BB's thread about higher frequency blades being faster.

[hipnotic]

Did you see the video of the balls hitting the Toxic 5 paddle? The paddle absorbs the energy of impact. Since it is a hard bat there is no sponge to absorb energy. So only the blade, the pips and the ball absorb energy.
It is easy to see the blade deform due to the impact. It is easy to see the vibrations. One can count the number of frames it takes to make one cycle. The video was recorded at 2000 FPS.
The Toxic 5 is made of Willow wood.
I have video of balls hitting my Firewall+. One can't see any vibrations. The Firewall+ is made mostly of balsa but it is 9mm thick. Also the vibrations are dampened because of the rubber on it.
Thickness plays a part in the frequency of vibrations.
I believe the Toxic 3 was only a 3 ply blade whereas my Toxic 5 is a 5 ply blade. The Toxic 3 was slower yet..

I did, altought I don't need to because I know exactly how a blade behaves and the different modes of vibration that are being excited. It's a pretty good video actually, you can clearly see how the blade deforms, if you weren't so stuck up on imposing your ideas, maybe you would see it too.

But you have not answered my questions so I will repeat:

Why and how does it deform?

What is the frequency we read?

What variables can we change in the composition of a blade to change the frequency?

Why do we have blades with the same composition but with different frequency?

Think man, think! (Or you can just say you don't know, nobody will be offended)

Oh, and one more for you. If you bounce the ball on a concrete slab it bounces much more than on the blade. Is the slab in phase with the ball?

 

[zeio]

1kHz blade? Man, same old crap some 34 months later. 唔撚好再用屎忽諗嘢。/Think with your ass do *bleep* not. Delay no more!

The frequency of the "diving board" mode (see quote 1) excited in your clamped Toxic 5 hardbat (as if the OP and recent atmosphere are not toxic enough) is way lower than even that of the 1st bending mode in a hand-held cheap premade double-inverted (see youtube video). Even a blade as stiff as Primorac Carbon would have an 18ms period for the diving board mode (see quote 2). The 1kHz you are referring to is the membrane mode, which is what people are measuring with the microphone, FFS.

Apparently that shows you don't understand the different modes at work here. What you're seeing in your slo-mo doesn't exist with a hand-held racket. There's a fitting name for that mode. The fundamental mode of a hand-held racket is different. The higher modes are difficult to capture on video. You need a vibrometer for those. They DO have a contribution in the ball-racket interaction.

Just throwing it out there.

1st Mode of Vibration (Hz)
A certain PLStar 5-ply all-wood blade - 39.58±0.86
A certain Keyshot Light 3+2 Vectran blade - 39.97±1.21
A certain Primorac Carbon 3+2 Carbon blade - 54.56±0.49

Coefficient of Restitution in the Normal Direction at Low/Medium/High Impact Velocity (7.41±0.4/8.28±0.52/9.16±0.46 m/s)
Blade Alone
5-ply all-wood - 0.7±0.01, 0.7±0.04, 0.73±0.04
3+2 Vectran - 0.7±0.03, 0.7±0.03, 0.71±0.02
3+2 Carbon - 0.75±0.05, 0.75±0.05, 0.79±0.06
With Sriver in 2.0 On Side of Impact
5-ply all-wood - 0.92, 0.86, 0.84
3+2 Vectran - 0.92, 0.87, 0.84
3+2 Carbon - 0.93, 0.89, 0.86

Contact Duration (ms) at Low/Medium/High Impact Velocity (7.41±0.4/8.28±0.52/9.16±0.46 m/s)
Blade Alone
5-ply all-wood - 1.74±0.17, 1.53±0.10, 1.40±0.07
3+2 Vectran - 1.68±0.08, 1.47±0.06, 1.38±0.21
3+2 Carbon - 1.44±0.23, 1.40±0.07, 1.32±0.05
With Sriver in 2.0 On Side of Impact
5-ply all-wood - 1.67, 1.47, 1.33
3+2 Vectran - 1.67, 1.43, 1.27
3+2 Carbon - 1.37, 1.2, 1.1

BTW, the blades are rated medium, medium-fast, and fast by the manufacturer.

Feel free to thank me by filling up my piggy bank.

2023/8/5 Added blade model and dwell time

https://youtu.be/ekalYkdrwI8?t=1748

 

[hipnotic]

1kHz blade? Man, same old crap some 34 months later. 唔撚好再用屎忽諗嘢。/Think with your ass do *bleep* not. Delay no more!

The frequency of the "diving board" mode (see quote 1) excited in your clamped Toxic 5 hardbat (as if the OP and recent atmosphere are not toxic enough) is way lower than even that of the 1st bending mode in a hand-held cheap premade double-inverted (see youtube video). Even a blade as stiff as Primorac Carbon would have an 18ms period for the diving board mode (see quote 2). The 1kHz you are referring to is the membrane mode, which is what people are measuring with the microphone, FFS.





https://youtu.be/ekalYkdrwI8?t=1748

Hey, don't spoil the fun, I was trying to get there 😅

 

[UpSideDownCarl]

NO! Haven't you ever heard the term weasel words? LOOK IT UP! It means to be ambiguous.

Okay. Fair enough. I misunderstood. But telling someone they are using weasel words: you are using that to insult them.

Also: what does woke actually mean? And what do you mean when you use it?

You are clearly using it as an insult. So, your general attitude of being insulting and talking down at people does not seem to be making you too many friends.

 

[brokenball]

Harder material vibrates in higher frequencies and bends less. I think it’s a matter of loosing less energy by bending less.

Cheers
L-zr

1kHz blade? Man, same old crap some 34 months later. 唔撚好再用屎忽諗嘢。/Think with your ass do *bleep* not. Delay no more!

The frequency of the "diving board" mode (see quote 1) excited in your clamped Toxic 5 hardbat (as if the OP and recent atmosphere are not toxic enough) is way lower than even that of the 1st bending mode in a hand-held cheap premade double-inverted (see youtube video). Even a blade as stiff as Primorac Carbon would have an 18ms period for the diving board mode (see quote 2). The 1kHz you are referring to is the membrane mode, which is what people are measuring with the microphone, FFS.





https://youtu.be/ekalYkdrwI8?t=1748

Notice that the frequencies measured are in the 50 HZ range. NOT the 1000 Hz range. This is more realistic for the primary mode of oscillation.

That I am trying to get you guys to realize is that things that vibrate require the forces to be in phase with what is vibrating. Think of pushing a small person on a swing. You must push in phase with the swing or you are fighting the motion. The same applies to the spring board divers or those jumping on a trampoline. The higher frequency vibrations of a blade are so small that they do little if anything to make the blade faster.

 

[zeio]

Notice that the frequencies measured are in the 50 HZ range. NOT the 1000 Hz range. This is more realistic for the primary mode of oscillation.

That I am trying to get you guys to realize is that things that vibrate require the forces to be in phase with what is vibrating. Think of pushing a small person on a swing. You must push in phase with the swing or you are fighting the motion. The same applies to the spring board divers or those jumping on a trampoline. The higher frequency vibrations of a blade are so small that they do little if anything to make the blade faster.

 

[Zwill]

That I am trying to get you guys to realize is that things that vibrate require the forces to be in phase with what is vibrating. Think of pushing a small person on a swing. You must push in phase with the swing or you are fighting the motion. The same applies to the spring board divers or those jumping on a trampoline. The higher frequency vibrations of a blade are so small that they do little if anything to make the blade faster.

I always thought that harder and stiffer blades are resonating on a higher pitch and this resonation is just a byproduct of the blade being hit and the resonation does basically nothing to the ball. In fact the less it does to the ball the better it is.
And since the vibration is after the contact anyway the ball doesn't care.

I also don't want a blade that works like a springboard. Sounds illegal to me.

 

[hipnotic]

I think I have to retract my comment, you're not that smart after all... I was trying to take this debate to the next level, but you can't even answer these simple questions:

Why and how does it deform?
What is the frequency we read?
What variables can we change in the composition of a blade to change the frequency?
Why do we have blades with the same composition but with different frequency?
If you bounce the ball on a concrete slab it bounces much more than on the blade. Is the slab in phase with the ball?

Also, I'm not that bright either, but I sense some contradiction in here somewhere. Your speech is all: Wake up guys! Dwell time is not real!

But now you are saying that there has to be some contact time so that the blade can push the ball back, and that stiffer blades decrease this contact time?!

This would be optimal if the contact time is also 1/2 millisecond because the blade would be pushed back by the ball for the first quarter millisecond and then the blade would push the ball back during most of the second quarter of a millisecond. The longer the blade can keep the rubber in contact with the ball the more energy it can return to the ball.

Oh, and your diving board analogy is marvelous too, you can clearly see how the boards bends and springs back. But what happens if a diver with a different weight tries to use it?

 

[zeio]

The longer the blade can keep the rubber in contact with the ball the more energy it can return to the ball.

Are you smoking? Remember your stance over "wrapping the ball"? Your quote above is in direct support of it. And what about the experiemental results I just quoted? Your quote above is in direct opposition to them, that generally, the higher the COR, the lower the contact duration.

https://www.tabletennisdaily.com/forum/topics/wrapping-the-ball.31447/post-413731

https://www.tabletennisdaily.com/forum/topics/wrapping-the-ball.31447/post-414869

I was going to write more but just answer hipnotic's questions.

 

[vvk1]

...
https://youtu.be/ekalYkdrwI8?t=1748

Thank you for this video - very educational and a great example of how to present physics of table tennis.
Someone should send a Cypershape to the professor - both as a thank you and an attempt to tempt him into making a follow-up video

P.S.: And the bit about another prof re-discovering antispin in order to beat his students is absolutely hilarious!

 

[Tinykin]

A compact, efficient delivery of force to the ball is way more valuable than an increase in frequecy spec of the blade.

I have a relatively low frequency blade (as compared to the modern missile launchers) and a real soft rubber (42-ish on BH) and when I crack that backhand it rivals or exceeds those missile launchers.
There are other factors more important... and it is good to discuss those technical technique things... but 99 percent of the forum would rather start another H3 boosting thread, drool over a top CNT player, or make a useless list of dream rubbers...

...sum of this forum crowd would sooner get a colon cleansing with a Viking Mace dipped in H2SO4 before they discuss how to improve their technique and actually get better in this sport.

"There are other factors more important... and it is good to discuss those technical technique things... but 99 percent of the forum would rather start another H3 boosting thread, drool over a top CNT player, or make a useless list of dream rubbers..."

A little unfair methinks.
Like most here, I don't contribute on these technical threads because I am simple not knowledgeable enough. But I still read or scan them.
Like many members, I read most threads. Why? Because we love tt and love to talk about tt whether said thread is meaningful or meaningless or just entertaining 🏓

 

[bobpuls]

I can see only flex of the blade, not he vibration frequency.... Let's be clear on this first... Inner frequency can be measured only by some kind of high speed laser or sound.... That's all

 

[brokenball]

I can see only flex of the blade, not he vibration frequency.... Let's be clear on this first... Inner frequency can be measured only by some kind of high speed laser or sound.... That's all

In industry, accelerometers are used to measure frequency. The recorded data can be processed using a FFT so all or most of the frequency components can be displayed along with their relative amplitudes. USCD deleted the formula but as frequency goes up the amplitude goes down quickly and if the there is no amplitude, the blade can't contribute mush to the rebound. The vibration you feel is wasted energy.

I have been waiting for a 10KHz accelerometer for years now. With one of those, one could plot the swing and detect when the ball hits the blade.

 

[brokenball]

Are you smoking? Remember your stance over "wrapping the ball"? Your quote above is in direct support of it. And what about the experiemental results I just quoted? Your quote above is in direct opposition to them, that generally, the higher the COR, the lower the contact duration.

No! They are two difference cases! Are you hitting through the ball when "wrapping"? NO! In this case the force is more tangential and not normal where the speed of the blade plays a bigger part.
How fast must the paddle accelerate to increase the dwell time? When "wrapping" you are not accelerating through the ball but around the ball. What is the force of impact? I know it varies but make an assumption that the ball impacts the paddle at 10 m/s ( not fast ) and sinks 1 mm into the rubber. Assume the impact area is 1 cm^2.
Do that an come back when done. That will show you have a clue.

 

[zeio]

Definitely smoking. Once again, 2 separate studies show that elite players hit through and then brush the ball, on both FH and BH loops, one against topspin and backspin balls close to the table and the other from mid-distance. 2 other separate studies show that the forearm pronates through the contact on FH loops. 1 study shows that even recreational players with no formal training wrap around the ball in FH counterhits.

At the end of the day, your statement is contradicting your own stance. Don't stall and evade here. Just answer hipnotic's questions already.

 

[Der_Echte]

"There are other factors more important... and it is good to discuss those technical technique things... but 99 percent of the forum would rather start another H3 boosting thread, drool over a top CNT player, or make a useless list of dream rubbers..."

A little unfair methinks.
Like most here, I don't contribute on these technical threads because I am simple not knowledgeable enough. But I still read or scan them.
Like many members, I read most threads. Why? Because we love tt and love to talk about tt whether said thread is meaningful or meaningless or just entertaining 🏓

I would disagree with your premise that you (and many others) cannot substantially contribute to a discussion on technique-oriented discussions for TWO immediate reasons.

1- I would believe that Tinykin has a LOT of experience that is worthy of sharing in a multitude of areas.

2 - QUESTIONS can be asked by anyone of any level... and often, a question, especially one that leads to the reasoning behind things, is an outstanding and revealing thought provocative question that results in many good things.

 

[brokenball]

I think I have to retract my comment, you're not that smart after all... I was trying to take this debate to the next level, but you can't even answer these simple questions:

Why and how does it deform?
What is the frequency we read?
What variables can we change in the composition of a blade to change the frequency?
Why do we have blades with the same composition but with different frequency?

Asked and answered.

If you bounce the ball on a concrete slab it bounces much more than on the blade. Is the slab in phase with the ball?

No!, The concrete doesn't absorb any energy to lose. LOOK AT THE TOXIC 5 VIDEO! You can see the blade does not rebound in phase with the ball bouncing back. That energy the ball imparts on the blade is lost. Now what if the blade has a vibration of 2000 Hz? I have explained that above.

Also, I'm not that bright either, but I sense some contradiction in here somewhere. Your speech is all: Wake up guys! Dwell time is not real!

Where did I say that? Stop making stuff up.
Dwell time/contact time is real, but it is short and is a function of the impact speed.

But now you are saying that there has to be some contact time so that the blade can push the ball back, and that stiffer blades decrease this contact time?!

Yes, if the vibrations are going to have anything to do with speed. Otherwise the vibratins are just wasted energy.

Oh, and your diving board analogy is marvelous too, you can clearly see how the boards bends and springs back. But what happens if a diver with a different weight tries to use it?

Finally a good question. The board's fulcrum needs to be adjusted or "tuned" to the weight of the diver obviously.
What do you think will happen if the board is too stiff or too loose. The same goes for the trampoline.

So the question is if a 1500 Hz blade is fast, is a 15000 Hz blade faster? Why not!!
I USDC deleted the post about amplitude and damping.

 

[UpSideDownCarl]

I USDC deleted the post about amplitude and damping.

I undeleted any deleted post you made in this thread.

 

[NextLevel]

It amazes me that, for such a smart guy, you still fail to comprehend some very basic concepts...

You like to ask questions and make others think, so let me ask you you a few questions:


Why and how does it deform?

What is the frequency we read?

What variables can we change in the composition of a blade to change the frequency?

Why do we have blades with the same composition but with different frequency?

@brokenball,

These questions.

 

[brokenball]

@brokenball,

These questions.

Asked and answered.
Meanwhile you don't answer my questions so why should I even bother.
You you really think a 1200 Hz paddle is 33% faster than a 1500 Hz paddle? Anybody?