Bob Jewett Make Your Own Do-it-yourself help with aiming. Last month I showed you some pool Diagram 2 shows how to make such a tri- function of trigonometry. aiming aids. One of them was Colonel C. angle. If you use regular 8.5-by-l 1-inch Suppose your set of balls has less throw, M. Western's amazing "Pointer," which has typing paper, and you use the 11-inch side or you want to use a different size of paper. multiple rotating arms, sliders, You will need to somehow cal- finely engraved scales, and a culate the length for the mechanical monkey that plays unknown side of the triangle. the accordion. Well, almost. It Fortunately, www.google.com tells you exactly how full to hit has generously agreed to do any cut shot on the table and these calculations for us for where the cue ball will then go free. Just go to its Web site, for any amount of draw or fol- and type into the search win- low. If you're still scratching dow the formula in the format your head about how it works, above. If you prefer to spell you're not alone. As soon as I out "tangent," Google is smart decipher the 154-page instruc- enough to know what you tion book, I'll try to make its mean. This will allow you to operation perfectly clear. figure out the second leg for In the meantime, here are two any size and angle. As a final simple devices that you can example, if you want to make make yourself to help visualize both a 30-degree triangle with 22-inch aiming and position play. paper, type in "22 * tangent(30 The first will help you find the true degrees)" and you will get 12.7 half-ball angle and aiming align- inches. ment. This sounds easy — anyone In Diagram 3 is an example use can see the edge of the object ball of the second aid. It is shaped just and send the cue ball in that direc- like the first, but it tells you where tion. But in my own case, I found the cue ball is going to go when it that even though the target is obvi- leaves the object ball for a half-ball ous, I was off by a little in my cue shot. Placement is a little trickier. delivery and that cuts to the left were One side is still along the line of the different than cuts to the right. cue ball's approach, but the circle is The aiming device is shown in use not placed at the ghost-ball posi- in Diagram 1. It's formed from two tion. Instead, it is pulled back some. simple shapes: a triangle and a circle. This is an allowance for the fact that The circle is placed at the ghost ball the cue ball slides some to the side location (where the cue ball will just after it hits the object ball, be when it hits the object ball) and this gives an apparent with one side of the triangle starting position somewhat pointed toward the pocket. back from the ghost ball. How Place the cue ball so it is along far? That depends on your the extension of the other side speed, cue ball, cloth, object of the triangle. It it is easier to ball, and a few other things. see this line if the triangle is What angle should you fairly large, but you could use a make the triangle? Start with string to extend the line for a 34 degrees. That should get small one. you close enough that you can The circle is the easy part to place the cue ball for a scratch make, but make sure that its every time on the shot shown. diameter is exactly the same as Once you have that angle the ball's: 2.25 inches. The tri- down so that you can split the angle is a little harder. First you pocket precisely, try placing a have to decide on the angle. If there is no for one side, the other side has to be 5.85 9 ball, for example, half a diamond from throw, the angle would be 30 degrees, but inches long. The formula is shown in the the pocket and see if you can set up a bil- with throw included, the cut angle is per- diagram: 11 * tan(28 degrees), where tan is liard to make the 9. I think you'll be pleas- haps two degrees less — 28 degrees. the standard abbreviation for the tangent antly surprised. 3 4 B D - JANUARY 2D05 Bob Jewett Frozen Bank Shots Heat up the table with your new skills. In Diagram 1 you'll find a situation that wor- leave the cushion "shorter," or more perpendic- ries beginners and champions alike. The object ular to the rail. ball is frozen to the cushion, and the only shot Why is a stun shot the same as left English on available is a bank shot. Will the cue ball double- the cue ball in this situation? The important fac- kiss the object ball? After this column, you tor in throw and transfer of sidespin to the should be a lot more comfortable with this kind object ball is the direction of the motion of the of problem. cue ball's surface when it hits the object ball. First, you need to have some organized experi- For the shot shown at A, there will probably be ence with the shot. Go to a table and try the fol- some cut to the left as seen from the cue ball, so lowing drill. Place the object ball in a convenient that for a stun shot, the cue ball will be moving place such as at the first diamond from the cor- to the right when it hits the object ball. This will ner pocket (A). Place the cue ball where you both throw the object ball to a shorter line and think you can bank the ball to pocket P without transfer right English to the object ball, which a double kiss. Mark that spot with a coin, as will also help to shorten the rebound angle. shown. At first, don't try any technique that you Left English on the cue ball is a surer way to already know that might help prevent a kiss; just get this effect, because as the hit gets fuller, the play the cue ball with "collision-induced follow and just throw" of the plain enough speed to get stun shot will have the object ball to the less effect. Also, if pocket. there is any draw or If you make the follow on the cue shot from one loca- ball when it gets to tion, move the coin a the object ball, that little farther up the will make the surface table and try again motion less effective with the cue ball in in making the shot the new position. go shorter. To make Remember that if the left English most you do get a double effective, try for a kiss from one posi- stun shot along with tion, it doesn't neces- the sidespin. sarily mean that you The third technique can't make the shot, for extending the since your aim may march of the coin up have been off. to a fuller hit is to Once you have the shoot harder. Until coin up the table as recently, it was far as you can get it, believed that shoot- note where on the ing a bank hard side cushion you are shooting "from." That is, caused some kind of rail deformation that note where your stick passes over the rail closest would make the ball rebound at a shorter angle. to you. In fact, on most tables the speed of the shot does Next, try some techniques to advance the coin not significantly affect the banking angle for a farther. For the shot shown, left English should frozen ball. help. Playing the shot with enough draw to be a Please note that I said "frozen ball." On a slow stop shot should also help. (A stop shot with a bank shot, if the object ball starts a distance little cut angle is often called a "stun" shot.) from the cushion, it will have a chance to devel- Finally, shooting the shot harder should permit a op forward roll before impact. After impact, as fuller hit. the ball moves away from the cushion, it contin- The first two methods actually work by the ues to spin toward the cushion. This will tend to same mechanism. The idea is to get the cue ball carry the ball back toward the cushion, curving to rub on the object ball to put right English on its path. it. This will be "reverse" English as the object A very interesting (and useful) phenomenon ball goes into the cushion, and will make the ball having to do with banking is shown in Diagram 32 BD-FEBRUARY 2005 Bob Jewett 2, which looks like a film strip. The images entire sequence took place in l/30th of a cushion to a surprising depth of almost half are from the Jacksonville Project video, in second, or in the time of a single frame of a an inch. The object ball returns to hit the which lots of stick/ball/rail interactions standard video. cue ball full, and stops nearly dead in turn.