How to Drill a Bowling Ball at Home

Drilling holes into a bowling ball is not a simple task. Bowling pro shop technicians spend hours learning drilling techniques. However, if you purchase a new bowling ball with no holes or need to change the holes on your existing ball, you can do so from home, but you will need the proper equipment. Unless you drill holes in bowling balls correctly, you may have some difficulty getting the finger and thumb holes just right for your hand.

Things You'll Need

  • Measuring tool
  • Drilling machine
  • Ball marker
  • Low grit sandpaper
  • Bowling ball polish
  • Bowling ball scale
  • Bowling ball plugs
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Instructions

    • 1

      Check the surface of the ball. If you are drilling a previously used ball, there may be finger holes you need to fill using a hardening plastic.

    • 2

      Make two measurements of your hand. Make one from the first joint from the tip of the bowler's index finger to the joint in their thumb. The second should start from the same place on the middle finger to the same place on the thumb. Subtract 1/4 inch from these measurements to take into account that your hand does not rest on the ball when bowling. If you have any hand abnormalities, such as flexibility issues, take those into account when measuring your hand. Test your hand to see what a comfortable grip feels like and adjust your measurement.

    • 3

      Place the ball in your drilling machine. Take into consideration how deep to drill the holes (if you want your fingers to go one or two finger joints deep) and the pitch, or angle toward the core of the ball. Ensure the ball is secure in the machine's clamp ring so it does not move around during drilling.

    • 4

      Mark the ball. Start by marking the center of gravity (CG), which you can find by locating the small punch mark on the surface of a ball. From there, mark two lines in a cross-hair patter around the ball. The mid-line runs horizontally and the center-line of grip (CL) runs vertically. Divide the span measurement in two and mark the thumb hole on the CL below the CG using this half-measurement. Measure from the thumb hole mark going up the CL, but not directly on it. Mark the two finger holes roughly one-to-two inches apart with the CL running directly between them. For a right-handed bowler, mark the index finger hole on the left side. For a left-handed bowler, mark it on the right side.

    • 5

      Drill the holes using your drilling machine. You should use a different sized drill bit for each hole. The bit size depends on the size of your fingers. You should drill holes wide enough to easily fit your fingers, but not so wide that it makes the ball difficult to grip. If drilled correctly, you do not need more than three different drill bits to finish your drilling.

    • 6

      Sand and clean the ball. The drilling will have created a considerable amount of dirt and dust, so wipe the ball off with a cloth. Use a low grit sand paper to remove any scratches on the ball and to smooth the finger and thumb holes. You may also want to polish the ball.

    • 7

      Weigh the ball using a scale. Most bowling leagues require bowling balls to fit a certain set of regulations, including weight. If the ball does not fit the specifications of the league that you bowl in, you will either have to plug the holes and start over, or drill additional holes elsewhere, depending on whether your ball weighs too much or too little.