Daily Table Tennis Chit Chat

[kindof99]

Still a few days left. Have sent out one Xiom HAL. Not sure why people are reluctant to submit entries. Maybe I should give out Butterfly blades lol...

I tried bouncing a ball on table edge. It is the first time I did it and it took about 30 minute’s practice. It is actually quite fun experience.

 

[NextLevel]

I tried bouncing a ball on table edge. It is the first time I did it and it took about 30 minute’s practice. It is actually quite fun experience.

You get some credit for the attempt but tou need to do more to be able to choose a prize. The table bounce on the side needs ro be sustained for a longer period and the pancakes have to either have spin (easy, like in the video I presented of myself) or harder like @TampaBayTableTennis where he tries to mimic Freitas and roll the ball over the tip onto the other side (much harder). If you can get the ball bouncing on the side to at least 20-30 seconds and then make the pancakes either be like mine or @TampaBayTableTennis , then you have an automatic win. Otherwise, you will have to wait till the deadline and hope no one else submits and the Lord unhardens this dictator's heart so he can let the blades out of Egypt and all that stuff...

Thanks for the submission, it definitely merits something. You might just have be patient...

 

[Archosaurus]

Yes, it is more of a mindset change rather than a technical change. There is no '1 stroke for everything' in table tennis, you gotta respect the variation in every incoming ball in TT. The advanced players don't have a shot that deals with everything, but rather they are watching the ball like a hawk and constantly adjusting their contact points, stroke trajectory and body positioning for all the variations. There is no 'brute force' spin loop that deals with everything.

So, the spin reading and positional awareness is super important in TT, and also makes it possible for people who have very ugly strokes to do well.

Proper serve recovery for FH serves from the pivot position is only possible if you do the ball toss and serve contact with weight transfer and ride the rotation, otherwise imo it is just too slow regardless of what you do. The benchmark is that you have to reach the ready position before your opponent contacts the ball (because you have to split step when they do). If you videoed yourself it is almost impossible to achieve this without the weight transfer mechanism.

The alternative is BH serving which is a shortcut since you already are in the ready position during the serve. Much simpler.

Ugly strokes can be good up to a decent enough level, because they can be pretty difficult to read if you're just used to looking at orthodox technique. I know I struggle a lot more with the old guys who have been playing casually for 30+ years than the juniors, even if their play level is otherwise similar. They know a lot of tricks like zero backswing shots, weird fades, sidespin droshots against rallying shots. They give a lot of chance balls, but it's pretty easy to just miss on them.

Yeah I know quite a bit about pendulum. Nothing I haven't done or heard. I've coached some mid-high division players how to serve it and everyone is surprised at the quality and keeps making errors on it, so either they're just stupid or there's something to it.

It's just a mindset thing, I'm bloody lazy most of the time. It helps that I'm getting my ass beat by most people right now and I can tryhard as much as I like, so every day I become slightly less lazy. The easiest adaptation for sure is to just always serve like I do in serve practice, no matter who I'm playing or when. It won't require learning anything new, just a new mindset and comfort level.

Hit a little today, and nothing's really improved, but I made sure to always have the basics more in check, so I'd say my minimum level was higher than last time. My opponents said I'm playing sharper today, but I don't know about that.

EDIT: Some interesting measurements:

DHS Hurricane 3 Provincial Blue Sponge 41A 2.15 BLACK
Topsheet 29.0 - 30.5 A / 52.5 - 53.0 O
Sponge 35.5 - 37.5 A / 55.5 - 56.0 O
has been boosted a few weeks ago with Haifu White so it's about 0.5 O softer right now than new

Loki Arthur China 40A 2.10 BLACK
Topsheet 29.0 - 30.0 A / 48.5 - 50.0 O
Sponge 30.0 A / 48.0 - 49.0 O

I think the huge hardness discrepancy is because of the topsheet being in series with the sponge combined with the higher pressure indenter + Loki just lying about their sponge hardness to appear fashionable . If you separated them I bet you'd get really different numbers! However this is more realistic for actual use, and it's why ESN reports them as series I bet.

Also note how the relative difference varies. The A hardness for the topsheet is quite similar, while the O is quite dissimilar. That gives you an idea for the curve if you do some math. Note also how the consistency is different at different pressures and depths.

I think I forgot to mention the series stiffness part in the earlier Tenergy discussion. The nice part is that the pimple geometry, relative thicknesses and indenter used will change how in series it is, so there's no rule of thumb that actually works. You just gotta measure it or simulate it.

EDIT: One more. Surprising result!

DHS Hurricane 3 Commercial 40A 2.20 BLACK
Topsheet 32.5 - 33.5 A / 53.0 - 55.0 O
Sponge 37.5 - 38.0 A / 56.0 - 56.5 O

EDIT: Some more when I'm doing it.

729 Battle 2 National Super Select Blue Sponge 41A 2.10 BLACK
Topsheet 31.5 - 32.5 A / 53.0 - 53.5 O
Sponge 35.5 - 36.0 A / 55.0 - 55.5 O
This one's surprising because it doesn't feel as easy to play with as H3 blue sponge, even if it's softer!

729 Battle 2 Gold RED
Topsheet 28.5 - 30.0 A / 51.0 O
Sponge 32.0 - 33.0 A / 54.0 O
Even if softer than the blue sponge, I didn't find it particularly easy to use. I tried it as a backhand rubber and it was too stiff for me. Weirdly the blue sponge H3 was easier as a backhand rubber! I must use the topsheet more than the sponge.

Yinhe Jupiter 3 Asia 38A RED
Topsheet 28.0 - 29.5 A / 50.0 - 51.0 O
Sponge 30.0 - 31.5 A / 48.5 - 49.0 O
Used as backhand rubber, easy to use and spinny, not super powerful. Honestly feels like what the numbers say. Would not use on forehand at least in this hardness, but probably not in the highest one either.

729 Battle 3 40A 2.10 BLACK
Topsheet 32.0 - 33.0 A / 55.0 - 56.0 O
Sponge 39.0 - 40.0 A / 57.5 - 58.5 O
Not very surprising because it also feels harder to use than H3, but the quality is lower unless you really lay into it. It might match H3 spin, but at higher forces. Easier to use than Battle 2 for me. Great cost-performance and feel is subjectively kinda close to blue sponge H3.

Sanwei Target Provincial (Red package) 40A 2.15 BLACK
Topsheet 32.5 A / 55.0 O
Sponge 34.5 - 35.5 A / 53.0 - 53.5 O
I liked it, but lower shot quality than H3. Really nice topsheet consistency on my sheet! Extreme cost-performance.

 

[dingyibvs]

Ugly strokes can be good up to a decent enough level, because they can be pretty difficult to read if you're just used to looking at orthodox technique. I know I struggle a lot more with the old guys who have been playing casually for 30+ years than the juniors, even if their play level is otherwise similar. They know a lot of tricks like zero backswing shots, weird fades, sidespin droshots against rallying shots. They give a lot of chance balls, but it's pretty easy to just miss on them.

Yeah I know quite a bit about pendulum. Nothing I haven't done or heard. I've coached some mid-high division players how to serve it and everyone is surprised at the quality and keeps making errors on it, so either they're just stupid or there's something to it.

It's just a mindset thing, I'm bloody lazy most of the time. It helps that I'm getting my ass beat by most people right now and I can tryhard as much as I like, so every day I become slightly less lazy. The easiest adaptation for sure is to just always serve like I do in serve practice, no matter who I'm playing or when. It won't require learning anything new, just a new mindset and comfort level.

Hit a little today, and nothing's really improved, but I made sure to always have the basics more in check, so I'd say my minimum level was higher than last time. My opponents said I'm playing sharper today, but I don't know about that.

EDIT: Some interesting measurements:

DHS Hurricane 3 Provincial Blue Sponge 41A 2.15 BLACK
Topsheet 29.0 - 30.5 A / 52.5 - 53.0 O
Sponge 35.5 - 37.5 A / 55.5 - 56.0 O
has been boosted a few weeks ago with Haifu White so it's about 0.5 O softer right now than new

Loki Arthur China 40A 2.10 BLACK
Topsheet 29.0 - 30.0 A / 48.5 - 50.0 O
Sponge 30.0 A / 48.0 - 49.0 O

I think the huge hardness discrepancy is because of the topsheet being in series with the sponge combined with the higher pressure indenter + Loki just lying about their sponge hardness to appear fashionable . If you separated them I bet you'd get really different numbers! However this is more realistic for actual use, and it's why ESN reports them as series I bet.

Also note how the relative difference varies. The A hardness for the topsheet is quite similar, while the O is quite dissimilar. That gives you an idea for the curve if you do some math. Note also how the consistency is different at different pressures and depths.

I think I forgot to mention the series stiffness part in the earlier Tenergy discussion. The nice part is that the pimple geometry, relative thicknesses and indenter used will change how in series it is, so there's no rule of thumb that actually works. You just gotta measure it or simulate it.

EDIT: One more. Surprising result!

DHS Hurricane 3 Commercial 40A 2.20 BLACK
Topsheet 32.5 - 33.5 A / 53.0 - 55.0 O
Sponge 37.5 - 38.0 A / 56.0 - 56.5 O

That hasn't been my experience at all. I use a Shore C durometer, which IMO is the best for TT rubbers because other tips are too thin and there's too much variation depending on whether you're pressing on a spot in between the pips or right on top of the pips. Because of how thin TT sponge is, I think the thinner tips also measure the underlying surface too much.

One thing you could do is actually stack 2 sheets together and then measure, and it helps to neutralize these variations a good bit, but of course that would give you the average of 2 sheets, so only useful if comparing between 2 different types of rubbers instead of measuring specific sheets. To measure individual rubbers, you could have a designated "base sheet" that you measure all other rubbers on.

IMO, the fact that you're not getting very similar values when measuring from the topsheet or the sponge side suggests that something is wrong with your technique. Both the topsheet and the sponge are too thin to be measured separately by typically commercially available durometers. You should only be able to measure the combined whole of the rubber. I think most likely you're not pressing down hard enough on the durometer. You should try stacking 2 sheets together then press down until the number no longer increases with how hard you press, then you should get the real values.

Anyhow, My H3N BS 40 degrees 2.1mm measure very similarly to my Loki Arthur China, and there's also very little change whether I measure from the topsheet side or the sponge side. That's obviously the case when stacked, though it was like that without stacking as well, there was just more variation in the measurement.

My H3 measures fairly consistently in the 56-58 degrees range, and my LAC more in the 55-57 degrees range, both measured from the sponge side. Measuring from the topsheet side only changes the hardness by 1-2 degrees. Stacking the H3 narrows the measurements to 57.5-58.5 on the 2 sheets I just measured on, both boosted once. I only have 1 used sheet of LAC, and I don't want to open the other ones' packaging yet, so I haven't tried stacking.

 

[Archosaurus]

That hasn't been my experience at all. I use a Shore C durometer, which IMO is the best for TT rubbers because other tips are too thin and there's too much variation depending on whether you're pressing on a spot in between the pips or right on top of the pips. Because of how thin TT sponge is, I think the thinner tips also measure the underlying surface too much.

One thing you could do is actually stack 2 sheets together and then measure, and it helps to neutralize these variations a good bit, but of course that would give you the average of 2 sheets, so only useful if comparing between 2 different types of rubbers instead of measuring specific sheets. To measure individual rubbers, you could have a designated "base sheet" that you measure all other rubbers on.

IMO, the fact that you're not getting very similar values when measuring from the topsheet or the sponge side suggests that something is wrong with your technique. Both the topsheet and the sponge are too thin to be measured separately by typically commercially available durometers. You should only be able to measure the combined whole of the rubber. I think most likely you're not pressing down hard enough on the durometer. You should try stacking 2 sheets together then press down until the number no longer increases with how hard you press, then you should get the real values.

Anyhow, My H3N BS 40 degrees 2.1mm measure very similarly to my Loki Arthur China, and there's also very little change whether I measure from the topsheet side or the sponge side. That's obviously the case when stacked, though it was like that without stacking as well, there was just more variation in the measurement.

My H3 measures fairly consistently in the 56-58 degrees range, and my LAC more in the 55-57 degrees range, both measured from the sponge side. Measuring from the topsheet side only changes the hardness by 1-2 degrees. Stacking the H3 narrows the measurements to 57.5-58.5 on the 2 sheets I just measured on, both boosted once. I only have 1 used sheet of LAC, and I don't want to open the other ones' packaging yet, so I haven't tried stacking.

DHS claims the sponge hardness is separately measured, but I don't know about the others. I know ESN is usually a series stiffness.

With my method I get +-0.50deg from the numbers ESN claims for their series stiffness on ESN sheets, so I'm not inclined to believe it's incorrect.

The correct technique for using a durometer is to sit the foot flush and let the indenter sink by itself. You will press only as much as is needed to find the "deadzone" where it doesn't change much at all unless you start sinking the foot in as well. That is likely what ESN does as well. That's what the instruction manuals say to do with these.

Just FYI but 58 Shore C is about 90 Shore A. I'm not sure about that...

EDIT:

H3 BS and LAC stacked, with LAC on top, pressing on sponge, foot flush vs pressing like a madman until it stops increasing:
55.5 O / 70.0 O
29.5 A / 44.5 A

H3 BS and LAC stacked, with H3 BS on top, pressing on sponge, foot flush vs pressing like a madman until it stops increasing:
51.0 O / 67.0 O
33.0 A / 44.0 A

EDIT: You're right though that the topsheet+sponge is too thin to reliably measure. I think the recommendation is 6mm or whatever. You can probably get away with measuring an uncut sponge and then doing some math to get the number for the thickness you want. I don't know how the OEMs do it although I could swear I've seen some ancient video where they were measuring cut sponges with a hand durometer.

I think stacking actual completed sheets on top of eachother is a bad idea because then the topsheet and pimple geometry become very significant, as you see in my results that completely change based on which is the side with the higher pressure ie: being measured.

EDIT: ASTM D2240-00 says the sample should be a MINIMUM of 6.0mm, so okay, I can give Loki some slack and probably my method is just way too in series with the topsheet or something.

Ultimately unless you're making a sim or something it doesn't really matter what the real hardness is, only the one you get when you're using the sheet. It's gonna be really different if your indenter is a 40mm table tennis ball, anyway.

I've had one idea to make a dyno with a 40mm indenter with similar properties to a TT ball and measure force/deflection curves with that; probably more realistic than using durometers. At least on a "how hard does it feel to the hand" basis.

Will I do it? Hell no; but I had the idea.

 

[Tyce]

I think several (most?) manufacturers only measure sponge hardness, and stacking up a few pieces of sponge is easy even using cutoffs from the same sheet. It would be preferable to be able to measure topsheet but like you say, geometry makes it nearly impossible and frankly useless.

 

[Archosaurus]

I think several (most?) manufacturers only measure sponge hardness, and stacking up a few pieces of sponge is easy even using cutoffs from the same sheet. It would be preferable to be able to measure topsheet but like you say, geometry makes it nearly impossible and frankly useless.

Maybe a decent measurement can indeed be had if you remove the topsheets from the bits that were discarded when the sheet was cut and stack a bunch of sponges together, then do some math to get the hardness for the thickness you want.

If you assume it's linear (it won't be, but it'll be pretty close for these sponges at that thickness) and they're all the same sponge then the math is easy if you know some indenter parameters. Well, in theory. It's probably not easy to get a bang-on exact number without validating with FEA. Of course in reality how much the sponge actually sinks for a given force depends quite a lot on the topsheet params so you shouldn't ever use isolated numbers as some kind of absolute.

A bunch of brands using ESN claim their hardness is in series with the topsheet. My Xiom Vega Europe DF was somewhere between 37.0 and 37.5 and they claim 37.5 nominal.

 

[Tyce]

Maybe a decent measurement can indeed be had if you remove the topsheets from the bits that were discarded when the sheet was cut and stack a bunch of sponges together, then do some math to get the hardness for the thickness you want.

If you assume it's linear (it won't be, but it'll be pretty close for these sponges at that thickness) and they're all the same sponge then the math is easy if you know some indenter parameters. Well, in theory. It's probably not easy to get a bang-on exact number without validating with FEA. Of course in reality how much the sponge actually sinks for a given force depends quite a lot on the topsheet params so you shouldn't ever use isolated numbers as some kind of absolute.

A bunch of brands using ESN claim their hardness is in series with the topsheet. My Xiom Vega Europe DF was somewhere between 37.0 and 37.5 and they claim 37.5 nominal.

It makes sense to keep the topsheet "hardness" (probably pliability is more accurate with the pimples and all?) in line with the sponge. If you make the topsheet significantly harder, then what use is the sponge? Softer topsheet could have some merit but too much of it would make touch play pretty hard I think.

 

[Archosaurus]

It makes sense to keep the topsheet "hardness" (probably pliability is more accurate with the pimples and all?) in line with the sponge. If you make the topsheet significantly harder, then what use is the sponge? Softer topsheet could have some merit but too much of it would make touch play pretty hard I think.

I think against an actual real ball that will compress more pimples as it sinks more, the actual real-world k is a lot more progressive than what an isolated test in a tiny point would suggest.

Just intuitively I'd think the topsheet will always want to be a bit softer, and easy to sink into the sponge via the pimples. Even if the actual rubber might be harder than the sponge is, which it probably is.

EDIT: And I'd use "compliance" .

 

[dingyibvs]

DHS claims the sponge hardness is separately measured, but I don't know about the others. I know ESN is usually a series stiffness.

With my method I get +-0.50deg from the numbers ESN claims for their series stiffness on ESN sheets, so I'm not inclined to believe it's incorrect.

The correct technique for using a durometer is to sit the foot flush and let the indenter sink by itself. You will press only as much as is needed to find the "deadzone" where it doesn't change much at all unless you start sinking the foot in as well. That is likely what ESN does as well. That's what the instruction manuals say to do with these.

Just FYI but 58 Shore C is about 90 Shore A. I'm not sure about that...

EDIT:

H3 BS and LAC stacked, with LAC on top, pressing on sponge, foot flush vs pressing like a madman until it stops increasing:
55.5 O / 70.0 O
29.5 A / 44.5 A

H3 BS and LAC stacked, with H3 BS on top, pressing on sponge, foot flush vs pressing like a madman until it stops increasing:
51.0 O / 67.0 O
33.0 A / 44.0 A

EDIT: You're right though that the topsheet+sponge is too thin to reliably measure. I think the recommendation is 6mm or whatever. You can probably get away with measuring an uncut sponge and then doing some math to get the number for the thickness you want. I don't know how the OEMs do it although I could swear I've seen some ancient video where they were measuring cut sponges with a hand durometer.

I think stacking actual completed sheets on top of eachother is a bad idea because then the topsheet and pimple geometry become very significant, as you see in my results that completely change based on which is the side with the higher pressure ie: being measured.

EDIT: ASTM D2240-00 says the sample should be a MINIMUM of 6.0mm, so okay, I can give Loki some slack and probably my method is just way too in series with the topsheet or something.

Ultimately unless you're making a sim or something it doesn't really matter what the real hardness is, only the one you get when you're using the sheet. It's gonna be really different if your indenter is a 40mm table tennis ball, anyway.

I've had one idea to make a dyno with a 40mm indenter with similar properties to a TT ball and measure force/deflection curves with that; probably more realistic than using durometers. At least on a "how hard does it feel to the hand" basis.

Will I do it? Hell no; but I had the idea.

1) Hardness almost always refer to just the sponge, and my understanding is that many manufacturers create their own scale, so they don't even correspond to any Shore scale. As such, IMO what's important is comparison between rubbers, not its absolute measurement. With my durometer, for example, I think it's actually a mislabeled Asker C durometer and not Shore C. Besides 58 corresponding to shore A in the 30s, which is reasonable, it also has a rounded tip like an Asker C durometer instead of a tapered flat tip of a Shore C durometer. That doesn't really matter though so long as it allows me to compare between rubbers. On a side note, the fairly large rounded tip is why I chose it as the tiny Shore A tip, which I also have, is too easily affected by pimples and I was getting wildly different results on the same rubber.

2) You can of course measure the hardness of things thinner than 6mm, but just not with the typical durometers we can buy on Amazon. I'm sure TT manufacturers have their own durometers for measuring thin sponges.

3) By stacking, I mean stacking 2 sheets of the same rubber. 2 sheets of the rubber would give you ~8mm of thickness, which allows you to get an accurate read of the sponge/topsheet combo.

 

[Archosaurus]

1) Hardness almost always refer to just the sponge, and my understanding is that many manufacturers create their own scale, so they don't even correspond to any Shore scale. As such, IMO what's important is comparison between rubbers, not its absolute measurement. With my durometer, for example, I think it's actually a mislabeled Asker C durometer and not Shore C. Besides 58 corresponding to shore A in the 30s, which is reasonable, it also has a rounded tip like an Asker C durometer instead of a tapered flat tip of a Shore C durometer. That doesn't really matter though so long as it allows me to compare between rubbers. On a side note, the fairly large rounded tip is why I chose it as the tiny Shore A tip, which I also have, is too easily affected by pimples and I was getting wildly different results on the same rubber.

2) You can of course measure the hardness of things thinner than 6mm, but just not with the typical durometers we can buy on Amazon. I'm sure TT manufacturers have their own durometers for measuring thin sponges.

3) By stacking, I mean stacking 2 sheets of the same rubber. 2 sheets of the rubber would give you ~8mm of thickness, which allows you to get an accurate read of the sponge/topsheet combo.

DHS and 729 quite literally have posted PSAs where they claim that their products are Shore A and "European" are Shore O. The most unique one is Butterfly who uses a JIS scale. Nobody's making their own scale.

The durometer measurements are just for QC and consumer information anyway, actual engineering cares more about the elastic modulus curve when measured on a dyno to failure.

I figured it's probably Asker C. In the end it doesn't really matter which one you use, but it's good to use many so you can compare between models which are measured in a variety of ways, and maybe find a combination which you really like.

Many ESN brands claim their hardness is in series. Usually it's the sponge itself, though. I think most new rubbers are sponge only. I'll change to G-1 2.0mm on the backhand sometime later and I'll post my numbers when I do and see how it compares to the claimed 47.5.

 

[dingyibvs]

DHS and 729 quite literally have posted PSAs where they claim that their products are Shore A and "European" are Shore O. The most unique one is Butterfly who uses a JIS scale. Nobody's making their own scale.

The durometer measurements are just for QC and consumer information anyway, actual engineering cares more about the elastic modulus curve when measured on a dyno to failure.

I figured it's probably Asker C. In the end it doesn't really matter which one you use, but it's good to use many so you can compare between models which are measured in a variety of ways, and maybe find a combination which you really like.

Many ESN brands claim their hardness is in series. Usually it's the sponge itself, though. I think most new rubbers are sponge only. I'll change to G-1 2.0mm on the backhand sometime later and I'll post my numbers when I do and see how it compares to the claimed 47.5.

I don't recall DHS and 729 posting PSAs, most of those older Chinese companies are terrible at engaging customers so it'd be kind of out of character for them to actually clarify something lol.

 

[kindof99]

You get some credit for the attempt but tou need to do more to be able to choose a prize. The table bounce on the side needs ro be sustained for a longer period and the pancakes have to either have spin (easy, like in the video I presented of myself) or harder like @TampaBayTableTennis where he tries to mimic Freitas and roll the ball over the tip onto the other side (much harder). If you can get the ball bouncing on the side to at least 20-30 seconds and then make the pancakes either be like mine or @TampaBayTableTennis , then you have an automatic win. Otherwise, you will have to wait till the deadline and hope no one else submits and the Lord unhardens this dictator's heart so he can let the blades out of Egypt and all that stuff...

Thanks for the submission, it definitely merits something. You might just have be patient...

Ok, let me see whether I can practice a little more and get some new videos. It is harder than how it looks like for someone having not tried it before. But it is a fun learning process. Encourage more people to try it with or without the bonus blade.