follow

• accuracy
• effects of tip offset, speed, distance, cut angle
• normal roll, maximum offset, and overspin
• rail dribble

for more information, see Section 4.03 in The Illustrated Principles of Pool and Billiards

accuracy

Is a follow shot more accurate than a center-ball hit or draw shot?

I think this is definitely true for shots like the straight-up-and-down-the-table drill. Here are some possible reasons:

• It is easy for some people to hit the CB's centerline when the cue tip is closer to the top of the ball where the top of the tip is more closely visually aligned with the top of the ball.
• The cue can be closer to level (not elevated) with a follow shot as compared to a draw shot with the same cue clearance above the rail. This will result in less swerve when the CB is hit slightly off center.
• When the CB is hit slightly off center, the effective squirt (the net effect of squirt and swerve) can be less with a follow shot vs. a draw shot (see my October '07 article).
• The slowing drag effect of a draw shot increases the effect of the sidespin off the rail. Both follow and draw shots will have the same amount of sidespin (for the same amount of offset from the vertical centerline); but with a draw shot, the CB will be moving slower at the rail causing the sidespin to alter the rebound angle more.

FYI, some of this is described and illustrated in my October '07 and March '08 articles.

effects of tip offset, speed, distance, cut angle

On a follow shot, does it matter how high I hit the cue ball, if roll develops naturally?

Yes, depending on the shot speed and distance to the OB. At low speeds and large distances from the OB, it doesn't matter how high or how low you hit the CB, it will be rolling when it hits the OB (due to drag action). However, for fast shots close to the OB, the tip contact height makes a big difference in how much the CB curves after OB impact. As I pointed out before, the other important thing with follow shots is how much spin vs. speed the CB has after OB contact. A fast follow shot will create more follow action when the OB is hit more fully. Most of the speed is lost, but most of the topspin is retained, and there is more topspin with more initial speed and tip offset.

I have a demo of the effects of various types of English in NV 4.25. The actual cut angle, how much you cheat the pocket, and speed are also important factors. I have an English drill in the instructor and student resources section of my website that is helpful in learning to experimenting with all the factors.

normal roll, maximum offset, and overspin

What tip height is required for a rolling cue ball, and is it possible to get more spin than normal roll?

Concerning the amount of center ball offset required for immediate natural roll, the answer (and analysis) are in TP 4.2. The technical term for the contact point for natural roll is "the center of percussion." The required contact point offset from center ball is:

2/5 R = 2/5 (2.125 in / 2) = .45 in

The maximum recommended offset, beyond which miscues are very likely, is usually cited in the range:

1/2 in to 9/16 in = .50 in to .56 in

Therefore, follow (topspin) in excess of normal roll is possible (i.e., .45 is less than .5), but not by much. This is called overspin. With overspin, the CB will accelerate (i.e., speed up) as the spin wears off until the amount of topspin degrades to the "natural roll" amount. For more information, see my October '05 article. HSV B.26 also provides visual proof of off-the-tip overspin, and provides more explanation. NV B.27 shows a simple experiment to show how difficult it is to achieve overspin without miscuing.

Now, after a CB hits an OB, it can most certainly have overspin. For example, in HSV 4.3 and NV 4.8 the CB has topspin. Before it hits the OB, the amount of topspin is the natural rolling amount (i.e., there is no "overspin"). After the CB hits the OB, the CB has more topspin than the natural rolling amount (i.e., there is "overspin"). This is what causes the CB to "follow" the OB to the rail. After rebound off the rail, some of the spin is retained (which looks like bottom spin now) causing the CB to draw back to the rail.

The reason for extreme follow effects is all about speed. For a fast natural roll follow shot, the topspin angular speed goes up as the ball linear speed goes up. And for small cut angle shots, the cue ball loses most of its linear speed and retains most of the spin, causing significant follow effects. HSV 4.1-4.3 illustrate the principles fairly well.

rail dribble

Why is it that with some follow shots, the cue ball stays close to the rail?

NV 4.8 - Rail dribble follow shot, NV 4.9 - Normal follow shot into a rail, and HSV B.21 - follow-the-rail trick shot illustrate and explain the effects fairly well.

With almost all follow shots (regardless of speed), the CB is "rolling" at object ball impact. This is certainly the case in the "rail dribble" video. With more speed, there is correspondingly more topspin, but the CB is still rolling (provided you are hitting the CB high enough).

The amount of follow action depends on how little CB speed remains in relation to the amount of topspin retained. With a fast follow shot, the CB has lots of topspin (as the ball rolls at a higher speed). With a smaller cut angle, most of the CB's speed is lost, but almost all of the topspin is retained after OB impact. That's what produces the follow "action" ... lot's of spin, not much speed. That's why both speed and cut angle are important in this type of shot.

If the cue ball has lots of topspin and very little speed when it hits a rail, "rail dribble" occurs (see HSV 4.3 - Rail dribble follow shot).