Cue ball control: stop, stun, draw and follow.

Where on the cue ball to hit

Vertical tip position decides whether the cue ball arrives at the object ball with topspin, backspin or neither. Dr. Dave's guidance, measured as a share of the ball's radius from center (the miscue limit is the farthest from center you can hit without the tip slipping):

In absolute terms, natural roll starts at 2/5 of the ball's radius above center, about 0.45 inch on a 2.25-inch ball, and the practical miscue limit is about 0.50 to 0.56 inch off center. A handy practice tool: the stripe on balls 9 through 15 is one radius wide, so you can use a striped ball as the cue ball to see how low you are really hitting. Players often hit higher than they think.

Stop and stun

A stun shot is one where the cue ball has no top or bottom spin at the moment it hits the object ball. Hit straight on, a stun shot is a stop shot: the cue ball stops dead and hands all its motion to the object ball.

The cloth drags backspin away as the cue ball travels, so the farther the object ball, the lower or harder you must hit for the cue ball to arrive with zero spin. Short distances and faster speeds need less tip offset; slow speeds and long distances need more. Stop shots are much more forgiving of tip position than draw shots.

The 90-degree rule

With a stun hit, the cue ball and object ball separate at 90 degrees and the cue ball travels along the tangent line, whatever the cut angle. Speed does not change this; a stunned cue ball heads down the tangent line at any pace. Side spin does not change the tangent line either, though it can change the object ball's path through throw.

John Matranga's quick visual, shared on Dr. Dave's site: lay your three middle fingers along the tangent line. Together they span about 2.25 inches, roughly a ball's width, which shows both edges of the cue ball's path.

The 30-degree rule (natural angle)

A rolling cue ball (natural roll, not sliding) that hits the object ball anywhere between a quarter-ball and a three-quarter-ball hit deflects close to 30 degrees from its original direction. More precisely, it is about 34 degrees near a half-ball hit and about 27 degrees near quarter- and three-quarter-ball hits.

Dr. Dave's "peace sign" trick: a relaxed V between your index and middle fingers is close to 30 degrees for most people. Line one finger up with the cue ball's original direction and the other points where it will end up.

Outside the 30-degree range, different rules apply. On very full hits (fuller than three-quarter ball) a rolling cue ball deflects about three times the cut angle (2.5 times is closer for many shots). On thin hits (thinner than a quarter ball) it deflects about 70 percent of the angle between the aim line and the tangent line.

Follow and draw always start on the tangent line

With follow or draw, the cue ball leaves along the tangent line first and then curves as the spin takes hold. Faster shots stay on the tangent line longer before bending, so the curve starts farther down the line, but the final direction stays parallel to the slow-shot version.

Draw and the trisect rule

For a draw shot with "good action" at cut angles below about 40 degrees, the cue ball's final direction is about three times the cut angle away from its original line. A 30-degree cut sends it roughly 90 degrees off its original line. Dr. Dave defines "good action" draw as the amount that turns the cue ball perpendicular after a half-ball hit. Shots with spin in between the reference cases (stun, full roll, good draw) are "tweeners," and the cue ball ends up between the reference directions.

Practical draw findings from his articles:

• For long draw at maximum cue speed, the most draw comes at about 70 to 80 percent of the miscue limit. Going lower adds little.
• For medium distances, a slower cue with more tip offset gives better distance control than a faster cue with less offset.
• A level cue appears best for maximum draw; raising the butt (from about 0 to 15 degrees) reduces the cue ball's spin-to-speed ratio when it reaches the object ball.
• Draw is easier on slick, fast cloth.

His fixes for weak draw: keep the cue level by collapsing the bridge hand and lengthening the bridge, go back slowly, keep the grip relaxed, do not drop the elbow, chalk, and finish the stroke. The usual culprits are not aiming low enough, dropping the elbow before contact, tightening the grip, elevating the cue, rushing the transition, decelerating and jerking the cue back.

How far the balls travel

On a full-ball follow shot, the cue ball follows about 8 percent of the distance it would have rolled without a collision, while the object ball travels about 50 percent, so the object ball goes roughly 6 to 8 times farther. On a 45-degree stun shot, each ball travels about half the cue ball's no-collision distance. The two balls travel about the same distance at a hit slightly thinner than half ball, both deflecting about 30 degrees.

A drag shot uses backspin to slow the cue ball on its way to the object ball so it arrives with the speed and action you want.

The 1/8 rule for stroke length

Dr. Dave's rule of thumb for speed: with a high tip for follow and a very low tip for stop and draw, add 1/8 to your stroke length for every diamond of cue-ball-to-object-ball distance (for stop and stun), for every diamond of follow you want, or for both distances added together on draw shots.