Natural Roll

The Natural Angle is the widest deflection line that the cue ball can take after impact with an object ball, provided that the cue ball is rolling 'naturally' on contact. Natural Roll is when the cue ball is not skidding across the cloth and is carrying no sidespin.

Strokes Wider than the Natural Angle

There are three methods of widening this deflection angle and all three methods normally utilise a thick half-ball contact:

1. Pace

What happens

The cue ball will throw wider than the natural angle and will follow an arced (parabolic) path. (see Ball Paths for more on this).

When to use this method

This method is very useful for losing hazards if the object ball is close to a cushion, because the arc takes the cue ball out from the cushion. It is not so useful for cannons because it is very difficult to control all three balls when a fast pace is used. Furthermore, it is only really useful when there is sufficient distance between the cue ball and the object ball to enable the cue ball to acquire Natural Roll before impact.

2. Running Side

What happens

Firstly, the application of running side causes the cue ball to swerve a little before contact and to therefore come at the object ball from a different (slightly narrower) angle. This means that the initial deflection path is effectively already slightly wider.

A further widening of the angle occurs because, on contact, the side on the cue ball causes the object ball to throw slightly in the opposite direction. This, in turn, causes the cue ball to be thrown in the same direction as the applied side (Newton's Third Law of Motion!).

So, for example, if right-hand (running) side is applied to the cue ball the object ball will throw slightly to the left, resulting in the cue ball being thrown slightly to the right, thus widening the natural angle of deflection.

With about half maximum side you get the maximum throw of the cue ball, so there is usually no benefit of using any more than half maximum side to widen the angle.

When to use this method

This method is very useful when close to the object ball as judgement is much easier than for longer range shots. It is important to bear in mind the effect of the nap, even with short range shots.

Strokes can be made with running side if the cue ball is placed up to and including one ball wider than the standard shot.

3. Stun or Screw

What happens

If the cue ball has not aquired Natural Roll by the time it hits the object ball it will throw wider than the Natural Angle.

If the cue ball is stunned onto the object ball (skidding on impact) it will leave the object ball at a path that is approximately 90° from the path that the object ball takes. This is true for all object ball contacts (see 90° Stun rule) but is normally used for the thick half-ball contact.

If the cue ball impacts the object ball at about the thick half-ball contact and with a significant amount of backspin, it will leave the object ball at a path that is approximately 90° from the cue ball's orginal path. (see 90° Screw rule). Thicker contacts will give an even wider deflection, with the extreme case being a full ball shot when the cue ball will come backwards. Even very fine contacts can be made to deflect wider than the natural angle if the balls are close together and a deep screw is used.

When to use this method

Using Stun or Screw is particularly useful when close to the object ball and can be very difficult to judge at long distances.

Strokes Narrower than the Natural Angle

There are three methods of narrowing the angle that the cue ball takes after impact.

1. Check Side

What happens

Firstly, the application of check side causes the cue ball swerve a little before contact and to therefore come at the object ball from a different (slightly wider) angle. This means that the initial deflection path is effectively already slightly narrower. In addition, on contact, the object ball is thrown slightly in the same direction as the sidespin on the cue ball and this in turn causes the cue ball to throw in the opposite direction, ie narrower again (Newton's Third Law of Motion!).

When to use this method

This method is very useful when close to the object ball as judgement is much easier than for longer range shots. It is important to bear in mind the effect of the nap, even with short range shots.

Strokes can be made with check side if the cue ball is placed up to and including one ball tighter than the standard shot.

2. Thick Contact

What happens

By hitting a thicker contact than the standard thick half-ball, the cue ball will take a narrower angle than the natural angle (see Ball Angles for more on this).

When to use this method

This method is useful a very narrow angle is needed, in which case the shot is played as a run-though.

3. Thin Contact

What happens

By simply hitting a thinner than half-ball contact the cue ball will take a narrower angle.

When to use this method

This method is particularly useful when close to the object ball as judging thin contacts at long distances is very difficult.