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PostPosted: 31 Jul 2019, 09:10 
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Debater wrote:
Thank you for your replies Felix. From my understanding, Shore A is for softer rubbers/elastomers than the Shore C scale. Does this mean the Goldarc series of rubbers are actually the "hardest" sponges/rubber combinations of any of the DHS table tennis rubbers you make? If not, why a different Shore Scale for the Goldarc please?

I think the reason would be that Goldarc rubbers are German-made ESN rubbers, so the German scale would have been used by the manufacturer.

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PostPosted: 31 Jul 2019, 19:48 
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Felix wrote:
2. About the measure stand of rubber, we adopt Shore A for most of rubbers and Shore C for Goldarc rubbers.


Surely GoldArc 5 and 8 are made (and the hardness testing done) in Germany? Or do you mean GoldArc 3? (I've always wondered why that was such an expensive sheet..)..

Incidentally, you've all seen this conversion scale, right? It's from the Yinhe catalog:

Attachment:
YinheCatalogSponge2013.jpg
YinheCatalogSponge2013.jpg [ 46.56 KiB | Viewed 1632 times ]


I had the bright idea of running it through Google Translate on my phone (haven't figured out how to do it on a PC yet). And the results are interesting. Apparently there's a "Tianjin School" (probably Yinhe, RITC and Palio, and also including the likes of Reactor, Tuttle, 61 Second, etc.) where they use a "ball hardness test" and a "Shanghai School" (probably DHS) where they use a "needle test" (probably Shore A, which actually uses a truncated cone). Tianjin is on the left, Shanghai on the right. There are several different Shore testers that use spherical probes, not sure which one is used by the Tianjin school. The translation simply says "Shaw's (probably means Shore) ball". If this is to be believed then the 38-39 degrees you get with H3 is VERY hard compared with the 42-44 degrees you encounter with 729 Batwings. 39 degrees would correspond to 50-52 on the Tianjin scale (which, incidentally, is what they say is the hardness for 729 Battle II).

In the past everyone thought this table was for translating Chinese to Japanese hardness... :lol:

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PostPosted: 01 Aug 2019, 03:14 
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Debater wrote:
Felix wrote:
Hi, first I would thank you for the insightful questions. You understand right about what I replied previously.

We actually measure the thickness and hardness of sponge for each rubber. The top sheet is made under the same criteria according to specific rubber type.

1. This question is related to our production method and is not able to answer.

2. About the measure stand of rubber, we adopt Shore A for most of rubbers and Shore C for Goldarc rubbers.

3. Like I have explained, we measure the thickness as well as hardness of sponge and make top sheet according to same criteria for each type to best guarantee the consistency of the rubber as a whole.

4. Same answer to question No. 3

I'd really admire your detail oriented thinking and hope you will be satisfactory to my answer. ;)


Thank you for your replies Felix. From my understanding, Shore A is for softer rubbers/elastomers than the Shore C scale. Does this mean the Goldarc series of rubbers are actually the "hardest" sponges/rubber combinations of any of the DHS table tennis rubbers you make? If not, why a different Shore Scale for the Goldarc please?

Very interesting to read your answer to question 3. If I understand this correctly, if the rubber is slightly harder on one batch of say, DHS Hurricane 8 than another, it will be matched with a slightly softer sponge so the two (rubber and sponge) balance each other out.

EG Sheet 1 of Hurricane 8 sponge of 43 degrees hardness matched with rubber sheet hardness of 57 degrees. Overall combined hardness of 50 (43+57)/2= 50

Sheet 2 of Hurricane 8 sponge 44 degrees hardness is matched with rubber sheet hardness of 56 degrees. Overall combined hardness of 50 (44+56)/2=50

Does this mean then the hardness rating on DHS packaging for table tennis rubbers is the combined hardness of both the sponge and rubber top sheet? If not, I'm not sure I understand what you mean by "we measure the thickness as well as hardness of sponge and make top sheet according to same criteria for each type to best guarantee the consistency of the rubber as a whole."

I'm a bit confused because whilst the ITTF don't test sponge as part of their technical leaflets they do require the combined thickness of sponge and rubber to remain within a maximum predefined limit. If you are selling a rubber (combined top sheet and sponge which comes in at the maximum allowable combined thickness of 4mm and you have to use a thicker sponge than originally tested and used to pass the technical ITTF tests, the combined rubber / sponge combination would exceed 4mm (assuming the rubber topsheet thickness is constant). That would make the rubber/sponge combination illegal?

Thank you for your help.


I suspect you're reading way too much into the answer for #3. All he's saying is that they test both the sponge and topsheets for hardness so that they're within specs. They're NOT matching hard sponges with soft topsheets, etc. And you DO want to make sure all the sponges you sell as "2.15mm" (or whatever) is within, say, +/- 0.005mm of 2.15mm. And of course, they do NOT sell assembled sheets that exceed 4mm in thickness, they probably measure this as well. In fact they probably make sure the sheets don't exceed, say, 3.95mm (or some other number below 4) because they KNOW (nudge nudge wink wink) that some, perhaps even a majority, of their users will Falco or Seamoon the things, which makes them thicker.

I suspect, for sponge hardness and weight, the tolerances are pretty loose, because, like other companies (even Daiki and ESN), they don't have the degree of control over their sponge manufacture that they'd like to have, hence the widely varying weights of even very expensive sheets (remember the discussion about Karis a year or two ago?). Sponges are tested for hardness, and put into bins for different uses. Thickness is easy to regulate, it's a matter of slicer adjustment so it's less of a worry and tolerances can be much tighter.

What happens to topsheets and sponge that don't meet the requirements? They go in the trash/recycling bin, or get sold down the road to someone who makes pre-made supermarket bats. The topsheets might get the logos cut off or they're assembled on the bats backwards so the logo gets cut off. I've seen a lot of Haifu factory seconds, and there's lots of 729 stuff sold that might be seconds, but I doubt DHS lets ANY seconds out of its factory unless it's suitably disfigured or disguised. Too much at stake. I'll bet there IS a significant amount of out-of-spec trash that's generated, though.

Iskandar


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PostPosted: 01 Aug 2019, 06:50 
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☛ ITTF TECHNICAL DIRECTIVES OF 2010 STILL REMAINS IN FORCE.☚ BE AWARE, PLEASE.

In early of Juley, Ms. Herweg, an ITTF official in charge of equipment matter, has informed about the test findings they got during Horvatia Open 2019. Of 120 rubbers tested 16 proved an outlaw because of exceeding 4.05 thickness limit. "Too many illegalities disclosed, it is far too much" she noted sadly.

Not all the players boosted on rubber, they just are being supplied with an illegal products from a manufacturer source. Some of manufacturers do not abide by the ITTF technical guidance which is still valid since the year 2010, that requested "all sandwich rubbers should be of maximum thickness of 3.85 millimeters"

Despite the ITTF directives, some manufacturers would go on producing sandwich rubbers 3.90 --3.95 millimeters thick, which is mostly caused by the factory tuning treatments. Those factory tuned rubbers came out some "clumsy assistance" for players, indeed. As you all aware, the usual repeated gluings by players may eventually add up to 0.2 mm extra layer to the factory sponge, and the sandwich rubber may become an outlaw as a result.

We do feel it a necessity that we advice Ms.Herweg to look closer into the "factory tuning problem". Hopefully ITTF will resolve the problem to the good of our sport.

Be happy.


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PostPosted: 01 Aug 2019, 11:11 
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ROFL!!! How DARE they??? Outrageous!!!! :lol: Horvatia?? Where the heck is Horvatia?? I suppose we'll be hearing next from Mr. Hiswatch from the Podunkistan Open about how 23.5% of the players had rubber that was too thick. I mean, if this were really a problem, why isn't there a report from, say, the Qatar Open or the European Championships? I suppose if you survey rackets from the U-1500 event at, say, the Los Angeles Closed you'd probably find 2-3 players still speed-gluing... :lol: I swear, I think Igor makes up half of this stuff.

I can't imagine why players would be repeatedly pulling rubber off their bats and regluing it UNLESS they're boosting. And if they're too poor to be buying new sheets of rubber every week to boost, then they're not part of a national team and who cares anyway? Besides, if you want to ban "factory tuning", then you'll have to ban Tenergy and all of those Tensors. If the rubbers are too thick it isn't due to "factory tuning", it's because someone nudged the dial on the sponge slicer and the QC people didn't catch it - it probably happens from time to time but is probably more likely at the smaller factories (e.g. 999), not at the major ones.

Iskandar


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PostPosted: 02 Aug 2019, 11:20 
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haggisv wrote:
Debater wrote:
Thank you for your replies Felix. From my understanding, Shore A is for softer rubbers/elastomers than the Shore C scale. Does this mean the Goldarc series of rubbers are actually the "hardest" sponges/rubber combinations of any of the DHS table tennis rubbers you make? If not, why a different Shore Scale for the Goldarc please?

I think the reason would be that Goldarc rubbers are German-made ESN rubbers, so the German scale would have been used by the manufacturer.


Yes, correct. The Goldarc rubbers are made in Germany. So the measuring scale is different from the DHS rubbers made in China.


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PostPosted: 02 Aug 2019, 11:40 
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iskandar taib wrote:
Felix wrote:
2. About the measure stand of rubber, we adopt Shore A for most of rubbers and Shore C for Goldarc rubbers.


Surely GoldArc 5 and 8 are made (and the hardness testing done) in Germany? Or do you mean GoldArc 3? (I've always wondered why that was such an expensive sheet..)..

Incidentally, you've all seen this conversion scale, right? It's from the Yinhe catalog:

Attachment:
YinheCatalogSponge2013.jpg


I had the bright idea of running it through Google Translate on my phone (haven't figured out how to do it on a PC yet). And the results are interesting. Apparently there's a "Tianjin School" (probably Yinhe, RITC and Palio, and also including the likes of Reactor, Tuttle, 61 Second, etc.) where they use a "ball hardness test" and a "Shanghai School" (probably DHS) where they use a "needle test" (probably Shore A, which actually uses a truncated cone). Tianjin is on the left, Shanghai on the right. There are several different Shore testers that use spherical probes, not sure which one is used by the Tianjin school. The translation simply says "Shaw's (probably means Shore) ball". If this is to be believed then the 38-39 degrees you get with H3 is VERY hard compared with the 42-44 degrees you encounter with 729 Batwings. 39 degrees would correspond to 50-52 on the Tianjin scale (which, incidentally, is what they say is the hardness for 729 Battle II).

In the past everyone thought this table was for translating Chinese to Japanese hardness... :lol:

Iskandar


Goldarc 3 was produced in Japan and had been discontinued for a long time. Actually regarding Shore A and C hardness, there is no definite conversion way to match the scale as different methods of measuring are used.


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PostPosted: 02 Aug 2019, 20:50 
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IIRC, GoldArc 3 was over $50 at Eacheng. Really expensive, even for some Japanese rubbers, though not as much as you'd pay for Tenergy.

Actually, I'm thinking Tianjin uses Shore O, not Shore C (which is actually for harder plastics). There is a lot of overlap between the upper part of Shore A and the lower part of Shore C, I've found several graphics online that demonstrate this, for example:

Attachment:
Durometer-Conversion-Chart-1024x775.jpg
Durometer-Conversion-Chart-1024x775.jpg [ 115.69 KiB | Viewed 1355 times ]


(This graphic has more than A and C.. it's also got O. Wish I'd seen this last night - it pretty much says the same thing the Yinhe table does - 39-40A -> 52-53O. And -> 13-14C. So we've nailed down the Tianjin and Shanghai scales - they correspond to Shore A and Shore 0. What does the ESN Scale and the Butterfly Scale correspond to? :lol: Also note that the handheld testers we can readily buy for about $30-50 on AliExpress - or the AUD200+ Shore O one that Haggis bought - need a certain thickness of material to give accurate results. Using it on table tennis sponge - or worse, topsheets - will result in "bottoming out", which means you get a bigger number than is the actual hardness. You can probably build and calibrate a gauge for measuring smaller thicknesses of material - probably by reducing the spring pressure and changing the dial - but these aren't standard. It's possible the manufacturers use such special gauges, but it's also likely they test hardness of thick cakes of rubber as they come out of the mold before slicing.)

Iskandar


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PostPosted: 15 Aug 2019, 14:20 
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I've been thinking about this some more. Apparently Hurricane 3 comes in sponge hardnesses of around 37-38 or so (Shanghai/Shore A scale), this corresponds to 50-52 on the Tianjin/Shore O scale. This makes those sponges VERY hard compared to what you usually get on 729/Yinhe/Palio/etc. rubbers, which are usually around 40-46 on the Tianjin scale.

So.. is this why H3 has the properties it does? Drop a ball from a foot onto a sheet of H3 (mounted on a blade, of course). The ball doesn't bounce much, it just dies on the blade. Some people say this is because the rubber is tacky, but it continues doing this even after you've played with the rubber for a while and it's no longer tacky. It sort of feels slow and dead, great for over-the-table pushes and drop shots. Yet, you can hit and loop the ball pretty hard with it, though you need a powerful stroke to generate the speed. Maybe this is because the sponge is that really hard - maybe a sponge this hard doesn't react to a soft ball as much as a softer sponge does, but it does store and release energy with a hard shot, where the sponge gets significantly compressed. Also, it does seem to be the consensus (from Timo Boll on down) that the top Chinese players, if not everyone else, boosts their H3. Maybe with sponge this hard, boosting IS necessary, especially at that level of play. It might be useless otherwise.

Iskandar


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PostPosted: 18 Aug 2019, 11:49 
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When will DHS produce/release a Hou Yingchao blade ?

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PostPosted: 23 Aug 2019, 07:17 
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http://www.dhs-sports.com/ is not working.


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PostPosted: 27 Aug 2019, 10:47 
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Is the DHS 08 anniversary addition still being offered? If yes, where can I buy one? Also, how is it different from the former PF4-08 from the years past?


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PostPosted: 29 Aug 2019, 03:21 
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lasta wrote:
Is the DHS 08 anniversary addition still being offered? If yes, where can I buy one? Also, how is it different from the former PF4-08 from the years past?


Let's see.. that's the old classic heavy basswood blade, right?

I can get Chinese bass plywood here... Hmmmm… Problem would be finding a nice, flat piece...

Iskandar


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PostPosted: 29 Aug 2019, 20:25 
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d1244 wrote:
http://www.dhs-sports.com/ is not working.

They're aware and working on it. I believe it's not just a technical issue, they need to get the website 'audited' as well.

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PostPosted: 02 Sep 2019, 20:22 
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d1244 wrote:
http://www.dhs-sports.com/ is not working.

It's back up now. :up:

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