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  1. igorponger is offline
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    Jan 2012
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    #1

    Be alert of the false (untrue) specs on Chinese rubber products.


    Be alert of the false (untrue) hardness numbers on Chinese rubber products.
    ///
    ФАКТИЧЕСКАЯ ТВЕРДОСТЬ ТЕННИСНОЙ ГУБКИ. ЗАЧЕМ ОНО НАДО ДЛЯ ХОРОШЕГО ТЕННИСИСТА.

    Разница в показаниях твердости более 2-х единиц дает кардинально новые игровые осчущения. Это значит что губка 38 и 41 единиц (на одной шкале Шора) будет играть как две разные накладки, и вам придетца перенастраивать свою игру заново.
    То же самое мы имеем с бустировкой резины маслом для своей личной потребы. Активный минеральный бустер сделает вам очень мягкую резину, и вы потеряете контроль мяча напрочь.
    Опытные спортсмены откровенно презирают китайские продукты, потому что вы получаете в пакете резиновый лист, реальные свойства которого могут значительно отличатца от заявленных на этикетке.
    Китайские резиновые мануфакеры могут загубить вашу игру напрочь. И тут без точного, надежного дуромера обойтись никак невозожно.

    * * * * * *
    ::: ПОВЕРКА КИТАЙСКОГО ДЮРОМЕТРА В ДОМАШНИХ УСЛОВИЯХ. :::
    Прежде чем пользовать дуромер Шора из популярного китайского магазина
    Тип А
    Тип О
    всегда следует сделать поверку прибора, чтобы убедитца что прибор дает точные показания без дураков, и тогда душа будет спокойна.

    ПОВЕРКА 1.
    вдавить шток до упора на твердом гладком столе и шкала должна показать ровно 100 единиц.

    ПОВЕРКА 2
    нам потребуетца кухонные электронные весы с точностью измерений до 1 грамма, имеющие твердую гладкую опорную чашу.
    — Установить дуромер на центр в чашу весов и плавно надавить кнопку дуромера большим палцем, строго вертикально.. Когда дуромер покажет 50 единиц, весы должны показать 439 граммов, +/- 8 граммов.
    Если ваши поверочные цифры соответствуют моим инструкциям, значит вам повезло — китайский прибор ГОДЕН к работе. Если погрешность показаний более 4% тогда прибор надо выкинуть в МУСОР, значит пружина сдохла и не подлежит реставрации от слова совсем.

    ________________________________________
    Article translated by Google Engine, editorial refinement by the author.

    KNOWING ACTUAL HARDNESS OF THE SPONGE MATERIALS WILL SECURE YOU AGAINST MISHAPS AND DOWNFALLS.

    The difference in hardness of more than 2 units will give you radically new playing feelings. This means that the sponge 38 and 41 units (on the same Shore scale) will play as two different setups, and you will have to reconfigure your game entirely.
    We have the same thing when boosting rubber with oil manually. An industrial mineral booster will make your rubber overly soft, and this invariably wi,ll cause you to lose control of the ball in play.
    Experienced athletes openly decry Chinese products in loud voice, because you get a rubber sheet inside the package, the real properties of which may differ by far from those stated on the rubber label.
    Chinese rubber manufacturers can destroy your game completely. And here is where an accurate, reliable Shore durometer is a must-have device in your sporting bag.

    * * * * * *
    Engineering lifehacks from IGORPONGER, ITTF superviser in charge of racket control.
    ::: VERIFICATION OF THE CHINESE DUROMETER AT HOME (no tricky lab devices needed) :::

    Before using the Shore's durometer from a popular Chinese store
    Type A
    Type O
    you should always make a verification of the device to make sure that the device gives you a corret reading of hardness units within a standard allowance.

    VERIFICATION 1.
    Press the rod full lenght down on a hard, smooth tabletop and the scale should show 100 units exactly.

    VERIFICATION 2
    we need a kitchen electronic scale with an accuracy of up to 1 gramme.
    -- Place the durometer in the center of the scale plate and gently press the upper button with a tumb finger, strictly vertically.. When the durometer shows 50 units, the scale should show 439 grams, + / - 8 grammes.

    If your verified numbers well correspond to my instructions, then you are lucky — the Chinese device is quite fit for making measurement on rubbers. If the reading error is more than 4%, then the device should be thrown into the waste basket, beause the inner working spring is dead and is not subject to restoration not for the world.
    Last edited by igorponger; 06-30-2021 at 11:02 PM.

  2. brokenball is offline
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    #2
    Durometer readings are not the best way to test rubbers but everyone seems to use them out of ignorance. The problem with durometer readings is that they are meant to test hardness ( yes, we know that ). However, it uses a small pointer that is not the same as a round TT ball. Durometer readings are good for measuring the hardness of pure rubber in a relative way but TT rubbers are made of a top sheet and sponge. Maybe there should be two readings. One is the hardness of the top sheet and the second is the spring constant of the sponge. The sponge should have units of Newtons per millimeter.

    I will challenge the forum yet again. What calculation can you do with are durometer reading that really doesn't have any units. Yes, you get a number that can be compared with another number but the numbers are really meaningless without units. A spring constant has units and can used for calculations like how much it will compress given the impact speed of the ball. If you model the sponge as a bunch of small springs you can make a fairly accurate model of the how the sponge will react to the impact of a TT ball.

    Just because this is the way it has always been doesn't mean it is right. At one time the earth was flat. Now we know better except for a few on the OOAK forum.

    My company has used durometer readings to measure the hardness of rubber belts. This was necessary because a knife was cutting a potato strip and make contact with the belt as the knife went through the potato strip. Harder belts did not wear as much as softer belts.
    I know about durometer readings. It isonly a way to measure hardness, but the hardness of what? The top sheet or the sponge?





  3. Ch3nM3ng is offline
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    May 2021
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    #3
    it's pretty clear that speed, spin and "control" rankings in rubbers and blades in all TT products are BS to a certain degree and that's not limited to Chinese products.
    Ok maybe the Speed characteristic is gonna be accurate but the latter 2 parameters are purely subjective.
    The whole All, All+, Off-, Off, Off+ rankings aren't measured on the same scale either but only on that specific line of blades for example
    [Product Name] All Carbon is gonna be faster and stiffer than [Product Name] Offensive Wood by the same company.

    In fact Off+ isn't enough. The 10mm 1 ply Hinokis are Off+++ , the Schlagers and unusually thick (7mm+) Carbon blades and 9mm Hinokis are Off++,
    the 0.8-1mm thicker core, slightly stiffer, marginally more Composite material version of a product line (Say the Carbonados for example) are Off+ (in fact you can put these into 2 different tiers as well) and regular 5.8mm Composite blades are Off.

    Off+ just isn't a good enough umbrella term with the variety we have these days.

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