• Join our newsletter: 
  • Welcome Guest


    Results 1 to 6 of 6
    1. Top | #1
      igorponger is offline
      This user has no status.
       
      Advanced TTD Member Country: Former Soviet Union


      Join Date
      Jan 2012
      Posts
      435
      Reviews
      Read 0 Reviews
      Liked 132 Times in 94 Posts

      Expert opinion: The non-slippery tables CoF>0.20 is the best

      Expert opinion: The non-slippery tables CoF>0.20 is the best



      The most notable example of how dramatically a friction quality of the given table surface could affect/interfere players' perfomance is the newest model of <Stiga Gëteborg> as been presented for the recent 2019 Swedish Open tournament. The STIGA table is featuring an improved friction CoF = 0.25, far better to the DHS Rainbow commercial model CoF = 0.12.
      The Japanese young hopeful MIMA Ito impressively outplayed all Chinese opponents in women's single directory, just because the ball would bouncing more upwards and got decelerated upon impact on the table, the Chinese did not like it very much.


      /Be happy/

    2. Top | #2
      Aurelian Mihai is offline
      This user has no status.
       
      TTD Member Country: Aaland


      Join Date
      Jun 2020
      Posts
      72
      Reviews
      Read 0 Reviews
      Liked 15 Times in 15 Posts
      So, if I understand well, a good table is the table that helps the flat hitters?

      Sent from my moto g(7) power using Tapatalk

    3. Top | #3
      zeio is offline
      says 快、準、狠、變、轉
       
      Master TTD Member Country: Hong Kong
      zeio's Avatar

      Join Date
      Jan 2018
      Posts
      5,018
      Reviews
      Read 0 Reviews
      Liked 7,171 Times in 3,119 Posts
      Off on a tangent again. What about the following counterexamples?

      https://youtu.be/citghr9CPvs
      https://youtu.be/k5dryr0JXBU

      Shortpips and the fast-attacking style actually work better on tables with a low friction since the shots don't slow down as much after bounce, where the friction turns the speed into spin.

      Here's what Kesao YOSHIZAWA of San-Ei says about the Coefficient of Friction. "The ball stops" for a CoF near 0.4. "The ball skids such that ball control is poor" when approaching 0.2. Therefore, they aim for somewhere around 0.3. That means it takes more skills to play on DHS tables if your number is reliable.

      https://www.jstage.jst.go.jp/article.../_pdf/-char/en
      規格では摩擦係数が「0.6以下」という比較的幅の広い数値となっているが,経験上0.2に近づくと「滑ってボールコントロールが利かない」,0.4に近づくと「ボールがストップする」と評価される.条件的に見れば,0.3付近に収しゅう斂れんするわけであるが公認試験(4)光沢を勘案すること,また,規格にはないボールやラケットなどによるキズ付きを防止する要素を含めた場合,複雑な関係性が発生する.
      Race for Tokyo 2020+1 - Women's Top 11, Japan
      Time capsules - 2020, 2024, 2028

    4. Top | #4
      brokenball is offline
      This user has no status.
       
      Senior TTD Member Country: United States


      Join Date
      Jul 2017
      Posts
      542
      Reviews
      Read 0 Reviews
      Liked 254 Times in 170 Posts
      The ball will not stop if the CoF is 0.4 unless there is back spin.
      Whether the ball slows down or speeds up depends on the relative spin to speed ratio.

    5. Top | #5
      langel is offline
      This user has no status.
       
      Master TTD Member Country: Bulgaria

      Equipment:
      Blade Xiom Vega Tour
      Forehand Rubber Xiom Omega VII Asia 2.2, Xiom Omega V Tour 2.2
      Backhand Rubber Xiom Omega VII Asia 2.2, Xiom Omega V Tour 2.2

      Join Date
      Apr 2017
      Posts
      1,931
      Reviews
      Read 0 Reviews
      Liked 894 Times in 622 Posts
      The angle of contact is an important factor too.

      The higher CoF has a greater impact on the spin after the contact. The higher CoF accelerates the top spin more and decelerates the back spin more than the lower CoF.

      But there are other factors that impact the rebounce height - altitude, air pressure, humidity, even the ceiling height.
      And the exact table surface hardness matters too.

    6. Top | #6
      brokenball is offline
      This user has no status.
       
      Senior TTD Member Country: United States


      Join Date
      Jul 2017
      Posts
      542
      Reviews
      Read 0 Reviews
      Liked 254 Times in 170 Posts
      Quote Originally Posted by langel View Post
      The angle of contact is an important factor too.
      The vertical speed at which the ball hits the table determines the force. The Cof is multiplied by this force to get the tangential force that will change the rotational speed of the ball.

      The higher CoF has a greater impact on the spin after the contact.
      yes

      The higher CoF accelerates the top spin more and decelerates the back spin more than the lower CoF.
      You assume too much. What if the spin on the ball is high relative to the speed?



      But there are other factors that impact the rebounce height - altitude, air pressure, humidity, even the ceiling height.
      And the exact table surface hardness matters too.
      Altitude, air pressure and humidity get factored into the air density. I have never seen an equation the uses altitude, humidity or air pressure by themselves.


      I would like to see an explanation as to why the ceiling height makes a difference.

      There is a specification for the COR of the table as outlined in the video. It is a shame that these numbers are not specified for each table. On top of that the bounce will probably vary a bit depending on the location of impact on the table. We don't know if the table we buy has dead spots.

      I bought a table before I knew what I was doing. It is a Stiga Table but made by Escalade sports in the US. The quality is awful. It seems one must spend about $1000 in the US to get a decent table and a few hundred dollars more to get a good one.
      We still play with it but the ball bounces differently at different spots especially when the ball hits a white line. The ball bounce out low because of the lower coefficient of friction or the paint reduces the coefficient of restitution.

      Don't buy a table unless it is tournament rated.

      I know about cutting veneer in Japan since I have installed 3 machines that automate cutting veneer. The quality is very good. In the San-ei video I noticed the wood they were using was "clear", no defects or knots.

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •  
    Log in or Register
    BACK TO TOP