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The proprietary methods to calculating rubber/blade stats?
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Author:  notcras [ 14 Sep 2018, 09:19 ]
Post subject:  The proprietary methods to calculating rubber/blade stats?
I am an engineer and I've always wanted to know the insider tests used to calculate speed, spin, and control by the table tennis companies for both rubbers and blades. Now, I understand that each company has a proprietary method and that the numbers won't match up between companies, but within companies there has to be some sort of standardized method to calculating this, right? Or is it all just marketing?

EDIT: For reference, when we measure the properties of a material (like percent elongation of a rubber) there is an ASTM standard that engineers follow so our results are the exact same across labs. Anyone have any idea of a standard test used within a company like Stiga or Yasaka? Just curious!
Author:  iskandar taib [ 17 Sep 2018, 11:05 ]
Post subject:  Re: The proprietary methods to calculating rubber/blade stat
Butterfly might have something like this. That ITTF lab in Singapore might have something like this. ESN probably does. Everyone else? I'll betcha it's simply two or three experienced players hitting with different setups and comparing them head-to-head and taking notes. With some of the smaller outfits they might even retire to the bar afterwards to compare notes and assign numbers over a couple drinks.. :lol: In other words - I don't believe much of this is very objective or quantitative. It's still far better than tabletennisdb or whatever it's called now.

Iskandar
Author:  igorponger [ 17 Sep 2018, 17:09 ]
Post subject:  Re: The proprietary methods to calculating rubber/blade stat
Chiell JOHNSSON A GREAT EQUIPMENT JUDGE.

100 point evaluation scale is the most relyable. Look into Paddle Palace chart table, Contra catalogue of Germany. A Chief Evaluator alone, usually a versed pro player, would made the evaluations manually, in accodance to his own experience and perception.
Chiell Johansson used to be an Evaluator for Contra, for long while..
Author:  haggisv [ 17 Sep 2018, 22:40 ]
Post subject:  Re: The proprietary methods to calculating rubber/blade stat
notcras wrote:
I am an engineer and I've always wanted to know the insider tests used to calculate speed, spin, and control by the table tennis companies for both rubbers and blades. Now, I understand that each company has a proprietary method and that the numbers won't match up between companies, but within companies there has to be some sort of standardized method to calculating this, right? Or is it all just marketing?

EDIT: For reference, when we measure the properties of a material (like percent elongation of a rubber) there is an ASTM standard that engineers follow so our results are the exact same across labs. Anyone have any idea of a standard test used within a company like Stiga or Yasaka? Just curious!

The problem is, you can't just assign a single number to speed, spin and control, because there are too many variables, like impact speed, angle, incoming spin, etc.

No doubt you could setup an experiment to take measurements for a very specific and fixed contraption, which would allow you to compare different rubbers/blades from different manufacturers. However the values would then only be true for that specific setup, and this may not actually relate to real-life perception of the property.
Author:  pgpg [ 17 Sep 2018, 22:58 ]
Post subject:  Re: The proprietary methods to calculating rubber/blade stat
Given that there is no good way even to define what "Control" actually is - good luck constructing an objective measurement approach.

It's mostly marketing.
Author:  maddrag [ 17 Sep 2018, 23:46 ]
Post subject:  Re: The proprietary methods to calculating rubber/blade stat
as a ping-pong rubber is just for fun, there is not a significant need to spend thousand of dollard to do the test. As anyone hit th ball differently, it is not significant to have precise test.

I think renown players or VIP in ping-pong field opinion is doing the job and much more apreciated by players If we were building bridge I would understand the importance of having such precise tests.
Author:  Retriever [ 18 Sep 2018, 08:07 ]
Post subject:  Re: The proprietary methods to calculating rubber/blade stat
We need to be able to specify a common set of criteria for any tests. The tests would only be able to give one a relative measure between equipment. Already people say that one rubber is spinnier or faster or more controlling or ... than another rubber without objective measurement. Also the contention of how much less spin is on the 40+ ball than the 40 ball.

Testing Equipment
First the equipment to be used. I would suggest that a robot would be useful for testing both blades and rubbers. Unfortunately most robots are not totally consistent in that on a particular setting the speed and spin that they produce can be variable. I suppose that this could be allowed for by measuring the speed and spin of each ball thrown from the robot and averaging used.
Equipment used for securing the blade and / or rubbers must be also specified, ie not allow for what in a human is a loose grip. To accurately measure speed of a ball and its spin some expensive high speed camera equipment is needed. Ah yes, and which ball should be used? NP40+, DHS D40+, XSF 40+ seamless, ... Also how to account for the variability of balls and their age?

The Blade
Unfortunately no 2 are alike, even within the one "model". The test would have to be without rubbers, as that would give unwanted variability. I would measure the bounce off a bare blade of a ball fired at it at various speeds. It would have to be secured to a rig that allows no movement and a particular "tightness". A robot could be calibrated to fire the balls at particular speeds, with absolutely no spin.

The Rubbers
Because of variability of blades, I would suggest that that the rubbers be attached to a steel plate of particular density and dimensions. Also, as with blades, there can be variability of rubber within a batch. We already attempt to measure the density of the top sheet and sponge combination. Next question is how to attach them? Glue sheets? Water based glue? Older VOC glues? Variability galore.
Balls with a variety of speeds and spins should be fired at the rubber and the bounce and direction off the rubber measured. Next what combinations of speed and spin to test?
Given that there are hundreds of rubbers in the LARC, and then within that there are the various thicknesses of sponge with most of them, then there is the retail / provincial / national / CNT versions of some Chinese rubbers, also cases where the there appears to be different "versions" of certain Chinese rubbers, the job to test all rubbers in a scientific way seems to be a Herculean task. Oh and I almost forgot, only the top sheet is really specified in the LARC, and it is possible to mix and match the underlying sponge with the top sheet, and you can buy sponge separate from top sheets.

The Combination?
Then there is the effect reported by some of the effect of the rubber on the other side of the blade on how a rubber plays on a particular blade. Measuring that just complicates things to the nth degree.

Then there is the effect of how a particular blade complements a particular rubber for a particular player, or at least the belief in that effect that fuels the eternal EJ.

I could go on :)
Author:  iskandar taib [ 18 Sep 2018, 09:56 ]
Post subject:  Re: The proprietary methods to calculating rubber/blade stat
Add high speed cameras to all of the above. With proper backdrops. You'd need some sort of super-robot capable of firing balls at known speeds and RPMs.

I'm pretty sure Butterfly and ESN have this stuff. Plus a lot of evaluator-players who play under controlled conditions as well, with cameras and such.

Iskandar
Author:  notcras [ 22 Oct 2018, 17:13 ]
Post subject:  Re: The proprietary methods to calculating rubber/blade stat
Retriever wrote:
The tests would only be able to give one a relative measure between equipment. Already people say that one rubber is spinnier or faster or more controlling or ... than another rubber without objective measurement.

That's kind of what I was thinking of, and I get that things would get complicated really fast. But I think we can reasonably handle a lot of the uncertainty... let's say we set the ball to Nitakku 3* Premium balls (because that's the official tournament ball, right?). Makes sense to stick the rubber on a plate to isolate its performance from a blade's. We could stick to using the manufacturer-provided sponge with the rubber being tested, just to choose the product sold by the manufacturer. And concerning variation, you don't have to take one data point per rubber - if you got multiple you can reasonably account for variation by taking an average of all of the values. I would be the first to say its not perfect, but it might not have to be perfect to be able to get some conclusions from the data. Now it sounds like I'm advocating to make a test... not the intent at all, just sharing thoughts xD. I find this to be fun.

maddrag wrote:
I think renown players or VIP in ping-pong field opinion is doing the job and much more apreciated by players If we were building bridge I would understand the importance of having such precise tests.

I understand, but people seem to generally disagree with most manufacturing provided specs, and since we can't expect the renown players and VIPs to test every rubber (right? Is it?), I still feel like there's reason to have the manufacturers to have a consistent test between their own rubbers. Just surprised its less rigorous than I thought, given the other types of manufacturers that I deal with (who characterize everything about their materials).

pgpg wrote:
Given that there is no good way even to define what "Control" actually is - good luck constructing an objective measurement approach.

Or maybe these metrics (spin, speed, and control) could be broken into more specific attributes that could be more telling. Thoughts?
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