Bowling Ball Drilling and Finger Fitting Guide

Fit comes before layout

A personal bowling ball should be fitted to your hand, not copied from another bowler or chosen from a generic chart. A qualified ball driller considers finger and thumb size, thumb shape, span, flexibility, grip style and the way you release the ball. A good fit should let you hold the ball with relaxed grip pressure; it cannot guarantee a particular hook, score or freedom from injury.

Do not drill or enlarge gripping holes at home. Drilling changes the ball permanently, and an error in size, span, pitch or depth can require plugging and re-drilling. Use a qualified pro-shop professional with the measuring and drilling equipment needed for the job.

Conventional and fingertip grips

Conventional grip

In a conventional grip, the middle and ring fingers are inserted to the second knuckle. This can feel familiar to bowlers used to house balls, but a personal conventional grip still needs individual hole sizes, span and pitches.

Fingertip grip

In a fingertip grip, only the fingertips are inserted. This changes how the fingers leave the ball, but it does not automatically create a strong hook or suit every bowler. Finger inserts are optional fitting components, not a substitute for correct measurements.

Neither grip is reserved for a particular skill level. Choose with a qualified driller or coach after considering comfort, flexibility, control and the release you are learning. Changing from conventional to fingertip is a new fitting job, not simply a matter of making the existing holes larger.

Span, hole size and pitch work together

• Span: the distance between the thumb and finger holes. It must allow the hand to lie naturally rather than feel stretched or cramped.
• Hole size and shape: the fingers and thumb should insert to their intended depth and release without catching. Holes should feel snug, but they should not force you to squeeze or twist the hand.
• Pitch: the angle at which each hole is drilled. Pitch is selected for the individual hole from the bowler's span and flexibility; it is not a universal forward-or-reverse setting.

These measurements interact. A symptom that seems to come from one hole may involve span, pitch, shape or grip pressure, so avoid copying measurements or asking for one isolated change without a complete fit check.

Finger inserts and interchangeable thumbs

Finger inserts can change diameter, texture and feel, while a thumb slug can give the driller a consistent material to shape. Both still need to fit the bowler's actual hand. Replace or adjust a component when a qualified driller finds wear, damage or a fit change; a fixed game-count rule cannot describe every bowler.

An interchangeable thumb system uses a removable fitted thumb piece in compatible balls. It can preserve the same thumb feel across an arsenal, and separately fitted sizes can accommodate temporary changes such as swelling. The system is optional and must be installed, fitted and checked by a qualified driller. Stop using it if the insert will not lock, sits proud of the ball or feels damaged.

When to request a fit check or re-drill

• The ball requires squeezing: check hole size, shape, span and pitch rather than assuming the ball is too heavy.
• The thumb or fingers stick, rub or leave a pressure point: stop and have the complete fit assessed.
• Your hand has changed: growth, swelling, injury or a lasting change in mobility can alter the fit.
• Your grip or release has changed: moving between conventional and fingertip, or making a major technique change, calls for a new assessment.
• The ball is used or previously drilled: another person's holes are not your fit.

A pro shop should inspect a used or previously plugged ball before deciding whether another plug and re-drill is appropriate. The decision depends on the existing holes, the proposed fit and layout, and the ball's condition.

What to expect from a qualified pro shop

1. Conversation: explain your grip, release, bowling goals, hand changes and any prior discomfort.
2. Measurement: the driller measures each finger, the thumb in both directions, span and flexibility rather than using one standard fit.
3. Grip and component choice: agree on conventional or fingertip, inserts or a thumb slug, and whether an interchangeable thumb is useful.
4. Drilling and finishing: the trained operator sets the pitches and depths, bevels the edges and fits any components.
5. Fit check: insert the bowling hand without forcing it and, where facilities allow, test a few normal deliveries. Report sticking, rubbing, pressure or the need to squeeze before leaving.

Ask for a written copy of the final measurements for future reference. Treat it as your fitting record, not as a do-it-yourself drilling plan: hands and releases can change, and each new ball still needs professional inspection.

Pain is a stop signal

If pain or other symptoms begin while bowling, stop rather than bowl through them. A pro-shop professional can assess equipment, but cannot diagnose an injury. If symptoms do not go away or get worse, seek advice from an appropriate healthcare professional.

Plan before drilling

Choose a controllable weight before the fitting with our ball-weight guide. If you are learning the sport, review the beginner's guide. Discuss your intended release with a coach and compare hook and straight styles before committing to a grip.