cell in series with it, where there are no friction point impeding the tension.
Click to expand...
@Irvin as always: you react without reading the postings.
Just look at the video's that @fritzhimself posted. Can you do that for your eCP?

(So far not much measurements done. Does everyone have a lockout...)
 
MathieuR said:
@Irvin as always: you react without reading the postings.
Just look at the video's that @fritzhimself posted. Can you do that for your eCP?

(So far not much measurements done. Does everyone have a lockout...)
Click to expand...
Yes I can do that on my machine but that is not real tension in either the mains or crosses as you suggested in the OP that’s reference tension at Fritz showed in his video. Had Fritz ran the string through the grommet holes in the frame with the gauge in series with string being tension he would have had actual. Then as you suggested in the original post if the string had been clamped you tension would have dropped even more.
 
Irvin said:
but that is not real tension in either the mains or crosses
Click to expand...
The question is NOT the final tension in M/X's. That is really complicated.
Question is: how accurate is your eCP (how big is the fluctuation in the stringtension when the eCP is trying to keep it "constant" during the string-stretch).

And then measured exactly the way @fritzhimself did it.
 
MathieuR said:
So, you vote for "I don't care. I set my tension and work consistent "
Click to expand...

I can likely almost agree to this. I mean, yeah I need to know what my reference is, so I do test my machine once a year. I use 4 pieces of kevlar string and a metal fish scale I calibrate with metal weights.
But...Of all the club members I string for, only two are former or current college players. The rest are recreational.
In most cases, if I mention a tension to them, it is meaningless.
If it is the case they are a good player that requires consistency, I do my best to match what they usually might have used. Sometimes this takes a bit of time and research like testing a racquet of theirs that is still strung. Checking for the string type and tension and if there is a date on the stringing if it has a tag(which is very, very rare - most tags I see are my own).
Why other stringers in Ireland do not label their work is beyond me. It is helpful both to the owner and the new stringer.
If they are purely recreational, I string it like I think would best suit them.
I label it and tape it to the inside of the frame, but they won't bother looking. It's more for my next stringing than their own records.
I used to calibrate my machine often. Now I do it once a year at the beginning of the season.
But in the end, it likely does not matter what the tension actually is, so long as it is the same as they got last time, or near enough.
 
WYK said:
But in the end, it likely does not matter what the tension actually is, so long as it is the same as they got last time, or near enough.
Click to expand...
Agree.
Funny though, that most stringers are not even interested to know the accuracy of the "constant" pull.
 
MathieuR said:
There was a discussion a while ago. @Kentse refused a MS140, cause it had 2% difference between pulls. In that thread people were asked what the accuracy/pull-repeatability was of their eCP's. No reaction there.
That triggered my curiosity.
Click to expand...
Well let's be accurate in saying he was sold on the advertising of within more than (under) 1% accuracy of said MS140. Furthermore the constant pull did not show any variance at all, so it stabilized? It would be hard to accept that when the delivered machine is 2x advertised accuracy that and requires 2 or more pulls to achieve tension?
As for ECP accuracy, my test on the Cybex is +/- 0.7% variance when adjusting for stretch with poly strings. I haven't tested gut, but I suspect it'll be a bit more variance due to the stretchiness of gut.
 
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