(This is today's bit of advice from the book Safety Toolbox.)
Work on coming to the cushion with various top and draw side spins and speeds after contacting the object ball. Start with slower speeds and work your way up, watching what happens. It is necessary to know the results of each variation. Different distances out from center add more cue ball spin and exaggerate the out angles even more.
The purpose of becoming specific with your shots is to ensure predictability. When you send the cue ball off a rail with spin, you must have confidence in the results and not make some wild stab and pray attempt. Many safeties that require careful positioning are possible with controlled cue ball spin.
There are important factors to keep in mind with side spins. When coming into the rail at an angle, running spin is easily demonstrated when shooting the ball three rails around the table. Regardless of the starting side spin, by the third rail, the ball spins at about 45 degrees. With running spin, the angles out are opened and the spin helps the cue ball travel further.
Reverse spin is when the ball goes into the rail spinning in the opposite direction. The rail absorbs much of the speed and spinning energy. As a result, the ball comes out slower and the angle out is shortened. This spin is often used to kill ball speed.
Speed is another factor. When the ball contacts a rail at a high speed, any spin does not have enough time to fully interact with the cushion. There is always some affect from side spin. That angle out is a fraction of the possible angle if the ball traveled slower.
The first two examples help you learn how to control spin and speed. Use all of the clock positions and different tip widths out from center (i.e., ½ tip, 1 tip, 1-1/2). Make positioning predictable. Shoot it over and over until you can consistently roll the cue ball in the planned direction. The second two examples help you pocket a ball while using various spins and speeds. Learn how to be precise (and successful).
Side spin skill development, exercise 1
Use this to learn predictable paths with various spins when going straight into the rail. Start with the left, and then try the right side.
Side spin skill development, exercise 2
Use this to learn predictable paths with various spins when coming into a rail at an angle. Figure out how to make it work - consistently.