How to Drill an Asymmetrical Bowling Ball

Bowlers who throw a hook bowling ball want to generate as much of a hook as possible. Much of the power generated by the hook comes from the bowler's arm action and grip release motion. Some bowlers want to achieve more reaction from their bowling ball. To do this, they purchase an asymmetrical bowling ball with a core poured to be slightly off-center. Drilling an asymmetrical ball properly generates more side rotation and creates a pronounced hook and more pin action.

Things You'll Need

  • Measuring ball
  • Metal span ruler
  • China marker
  • Drill press
  • Drill bits
  • Ball jig
  • Ball clamp
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Instructions

    • 1

      Use a measuring ball to gauge how deep and wide the finger and thumb holes should be and the length of the hand span for the grip.

    • 2

      Find the center of gravity on the ball's coverstock by locating the manufacturer's mark, typically noted with a three-ring bull's eye. Locate a dot in the surface of the ball; this is where the core was poured into the bowling ball's mold, then covered with a plug.

    • 3

      Rest the ball on the jig base on the drill press. Find the mid line, approximately 1 3/4 inches below the pin. Mark the mid line horizontally around the ball with a china marker and a metal span ruler.

    • 4

      Mark the grip center line, which intersects the pin halfway vertically, all the way around the ball so that it crosses the mid line.

    • 5

      Find the mass bias of the bowling ball by drawing a line from the pin to the center of gravity. Use the metal span ruler, going around the curvature of the ball, and mark a spot that is 6 3/4 inches from the positive access point (the spot on ball that is equidistant from all points of the ball’s track) with an "MB."

    • 6

      Rotate the pin so that it's in the 11 o'clock position (if you were looking at the hands of a clock). Mark the edge of the thumb hole 3 inches from the MB mark. Use the measurement from the measuring ball and mark the edge of each finger hole the proper distance from the thumb hole and equidistant between the grip center line. Mark a dot in the center of where each hole should be drilled.

    • 7

      Recenter the ball in the jig on the drill base. Attach the drill bit needed to drill the thumb hole. Center the thumb hole under the bit and clamp the bit down onto the jig. Turn on the drill press and drill the thumb hole to the desired depth. Unclamp the ball, rotate the ball to where the center of the middle finger hole is marked and repeat the drilling process. Repeat for the ring finger hole.