Pin- This is a small polyester or urethane stem which signifies the top of the weight block in a two-piece ball,or the puck in a three piece ball design.
Pin-In- The weight block is perfectly centered in the bowling ball. Pin-in balls will flare less than pin-out balls due to this factor.
Pin-Out- Generally, any ball with the pin two inches or more from the CG is considered a pin-out.
To create pin-out balls the weight block is not perfectly centered in the ball and this offsetting of the weight block tilts mass to one side of the ball creating a center of gravity away from the pin.
Pin-out balls induce roll since they will flare more by placing the pin in an unstable axis area for greater dynamics.
Pin-out balls often give the ball driller more latitude and drilling choices than pin in balls.
Top Weight- This is the variation of the core height in a bowling ball. A core shifted up higher in a bowling ball creates higher top weight.The higher the top weight,the higher the RG of that ball.
RG- An account of the location of the mass in an object.
High RG- High RG balls are those whose mass is displaced further from the center of the ball. These balls have a tendency to skid down the lane further and have a delayed breakpoint. Better for drier lane conditions or conditions needing strong,late hook.
Low RG- Low RG balls are those with mass displaced closer to the center of the ball. These balls have a tendency to roll earlier and have a more predictable,smoother hook style. Better for more oiler lane conditions since the ball wants to hook sooner
CG- The CG is the center of gravity or the center of mass which is the point on the bowling ball where the entire mass may be considered to be concentrated. It is the point of zero balance on a DoDo scale.
Track Flare- This is defined as axis migration. Flare is seen on a bowling ball as the side-by-side rings that occur as the ball spins down the lane and later rolls down the lane. This is due to the ball changing its axis of rotation while seeking its preferred spin axis.
Track flare has two main functions being first of all it is to orient the core to a more inertial position,(meaning resistance to change in rotation) and to provide the ball with an oil free surface area so that when the ball hits the dry part of the lane the friction is at its maximun potential. Track flare size is dependent on the amount of revolutions the bowler has,where the ball is drilled,what type of RG it has,the amount of differential RG and how much friction is present.
Starting with zero track flare,as flare is increased the increase in reaction starts at the backend and the more the flare is increased the more the increase in reaction moves toward the bowler.
The more track flare the earlier the ball hooks and less track flare creates better length and later hook.
Preferred Spin Axis(PSA)- The axis which a ball desires to rotate around,and which it flares to acheieve this rotation.
Mass Bias- The position in a bowling ball,other than the pin where the mass is closest to the outside circumference of the ball.
Positive axis point(PAP)- This is the point on the surface of the ball that is the end of the bowlers axis of rotation on the positive side of the ball.
Axis Tilt- This is the angle of rotation put on the ball by the bowler. The rotational positioning of the ball is critical to creating the potential for hook.
The wider the angle between the rotational axis and the forward path of the ball,the greater potential for hook. If the angle is zero, then no hook will occur.
Heads- The portion of the lane which extends from the foul line to the arrows which are generally located 20 feet down the lane.
Pines- Generally refereed to as the middle 20 feet of the lane.
Backends- The last 20 feet of the lane where the least amount of lane conditioner is found and where a bowling ball usually makes its biggest break towards the pins.
Break Point- The portion of the lane where the bowling ball completes its transition from skid to traction and provides the greatest amount of hook.This generally occurs in the last 20 feet of the lane.
Ball Track- The portion of the ball which comes in contact with the lane as it rolls down the lane.
Revolutions- The number of times in which the weight block makes one full rotation around the axis line as it rolls from the foul line to the head pin.
Coverstock- The coverstock is the part of the ball that encases the core or weight block It makes up the outer shell.
Surface- The composition of the outside of the ball. Also refers to the texture and finish of a bowling ball.
Weight Block- The inner portion of a two piece bowling ball which influences reaction based on its density and postition to the bowlers axis.
Static imbalance- The measure of weight in an object at rest.
Dynamic Imbalance- The measure of weight in an object in motion.
Balance Hole- An extra hole drilled in a specific position in the bowling ball. This hole is used to balance the ball statically and alter the overall reaction of the ball.