The only thing you’ll need is your shooting equipment, a pool table, billiard balls and a quarter. A quarter? Yes a quarter. In this article we will go over the geometry and some very minor physics to help you improve your rail, bank and kick shots. There are two fundamental errors that most shooters make when performing these shots.
Fail to account for geometric volume
Fail to account for effects of physics
Now before you get all frustrated and think you can’t do this because of math, don’t worry. There won’t be any math in this post. It’s simple concepts of geometry and physics that don’t require any math, just a basic understanding of the concept.
Geometric volume essentially is the amount of space a 3 dimensional object (Cube, Cone, Sphere, Cylinder, etc.) takes up. When it comes to billiards of any kind, spheres are what you are dealing with. Too often shooters forget this and transform the cue ball (a sphere) into a 2 dimensional object or plane. This causes problems with all shots not just the rail, bank and kick shots. Take image below for example.
First notice the two red lines going through the center of the cue ball and the 9 ball. Now notice where the two balls are touching each other at the point where the third red line crosses between them. Notice that half of the cue ball, and half of the 9 ball exist between the center of each ball and the contact point. If the 9 ball is not contacted at this specific point by the cue ball, no matter where on the table it comes from, the 9 ball will not enter the pocket. Most do not consider this on even the cut shot (which is the majority of shots taken in the game). Generally people will aim the center of the cue ball at the point they are trying to hit the object ball. This would work if we were talking about hitting a point on a 2 dimensional plane, but it doesn’t work because half of the ball is the way causing the cue ball to strike the object somewhere that wasn’t intended. This is the cause for many of the missed shots we experience in the game. Let’s take this to rail for some visual cues on this that will make understanding this a little easier.
In the following image there are several things to notice. First, the black dot on the cue ball represents the center of cue ball and where the cue ball is touching the table underneath. Secondly, the verticle red line is showing where the cue ball is touching the rail. This contact point makes a straight line from the diamond, through the quarter, through the center of the cue ball, and across the table to the corresponding diamond. The horizontal red line runs through the center of each ball and parallels the rail. The diagonal red line shows where the two contact points of the cue ball are (Notice it forms a 45 degree angle splitting the square into two halves or two triangles). The first contact point is at the rail (noted by the quarter’s edge and the letter A), and the other is at the object ball. The two greenish yellow lines connect all three contact points in this image between the cue ball and object ball, between the cue ball and the rail, and between the object ball and the rail. With these lines intersecting the red lines, you’ll notice that it forms a square. This is the area that is overlooked and not accounted for when the shot is missed. This is what I call the quarter zone, because the distance between the center of the cue ball and the very edge of the ball that makes contact is a quarter’s width apart.
You’ve most likely heard the term “Ghost Ball” if you have been playing pool for some time. This training method is actually attempting to get the understanding of this concept into your mind. Others use different methods and usually in conjunction with training to improve aim. Well, the concept I am sharing with you is the reason “Ghost Ball” training and other methods work.
The important thing is that you understand the concept no matter how it is taught. This is how I became exponentially more effective with my cut, rail, bank, and kick shots which is why I’m sharing this with you. It took my understanding of my training to another intangible level improving my accuracy with these shots from 40% to 78% in a matter of a few hours. Since then, I’ve been averaging 82% percent on these shots.
That’s enough of my rambling for now. Let’s move on. In the image below, I removed the cue ball leafing the 12 in place.
Notice that the quarter zone doesn’t change. No matter where the cue ball starts out the contact point on the 12 is the same to run it down the rail to a pocket. The key thing is that the cue ball’s center must be in the spot shown by the black dot for it to make contact with the rail and the 12 to properly to make the shot.
Now take notice of the white lines. These are routes of approach. This is where the physics comes in working with the geometry. These white lines show the line of aim through the center of the cue ball in order to make the shot from that angle of approach. The quarters are there to help show the center point of the aim on the rail for each angle. This part addresses the geometry of the shot. Now for the physics. Keep in mind that the rail is going to give and absorb some of the cue balls energy. That means that the cue ball will “Sink” into the rail a little after making contact with the 12 when the shot is aimed correctly, keeping the quarter zone in mind. If it is not hit correctly, the 12 will also “sink” into the rail and be propelled away from the rail causing you to miss the shot. Below is the most common way this shot is missed not using the quarter zone concept.
Notice that the line of aim put the center of the cue ball aimed at the intended contact point. Notice the space between the cue ball and the rail. There is a quarter’s width from the rail. This is because the quarter zone was not accounted for. Now, generally speaking, if you’ve been playing for a little while, you won’t miss this shot that badly just because of experience, but even a little off on this shot will cause the same effect even if it missing the shot by a hair at the pocket. This same concept holds true with banks and kicks. To demonstrate this to yourself, take a look at this next image.
This is how trick shot artists get the quarter to jump off the table as you can see in the latest video I posted. To set up a practice for this concept, take a quarter and place it on the rail directly in front of the second diamond on the long rail adjacent to the foot spot. Then take the cue ball and set it up on the head spot. Now with no spin (center cue ball hit) attempt to knock the quarter off the table by shooting the cue ball to hit the rail directly in front of the quarter as shown in the image above. If you hit the right spot the quarter will jump off the rail and off the table. If you don’t, it might hop, or even move a little if you got close. To get it to jump off the table you must hit the spot on the rail as shown.
This will help you adjust the way you aim and consider your bank shots and cut shots. This is where you will start to see the effects of the quarter zone for yourself. Once you understand this, and have a good handle on how to aim to jump the quarter off the table every time you shoot at it, hitting your banks and kicks just got exponentially easier.
In the image above, the red lines indicate the normal way people take this shot on an 8 ft table. Performing this shot in this manner will yield the same or very similar results every time unless you use some spin. The reason again is the quarter zone was not taken into account. The dark blues lines indicate the way this shot would look on a 9 ft table aiming from the corner pocket to the second diamond. On an 8 ft table however, the object ball must be cut into the rail at the precise point indicated by the light blue spot.
This is where the quarter zone comes in. To hit that precise spot you must account for it and adjust your aim accordingly (meaning cutting the shot aiming the 15 a little farther down rail) as shown by the light blue line. The green spot by the 15 represents the placement of the center of the cue ball when contact is made. This in turn causes the 15 ball to strike the rail at the blue spot rather than the yellow spot at the point where the red lines intersect at the rail. You guessed it, it’s about a quarter’s width difference. This is why the quarter zone is so important and why I spent so much time attempting to explain it.
Perform the afore mentioned shot with the quarter on the rail.
Set up generally simple bank shots (like the one in the diagram), mark the spot on the rail by placing the edge of a quarter directly in line with it on the rail. Perform the shot attempting to jump the quarter off the rail. If you jump the quarter properly, then you will make the shot center pocket. If not, you might still make it with a little bit of bobble or miss the shot completely because you didn’t place the quarter in the right spot on the rail.
Hopefully I haven’t confused you with this concept. It really isn’t easy trying to explain in this venue which is why I was hesitant on sharing this here. It really is much easier demonstrating it in person. None the less, take some time to work with the practice suggestions I provided and it will become more clear to you as you see it happening first hand. Please, feel free to use the images if you need a reference to practice with. Until next week, happy shooting and may your game improve.