Bowling Ball Pin Locator

bowlingball.com, Originally Posted: 11/2/2013; Updated: 9/12/2021

There are several key points on the surface of your bowling ball which assist a pro shop professional when it comes time to map out a drilling layout, before drilling your new ball.


One of the key points the pro shop must locate is the “Pin” placement which identifies the weight block location inside the bowling ball.
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.
The mass bias marking is best defined as the part of a bowling ball in which the internal mass of a bowling ball is closest to the outside edge of the coverstock.


This is a separate marking from the Pin location marking.
While your ball is in motion, the point on the pocket side of your bowling ball at the end of the axis of rotation is referred to as your bowling ball positive axis point.

By identifying your positive axis point, the location of the secondary marking on the ball surface, the “mass bias marking”, and your “Pin” locator, your pro shop professional may then proceed mapping a chosen drilling layout.


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. However, the locator “Pin” is another useful key ultimately used in planning any given drilling layout.