OOAK Table Tennis Forum

Is there any way for the average Joe to be able to measure, or even approximate the amount of friction produced by his rubber (ie. LP, but could apply to SP or Inverted)? It would be nice to know how to compare the friction produced by different rubbers with some home test. I mean you can rub a ball across a rubber and get "some' idea, but I would have no idea whether it was 25nm, 50nm or 100nm. If they are going to set this friction limit, then there should be some way, besides some machine that might turn up at the ocassional tournament for a person to tell. I mean even breathalysers have home testers you can buy, rather than relying on knowing once the policeman tests you and you get penalised.

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I'm always in the dark, but the Dark sheds lights upon everything!! Beauty is only pimple deep! Beauty is in the eye of the pipholder!
S/U 1: Blade: Bty Gergely . FH Black Andro Rasant 2.1 . BH Red Tibhar Grass Dtecs
S/U 2: Blade: Bty Gergely . FH Black Hexer+ 2.1 . BH Red GD Talon
S/U 3: Blade: Bty Gergely . No rubbers...thinking of adding Red Dtecs and Black Rasant
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Yeah, I've like to learn this, especially to know when to start thinking and saving up for a new rubber.

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Viscaria. H2 Neo 2.15. Tenergy 05 1.9.

You can get (or used to be able to get) little force gauges - pretty much two rings attached together by a calibrated spring. What you'll need to find out is the mass they use to test the rubbers and a force gauge of appropriate scale. I don't know how hard it will be to find something in this 0-100 N range.

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Chasse Patate

I'm having problems finding any sort of procedure on how they test.

Since they publish in Nm, I figure they drag a specific mass over x distance (that is, force required to shift the mass one metre.)

I'm sort of wondering why they publish in Nm and not just N.

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Chasse Patate

The problem is the accuaracy of the testing. Between 50 & 25 maybe good enough but you may have the problem if your rubber is 26-28.

Is it just me, or does it seem ridiculous to introduce such a test when someone like Silver doesn't even quite understand it! I mean your average Joe isn't going to get it, and many of those who think they know something will be trying to claim your rubber doesn't have enough friction whether they can prove it or not (as I have recently found out)!

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I'm always in the dark, but the Dark sheds lights upon everything!! Beauty is only pimple deep! Beauty is in the eye of the pipholder!
S/U 1: Blade: Bty Gergely . FH Black Andro Rasant 2.1 . BH Red Tibhar Grass Dtecs
S/U 2: Blade: Bty Gergely . FH Black Hexer+ 2.1 . BH Red GD Talon
S/U 3: Blade: Bty Gergely . No rubbers...thinking of adding Red Dtecs and Black Rasant
Aussie Table Tennis Shop / Aussie Table Tennis Facebook Page / Equipment Review Index / Read my Reb Report Blog: click here.

Hey, I'm an electronics, not a mech engineer I've only done the pre-requisite 1st year statics and dynamics subjects...

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Chasse Patate

I've never seen the info published anywhere. I also think they measure the force required to drag a mass over the rubber... the mass would be useful to know, as it will indicate if it's enough to bend the pips or not...

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If they measured the force needed to move the ball a certain distance, it would have to be expressed in N/m, not Nm. I believe there's some confusion: I thought they would be publishing in µN (= 10^-6 N, micro-newton, or one millionth of a newton). This is for the better, because frictional force on a ball (celluloid plastic) on pips rubber at low speed would be a very small number if expressed in newton, instead of µN (micro-newton).

PS expressing it in Nm (newton metre) would be a very silly thing to do, since Nm is the SI unit of torque (rotational force), which has very litlle (nothing to be precise ) to do with the physics of friction(less) long pips.

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I think that this is just a question of order. The current friction limit is 25 or 30 mN (mili newtons). As Jasper said Nm would be something like Newtons xmeter which makes no sense, and nm would be nanometers.

Regarding the test itself I know they are using a kind of quite complicated machine. In the spanish forum I asked for the exact protocol of the procedure to measure the friction in a rubber, and a spanish international referee, just send in the picture of the machine, so I guess it's not easy to have a cheap test at home.

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Blade: Butterfly Legout
FH: YinHe Saturn 2.0 38º
BH: Meteor 8512 0.5 mm OFF

Indeed! Which makes it a stupid rule to impose! No doubt this machine will be expensive too, so perhaps there is some deal between its makers and the ITTF? Has the TT world gone crazy? I mean without guys like Jasper and Quelis (and Silver to a lesser or is that sideways degree lol, don't worry I have degrees to but none in Physics - the closest I got to this was my roommate in college was a Quantum Physicist doing a Nursing course to hit on the chicks LOL), we would have no idea of what this all means (not sure we still do even with them LOL).

It is insane to even expect TT players in general to understand and follow such an expert rule. Is a ref in a tourney going to have the expertise to argue that a rubber doesn't meet the rules. Especially if you get him up against a Jasper, who can perhaps even show him that his machine is incorrectly calibrated? So the Quantum Physicist TT players will have an advantage over everyone else. This is discrimination and should be taken to the Equal Opportunity Commission LOL!

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I'm always in the dark, but the Dark sheds lights upon everything!! Beauty is only pimple deep! Beauty is in the eye of the pipholder!
S/U 1: Blade: Bty Gergely . FH Black Andro Rasant 2.1 . BH Red Tibhar Grass Dtecs
S/U 2: Blade: Bty Gergely . FH Black Hexer+ 2.1 . BH Red GD Talon
S/U 3: Blade: Bty Gergely . No rubbers...thinking of adding Red Dtecs and Black Rasant
Aussie Table Tennis Shop / Aussie Table Tennis Facebook Page / Equipment Review Index / Read my Reb Report Blog: click here.

Hi Reb,

I'm sure you know, but it's just a marketing question. It's all about marketing and selling more rubbers and selling different glues, and selling, and selling and selling even more.

I'm against any kind of bans. And this particular one has been very (let's say) scarcely explained.

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Blade: Butterfly Legout
FH: YinHe Saturn 2.0 38º
BH: Meteor 8512 0.5 mm OFF

Just a few more thoughts about this thread:

TT has a serious problem nowadays. The International Federation is under great pressure from the Companies selling TTstuff and their marketing strategies. What has TT gained with a ball of 2 mm more of diameter? Everybody knew that VOCs from organic glues were toxic, why has the prohibition taken such a long time to come? Have you realised that almost no chinese company produced frictionless pips? And even so, 755 Faster and 799 have not reached the minimum. Have you seen the protocol (the exact procedure) to test a LP rubber for friction anywhere?
Sometimes it seems that ITTF is too weak and sometimes it seems that they just hate that asiatic (let's say it clearer: chinese) players win a 90% or more of competitions. But people is beginning to realise that you can have a nice rubber for 15€ instead of 60 and that chinese players win because they have more federated players than in any other counttry in the world and because they train harder than in any other place.
I'm just asking for a quiet period of TT without more changes in rules and materials beacuse I'm tired of all them we've got so far.

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Blade: Butterfly Legout
FH: YinHe Saturn 2.0 38º
BH: Meteor 8512 0.5 mm OFF

Force of friction = µN,

where µ is the coefficient of friction between the object (i.e. ball) and the surface (rubber surface) on which the ball is draged and N is the normal reaction.

According to Newton's Third Law of Motion, to every action there is an equal and opposite reaction.

Weight of the ball exerts a force on the ball and the surface of the rubber exerts a force on the ball which is called the Normal Reaction, N.

N = mg where m is the weight of the ball and g =9.8 m per sec per sec.

g is the gravtional acceleration.

quelis, I 110% absolutely agree with you!

GR, thanks for the physics lesson, which I understand as much as a non-physicist can. But please tell me what other sport has rules that have to dig into that much science to produce rules?

I feel like starting my own competition called FTT (Freeworld Table Tennis) that has its own rules that are nothing to do with the ITTF. Anyone feel like joining me? LOL.

_________________
I'm always in the dark, but the Dark sheds lights upon everything!! Beauty is only pimple deep! Beauty is in the eye of the pipholder!
S/U 1: Blade: Bty Gergely . FH Black Andro Rasant 2.1 . BH Red Tibhar Grass Dtecs
S/U 2: Blade: Bty Gergely . FH Black Hexer+ 2.1 . BH Red GD Talon
S/U 3: Blade: Bty Gergely . No rubbers...thinking of adding Red Dtecs and Black Rasant
Aussie Table Tennis Shop / Aussie Table Tennis Facebook Page / Equipment Review Index / Read my Reb Report Blog: click here.