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Pro Shop Glossary

The following is a glossary of terms commonly used in the Pro Shop industry:

Actual Span: Distance from edge of thumb hole nearest to center, to edge of finger holes nearest to center, including all inserts and/or grips.  (See also: True span, full span)

Angle of entry: Angle, measured parallel to the boards, at which the bowling ball hits the pocket after completing its path down the lane.

Angular velocity:  Spin or revolutions put on the ball by the bowler. (See also: Rotational energy)

Arc: Ball path from foul line to headpin that does not have a sharp, defined break point.

Axis of rotation: Imaginary line, perpendicular to the track, along which a bowling ball rotates during its path down the lane.

Axis Point: One of two points located on opposite poles marking the endpoints of the axis of rotation.

Axis leverage: Type of drilling in which the label, or center of gravity, is placed on the bowler’s positive axis and the pin is positioned between the positive axis point and the center of grip, usually above a line from the positive axis point to the ring finger.

Axis tilt: Angle between axis of rotation and the horizontal plane - caused by the bowler at the release, represents an angle of the axis rotation above a horizontal line through the middle of the ball.

Axis rotation: Angle between the translational and rotational energy vectors. The degree the axis is rotated on the horizontal axis.

Axis weight: Method of drilling in which the weight block is positioned so that its mass is evenly distributed around the axis of rotation. (aka: pin on the axis)

Back of hole: Portion of hole facing away from the center of the grip.

Back swing: Portion of bowler’s delivery from the time the ball breaks the lateral plane of the body until the ball reaches the apex of the bowler’s swing.

Backend: Fifteen feet of lane directly preceding the headpin.

Backup ball: Style of bowling in which the movement of the ball is from left to right for right-handers and from right to left for left-handers.

Balance hole:  A hole placed in the ball (usually on the bowler’s vertical axis line to bring a ball back into ABC legal specifications.

Ball reaction: Change in direction of the ball’s path.

Bevel: Rounded edge of any hole drilled in a bowling ball.

Blister: Raised sac under the skin’s epidermis containing watery fluid, caused by irritation to the area.

Boards:  Any one of 39 individual strips of wood pieced together to comprise the surface of the lane.

Bottom weight: Imbalance in which the half of the ball opposite the center of the grip weighs more than the half containing the center of the grip.

Break point: Point in the trajectory of a bowling ball at which the ball makes its greatest change in direction.

Bridge: Distance between the finger holes.

Callus: Thickened, hardened area of skin caused by buildup due to friction against the skin.

Carry down:  Oil moved down the lane by the passing of bowling balls.

Center of gravity: The point in a body or system around which the whole mass is concentrated any may be assumed to act. The point on the surface of the bowling ball where the static balance is zero in all directions on a do-do scale - usually marked by a logo.

Center line: Vertical line between the fingers and through the middle of the thumb.

Center line transposition (CLT): Lateral shift of the center line, after drilling the thumb first.

Conventional grip: Grip in which the bowler places his/her fingers in the ball to the second joint at a 90 degree angle, while placing his/her entire thumb in the ball.

Cosmetic bevel: Bevel at the extreme top of the hole which provides a neat appearance to the finished hole.

Cranker: Bowler who generates revolutions by a cupped wrist, bent elbow or muscled armswing.

Cut span/cut-to-cut span: Distance from edge of thumb hole nearest to center, to edge of finger holes nearest to center, excluding all inserts and/or grips. (see also Edge span/edge-to-edge span)

Deflection: Amount of displacement incurred in a bowling ball’s trajectory after making contact with a headpin.

Degree of oval: Degree of oval of a hole will be to the center line measured on a horizontal line from the center of the thumb hole.

Differential of radius of gyration: Differences between the Rg axes XYZ.

Dropped ring finger: A fit in which the ring finger span is intentionally shortened to be less than the middle finger span.

Dull finish (less than 600 grit): Surface of a bowling ball appearing without reflection (unpolished). In general, a dull bowling ball is one in which the pores are open and clean.

Durometer: Device used to measure the hardness of a bowling ball.

Dynamic imbalance: Measure of weight in an object in motion.

Dynamics: Characteristics of the mass inside a bowling ball. This includes moment of inertia and differential of Rg, which in turn contribute to the ball’s preferred spin axis.

Edge span/edge-to-edge span: Distance from edge of thumb hole nearest to center to edge of finger holes nearest to center, excluding all inserts and/or grips. (see also cut span/cut-to-cut span)

Equator: Line around the ball, perpendicular to the midplane and the midline covering the entire circumference of the ball.

Finger tip: Style of grip in which the bowler inserts fingers to the first joint, with the combined total of angle of the two joints equaling 90 degrees, while placing the entire thumb in the ball.

Finger weight: Imbalance which effectively makes the side of the ball, divided by the midline, containing the finger holes, heavier than the side containing the thumb.

Flare: Refers to the bowling ball changing its axis of rotation while seeking its preferred spin axis during its path down the lane. The result is several distinct oil rings being visible around the ball. (see also: Track flare)

Follow through: Portion of the bowler’s delivery following the release of the ball.

Forward pitch: The drilled hole, either finger or thumb, is angled toward the midline (center) of the grip.

Front of hole: Portion of the hole facing toward the center of grip.

Full roller: A bowler whose track passes between the thumb and fingers and whose track measures the circumference of the ball.

Full span: Distance from edge of thumb hole nearest to center to edge of finger holes nearest to center, including all inserts and/or grips. (see also: True span, actual span)

Functional bevel:  Any bevel on the ball produced to create a smooth edge or release of pressure on any part or all, of a hole.

Gripper/Squeezer: Someone who holds on to the ball with excessive force.

Heads: Portion of the lane from the foul line to the range fingers which are generally located 15 to 18 feet down the lane.

Heavy hit: A pocket shot that makes more contact with the headpin than an ideal shot.

High performance balls: Balls designed to create specific reactions for different bowlers.

High track: A track outside of the thumb hole and finger holes that is no more than an inch from either.

Hinge angle: Angle at which the thumb is connected to the hand.

Hit the ball: Acceleration of the hand around the ball, from bottom to side, at the release point.

Hook: Amount, measured in boards and angle, that a bowling ball deviates from its original trajectory in its path down the lane.

Hook angle: Angle at which the bowling ball changes direction at its break point.

Hook potential: Degree to which the properties designed into a bowling ball aid in its potential to traverse the boards during its path down the lane.

Horizontal axis measurement: Distance, measured perpendicular to the centerline of the grip, along the midline, at which the positive axis point is located.

Imbalance: Displacement of the center of gravity from the geometric center of a bowling ball.

Inside: The portion of the lane bounded by ten boards on each side.

Label shift: Displacement of the label from the center of the grip.

Lateral pitches: Right and left components of hole angle in any drilled bowling ball.

Leverage position: In bowling, it is the position at which the bowler is able to use his body to create rotation, speed and momentum on the bowling ball.

Lift: Vertical component of a bowler’s release.

Line: Intended path of the ball down the lane.

Linear velocity: Ball traveling down the lane toward the pins. (see also: Translational energy)

Loft: Distance the ball travels before actually making contact with the lane surface.

Low track: A track outside the finger holes and thumb hole, but more than two inches from either.

Mark: Point on the lane at which the bowler is aiming.

Mass Bias:  Weight in a particular area of the ball.

Midline: Line that perpendicularly bisects the center line of the grip. A horizontal line halfway between the fingers and thumb.

Midplane/Vertical Axis Line: A line perpendicular to the midline that passes through the bowler’s positive axis point and the negative axis point when extended completely around the ball.  Separates top of ball from bottom of ball on the bowler’s axis of rotation.

Mid or half weights: A ball with a net weight of more than .35 or below .8 of an integral weight.

Moment of inertia: Amount of force required to spin an object.

Negative weight: Imbalance which causes thumb, negative side or bottom weight.

Negative side weight:  Imbalance in a ball that effectively makes the left side of the ball heavier for right-handed release players, and the right side of the ball heavier for left-handed release players.

Normal callus: A callus formed because of the weight of the ball is bearing on certain parts of the hand.  (Not necessarily a problem for the bowler.)

Offset: Difference in span between middle and ring fingers.

Open: To open is to rotate part of one’s body in such a way pointed on a line away from the center of the lane.

Ovaled: The shape of a hole being out of round.

Pie Chart Formula: Theory that breaks fitting a ball to the bowlers hand in 3 parts: span, pitches and hole sizes. The standard starting percentages being 40% span, 40% pitch and 20% hole sizes.

Pin: A small round discoloration on a bowling ball that marks the top of the weight block.

Pin action: The manner in which the pins react to the impact of the bowling ball.

Pin shift: The process of creating reaction in a bowling ball by displacing the pin from the axis of rotation or the PAP.

Pitch: The angle at which a hole is drilled into a bowling ball in relationship to the center of the ball.

Positive axis point (PAP): Point on the surface of the ball that is the end of the bowlers axis of rotation, on the positive side of the ball.

Positive weight: Imbalance which causes finger, positive side or top weight.

Positive side weight:  Imbalance that effectively makes the right side of the bowling ball form the center of grip heavier than the left for right handed release player, and left side of the ball heavier than the right for left handed release player.

Preferred spin axis: The axis about which the bowling ball wants to rotate.

Pull the ball: Result when a bowler misses his/her target to the inside of the armswings intended direction.

Push Away: Portion of delivery in which the bowler sets the ball in motion.

Radius of gyration (Rg): An account of the distribution of the mass in an object.

Release point: Point in the delivery at which the ball leaves the hand.

Reverse pitch: The drilled hole, either finger or thumb, is angled away from the midline (center) of grip.

Reverse block: A lane condition in which the inside portion of the lane is covered with less conditioner than the outside.

Revolutions: The number of times the bowling ball makes a complete rotation about its axis during its path down the lane.

Rotational Energy: Spin or revolutions of the ball caused by the bowler. (see also:  Angular velocity)

Safe zone: The area on the ball from one inch inside the midplane to a line from the bowlers PAP to the ring finger and from the PAP to the equator, in which the pin of a ball can be placed safely without the track and holes interfering with one another.

Semi tip: A grip in which the bowler places his/her fingers in the ball between the first and second joint while placing the entire thumb in the ball. (Not a recommended grip pattern)

Shell: The outer portion of a bowling ball surrounding the core.

Shiny: A ball that looks glossy.  In general, shiny balls have fewer open/exposed pores.

Skid:  The portion of the ball’s path in which the velocity of the contact point on the ball is greater than zero and the ball is therefore actually not rolling but is instead sliding down the lane.

Snap: A ball path which has a sharp, defined breakpoint. However, when referring to the actual break point, the term snap is often used as a quantifying term.

Span: Distance from edge of thumb hole nearest to the center, to the edge of finger holes nearest to the center.

Squirt: The action of a bowling ball as it hydroplanes past its breakpoint.

Stacked leverage: A layout where the pin and CG are the same distance from the bowler’s positive axis point.

Static weights: Measurements of forces at work in systems that are at rest - side, finger and top.

Stroker: Someone who has smooth swing and delivery without sudden acceleration.

Surface: The texture, both finish and hardness, of a bowling ball.

System of Bowling (SOB): ABC/WIBC regulations concerning balls, pins, lanes and dressing distribution.

Tapered: Any hole in which the upper diameter of the hole is larger than the bottom.

Thumb weight: An imbalance in a bowling ball which effectively makes the half of the ball containing the fingers, separated by the midline.

Track: Area of bowling ball that makes contact with the surface during its path down the lane.  Because of revolving motion, this area is usually in the form of a ring or rings around the ball.

Track Flare: The result of migration of a bowling ball from the bowler’s axis of rotation to the ball’s preferred spin axis.

Track flare management: The regulation of the position of the flare intersections and thus the amount of flare.

Translational energy:  Created by the ball traveling down the lane towards the pins.

True positive axis point (True PAP): The axis point for a bowler taken from a ball with minimum track flare potential.

True span: Distance from edge of thumb hole nearest to center, to edge of finger holes nearest to center, including all inserts and/or grips.  (see also: Full span, actual span)

Vertical Axis Measurement: The perpendicular measurement form the midline to the bowler’s PAP.

Weight block: Traditionally, the dense part(s) of material found in the interior of a bowling ball.

Weight hole: See Balance hole.



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Jayhawk Bowling Supply and Equipment, Inc.
355 North Iowa Street
Lawrence, KS 66044
(785) 842-3237