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Balance Holes In Bowling Balls, Originally Posted: 10/2/12; Updated: 4/13/21

**2021 Update: Per USBC Official Rules, balance holes in bowling balls are now considered illegal and must be plugged in order to be used in USBC sanctioned events. For more info, please click here. **

Balance holes in bowling balls
are an extra hole (balance hole or weight hole) in a ball which is used to get the ball within United State Bowling Congress (USBC) specifications for imbalance (static balance).

The maximum allowable diameter is 1-1/4" for USBC sanctioned play. Balance holes in bowling balls are non-gripping holes drilled into the ball to adjust the static weights and to create dynamic influence.

The effect of static weights is extremely minimal on the ball's reaction. So the major influence in the effect of a balance hole lies in the effects that it has on the ball's dynamics, those forces affecting the ball when it is in motion.

The location of a balance hole with regard to the distance from the pin is the primary tool for altering the dynamics of the ball's core. The strength of the core is measured by the Differential rating.

Higher Differential results in more track flare potential, and will induce the ball to release energy quicker when the ball encounters friction. The ball motion at the break-point will be stronger and will increase the overall hook potential.

The USBC states that a bowling ball may have no more than one (1) ounce of side weight after the holes are drilled. While many people have their opinions about whether or not this rule is valid, it is still in effect. You need a DoDo scale to weigh the ball for side weight.

If you are over one (1) ounce (we recommend 3/4 ounce) then there is a weight hole removal chart (or guide) pro shop professionals use to help determine what size drill bit to use, and how deep a balance hole should be drilled.

At, we feel it helps to know some of the information about specifications pro shop professionals use so you gain greater insight into the net affect balance holes have influencing bowling ball motion.

After choosing a bowling ball with the coverstock you think matches with the lane conditions you are targeting, the static weight balance dynamic shifts in accordance with the chosen drilling layout pattern after gripping holes are drilled into the ball.

Use of a balance hole would be the important final factor in achieving the desired ball reaction. The drilling technique consists of the layout and the balance hole location and size (if a balance hole is desired).

Drilling a balance hole in your bowling ball will change the Differential ratio when the ball is in motion. Since the Differential ratio will influence the ball motion, you can control the degree of transition your ball makes as it travels through the mid-lane and when it transitions again at the break point down the lane.

We hope this information helps you in understanding the purpose of balance holes in bowling balls and how it can affect ball motion. We recommend you consult your local pro shop professional when selecting a new bowling ball and a drilling layout and to determine if a balance hole will improve your ball motion.

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