OOAK Table Tennis Forum

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.

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

Iskandar

Do you guys know what scale 729 uses? Seems like neither shore O nor A.

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.

Iskandar

What about stacking multiple sponge layer together? Might not be accurate, but should be good at least for comparitive no?

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.

Iskandar

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/

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").

Iskandar

http://www.yapfiles.ru/files/2311188/d4b41328b9bd3420e8888f04684142a8.mp3?token=MDIzMTExODgtMTU3ODI4MTcxNQ

/Be happy/

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..)

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

Iskandar

The hot female-technician sorting out the sponge sheets,. A view behind the scene ESN factory.




RASANT Hardness Chart (green sponge)

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

ASKER C indenter hemisphere d=5.08 mm
Shore O indenter hemisphere d= 2.34 mm = 3/32 in.

Till the year 1990, Tamasu Batterfly® did exclusively use ASKER-C device for tribological works on all their rubbers. And then they switched to SHORE A.

Tribological. Eu eu buck.

Iskandar