The 3-piece, full-size core has been an industry staple throughout bowling's history. The original core construction of a bowling ball was a single density sphere. Technology evolved and a weight mass was placed inside the upper edge of the core to counterbalance the weight that is removed from the top half of the ball during the drilling process, creating top weight. Although there is not a limit on top weight in an undrilled ball, the ABC restricts the amount of top or bottom weight in a drilled ball to 3 ounces. Ebonite's upper limit on top weight in an undrilled ball is five ounces and lower limit is one and one-half ounces. The upper limit on lighter weight balls is on a descending sliding scale to reflect the density differences on the core weight. This ensures that the drilled ball will be within ABC specifications for top/bottom weight.
A higher density polyester compound is poured into the core mold and is allowed to harden before the lower density material, which makes up the rest of the core, is added. This high density weight mass has the same round contour as the core on one side and is flat on the other side. Appropriately, the name "pancake" has been assigned to this weight mass. Bowlers found a stronger hook potential when the pancake was introduced to the core construction. The amount of top weight in an undrilled ball can be altered by varying the density of the pancake material or by increasing its thickness. Higher top weight creates a ball reaction that goes further down the lane and has a stronger backend hook. Lower top weight causes an earlier breakpoint and a smoother hook pattern. The center of the top weight is signified by a mark called the center of gravity. It is called "CG" for short.
Moving the CG above the center of span, towards the fingers, creates finger weight. This increases the skid characteristics of the ball. Moving the CG below the center of span, towards the thumb, creates thumb weight. This causes an earlier breakpoint. Moving the CG to the right of the center of span (to the left of the span for lefthanders) creates positive side weight. This increases the overall hook. And moving the CG to the left of the span (to the right of the span for lefthanders) creates negative side weight. This reduces the amount of hook. The ABC limit on finger, thumb, positive, or negative weights is 1 ounce.
The 3-piece, full size core is higher in RG and low in RG Differential. The higher RG creates a delayed breakpoint. The low RG differential results in an easy to control, lower hook potential. The 3-piece core is best for drier lanes, slow ball speeds, and those who like to play a straighter line to the pocket.
Choosing the proper ball construction and surface texture for your bowling style and lane condition will be the most important decision you and your pro shop operator will make. Choosing a drilling layout will alter the ball's characteristics within its performance parameters to fine-tune the overall reaction. Drilling layouts will not produce ball reaction without proper mechanics from the bowler and proper surface texture.

CG Locations