Now that the technical aspects of how hard it may be are behind us, what I want to talk about here is how to "Easily Make a Bank Shot". How do you measure the angles of a shot into and off the cushion? How do you know where to hit? How do you know if more/less speed, or english is necessary? You may have heard of "angle-in vs angle-out". It works assuming other factors are taken into account, such as speed and english, as noted above. What about those times where those angles are not obvious, or where the position of the balls makes it almost impossible to observe angle-in/angle-out? The most important question, is how do you do bank shots consistently?
What I have done is taken some tried and proven techniques from various instructions from various pro's and condensed it into understandable steps.
Looking at diagram (2) below for reference, if you follow the steps you will understand.
Align any side bank shot with the OB and CB at the approximate positions shown in the diagram, then;
Step1: Draw a straight line from the OB to the cushion you intend to bank from. (Line A) (Where the CB is does not matter, as long as it is in position to make the bank.)
Step 2: Put your cue tip on the cushion where line A ends.
Step 3: Put the other end of your cue in line with the pocket you intend to bank to. Here I use an "orange" line, Line B. (make sure you put the pocket end of Line B at the best point of pocket entry to assure the best odds of making the shot. In this example, I have it going into the pocket away from the near cushion tip.)
Remember Line B, the orange, line points to your target pocket on all the below diagrams.
Step 4: Identify the pocket opposite on the table from the target pocket. (in this case the opposite side pocket)
Step 5: Visualize a line between that opposite pocket and the center of the OB. (Line C). This is also called "drawing the X" because line B and C cross.
Step 6: Where Line B and C intersect, draw a line parallel to line A to the same banking cushion, -- Black line, to Point D. Point D is where OB needs to rebound to make it back in the opposite side pocket.
Your contact point on the OB is directly on the opposite side of point D on the OB. Aim your CB at the OB with center hit (no english, top or bottom) and hit at medium speed. The OB will contact the cushion at point D, and bank into Pocket on opposite side.
If you come up short, you hit to hard...long you hit too soft, assuming you put no side english on the CB. In that case you will throw the OB off path either way depending on english. Remember if you use english here the effect on the OB is reversed from what you put on the CB. That is why I suggest, until your skill is more advanced, shooting these shots with NO english or top/bottom so the effects of ball speed, cushion compression/rebound, and english are minimized.
Once you master this technique you can move on to hard/soft and english variations. Sometimes those shots come in handy if other balls are in the OB or CB path.
Another note on this shot, if the CB is near the same position...say within a foot in any direction, you can use the same angle of cushion bank point (D) and contact point on the OB, you just need to aim the CB at the 1 ball a bit differently to maintain the "D" OB contact point hit but be aware of possible secondary collisions between OB and CB. This is nice because your calculated angle into and out of point "D" is good for a wide variety of CB positions. Once you do this many times in practice you will learn to closely approximate the position of point D, thus making all this measuring unnecessary. The more you do it, the better you get at it!
Remember, point D will be the same regardless of CB position (assuming you can make the bank)... but you do have to account for the possibility of secondary collision between CB and OB, or possible scratch.
Diagram 2
