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  1. #52
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    We are happy that several guys joined the project team now, and we will make a project plan this week.

    I am a little amazed about the general attitude that most players seem to have concerning their equipment.

    But you do not need millions of followers to make this project useful.
    We have some units left from the first series for the project but not so many because we also received other orders in the meantime.

    Thanks for all the feed back up till now

  2. #53
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    I said this in the other thread:

    The stiffness and the SBS can both be measured in a very simple way without our tool.
    If you are interested I can make a sketch.
    If there is interest to design a simple “home-made” stringbed- and stiffness tester we can involve that in our project.

    There is nothing complicated about the test, there is only a force and a displacement.

    It is like measuring the Swingweight of the racquet with the scale.

    No need to buy our special “machine” than.

  3. #54
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    I think a few of us here would be interested in this simpler set up. Post it up with a photo.

  4. #55
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    “I think a few of us here would be interested in this simpler set up. Post it up with a photo.”
    I was doing my late afternoon walk and thought about a simple set up.
    The principle is simple but there are still some mechanical parts, which are difficult to make at home.

    This is our calibration unit.
    It works as follows:

    - you slide the weight to the stop at the hinge side.
    Then you read the clock position.
    - Now you slide the weight to the end stop near the end, so that the force on the pull rod goes up.
    - Now you read the position again.

    When you know the difference of the forces in both position you can calculate the sbs by dividing this difference in force by the difference in position in both situation.

    This supplies the sbs in kg/cm.



    It thought about using the same principle but then in a wooden configuration with a solid scale instead of the clock.
    I can make a sketch of such a system.

  5. #56
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    Default Home made SBS and Shaft test system

    Hi Guys,

    I made some picture that show the principle of a simple Stiffness tester. All the parts can be made of any kind of wood or steel.


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    It works like this:
    - Put the racquet on the top plate, and move the pull rod through the stringbed.
    - Hook the pull rod into the little hook in the tension bar.
    - Move the weight against the pin at the side of the hinge.
    - Adjust the line in the scale at “0” with the knob on the pressure ring.
    - Now move the weight against the pin on the other end.
    - The scale shows the stringbed stiffness in kg/cm now.

    Perhaps this makes it possible to measure the sbs and shaft stiffness for those who do not want to buy a stiffness tester?

  6. #57
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    Default Faulty Scale direction

    I made a mistake in the scale.
    When the par moves down more the stiffness is lower of course.

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    When people are interested to create their own system it is very easy for me to create drawings with dimensions of the different parts.
    I can also make an Excel sheet which calculates the scale from the specs of the weight and the length of the lever.

  7. #58
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    Default RA test

    This picture shows how to use the set up to test the stiffness of the shaft. It is very important for the understanding that the sbs and shaft-stiffness are measured in the same units.

    Measuring at the stiffness of the shaft in the sweet spot of the string bed is better because that is what the player feels.

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  8. #59
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    I and a few of us on BC have used the stringbed frequency method to monitor tension for the past 2 yrs with great accuracy and repeatability. I can tell you that the frame doesn't matter as long as you're comparing an isometric racket to an isometric racket.


    As long as it's a standard isometric shaped racket with the usual 22x22 or 21x22 stringing pattern, the frequency of the stringbed can be comparable to other brands or types of rackets, irregardless of frame cross section, type, material, or stiffness, ie independent of the frame
    Perhaps it will be easy to find the relation between frequency and sbs.

    I just ordered an Ipad (do not have an Iphone), so if I download the app, I can compare sbs on the new tool with the frequency, measured with the app.

  9. #60
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    ^ Yes, that would be interesting and very useful to compare the RacqueTune app readings with your actual measurements.

    Also please use CarlTune in Android or ClearTune in ios to measure your frequencies to compare with your SBS measurements. That would be very informative for all of us.

  10. #61
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    I am just making a test list for the stringers in the project-team.

    I can add one tune system but do not want to make it too complicated.

    Which one of the 3 you mentioned is the best to use?

    Do you get a fixed relation between the stringing tension that the app calculates and the stringing tension that was used to string the racquet?

  11. #62
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    The best ones would be free ones.

    For Android devices, that would be CarlTune.

    For iOS devices, CarlTune too. But for those on iOS lower than 6.1, n-Track Tuner is sufficient.

    In any case, best way to generate a tone from the stringbed is to strum it like a guitar with the back of your fingernails stroking away from you, with the stringbed close to the microphone.

  12. #63
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    Btw these 2 apps only measure frequencies, they don't calculate tensions. That's up to us to correlate ourselves, in your case with SBS.

    Somehow the RacqueTune app only calculates tension from frequency for tennis rackets only. Must be because there's not enough data points for badminton rackets.

  13. #64
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    What frequency do you get with a tennis and with a badminton racquet?

    In the Itune app in the other thread it shows a value for tension or sbs?

    So that does not work for badminton?

  14. #65
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    Default Test list / freq vs sbs

    I made a test-result-list for the stringers on the project team.
    If anything is missing or should be different please let me know. (apart from date and temp)

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    Btw
    There will always be difference between the sbs test en the Itune-type.
    The Itune test only relates to the stringing tension , while on the sbs test the stiffness of the string also has influence.
    The reason for this is that the stringbed is deflected so much on the sbs test that the string actually stretches, this is not the case on the frequency test.

  15. #66
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    Default progress

    Hi guys, hereby an update about the Stringlab 2 project.

    The production goes quite well so we hope to start shipping the units directly after Christmas.
    The first number of units go to the “project guys”.

    We only have some units available of the first series so we end the special offer with Christmas.

    We are making progress with the simulation system of a badminton stroke, we are testing the system with practical tests to check the parameters.

    We think that it might supply some nice discussions here.

    I wish you all a nice Christmas and a happy new year.
    Stringtechno

  16. #67
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    Default Stringlab 2 manual

    We will ship the first units of the Stringlab 2 to the members of the badminton project this week
    Those who are interested in the functions of the Stringlab 2 can download the concept manual here.

    http://www.stringway-nl.com/pdf/STRINGLAB 2 MANUAL.pdf

  17. #68
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    Default Please start to test!

    All Dutch project stringers have their Stringlabs now for 2 weeks and we get some response already.
    The only request that we can make is:
    Please start to test your string beds in your own interest and the interest of the players!

    It is obvious that the differences in string-bed-stiffness between different stringers is huge, so the players really do not know what they play with.

    - Yesterday one of the guys wrote me that his sbs is 11 kg/cm with a stringing tension of 9,5 kg (20,8 lbs, while the SBS for 9,5 (depending on the string) should be between 20 and 25 kg/cm).

    - Another project guy took his ST to a tournament as a service for the players.
    He tested the racquets which were strung by the tournament stringer, >>>>> SBS 16 kg/cm and lower, certainly too low for high level players.

    Of course I understand that many of you do not want to spend a lot of money on an expensive electronic tester, but maybe we can find simple ways to test the sbs.
    It is not necessary to measure very accurately, the first importance is to know in what range you are stringing.

    Perhaps this system is easier to realize compared to the design somewhere above:

    Buy this kind of gauge it should not be more expensive than $20.
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    Take a piece of wood or other rectangular material and drill a hole of 5/16”in the middle .
    With the clock in the slat your measuring system is ready.

    Now saw a piece of multiplex with a diameter of 4 cm and screw a little hook in the centre of it.

    Now you can test:
    - Put the racquet head flat on a workmate kind of thing with the disc on the string bed and the hook through the string bed.
    - Now put the measure system on the racquet with the test pin of the gauge on the middle of the disc.
    - Read the clock.
    - Now hang any kind of known weight on the hook
    - Read the clock again.

    - Divide the weight by the difference in clock readings and you know the sbs.

    It really seems in your own interest and in the interest of your players to know your sbs’s:
    - You have the possibility to check your product and to offer the player to test his stringbed.
    - The players know with what string bed they really play.

    It is very clear now that stringing tensions are a very bad reference for the playability of badminton string beds.

    If you need any kind of info to develop your own SBS tester I would like to give any kind of support.

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