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PostPosted: 30 Nov 2018, 20:09 
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Just m two cents...

All of the chinese players are playing DHS rubbers on their forehand. These rubbers are pretty hard, they are getting eventually softer of tuning but not a lot. The sponge hardness of them is about 38 - 41 degree chinas scale. This would start with something like Xiom Vega Pro and its just getting harder.
On the backhand its personal what they like and prefer. Some players are prefering medium rubbers, some of them more hard rubbers. But im pretty sure none of the player plays a really really soft rubber like T64fx on the backhand, the softest should be something like T05fx soft-medium.

The reason for the forehand is because as harder the rubber as more speed you finally get. This is not like each rubber in the world works but the chinese rubbers should work like this. On the other hand the rubber cant be too hard otherwise you couldnt play with it.


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PostPosted: 01 Aug 2019, 03:42 
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igorponger wrote:
Hi, Haggisv

Which Shore Type did you employ for testing the rubber samples? Could you give a real photo of your working device?
Thanks.

Shore A (truncated cone indentor) inbuilt spring force 0.82 kgf
Image

Shore D (conical indentor) inbuilt spring force 4.45 kgf
Image

Shore O (semispherical indentor) inbuilt spring force 0.82 kgf
Image

Shore C (truncated cone) spring force 4.45 kgf
(image same as Shore A)



Haggis uses Shore O (see his hardness table page). DHS uses Shore A.

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PostPosted: 05 Jan 2020, 01:32 
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Do you guys know what scale 729 uses? Seems like neither shore O nor A. :headbang:


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PostPosted: 06 Jan 2020, 01:13 
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Tianjin scale. (Same as Yinhe, Palio, 999, a bunch of others.) As far as I know that's Shore O. The problem with Haggis's measurements is that the material isn't thick enough (Haggis mentions this in the introduction). The gauge "bottoms out". It works up to a point, but when the rubber gets soft enough, the rubber gets compressed up against the backstop (i.e. the table) and so you get false readings, which, as the rubbers get softer, sort of "hit a wall". In other words, softer rubbers will give readings that are too high (i.e. will appear to be harder than they actually are) and for the extreme soft end of the scale, the readings for all samples will all be more or less the same.

I think it'd be possible to create a gauge that will work with thin material - you'd have to set it up to use less force. And then you'd calibrate it using materials of known hardness. The precision will be less. Incidentally, durometers are easily available on AliExpress, and they really don't cost that much.

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PostPosted: 06 Jan 2020, 01:25 
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What about stacking multiple sponge layer together? Might not be accurate, but should be good at least for comparitive no?


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PostPosted: 06 Jan 2020, 01:44 
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Yeah, that would work (though the topsheet gets in the way and would need to be removed if you want accurate numbers). What might also work would be to do the test with the rubber being tested lying on a thick sheet of material which would be of comparable hardness to the sponge (maybe just several layers of relatively hard sponge glued together). While it won't give you accurate readings, it would be better than doing the test using a hard surface as backing.

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PostPosted: 06 Jan 2020, 10:02 
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Iskandar my dear friend,
Luckily, you need not reinvent wheel. The specialized durometer for measuring on very soft materials, like Sorbothane rubber elastomers, does exist for years. It is denoted as Shore OO scale and using much lower spring force of 1.12 N versus 8.05 N on ShoreA.

The OO scale (uttered as 'eu-eu scale') is intended to be used on truly soft materials with hardness less than 15 ShoreA degrees.
You know some table tennis rubbers with sponge being that soft ?? I can't remember of the such.

And yes, you make a good point saying that the softer sandwich rubbers need a different testing procedure with the view to avoid false readings. At factory laboratory a thick piece of sponge (without topsheet) would be tested by Shore"A" or Shore"O" hardness scales. The best reasonable way for diminishing the interference of stiff underlayer (the kitchen desktop e.g.) would be using another rubber sheet as an underlayer.

/Be happy/


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PostPosted: 06 Jan 2020, 10:57 
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igorponger wrote:
Iskandar my dear friend,
Luckily, you need not reinvent wheel. The specialized durometer for measuring on very soft materials, like Sorbothane rubber elastomers, does exist for years. It is denoted as Shore OO scale and using much lower spring force of 1.12 N versus 8.05 N on ShoreA.

The OO scale (uttered as 'eu-eu scale') is intended to be used on truly soft materials with hardness less than 15 ShoreA degrees.
You know some table tennis rubbers with sponge being that soft ?? I can't remember of the such.


Exactly why a Shore 00 durometer won't work. These instruments probably also require a minimum thickness thicker than 2-4mm. That is NOT what I described above. Besides, it isn't pronounced "eu eu", it's pronounced "ought ought" or "oh oh". "Eu eu" doesn't even work in German ("eu eu" would sound like "oi oi").

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PostPosted: 06 Jan 2020, 13:10 
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http://www.yapfiles.ru/files/2311188/d4b41328b9bd3420e8888f04684142a8.mp3?token=MDIzMTExODgtMTU3ODI4MTcxNQ

/Be happy/


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PostPosted: 06 Jan 2020, 14:45 
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Should one rely on a Russian machine translator or native English speakers to decide what "OO" sounds like in English? (Never mind what is sounds like in Russian..) :lol:

(Igor's probably never heard of "Ought ought buck" before... :lol: )

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PostPosted: 07 Jan 2020, 10:18 
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A view behind the scene. Quality control at German ESN factory.


Image
RASANT Hardness Chart by SHORE-O scale

Shore"A" . . . Shore"O". . .ASKER"C"
40 . . . . . . . . . .50 . . . . . . .70
37.5 . . . . . . . . 47.5 . . . . . .68
35 . . . . . . . . . . 45 . . . . . . .65
30 . . . . . . . . . . 40 . . . . . . .60
28 . . . . . . . . . . 37.5 . . . . . .58

ASKER C, indenter hemisphere d=5.08 mm
Shore O, indenter hemisphere d= 2.34 mm
Shore A, indenter truncated conical

Prior to the year 1990, Tamasu Batterfly® is known to use ASKER-C scale as a hardness criterium of their rubber products.. They did switched to SHORE-A scale since then.


Last edited by igorponger on 10 Sep 2021, 13:03, edited 2 times in total.

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PostPosted: 07 Jan 2020, 10:56 
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Tribological. :lol: Eu eu buck. :lol: :lol:

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PostPosted: 10 Mar 2021, 19:42 
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When you ask people about hardness, some would say softer is faster/spinnier, and some would harder is faster/spinnier. Neither of these views is wrong, but it depends on how you look at them.

Soft rubber

If we drop the ball onto a softer rubber, the ball would bounce up higher than with a harder rubber, and it is also easier for the rubber to grip the ball, meaning easy speed and easy spin. In other words, with a softer rubber, we don't need to swing a bat as much to do a spinny serve, looping backspin, or any sort of offensive technique.

Hard rubber

If we drop the ball onto a harder rubber, the ball wouldn't bounce as high and it doesn't grip the rubber as good. With a harder rubber, we would need to put in more effort to do serves or any offensive technique to achieve the same quality as with a softer rubber. But, if we swing the bat fast enough, we can exceed the maximum speed and spin that is offered by a softer rubber.

And there are more advantages with using a harder rubber! Since harder rubbers don’t bounce the ball as high or grip the ball as much, pushes won't pop up as easy, meaning that the amount of spin and speed is easier to vary, especially when serving.

So which one should beginners use?

Well, this depends on your environment and what you want to do.

If you have serious coaching, then using a medium hard ESN 40°-45° should be fine, because the coaches can teach you how to play the techniques properly, so you should be able to use the full potential of a medium hard rubber with no problem. This is why a lot of people in China use hard rubber to start with, because their environment offers intensive training.

If you only play 2-4 hours a week and can't get proper coaching but still want to win some games, soft rubbers at ESN 35°-40° would allow you to do speedy and spiny play with high consistency easily even if you haven't mastered the basic techniques.

If you are under 14 years old or doesn't have a strong arm, ESN 35°-40° soft rubber would be better. If you use a hard rubber while your body strength can't handle them, no matter how hard you hit the ball you still won't be able to achieve the full potential of it.wholesale folding chairs


Last edited by tyresebro1 on 12 Mar 2021, 22:04, edited 1 time in total.

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PostPosted: 11 Mar 2021, 01:33 
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tyresebro1 wrote:
This is why a lot of people in China use hard rubber to start with, because their environment offers intensive training.


I think people tend to over-state what goes on in China. The above would be true for, say, school team players, or people who join formal table tennis clubs.. I'll bet MOST Chinese players belong to the general public - they play for fun, like us, and don't get any coaching at all.

I don't disagree with what you say, but I think it's being too over-analytical. The casual player (anyone rated under, say, 1800) isn't going to over-strain themselves by using hard sponge, and they're not going to "achieve the full potential" of anything they use. For a lot of these players, though, something like H3 will simply FEEL too slow so they won't use it. If they have the money they'd buy some medium Tensor, if they don't, something like AK47 Blue or Palio CJ8000 or Yinhe Mercury II or Reactor Tornado V5 would work just fine and cost a fraction of what the Tensor would. Most wouldn't even be able to tell the difference.

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PostPosted: 06 Sep 2021, 07:18 
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haggisv wrote:
Here is a growing list of sponge hardness levels of rubbers, as measured with my durometer. I've explained in there that adjustment needed to be made to the values and why, but the results tie in quite well with my expectations.

I'll continue to add values as I get access to them... Waht do you think?:

Sponge hardness measurement table


Hi, Haggis
We pleased to share some of our latest experiments on different rubbers, using Shore O Durometer.
We usually utilized a hard terracota plate as a base layer. Our most interesting findings are as follows.

1. WHEN MEASURING HARDNESS ON SPONGE the thickness of a sample sheet is the most decisive.
E.g. in measuring Yinhe Big Dipper (marked as 40* Shore A) on a single sheet we have got result of 54 degrees by Shore O. Thereafter we tryed 2-sheet combination and we got 51 degrees. The latter result is very close to our theoretical expectation that 40 + 11 =51.
The increment of 11 - is the normal tabular divergence Shore-O from Shore-A.

Again, all the factory labs are known to use a thicker sponger sheet of 6-10 mm for their hardness tests.

CONCLUSION TO REMEMBER.
In order to get true numbers, we need to always apply a diminutive correcture of 3 degrees to all the tabular hardness as present in OOAK Hardness Table.

With best regards
Igor Novick, engineer.
Image size=604x453&quality=96&sign=3fc39fa565bd2dfbf2fff


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