How to Customize Bowling Ball's Dynamics

Everyone knows that a bowling ball has three holes -- one for the middle finger, one for the ring finger, and one for the thumb. 

But sometimes, one opening called the balance hole is drilled into a bowling ball to facilitate the adjustment of the ball's static weights so as to customize the ball's dynamics when it is in motion. 

A bowling ball's static weights are measurements of the ball's balance.  The American Bowling Congress (ABC) and the Women's International Bowling Congress (WIBC) set certain specifications of these weights. 

According to the ABC, for a ball weighing 10 pounds or more, the maximum difference between the weight of the top and the weight of the bottom of the ball is 3 ounces, and the maximum difference between the sides to the right and left of the finger holes, and between the front and back of the finger holes, is 1 ounce. 

These limits decrease along with the weight of the ball, as the limits for an 8-pound ball are a ¾ ounce differential between the sides and a 2-ounce differential between the top and bottom.

In many cases, the drilling of finger holes creates a difference in weight, as a certain amount of material is taken out of the ball to make room for the bowler's fingers.  This imbalance affects the way the ball moves down the lane, so perfecting the ball's static weights can give the bowler a distinct advantage.

To adjust this imbalance in weight, often a bowler will drill a balance hole in the heavier part of the ball to remove some material in an attempt to equalize the weight of the top and bottom of the ball. 

The ABC rulebook states that only one hole can be drilled for balance purposes, and this hole cannot exceed 1¼ inches in diameter, so bowlers must be careful not to exceed specifications, especially if they have any plans of competing in sanctioned events. 

Bowlers also drill balance holes in their bowling balls to affect the way the ball hooks, or curves when thrown a certain way.  An imbalance in weight from side to side can cause the ball to curve more dramatically in order to hit the pocket at a better angle.  It is recommended that a bowler start with a small balance hole to see what kind of effect it has on the movement of the ball, as a deeper hole can always be drilled later. 

For a more dramatic reaction, balance holes should be drilled 2½ to 3½ inches in depth, as it is at this level that some of the ball's core will be removed which will better affect the movement of the ball. 

If one drills a shallower hole, the material that is removed will be less dense, and this will not affect the overall mass of the ball as much.

In addition, the speed at which one throws the ball will also determine the suggested size of the balance hole.  For a slower ball speed, a smaller balance hole is recommended, while a bowler who throws the ball at a high rate of speed would best be served by a larger balance hole.

For advanced bowlers who are able to finesse the ball down the lane with a good deal of accuracy, the balance hole is one tool that can be used to affect the dynamics of the ball as it moves down the bowling lane.  As long as they are careful to not exceed the major bowling organizations' specifications on weight differentials and the amount and size of the balance holes, bowlers are free to use this equipment customizing technique to their advantage.