OOAK Table Tennis Forum


A truly International Table Tennis Community for both Defensive and Offensive styles!
OOAK Forum Links About OOAK Table Tennis Forum OOAK Forum Memory
It is currently 20 Oct 2020, 12:48


Don't want to see any advertising? Become a member and login, and you'll never see an ad again!



All times are UTC + 9:30 hours




Post new topic Reply to topic  [ 102 posts ]  Go to page Previous  1 ... 3, 4, 5, 6, 7
Author Message
PostPosted: 30 Nov 2018, 20:09 
Offline
New Member

Joined: 17 Oct 2018, 22:19
Posts: 1
Location: North Bergen,New Jersey
Has thanked: 0 time
Been thanked: 0 time
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.


Top
 Profile  
 


PostPosted: 01 Aug 2019, 03:42 
Offline
Goes to 11
Goes to 11
User avatar

Joined: 13 Jan 2014, 20:27
Posts: 9645
Has thanked: 2 times
Been thanked: 1179 times
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.

Iskandar


Top
 Profile  
 
PostPosted: 05 Jan 2020, 01:32 
Offline
Super User

Joined: 26 Jun 2018, 14:51
Posts: 528
Has thanked: 36 times
Been thanked: 89 times
Do you guys know what scale 729 uses? Seems like neither shore O nor A. :headbang:


Top
 Profile  
 
PostPosted: 06 Jan 2020, 01:13 
Offline
Goes to 11
Goes to 11
User avatar

Joined: 13 Jan 2014, 20:27
Posts: 9645
Has thanked: 2 times
Been thanked: 1179 times
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


Top
 Profile  
 
PostPosted: 06 Jan 2020, 01:25 
Offline
Super User

Joined: 26 Jun 2018, 14:51
Posts: 528
Has thanked: 36 times
Been thanked: 89 times
What about stacking multiple sponge layer together? Might not be accurate, but should be good at least for comparitive no?


Top
 Profile  
 
PostPosted: 06 Jan 2020, 01:44 
Offline
Goes to 11
Goes to 11
User avatar

Joined: 13 Jan 2014, 20:27
Posts: 9645
Has thanked: 2 times
Been thanked: 1179 times
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


Top
 Profile  
 
PostPosted: 06 Jan 2020, 10:02 
Offline
Super User
User avatar

Joined: 10 Jun 2007, 09:24
Posts: 910
Location: Universe
Has thanked: 19 times
Been thanked: 73 times
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/


Top
 Profile  
 
PostPosted: 06 Jan 2020, 10:57 
Offline
Goes to 11
Goes to 11
User avatar

Joined: 13 Jan 2014, 20:27
Posts: 9645
Has thanked: 2 times
Been thanked: 1179 times
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").

Iskandar


Top
 Profile  
 
PostPosted: 06 Jan 2020, 13:10 
Offline
Super User
User avatar

Joined: 10 Jun 2007, 09:24
Posts: 910
Location: Universe
Has thanked: 19 times
Been thanked: 73 times
http://www.yapfiles.ru/files/2311188/d4b41328b9bd3420e8888f04684142a8.mp3?token=MDIzMTExODgtMTU3ODI4MTcxNQ

/Be happy/


Top
 Profile  
 
PostPosted: 06 Jan 2020, 14:45 
Offline
Goes to 11
Goes to 11
User avatar

Joined: 13 Jan 2014, 20:27
Posts: 9645
Has thanked: 2 times
Been thanked: 1179 times
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: )

Iskandar


Top
 Profile  
 
PostPosted: 07 Jan 2020, 10:18 
Offline
Super User
User avatar

Joined: 10 Jun 2007, 09:24
Posts: 910
Location: Universe
Has thanked: 19 times
Been thanked: 73 times
The hot female-technician sorting out the sponge sheets,. A view behind the scene ESN factory.



Image
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.


Top
 Profile  
 
PostPosted: 07 Jan 2020, 10:56 
Offline
Goes to 11
Goes to 11
User avatar

Joined: 13 Jan 2014, 20:27
Posts: 9645
Has thanked: 2 times
Been thanked: 1179 times
Tribological. :lol: Eu eu buck. :lol: :lol:

Iskandar


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 102 posts ]  Go to page Previous  1 ... 3, 4, 5, 6, 7




All times are UTC + 9:30 hours


Who is online

Users browsing this forum: No registered users and 29 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Copyright 2018 OOAK Table Tennis Forum. The information on this site cannot be reused without written permission.

Powered by phpBB® Forum Software © phpBB Group