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Bowling Ball Drilling & Layout Terms

If you are relatively new to the game or simply are interested in learning about some of the common terms heard around pro shop circles today related to bowling balls, then understanding a little about bowling ball drilling and layout terms can help you next time you are in the selection process for a new ball.
Here are a few terms related to the bowling ball which pro shop ball drillers reference before mapping out a ball and choosing an appropriate drilling layout.
The following terms can clarify some lingo about bowling balls:
Drilling Layout - A drilling layout refers to where the pro shop professional places the locations of the gripping holes and/or a balance hole in relation to the bowling ball pin, positive axis point for a given bowler, and the mass bias location when mapping out a bowling ball prior to drilling the holes.
The specific drilling layout you choose will influence your ball motion by increasing or decreasing length potential (skid distance) and hook potential (amount of hook in the mid-lane and angle of entry on the back end) based on your delivery technique and the ball construction.
Positive Axis Point - The point on the pocket side of your bowling ball at the end of the axis of rotation while your ball is in motion is referred to as your bowling ball positive axis point.
When your bowling ball is delivered, the ball will revolve around an axis known as the axis of rotation. At the ends of the axis of rotation are the PAP and the NAP (negative axis point). The PAP is the one point most important in deciding on a drilling layout and ultimately in achieving a desired ball motion.
Mass Bias Marker - The part of a bowling ball in which the internal mass of a bowling ball is closest to the outside edge of the coverstock is commonly referred to as Mass Bias. This does not include the Pin.
Bowling ball mass bias helps control the shape of a given ball reaction on the back end of the lane. When the mass bias marker on the ball surface is moved to different locations, it will affect your ball reaction.
Pin Locator - The “Pin” locator is best defined as a polyester or urethane stem which is positioned in the weight block to hold the core in place as the coverstock is poured into the ball mold during the manufacturing process.
This “Pin” represents the top part of the weight block and is usually represented by a colored dot on the surface of the ball.

Center of Gravity - he position in which the ball is evenly balanced statically from the right side to left side and from the finger quadrant to the thumb quadrant. The perfect balance point where the weight on any straight line drawn through the c.g. is zero on either side of the c.g.. This spot is usually indicated by the position of the label or a punch mark.
There are several other terms such as “Span”, “Finger Pitches”, and “Top Weight”, and “Side Weight”, as examples, which are related terms to bowling balls but are not critical to the ball driller when mapping out a drilling layout.
It is not important that you become an expert at understand the technology of modern bowling balls nor understand these terms perfectly but rather that you develop a good working relationship with your pro shop professional when you decide to drill a new bowling ball.
The technology can be confusing and overly scientific for most bowlers. By taking some time to understand these terms, however, can help you gain insight into the manufacturers planning when introducing new bowling balls to the marketplace.