Table Differences

[fred bentivegna]

Billiard Table

Billiard Table

If the cushions on a Diamond are stiffer, then it seems to me that the ball should rebound longer (wider angle), unless --as NFS mentioned-- the deeper rails allow the cushions to compress more than on a GC.

I can see that I'm going to have to go to AZ and try to flag the science guys down... Dr. Dave's site doesn't have a "contact" menu.

Doc

Doc, an easy way to think about it is to remember what it was like to play on an old antique billiard table as compared to the new European style billiard tables. The old tables had softer cushions, ran longer and played slower.

Beard

I dont need no stinkin' science guys!

 

[lll]

thanks everyone if there is still more to reply dont be bashful

 

[One Pocket Ghost]

I think you guys will find this very interesting, like I did....

There's a guy over at azbilliards who is one of the top table mechanics in the country, and who also does work for Greg Sullivan/Diamond tables...I asked him about Diamonds banking shorter than Gold Crowns, and this is what he wrote me back, quoted and bolded below >>>

- Ghost

PS, Mum's the word guys, since I hope it's ok that I shared this info over here, because this guy didn't want to post this info up over at az - he would only tell me via pm.


"As a matter of fact, I redesigned Diamonds rails a few months back, so they no longer bank short or play springy off the cushions....in fact, they'll out bank any new GC on the market today, except the ones I've rebuilt. The US Open coming up will have the new Diamonds used in the tournament".

 

[gulfportdoc]

Doc, an easy way to think about it is to remember what it was like to play on an old antique billiard table as compared to the new European style billiard tables. The old tables had softer cushions, ran longer and played slower.

Turns out, we're both right, depending upon other factors. Here is a quote from Dr. Dave from Univ. of Colorado:

Inquiry by gulfportdoc:
Thanks for your reply, Dave. I realize that there are many different variables that affect rebound angles. But considering the single issue of cushion rubber softness: if all other facets are equal, could one hypothesize that a ball would rebound differently from a soft rubber cushion in comparison to a hard rubber cushion? If so, would the ball tend to rebound at a narrower, or wider, angle from a soft rubber cushion?

Answer from Dr. Dave: I think by "hard," you mean "stiff." I don't think stiffness alone is a determining factor. The cushion efficiency (coefficient of restitution), cushion nose height, and nose and table bed friction are more important than stiffness. Now, "soft" can mean "dead" or "inefficient" (i.e., very low coefficient of restitution), in which case balls go long.

With a less stiff cushion, the ball will tend to "bury" itself more, which can create more "throwback" (angle shortening) if the cushion provides sideways stiffness (tangential restitution), but there are also more friction losses which could create less or more angle, depending on the type of shot.

Again, this isn't a simple matter, and there are no simple answers.

Sorry,
Dave

Fred, I thought you'd particularly enjoy "coefficient of restitution". But to support your point, here is a nice regular speed and also high speed slo-mo of a bank shot from Bob Jewett, hit with two different speeds:

HSV B.41 - bank speed effects, with Bob Jewett​

Doc

 

[lll]

doc 2 comments . correct me if im wrong
conventional wisdom states hit the ball harder to shorten the bank
this video says the opposite.
could it be because its a combo bank????

 

[gulfportdoc]

doc 2 comments . correct me if im wrong
conventional wisdom states hit the ball harder to shorten the bank
this video says the opposite.
could it be because its a combo bank????

Well, not exactly, Larry. I think they used two gapped balls to make sure the banked ball was contacted without any spin (stun), and that also the shot could be repeated again and again from the exact same position, angle, etc.

But harder hit balls do shorten the angle up to a point. Then they can actually go longer. But Dave's point was that there are many other variables that enter into the equation.

We still don't have any definitive information as to why Diamond tables reportedly bank shorter than do Gold Crowns.

BTW, "Real King Cobra" --one of the country's premier table mechanics-- stated that Gold Crowns play easier than do Diamonds.

Doc

 

[fred bentivegna]

Shoulda got the book and DVD

Shoulda got the book and DVD

doc 2 comments . correct me if im wrong
conventional wisdom states hit the ball harder to shorten the bank
this video says the opposite.
could it be because its a combo bank????

lll, I have pounded that point in my books and DVDs that hitting a bank hard does not necessarily shorten the angle, and actually, properly stroked lengthens the angle on most shots.

Beard

 

[newfosgatesucks]

It is not the stiffness of the cushion that is the main difference, fellas. It is the PITCH of the rail as installed relevant to the balls incoming inertia. The diamonds have the nose of the rubber nearly level out from the rail. This promotes speed(hinted in my earlier post) and prevents the curl. The GC has a little bit of pitch there, allowing the rail install height to be SLIGHTLY higher - and resulting in the cueball digging underneath the rail as the rail compresses. THIS is the reason for the CURL the Beardman speaks of, and the reason the cueball Kills easier on the Gold Crown than the diamond. Also is the reason the GC plays fast on new cloth, slower on broke-in cloth, and fast again when the cloth is worn slap out and clean. And the Diamond plays fast regardless..

The 'Digging' of the ball compressing the cushion adds surface area of contact, and will add more running english as well-such as in a 3-rail kick. These types of Tables have a LARGE area on rail one you can hit on a 3-rail shot to the pocket, provided you load up with a ton of running english, for example. There are SEVERAL shots you will notice are different. That said, the extra running that is imparted on the cueball because of the slight digging will be enough reverse off the 3rd rail to kill the cueball if you hit short of the pocket. And the 'digging' into the rail allows THAT english(which is now reverse) to take even harder. Also explains why a diamond slightly reduces shot options when getting wrong on a ball.


This IS the "rail-big-difference" in the two tables....

Now, the backing(top layer of fibre) on the rail top HAS been different in the past few years, the distance from the tip of the nose of the rubber to the beginning of the fibre is different. Inconsistent, as well. Accu-fast is solid covered. This DEFINITELY affects the way a ball digs into the rail, it digs LESS and takes more spin to do the same old shot. BRING THE MICROSCOPE AND SCRUTINIZE!!! I am self-educated, so scrutinize all you want - forwaRd this to Dave if needed. If, IF I am right, who can get me a job as a table tech at the major tourneys? Or as a table engineer? I am Building an 8-footer SOON.

If the cushions on a Diamond are stiffer, then it seems to me that the ball should rebound longer (wider angle), unless --as NFS mentioned-- the deeper rails allow the cushions to compress more than on a GC.

I can see that I'm going to have to go to AZ and try to flag the science guys down... Dr. Dave's site doesn't have a "contact" menu.

Doc

 

[Deeman]

Very nice analysis!

Thanks,

DeeMan

 

[newfosgatesucks]

Your welcome...and ....BUMP!

Very nice analysis!

Thanks,

DeeMan

 

[lll]

It is not the stiffness of the cushion that is the main difference, fellas. It is the PITCH of the rail as installed relevant to the balls incoming inertia. The diamonds have the nose of the rubber nearly level out from the rail. This promotes speed(hinted in my earlier post) and prevents the curl. The GC has a little bit of pitch there, allowing the rail install height to be SLIGHTLY higher - and resulting in the cueball digging underneath the rail as the rail compresses. THIS is the reason for the CURL the Beardman speaks of, and the reason the cueball Kills easier on the Gold Crown than the diamond. Also is the reason the GC plays fast on new cloth, slower on broke-in cloth, and fast again when the cloth is worn slap out and clean. And the Diamond plays fast regardless..

The 'Digging' of the ball compressing the cushion adds surface area of contact, and will add more running english as well-such as in a 3-rail kick. These types of Tables have a LARGE area on rail one you can hit on a 3-rail shot to the pocket, provided you load up with a ton of running english, for example. There are SEVERAL shots you will notice are different. That said, the extra running that is imparted on the cueball because of the slight digging will be enough reverse off the 3rd rail to kill the cueball if you hit short of the pocket. And the 'digging' into the rail allows THAT english(which is now reverse) to take even harder. Also explains why a diamond slightly reduces shot options when getting wrong on a ball.


This IS the "rail-big-difference" in the two tables....

Now, the backing(top layer of fibre) on the rail top HAS been different in the past few years, the distance from the tip of the nose of the rubber to the beginning of the fibre is different. Inconsistent, as well. Accu-fast is solid covered. This DEFINITELY affects the way a ball digs into the rail, it digs LESS and takes more spin to do the same old shot. BRING THE MICROSCOPE AND SCRUTINIZE!!! I am self-educated, so scrutinize all you want - forwaRd this to Dave if needed. If, IF I am right, who can get me a job as a table tech at the major tourneys? Or as a table engineer? I am Building an 8-footer SOON.

great post. as Deeman said "good stuff"

 

[lll]

shoulda bought the book

shoulda bought the book

lll, I have pounded that point in my books and DVDs that hitting a bank hard does not necessarily shorten the angle, and actually, properly stroked lengthens the angle on most shots.

Beard

Freddy i DID buy the book and dvd
guess i gotta study harder