Center Of A Ball And The Rail

HawaiianEye · Nov 23, 2019

The "center line" of the cue ball or an object ball never touches the rail unless you are shooting straight up and down or across the table.

When you are shooting at an angle into a rail, (with either the cue ball or an object ball) the opposite side of the "contact point" on the ball is the point that touches the rail, not the center line of the shot.

So, why do people use the "center lines" of the balls when doing calculations?

Also, if you are shooting into a rail at an angle, the ball comes off the rail a bit "elongated" from the rebound off the rail. English and speed can compensate for this a bit, but I'm talking hitting the rail with "no spin" on the ball to begin with.

Think about it the next time you are practicing banks or kicking.

Not everything is a "mirror".

Adjustments need to be made.

CocoboloCowboy · Nov 23, 2019

Problem is people don't take time to think things out before shooting a shot in pool. Even the easyiest shot can be missed, if you forget to think on it, plan, execute, but just shoot it because it's easy.

Bob Jewett · Nov 23, 2019

HawaiianEye said:
... So, why do people use the "center lines" of the balls when doing calculations? ...

Some use the actual center of the ball for this stuff and use the rail groove as the reflecting point. Lots of billiard authors have the path of the cue ball touching the nose of the cushion. Robert Byrne saw that was clearly broken and his diagrams show the correct reflection point at the rail groove. He also shows the path of the cue ball only going to the center of the ghost ball before it is deflected by the object ball.

HawaiianEye · Nov 23, 2019

Bob Jewett said:
Some use the actual center of the ball for this stuff and use the rail groove as the reflecting point. Lots of billiard authors have the path of the cue ball touching the nose of the cushion. Robert Byrne saw that was clearly broken and his diagrams show the correct reflection point at the rail groove. He also shows the path of the cue ball only going to the center of the ghost ball before it is deflected by the object ball.

That is what I'm talking about.

Most people don't know how the system is "flawed" and how they need to correct for it.

They just see "diamonds" and "mirrors" and think that is supposed to work.

If you look at some of the diagrams that people post on here, you can see why people can't figure stuff out. They are being taught the wrong way.

Tin Man · Nov 23, 2019

Question- on one rail kicks using a 'bisect the line' type system, is there a difference between aiming the edge of the ball at the rail and aiming the center of the ball at the rail groove? Wouldn't they be the same?

If so, when does this difference make the biggest impact? I know on rail first shots I allow for the fact the cue ball doesn't actually overlap the rail. But where do people make the mistakes with this? I think my kicking is fairly accurate but if there are specific examples I'd be interested in seeing them. Thank you!

HawaiianEye · Nov 23, 2019

Tin Man said:
Question- on one rail kicks using a 'bisect the line' type system, is there a difference between aiming the edge of the ball at the rail and aiming the center of the ball at the rail groove? Wouldn't they be the same?

If so, when does this difference make the biggest impact? I know on rail first shots I allow for the fact the cue ball doesn't actually overlap the rail. But where do people make the mistakes with this? I think my kicking is fairly accurate but if there are specific examples I'd be interested in seeing them. Thank you!

I'll see if I can work it out at the table tomorrow and come back with something that I can explain. It is hard to do here in my head without working it out at the table.

Whenever I do any calculations, I'm using the contact point as the reference, not the edge of the ball or the center of the ball.

The contact points are the only things that "contact" anything...be it a ball or a rail.

Bob Jewett · Nov 23, 2019

Tin Man said:
Question- on one rail kicks using a 'bisect the line' type system, is there a difference between aiming the edge of the ball at the rail and aiming the center of the ball at the rail groove? Wouldn't they be the same?...

Suppose you are shooting a kick from the side pocket cross-corner to the corner pocket. The cue ball has two edges, I suppose, left and right. Which one are you aiming with? Which spot are you sending it towards? What are you sending the center of the cue ball towards if you are somehow using the rail groove in your calculations? Which line are you bisecting?

From those questions I'm hoping to make the point that unless you state your question a lot more clearly, it has no answer, just as most diamond systems are explained so poorly and with so little detail that you can't really expect them to work unless you use them as a very fuzzy guideline and fill in the rest with half a million shots of experience.

Patrick Johnson · Nov 23, 2019

HawaiianEye said:
... if you are shooting into a rail at an angle, the ball comes off the rail a bit "elongated" from the rebound off the rail. English and speed can compensate for this a bit, but I'm talking hitting the rail with "no spin" on the ball to begin with.

Think about it the next time you are practicing banks or kicking.

Not everything is a "mirror".

Adjustments need to be made.

https://forums.azbilliards.com/showthread.php?p=6524582&highlight=Table-to-table#post6524582

pj
chgo

Black-Balled · Nov 24, 2019

That is something I've never thought of, though I think there must be ways of figuring out (rail) contact points that eliminate there center vs edge error.

Does aiming at the diamond through the rail, as opposed to aiming at the cushion point of the diamond, not achieve a proper strike point?

Patrick Johnson · Nov 24, 2019

Black-Balled said:
That is something I've never thought of, though I think there must be ways of figuring out (rail) contact points that eliminate there center vs edge error.

Does aiming at the diamond through the rail, as opposed to aiming at the cushion point of the diamond, not achieve a proper strike point?

https://forums.azbilliards.com/showt...le#post6524582

pj
chgo

Black-Balled · Nov 24, 2019

Patrick Johnson said:
https://forums.azbilliards.com/showt...le#post6524582

pj
chgo

https://forums.azbilliards.com/showthread.php?p=6525504#post6525504

Patrick Johnson · Nov 24, 2019

Black-Balled said:
https://forums.azbilliards.com/showthread.php?p=6525504#post6525504

Dammit - it worked before... OK, here's the actual post:

Patrick Johnson said:
Here's a system for those table-to-table adjustments.

Because rolling balls rebound long they have to be aimed short of the equal-angle spot at the cushion nose. The actual aim target is somewhere on the rail behind the equal-angle spot, and it's a similar distance back on the rail for all rolling kicks on that table. I like to visualize the aim point on the rail behind the equal-angle spot as a fraction of the distance from the nose to the diamond, as illustrated by the yellow "rulers" in the pics below.

On this Virtual Pool table the aim points are right about at the diamond behind the equal-angle cushion nose spot - this is about how my usual table plays (Metro with Simonis 860). On a shorter-banking table, like one with faster or dirtier rails, the aim points will be closer to the cushion nose. On new slippery cloth the aim points can be behind the diamonds.

pj
chgo

bbb · Nov 24, 2019

HawaiianEye said:
The "center line" of the cue ball or an object ball never touches the rail unless you are shooting straight up and down or across the table.

When you are shooting at an angle into a rail, (with either the cue ball or an object ball) the opposite side of the "contact point" on the ball is the point that touches the rail, not the center line of the shot.

So, why do people use the "center lines" of the balls when doing calculations?

Also, if you are shooting into a rail at an angle, the ball comes off the rail a bit "elongated" from the rebound off the rail. English and speed can compensate for this a bit, but I'm talking hitting the rail with "no spin" on the ball to begin with.

Think about it the next time you are practicing banks or kicking.

Not everything is a "mirror".

Adjustments need to be made.

here is a few reasons why from my humble opinion
first of all
some billiard systems are designed for you to aim thru the rail to the diamond
second
its easier to diagram (poor reason i know)
so if you have to hit the nose of the cushion from an angle for a system to be accurate
if you have played enough you know where to aim to have the edge of the cue ball hit the spot on the nose of the cushion (in spite of the diagram )
an example would be
if i put a quarter on the rail so that a little bit of it hung over the rail on to the playing surface
and put the cue ball on an angle to it
and asked you to hit the edge of the quarter sticking out
based on the angle an experienced player would know how to aim to make the contact
he would know you cant aim right at the edge of the quarter
i think you are over thinking this although it is an excellant observation
jmho
icbw
more than 2 cents worth.....:grin:

HawaiianEye · Nov 24, 2019

bbb said:
here is a few reasons why from my humble opinion
first of all
some billiard systems are designed for you to aim thru the rail to the diamond
second
its easier to diagram (poor reason i know)
so if you have to hit the nose of the cushion from an angle for a system to be accurate
if you have played enough you know where to aim to have the edge of the cue ball hit the spot on the nose of the cushion (in spite of the diagram )
an example would be
if i put a quarter on the rail so that a little bit of it hung over the rail on to the playing surface
and put the cue ball on an angle to it
and asked you to hit the edge of the quarter sticking out
based on the angle an experienced player would know how to aim to make the contact
he would know you cant aim right at the edge of the quarter
i think you are over thinking this although it is an excellant observation
jmho
icbw
more than 2 cents worth.....:grin:

I know why people do it. They don't know any better.

I see people trying to measure and calculate angles all the time and they are pointing to spots on the rail that the ball will never hit. They are clueless.

I'm not overthinking this. I know where to aim.

I was making the post and asking the question to make people THINK!

bbb · Nov 24, 2019

HawaiianEye said:
I know why people do it. They don't know any better.

I see people trying to measure and calculate angles all the time and they are pointing to spots on the rail that the ball will never hit. They are clueless.

I'm not overthinking this. I know where to aim.

I was making the post and asking the question to make people THINK!

as i said great observation and true
but pointing to a spot on the rail that the cue ball wont hit doesnt mean its the wrong place to aim or that you wont hit it if you adjust your aim
..........

HawaiianEye · Nov 24, 2019

bbb said:
as i said great observation and true
but pointing to a spot on the rail that the cue ball wont hit doesnt mean its the wrong place to aim or that you wont hit it..........

Let me be a bit SIMPLER.

They look at the pocket they want the ball to go in or the object ball they want to hit on a kick shot.

They look at the cue ball.

They then go to the side of the table that they are banking or kicking to and look back at the cue ball.

They then look at the desired pocket or ball again.

They point at a spot on the rail where they think the proper spot to hit is. They may even put a piece of chalk on the spot.

They, then, go back to the shooting side of the table and line up on their "spot" and shoot.

They miss the pocket or ball by several inches.

They then scratch their head and give a sheepish look as they go sit back down.

Then, they do it, over and over again, when the shot comes back up.

Those are the people I'm talking about.

Patrick Johnson · Nov 24, 2019

HawaiianEye said:
I see people trying to measure and calculate angles all the time and they are pointing to spots on the rail that the ball will never hit. They are clueless.

The "mirror" system for sighting kicks/banks, a perfectlly legitimate and geometrically accurate system, uses aimpoints entirely off the table.

So there.

pj
chgo

HawaiianEye · Nov 24, 2019

Patrick Johnson said:
The "mirror" system for sighting kicks/banks, a perfectlly legitimate and geometrically accurate system, uses aimpoints entirely off the table.

So there.

pj
chgo

If you know what you are doing, it works.

That is what I said from the beginning.

Some people don't know how it works and I sit and watch them every Sunday when I stay around to watch some of the league play.

deanoc · Nov 24, 2019

I am one of those people

who make the same mistake over and over

furthermore i don't understand a word of this i am confused

i keep hitting banks short,why

bbb · Nov 25, 2019

HawaiianEye said:
If you know what you are doing, it works.

That is what I said from the beginning.

Some people don't know how it works and I sit and watch them every Sunday when I stay around to watch some of the league play.

so maybe they miss because they dont know how to figure out what they want to do?
or maybe they miss because their stroke is faulty and they hit the shot with unintended spin?
or maybe they cant hit what they are aiming at?
maybe it has nothing to do with what part of the cueball hits the rail??
maybe?????????????:shrug::shrug:

Center Of A Ball And The Rail

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