Don't blame the rubber if you don't get enough spin.

[Zwill]

Just to save me looking, does anyone have links to the videos BB posted of his play?

I think this is his latest one.

https://deltamotion.com/peter/TT/Jeff%20and%20Peter%20with%20Blocking%20LP%202min.mp4

 

[NDH]

I think this is his latest one.

https://deltamotion.com/peter/TT/Jeff%20and%20Peter%20with%20Blocking%20LP%202min.mp4

BB the one in black?

 

[Zwill]

BB the one in black?

Sorry, yes the player in black.

 

[NDH]

Sorry, yes the player in black.

Perfect.

Context really is everything here, and that’s why it’s so important to be able to showcase your ability level whilst trying to make a point.

I mean no offence to BB here, but I couldn’t care less about his academic background.

To be frank, the posts are far too boring for a table tennis forum if you ask me, and I typically skim read them at best.

BB, I’d love to see some video of you playing with a lot of spin.

The video I just watched demonstrated a player who does not have the stroke mechanics to impart a lot of spin on the ball, unless you were completely changing your style to suit the rubber (which is why I’d love to see some forehand loops for example).

As I said in the other thread, “you don’t know what you don’t know”, and based on that video, and your attempt to use theory to understand table tennis shots, I would suggest that you simply haven’t played at a level high enough to truly understand the concepts being discussed.

 

[Gozo Zyreruna]

 

[JustANoob]

View attachment 25040

There should've been some small print in there with

*as long as they keep giving me the balls to the center/middle

 

[Dominikk85]

Assuming you can swing the paddle at 30 m/s ( base ball pitchers throw balls at 40 m/s ) then you divide that by the radius of the ball to get radians per second and then divide again by 2*PI to get revolutions per second. The number is about 239 revolutions per second and this is MUCH higher than what best players get but that is because I have assumed the ball is being perfectly brushed which isn't really possible. If one brushes the 30 degree point ( some call that 2 o'clock ) then the sin(30 deg)=0.5 so multiply the 239 by 0.5. The result is about 120 rev/sec which is realistic. That is lot of spin but most of us don't have the consistency be swinging at 30 m/s so if you swing at 20 m/s then you can achieve 80 rev/sec which is still pretty good..
I am assuming the rubber doesn't and extra spin from a spring effect. So if it is possible to get this much spin with just friction and no spring effect then why do so many people think they need spinnier rubbers? I think their technique sucks.

So is H3 national that spinny or is it the top players know how to spin the ball? I think the top players know how to spin the ball.

I don't think that 30 m/s is anywhere near realistic and 20 might be a stretch too for most amateur players. Baseball pitchers Wind up like crazy and have a super long motion, not comparable to a table tennis stroke.

Couple years ago did a speed test with different rackets and was getting up to like 70 kph (20m/s). Timo was older already and said himself in the video he isn't the hardest hitter but probably still harder than most amateur players.

 

[lodro]

I don't think that 30 m/s is anywhere near realistic and 20 might be a stretch too for most amateur players. Baseball pitchers Wind up like crazy and have a super long motion, not comparable to a table tennis stroke.

Couple years ago did a speed test with different rackets and was getting up to like 70 kph (20m/s). Timo was older already and said himself in the video he isn't the hardest hitter but probably still harder than most amateur players.

I totally agree. I keep this video bookmarked it is a great reference point , well actually 2 points with the slow setup he only gets about 40km/h 😁
I also seem to remember seeing a video with Ovtcharov (the bloody animal 😁 please note this is a term of respect and endearment) He smashed the ball up to 100km/h, it was a FH shot absolute full tilt without aiming at anything and it looked nothing like TT-shot more like someone throwing a small ax at a buffalo.............if you get my drift.

 

[lodro]

 

[lodro]

 

[blahness]

I would really be interested to see Aruna, Calderano or heck even Fan Zhendong to try this - the results would be very interesting!

 

[brokenball]

Another ad hominem attack. If you can dispute the facts you attack the person.
Why can't you dispute the facts. Nothing you say below refutes what I said above.

Seriously, you don't know how to play table tennis.

You are a fu#$kin liar. Did you find my videos or are you just making stuff up.

You parrot a lot of things that betray an ignorance of what it actually takes to play high level tennis.

It is the people on this site that parrot myths. Now who am I parroting?

Then you hide behind claims about understanding a system with mathematics that even the mathematicians who model it will tell you that their models are simplistic and of limited value for explaining the dynamics of high level play.

Models are never perfect but in the case of spinning the ball the tangential paddle speed can be divided by the circumference of the ball to get the revolutions per second. That is simple. Even a nitt witt should be able to figure that out.

Good players wigh physics backgrounds are far more humble about what they can say about the physics of table tennis because they know that high level table tennis is largely composed of tacit knowledge acquired over many years.

I haven't really said much. It appears that even the simplest things are too much for this forum.

It is much easier to try something and learn from it than to pretend that sophisticated modeling will give you an understanding that makes you a better player. You were one of the low level posters at mytt that said something about all that matters is what happens at contact which failed to account for how the backswing and the follow through could create a turning effect that may not be easily described just by focusing on the contact.

The ball doesn't care what happens before or after contact. Only the conditions during contact make a difference but you seem to be too stupid to realize that.

But you play at too low a level to actually understand this and you then parrot the advice people give to beginners about not changing your racket angle during the stroke.

Again you lie. I never said anything about not changing the angle of the paddle.

The bottom line here is that you need to play much better table tennis to be taken seriously. I do commend you for posting your play so that people know how seriously to take you.

You know this how? Did you see it? I was playing c-pen. I don't normally play c-pen.

I have seen nothing from you wannabee.

 

[Zwill]

The ball doesn't care what happens before or after contact. Only the conditions during contact make a difference but you seem to be too stupid to realize that.

Actually, I always thought the wind that my swing creates influences the "incoming" ball especially when someone is lobbing and the ball has very little kinetic energy and when my swing creates the strongest wind and this is one of the reasons why it's not that difficult to make an error.

 

[yoass]

Taking it not from newtonian first principles, but from actual (reported) measurements, Ma Long reportedly produced a top end of ~7000rpm(~116rps), and Xu Xin of 7700rpm (~128rps). I'd say that's pretty much in line with BB's predictive computations.

Source: Spin Measuring at China Open.

 

[turbozed]

I don't understand this at all and I'm trying to follow along with the conversation. I do have a few questions:

Does the formula you describe apply for any material the ball impacts with?

If the answer is yes, then does the rubber only provide spring effect from elasticity? How would that be represented?

Does the formula account for any changes in ball trajectory or course from the ball sinking into the topsheet/sponge material?

I've seen slow motion videos of the ball impacting tacky rubber, and visibly climbing up the rubber before bouncing off the surface. Is this phenomenon accounted for in the formula, or is there a separate formula involved there?

I just find this sort of thing very fascinating, and your confidence is giving me the impression like you can answer these questions I've always wondered about. Thank you in advance!

@brokenball You may have missed these questions earlier. Do you have time to answer some of them now? Thanks in advance.

 

[OldUser]

Good on ye, powerful weapon a bass.
However, to impress both James and BB I had this in mind:

How can sound waves be used as a weapon?
Infrasonic weapons like the long range acoustic device (LRAD) rely on loud, low frequency sounds (infrasound). These bulky units have been used for crowd control . When on high power, the effects are like a “punch in the guts”, ranging from nausea to involuntary evacuation of the bowels. 😂 😂

Octaver pedals but with a synth bass setup, the Boss OC-2 Made In Japan, the Octabvre from 3Leaf Audio, man.. those bass pedals are sub harmonics generators ! there's also the speaker killer: DOD MeatBox pedal, it's a stronger octaver, ex Mars Volta bassist Juan Alderete used it, but only with those big "fridge" Ampeg 8x10 cabinets, man... if you put a single little 12" cab it's instantly blown away, really dangerous sub harmonics effect pedals.

Put headphones on

EDIT: this one is fun

 

[lodro]

Octaver pedals but with a synth bass setup, the Boss OC-2 Made In Japan, the Octabvre from 3Leaf Audio, man.. those bass pedals are sub harmonics generators ! there's also the speaker killer: DOD MeatBox pedal, it's a stronger octaver, ex Mars Volta bassist Juan Alderete used it, but only with those big "fridge" Ampeg 8x10 cabinets, man... if you put a single little 12" cab it's instantly blown away, really dangerous sub harmonics effect pedals.

Put headphones on

EDIT: this one is fun

Great.
I was never in this league, all I ever had was an Akai Wind-instrument. An early model but the analog synthesizer way back then still produced the greatest sounds, enough to blow your eardrums and make your guts vibrate 😂

 

[blahness]

Taking it not from newtonian first principles, but from actual (reported) measurements, Ma Long reportedly produced a top end of ~7000rpm(~116rps), and Xu Xin of 7700rpm (~128rps). I'd say that's pretty much in line with BB's predictive computations.

Source: Spin Measuring at China Open.

These are from Top pros with the best technique and boosted Hurricanes though. At max effort in training situations, CNT players can go up to 130+rps no problems (see Fang Bo's channel). However, brokenball is saying that amateurs with a dead bat can produce 80 rev/s easily - which shows that he's missing something in his overly simplistic model.

 

[turbozed]

Since @brokenball refuses to answer my questions after politely asking 3 or 4 times (he seems to be more interested in calling people stupid rather than actual table tennis conversation), maybe the rest of you can help me with this question.

@brokenball says:

If one brushes the 30 degree point ( some call that 2 o'clock ) then the sin(30 deg)=0.5 so multiply the 239 by 0.5. The result is about 120 rev/sec which is realistic.

How does brushing the ball at 30 degree point actually work in real life? How long is model assuming that the ball stays in contact with the surface of rubber/racket? Is the model assuming that the ball instantly leaves the racket and the only contact point is the 30 degree point of the ball?

I've seen super slow motion videos of the ball staying in contact with and spinning on the rubber for a good amount of time and crawling up surface of the rubber. So wouldn't the racket be in contact with the ball for an arc range (e.g. from 30 degrees to 40 degrees) rather than a specific singular point?

Also how does this model take into account stickiness and force of friction? Assuming you have an extremely sticky rubber, the ball would just stick to the surface and there would be no spin at all since the force imparting the spin is overcome by the adhesion force (or whatever the technical terms for these would be). For an example of this watch the Pongfinity guys video where they try to create the 'stickiest paddle.' The adhesion of the rubber surface doesn't seem to be accounted for at all in brokenball's model.

Finally, we get to the fact that the rubber is not a solid surface but multiple surfaces (topsheet rubber, pip structure, sponge, and wood). The model doesn't seem to account for the ball sinking into the sponge at all, and the varying depths of sponge penetration.

The highest level of physics education I've had is high school physics. But I can't imagine a model ignoring all these factors can be any bit reliable in approximating reality. Am I wrong and the above is factors/forces are relatively insignificant compared to the simple geometry involved?

 

[lodro]

Since @brokenball refuses to answer my questions after politely asking 3 or 4 times (he seems to be more interested in calling people stupid rather than actual table tennis conversation), maybe the rest of you can help me with this question.

@brokenball says:



How does brushing the ball at 30 degree point actually work in real life? How long is model assuming that the ball stays in contact with the surface of rubber/racket? Is the model assuming that the ball instantly leaves the racket and the only contact point is the 30 degree point of the ball?

I've seen super slow motion videos of the ball staying in contact with and spinning on the rubber for a good amount of time and crawling up surface of the rubber. So wouldn't the racket be in contact with the ball for an arc range (e.g. from 30 degrees to 40 degrees) rather than a specific singular point?

Also how does this model take into account stickiness and force of friction? Assuming you have an extremely sticky rubber, the ball would just stick to the surface and there would be no spin at all since the force imparting the spin is overcome by the adhesion force (or whatever the technical terms for these would be). For an example of this watch the Pongfinity guys video where they try to create the 'stickiest paddle.' The adhesion of the rubber surface doesn't seem to be accounted for at all in brokenball's model.

Finally, we get to the fact that the rubber is not a solid surface but multiple surfaces (topsheet rubber, pip structure, sponge, and wood). The model doesn't seem to account for the ball sinking into the sponge at all, and the varying depths of sponge penetration.

The highest level of physics education I've had is high school physics. But I can't imagine a model ignoring all these factors can be any bit reliable in approximating reality. Am I wrong and the above is factors/forces are relatively insignificant compared to the simple geometry involved?

Whatever physics I learned in my life I have mostly forgotten so I can not take sides here.
I know though that it is in some OPs interest to keep a thread going for as long as possible
and disputing every solid argument helps here.

I notice though that like many many threads this one also takes on a life of its own . If we would have stuck to the title of the thread ""Don't blame the rubber if you don't get enough spin. It's your fault.""" AND if we would leave out all the (for me) math and physics BS, I hate to say it
but BB is right. Regardless of what rubber we have , we are responsible to make the spin.
If we feel we can not make enough spin we can try every rubber on the market but in
the end we still have to create the spin.

Sorry ! 😂