chapter 6 – bowling ball parts and dynamics...bronze certification bowling ball parts and dynamics...

BRONZE CERTIFICATION BOWLING BALL PARTS AND DYNAMICS

Chapter 6 – Bowling Ball Parts and Dynamics

Overview

Acknowledgement

A special thank you goes to our colleagues from the International Bowling Pro Shop and Instructors Association (IBPSIA) for information included in this chapter. USBC Coaching strongly recommends that you and your athletes develop a strong partnership with a trained pro shop professional.

This chapter is divided into three sections. The first describes the details of a proper and improper fit and includes requirements for drilling a bowling ball for proper fit. The second provides a general working knowledge of bowling ball structure and components. The final section presents the physical science aspects that will help you understand bowling ball motion and dynamics.

Introduction

This chapter includes the following sections: In this Chapter

Section Number and Title Page

1 – Proper Fit 6–2

2 – Bowling Ball Structure and Components 6–15

3 – Understanding Ball Motion 6–37

© 2005 USBC Coaching Page 6–1

BOWLING BALL PARTS AND DYNAMICS BRONZE CERTIFICATION

Section 1 – Proper Fit

Overview

Just as no two bowlers are exactly alike, the fit of each athlete’s bowling ball is as unique to them as their fingerprints. Understanding components relative to the grip will help coaches evaluate the fit of their athlete’s bowling balls.

This section explains the importance of a proper fit, identifies the signs of an improper fit, describes the fingertip grip and provides details of hole size and pitch considerations.

This section covers the following topics: In this Section

Topic Page

Importance of a Proper Fit 6–3

The Fingertip Grip 6–7

Pitch 6–9

The Hole Truth 6–13

Page 6–2 © 2005 USBC Coaching


Importance of a Proper Fit

Without question, the most important aspect of a bowling ball is the seemingly basic concept of having a proper fit. A relaxed and pain free fit gives the athlete the best opportunity to reproduce the same relaxed delivery time after time.

Protecting the Body

The body is a wonderful machine designed to protect itself. When an athlete has equipment with an improper fit, the body will go into “survival mode” to minimize the potential damage that may be caused. The damage may not be limited to the hand. Prolonged usage of equipment with an improper fit may cause problems with the arms, shoulders, back and legs as the entire body must constantly adjust to delivering the ball.

An incorrect fit will cause a bowler’s release to be inconsistent and different shot-to-shot. No amount of coaching will improve this athlete’s game. It has been stated that, “You can’t out-coach a bad fit.” Unresolved issues regarding fit will restrict and limit the ability to develop the physical game.

Signs of an Improper Fit

Blisters, calluses and broken blood vessels on the athlete’s hand are signs of an improper fit. The illustrations that follow show some of the common hand problems and their causes. (Special thanks to Ebonite, IBPSIA for text information and Strikeability, Inc. for redesigned graphics.) Causes: Span too long Hole too tight Insert too tight Excessive forward pitch

Continued on next page



Importance of a Proper Fit, Continued

Signs of an Improper Fit continued

Causes: Span too short Insert worn out

Causes: Excessive L or R pitch Holes or inserts too tight

Causes: Finger used to support wrist OK unless pain




Importance of a Proper Fit, Continued Signs of an

Improper Fit continued

Causes: A – Span too short A – OK unless pain B – Excessive left pitch B – Hole too small

Causes: Excessive right pitch Holes too tight Span too long

Causes: Excessive reverse pitch Holes too big Span too short or too long




Importance of a Proper Fit, Continued

Signs of an Improper Fit continued

Causes: A – Span too long A – Hole too big B – Span too short or too long B – Hole needs more bevel B – Hole too big

Causes: Lack of flesh between first and second thumb joints Hole too tight Round hole drilled; should be oval

Friction points:

–6 © 2005 USBC Coaching


The Fingertip Grip

As noted in the introductory certification class, new and youth bowlers are strongly encouraged to use a ball with a “conventional” grip. This ball is fitted to the second joints (joints closest to the palm) of the bowler’s hand. This basic fit gives the bowler an opportunity to develop a good physical game. For the most part, this fit will produce a straight ball.

Conventional vs. Fingertip

As your athletes develop their skills, they will want to have the ability to roll a hook or curve ball. The best chance to deliver a hook ball is to use the fingertip grip. The fingertip grip differs from the conventional grip in that the span between the thumb and the fingers will extend out to the first joint of the fingers – or the joints furthest from the palm. The lengthening of the span for the fingertip grip creates an increased importance of the angles that the holes are drilled into the ball.

This increased span length of a fingertip grip will do two things: 1) put more ball surface in the palm of the hand; 2) create a noticeable separation of time from when the thumb exits the ball to when the fingers release.

The Span

Remember, the fit should not cause any pain or discomfort. The span should not be too long as to produce discoloring of the knuckles.

To check the span, have your athlete insert the thumb completely into the thumbhole. The thumbhole should be snug to allow a relaxed thumb to come out when the ball is being delivered. If the thumbhole is too large, it is true that the athlete will not have any problem with the thumb getting out of the ball. However, the athlete will end up squeezing or gripping the ball to hang on to it during the entire armswing.




The Fingertip Grip, Continued

When an IBPSIA pro shop professional is laying out a ball to be drilled with a fingertip grip, they will usually make a mark on the athlete’s bowling fingers that will indicate a distance half way between the first and second joints, as shown below in Figure 6-1 Measuring for Fingertip Grip. This mark designates where the gripping edge of the finger holes should intersect each finger, once the ball is drilled.

The Span continued

Figure 6-1 Measuring for Fingertip Grip

With the thumb completely seated into the thumbhole, have your athlete lay the palm and the fingers across the surface of the ball so that the fingers extend over top of the finger holes, as shown below in Figure 6-2, Fingertip Grip. With the fingers relaxed (not stretched) across the surface of the ball, check to see if the gripping edge of the hole is located half way between the 2 joints of the fingers.

Figure 6-2, Fingertip Grip

If the gripping edge of the finger hole is too close to the joint furthest from the palm, the span will generally be too long causing stretching of the finger and hand. Conversely, if the gripping edge is too close to the joint nearest to the palm, the span will tend to be too short where the knuckle of the finger will be forced against the furthest edge of the finger hole. This half way point measurement will allow the two joints of the finger to bend naturally and permit the fingers to comfortably fit into the holes.

The development of a free loose armswing begins with a relaxed hand. This comfortable fit will promote a tension free armswing and delivery.

Page 6–8 © 2005 USBC Coaching Updated – Feb 05


Pitch

Once the proper length of the span has been determined, there is the matter of drilling holes into the ball. There are two items of consideration when drilling holes into the ball. They include: 1) the direction that the holes are drilled into the ball (known as pitch) and 2) the size of the holes.

Drilling the Holes

When each hole is drilled into the bowling ball, consideration needs to be given to ensure a comfortable feel and ease of the release. Every bowler’s hand is as unique as that bowler. Some items of consideration that may affect how a ball is drilled include: strength, flexibility, size of hand, type of work and prior injuries.

The way for your pro shop professional to accommodate these and other factors is to adjust the angle at which each hole is drilled into the ball. The angle that a hole is drilled into a ball is known as pitch.

To understand the concept of pitch, you must first recognize that there is a geometric center of the bowling ball. A dot has been added to indicate the center of the ball shown below in Figure 6-3, Geometric Center. The geometric center is the reference point from which the angle or pitch is calculated.

Geometric Center

Geometric Center

Figure 6-3, Geometric Center




Pitch, Continued

There are four pitches or distinct directions a hole may be drilled into a ball: Geometric Center continued • Zero

• Forward

• Reverse

• Right or left lateral

Each of these pitches is described in the material that follows.

Zero Pitch: Simply stated, zero pitch means the hole is drilled directly toward the geometric center of the ball, as shown below in Figure 6-4, Zero Pitch.

Types of Pitch

Figure 6-4, Zero Pitch

Reverse Pitch: Reverse pitch is a hole drilled below the geometric center of the ball, as shown below in Figure 6-5, Reverse Pitch. The direction of the hole will fall under the geometric center of the ball. The finger position would be that of a more open hand.

Figure 6-5, Reverse Pitch




Pitch, Continued

Holes drilled with reverse pitch will promote an earlier release. This pitch is used for individuals with larger spans or very strong hands.

Types of Pitch continued

Forward Pitch: Forward pitch is a hole drilled in the direction going above the geometric center of the ball as shown below in Figure 6-6, Forward Pitch.

Figure 6-6, Forward Pitch

This pitch generally is for bowlers with shorter spans or who are not very strong. Pitching the fingers and thumb in this direction will promote a more secure feeling of holding on to the ball.

To better understand the concept of forward and reverse pitch we can use the analogy of holding a softball (forward pitch) versus a basketball (reverse pitch). Holding each of these objects with the palm facing the floor is very different. The softball is easy to hold as the hand will be in more of a closed position. It will obviously be more difficult to maintain a grip on the basketball as the hand will be in a more open position.




Pitch, Continued

Lateral Pitch: Lateral pitch refers to the direction either right or left from the center of the ball, as shown below in Figure 6-7, Lateral Pitch. This pitch is used primarily comfort and for ease of release and is related to the flexibility of the athlete’s hand and style of release.

Types of Pitch continued

Top view looking down at the holes

Figure 6-7, Lateral Pitch



The Hole Truth

An athlete must pay attention to the feel and fit of the holes. Although conventional logic suggests that larger holes will allow the fingers and thumb to exit the ball easier, it will also force the athlete to grip or squeeze the ball to hold onto it. Squeezing the ball will tighten muscles from the hand up through the arm and shoulder, affecting the body’s ability to relax during the delivery.

Hole Sizes

Conversely, if the holes are too small, the problems are obvious. There will be pain just trying to force the fingers or thumb into the holes. Since the fingers and thumb are not comfortably seated into the ball, it will be impossible for the ball to easily rest on the hand.

Snug thumb and finger holes will allow the athlete to hold onto the ball with minimum finger/thumb pressure.

After an athlete has the opportunity to have equipment drilled with a proper fit, they have problems releasing the ball – often complaining that the thumbhole is too small. Chances are the athlete has developed the habit of squeezing the ball during the release.

Knuckling the Ball

This problem is commonly called "knuckling the ball.” Squeezing or gripping the ball will cause the thumb to bend at the knuckle. This action will place pressure in the area of the knuckle and pad of the thumb as indicated by the arrows below in Figure 6-8, Knuckling the Ball. The pressure from gripping will prevent a clean release of the ball off the hand.

Figure 6-8, Knuckling the Ball


Updated – Feb 05



The Hole Truth, Continued

Work with your athletes to relax the hand. The athlete will need to apply very little pressure with the fingers and thumb when holding a proper fitted ball. Explain to the athlete when a ball is fitted properly, “The ball will let go of them” instead of “the athlete trying to let the ball go.”

Knuckling the Ball continued

Finding the proper fit is the first step to improve your athlete’s game. Once this fit has been fine-tuned it is important that this proper fit be maintained.

Maintaining a Proper Fit

Young athletes should have their ball fit checked frequently; once a month in some cases may not be unreasonable. At the very least, advise your young athletes to have their fit checked when their shoe size increases.

The body will continue to change over the course of a lifetime. Adults should have their fit checked every six months to maintain that good feeling. Also suggest to an athlete to have the fit checked if there is a noticeable fluctuation in weight.

Remember, establishing and maintaining a partnership with your local pro shop professional is an important part of the development of your athlete’s overall game. This individual will be able to make meaningful adjustments to your athlete’s equipment that the local general sporting goods store sales person cannot do.



Section 2 – Bowling Ball Structure and Components

Overview

This section is not designed to make you an expert on bowling balls. Rather, it will supply you with information to give you a better understanding of bowling balls and eliminate the mystery behind the many buzzwords casually tossed around. In this age of technology, a coach must have a general working knowledge of bowling balls to effectively help their athletes.

In this Section

This section covers the following topics:

Topic Page

Building an Arsenal 6–16

Consideration for Proper Ball Weight 6–17

Coverstock – The Bowling Ball Surface 6–18

Maintaining or Altering Ball Surfaces 6–19

Ball Construction and Dynamics 6–24



Building an Arsenal

As your athlete’s game continues to develop and the shots become more consistent, he/she will begin to notice that the lanes will play differently. The type of lanes, time of day, current weather conditions, number of games bowled and who has bowled on the lanes are just a few of the variables that will affect how a ball will react.

Making Smart Choices

Whether your athlete is ready to buy a second bowling ball or looking to add to his/her arsenal, you need to educate your athlete to make smart choices when investing in new equipment. A dangerous mindset is to always want the most powerful ball. If your athlete already owns a very aggressive ball, buying another very aggressive ball will mean having two pieces of equipment that essentially do the same thing.

When your athlete is considering purchasing additional equipment he/she needs to use the logic applied to golfing. Golfers will carry as many as nine different irons and four different drivers in their bags. Each club is designed to drive the ball different distances. Purchasing all aggressive equipment would be like golfers having only drivers in their bags.

An athlete should be looking to expand the ability to play on different lane conditions. Purchasing equipment ranging from very aggressive to fairly tame will provide the versatility to play the game.



Consideration for Proper Ball Weight

Several methods may be used when determining the proper ball weight for a bowler. Keep in mind that each athlete has different physical strengths and abilities.

Recommended Methods

One method is to have your athlete use the balls on the storage racks. The athlete needs to place the palm of the bowling hand facing the ceiling at about waist high. The forearm of the bowling arm is in a position that is 90 degrees from the torso of the body.

When placing a ball in the palm of the hand, look for a ball that will slightly push the hand downward. If the athlete has no problem holding a ball, it is too light. Conversely if the athlete has difficulty maintaining the hand and forearm at the 90 degree position it is too heavy. The ball that seems slightly heavy in most cases will feel fine once the ball has been drilled with the proper fit.

Another method is to again use balls from the storage racks. Utilizing a “see saw bag” or a “ball sling” (a piece of cloth that has two handles which is used to carry a ball) an athlete may again place different weight balls in this device and gently swing it back and forth to get a feel of what weight he/she can handle. If the direction of the armswing is easily changed then the ball is too light. If the ball pulls the body in the direction of the swing or the athlete has a difficult time maintaining their balance then the ball is too heavy. The ball that the athlete can not readily change the direction of the armswing and does not force the body to tense up will be the desired weight of the ball.

The key is to determine a ball weight that will work best for your athlete. An athlete should not be made to feel that they must use the maximum 16-pound ball. It is incorrect to assume that the heaviset ball will generate the most momentum going through the pins. The simplified equation for momentum below will show that this may not be the case:

Heaviest is Not Always Best

mass x speed = momentum

Inserting the following values into this equation shows that a 15-pound ball may actually generate more momentum than a 16-pound ball:

15 lbs. x 18 mph = 270 16 lbs. x 15 mph = 240

In terms of longevity and wear and tear on the body, using a lighter weight ball might be a smarter option.



Coverstock – The Bowling Ball Surface

Although manufacturers produce much information about what is inside the ball, the most important consideration when selecting a ball is actually the surface or coverstock. That is not to say what is inside the bowling ball is not important. The internal weight block must be compatible with the ball surface, which gives the edge to surface in terms of importance.

Importance of Ball Surface

The amount of friction (or the coefficient of friction) between the lanes and ball surface affect how much a ball will hook. A total absence of friction between the ball and the lane surface will result in a straight ball.

Today’s coverstocks greatly enhance the dynamics of what a ball is designed to do. The ball surface can be altered to reduce or completely negate the ball’s designed nature. Understanding the characteristics of today’s coverstocks will help you match the surfaces to your athlete’s style, thus maximizing the ability to compete.

In today’s game, there are four distinct coverstock types being used: Comparison of Coverstocks • Plastic (polyester)

• Urethane • Resin • Particle

These four coverstock types are compared in the table below.

Coverstock Description of Surface

Amount of Friction

General Characteristics

Recommended For

Plastic Very smooth Very low Generally straight Beginning bowlers or spare ball for advanced players

Urethane More porous/ texture will vary

Low to medium

Ability to generate some reaction with the ball

Beginners who are progressing into intermediate and above players

Resin Tacky surface Medium to high

Ability to be very aggressive on dry portion of lanes with less reaction in oil

Intermediate to advanced players

Particle Microscopic particles imbedded into the surface

High Greater hook angles. Has the ability to work in heavy oil

Advanced players




Maintaining or Altering Ball Surfaces

As noted earlier the coefficient of friction is the governing factor that determines hook potential. Maintaining or altering ball surfaces means adjusting the friction level of your athlete’s equipment so he/she can match up and effectively play the lanes. The process used to make changes to the surface of the ball is accomplished by:

Ball Surface and Friction

• Sanding

• Polishing

Modifying the surface of a ball will alter the path the ball travels down a lane by affecting when, where and how much a ball will react on a lane. A ball that has a rough (sanded) surface will have a high amount of friction creating the potential for the ball to react earlier on the lane. A ball with a smooth (polished) surface will have very little friction and hook potential which results in the ball reacting later on the lanes.

The process of sanding the ball may increase the friction between the ball and the lane. Sanding will scratch the ball, placing grooves on the surface, which gives the oil a place to go, just like a snow tire with deep treads. The oil will seep into the grooves, allowing the sharp peaks on the ball to touch the lane surface. The coarser sandpapers will create deeper scratches and grooves that will increase friction and the potential for ball reaction.

Sanding

Naturally, the sharp peaks created by sanding eventually will wear smooth, causing a slow change in the traction. Eventually, the ball will require sanding again to regain its previous surface roughness.

As the sanded grooves in the ball wear due to use, the surface roughness will approach the equivalent of sanding a ball with 600 grit sandpaper. A ball sanded with 320-grit sandpaper gradually will lose some of its hook as the surface approaches the equivalent of 600 grit.

It should be noted that using higher grit (1500 and higher) is super fine sand paper that will actually create a smooth surface ball. A ball sanded very smooth with higher grit sandpaper eventually will hook more as the ball’s surface gets scratched due to wear in the ball track. Again, this ball eventually will hook the equivalent of sanding with 600 grit sandpaper if the surface is not restored.


Page 6–19 Updated – Feb 05 © 2005 USBC Coaching


Maintaining or Altering Ball Surfaces, Continued

On dry lanes, the friction will be high. Your athlete will need a ball that skids and travels further down the lane before it hooks. Polishing the ball will eliminate the grooves on the ball, making the surface smooth and decreasing the friction between the ball and the lane. This action will decrease the hook potential of the ball.

Polishing

There now are liquid polishes available which have very small stones suspended in a fluid. By rubbing it onto a ball’s surface, small scratches are formed just like using sandpaper on the ball. These products specify their equivalent sandpaper grit such as 500, 1,000, 1,500, etc. Although liquid, the polish is abrasive, like sandpaper, and cannot be used on a ball during sanctioned competition. However, it may be used before or after league or tournament play.

Polishing a ball or sanding it with very fine sandpaper will cause any ball to hook less in the oiled area of the lane. With urethane and plastic balls, a smooth, polished surface lowers the overall ball friction, reducing the hook potential over the entire lane – a factor that helps on dry lane conditions. But don’t forget, while polishing a resin ball will reduce its hook in oil, it will maintain high friction on the dry portion of the lane. A sharp breakpoint usually results.

The difference between a ball sanded with 240-grit paper and a highly polished ball is extreme. You may want to make smaller changes, which can be done by using finer grades of sandpaper like 320, 400, 600 and 1,000.

Sanding and polishing is best done using a ball spinner at a pro shop. This will create a consistent surface over the entire ball.

Sanding and Polishing Tips

When sanding a ball, it is best to sand the entire ball parallel to the ball track and then rotate the ball 90 degrees and sand again to create a cross-hatch. This eliminates any prevailing sanding pattern on the ball. Be sure to wipe the ball after sanding to remove any sanding residue.

Remember, the grit of sandpaper used will drastically affect a ball’s performance. Obviously, a bowler’s style must influence the decision-making process as to what grit sandpaper to use. By all means, try different grades of sandpaper to adjust the ball to a particular lane condition.

Whether the lanes are flooded with oil or bone dry, using sandpaper or polish will increase the weapons in your athlete’s arsenal.





Your athlete’s arsenal may contain three types of ball cover finishes: A Ball for Each Condition • Sanded (dull)

• Benchmark (lightly polished or lightly sanded)

• Polished (shiny)

Equipment sanded with low grit sandpaper should be used on oily lane conditions.

A benchmark ball is one that is not set up to over or under react to the lanes. This type ball surface is used when lane conditions are not too oily or too dry. This is the ball that an athlete will usually use to determine the condition of the lane.

The polished ball will have a shiny surface and should be used on drier lane conditions.

Periodically polishing a ball will maintain its shiny, low-friction surface. Ball polishers found in many bowling centers are used to help restore this type of ball surface. Various types of polishing compounds designed specifically for bowling balls may be purchased at your local pro shops.

Before polishing a ball, it should be sanded lightly with smooth sandpaper (600 to 1500 grit). Sanding should be performed at the pro shop as it takes special skills and equipment to perform the job correctly.

The following table shows a summary of lane conditions and their corresponding types of ball covers:

Lane Condition Ball Cover

Oily Sand with 320 grit sandpaper

Medium Benchmark ball lightly sanded or lightly polished

Dry Polished, shiny ball





The appropriate use of sanding and polishing is shown below in Figure 6-9, Effects of Sanding and Polishing.

A Ball for Each Condition continued

None Moderate High

Polish

400 600 800 1000 1200 1500 2000

Grit

Sanding

Less Hook Potential

Later Roll

Light Oil

More Hook Potential

Earlier Roll

Heavy Oil

Benchmark

Figure 6-9, Effects of Sanding and Polishing





Each type of coverstock will respond to surface change in different ways. Below is an overview of how these four coverstocks are affected:

Coverstocks and Surface Preparation • Sandability

• Amount of traction

• General characteristics

• How long will the surface preparation be effective

Some type of coverstocks will hold a surface preparation longer then others. However, it is true with all types that the further away the surface preparation is from the benchmark, the quicker the surface will migrate back toward the neutral or benchmark position.

The following table summarizes the various coverstocks and their corresponding characteristics:

CoverstockSand ability of Surface

Amount of Traction

General Characteristics

Holds surface # of Games

Plastic Easy to sand Very lowShiny through dull Even arc (Banana)

25-50 Games

Urethane Difficult to sand Low to mediumShiny through dull Even Arc (Banana)

50-100 Games

Shiny Sharp angles less control (Hockey Stick)

Dull more control less angle.

Some EasyShiny Sharp angles less control (Hockey Stick)

Some DifficultDull more control less angle

Particle High 6-50 Games

Resin Easy to sand Medium to high 6-25 Games



Ball Construction and Dynamics

Listening to conversations about bowling balls can be intimidating. The information in this section will discuss basic components, concepts and terms associated with the bowling ball. Identifying and understanding these items will hopefully take away some of the mystery surrounding the ball that all new coaches have.

Terms and Concepts

Items regarding the bowling ball will include:

• Basic bowling ball math

• Weight blocks

• Pin

• Center of Gravity (CG)

• Pin-in/pin-out

• Radius of Gyration (RG)

• Preferred Spin Axis (PSA)

• Differential

• Track flare

• Static weights




Ball Construction and Dynamics, Continued

It is important to start our discussion with the basic dimensions of the bowling ball. Understanding how a bowling ball is divided up will give you a better feel for the recurring numbers that you will see when dealing with the ball. The numbers used in measuring a bowling ball will primarily be in inches, fractions and degrees.

Basic Bowling Ball Math

The entire circumference of a bowling ball measures 27 inches around. Dividing the ball in half will reduce the circumference to 13½ inches. Dividing the ball in half again will leave ¼ of the ball or 6¾ inches of the circumference or ball surface. A quarter of the circumference represents 90 degrees (or ¼ of 360 degrees). Dividing the remaining quarter of the ball in half one more time will leave 1/8 of the circumference or 3 3/8 inches. This remaining section represents 45 degrees. These divisions are depicted below in Figure 6-10, Bowling Ball Circumference Values.

1/4

1/8

1/2 Portion of Ball

Circumference (inches)

Circumference (degrees)

Whole 27 360 degrees

1/2 13 1/2 180 degrees

1/4 6 3/4 90 degrees

1/8 3 3/8 45 degrees

Figure 6-10, Bowling Ball Circumference Values

All bowling balls are not created equal. With the exception of general specifications established by the USBC Equipment and Specifications department regarding overall weight, diameter and circumference of the ball, the inner construction of the bowling ball can be as different as each player you coach.

Weight Blocks





The initial reason for the addition of a weight block into a ball was to compensate for weight loss resulting from the finger and thumbholes being drilled into the ball. Today’s bowling balls utilize these internal weight blocks to affect how the ball will react on the lanes. The location, size and construction of a weight block will exert forces on a ball in motion. A sample of a weight block is shown below in Figure 6-11, Weight Block.

Weight Blocks continued

W

Figure 6-11, Weight Block

When you look at the surface of a bowling ball, you will notice a quarter-inch round dot on the surface. This small circle is known as the pin, and is fairly easy to find as it is usually a different color than the surface of the ball. The pin is used to indicate where the top/center of the weight block (core) is located in the ball, as shown below in Figure 6-12, Pin.

Pin

Pin

W

Figure 6-12, Pin

Page 6–26

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SIDE VIE


© 2005 USBC Coaching



The addition of the internal weight block will create an uneven distribution of weight in the ball. This imbalance will result in a portion of the ball being heavier. Identifying the heaviest portion of the ball is the first step in being able to effectively use this imbalance.

Center of Gravity (CG)

Since a portion of the ball is heavier than the rest, logic would dictate that gravity will pull the heaviest side of the ball down to the bottom of the ball. With the heaviest portion now located at the bottom of the ball – the ball is completely at rest. The axis running from the point touching the ground through the top of the ball is known as the center of gravity (CG). The whole mass of the bowling ball is concentrated around this axis.

An easy way of understanding the concept of CG is using a top as an example. A top is an unbalanced object with one part being heavier then the other. When putting the top into motion, it will eventually spin or rotate around a fixed or central axis. This point or axis (where the weight of the object is evenly distributed) is the CG.

Some ball manufacturers will determine and identify the CG on the ball by putting a punch mark into the ball. This mark is usually located somewhere within the label of the ball.

The terms “pin-in” and “pin-out” are used to describe the relationship between the location of the pin and the CG.

Pin-in and Pin-out

A ball is classifed as a pin-in when the pin is located within two inches of the CG of the bowling ball, as shown below in Figure 6-13, Pin-in.

Pin CG

W

Figure 6-13, Pin-in


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Page 6–27



A ball is considered pin-out when the pin is greater than two inches away from that CG, as shown below in Figure 6-14, Pin-out.

Pin-in and Pin-out continued

SIDE VIEW

Figure 6-14, Pin-out

The term Radius of Gyration or RG is used to refer to the movement or displacement of mass inside a ball. IBPSIA defines RG as: “The measurement of the core’s resistance to change in motion.” The term RG will become clearer when we discuss center heavy versus cover heavy bowling balls.

Radius of Gyration (RG)

Center Heavy Ball (or low RG): A center heavy or low RG ball has the majority of mass of the weight block located closer to the center of the ball, as shown below in Figure 6-15, Center Heavy Ball.

SIDE VIEW

Figure 6-15, Center Heavy Ball





A good analogy to use is that of a figure skater. When a skater pulls their arms and legs in close to the body during a spin, the speed of the spin will increase. The same action takes place within the bowling ball when the mass of the weight block is located close to the center.

Radius of Gyration (RG) continued

The faster the ball travels down the lane, the less time the ball will have a chance to react. Since a center heavy ball will get into an earlier roll, this type ball would be more ideally suited for athletes with high ball speed.

Cover Heavy Ball (or high RG): In contrast, a cover heavy or high RG ball will have the majority of the mass of weight block located near the ball’s surface, as shown below in Figure 6-16, Cover Heavy Ball.

W

Figure 6-16, Cover Heavy Ball

Again using the figure skater analogy, the skater spin wiarms and legs are extended away from the body. The sawith the bowling ball when the weight block is locatesurface.

A ball traveling down the lane at a slower speed willonger allowing for later ball reaction. With the masslocated further away from the center of the ball it will tthe ball to get into a roll and generate ball reaction. Sball’s reaction is later down the lane it would be moreathlete with slower ball speed.


SIDE VIE

ll be slower when the me action takes place d closer to the ball’s

l remain on the lane of the weight block ake a little longer for ince the cover heavy ideally suited for an


Page 6–29



As stated earlier, adding the internal weight block will create an imbalance in the bowling ball that will affect the way the ball rolls. An imbalanced object, in motion, always will seek to move in a stable position. In bowling, the term used to describe this stable position of the weight block in motion is preferred spin axis (PSA).

Preferred Spin Axis

Let’s use the example of passing or kicking a football to demonstrate PSA. A football thrown in a tight spiral is an example of that object being in a PSA along the horizontal axis. The motion achieved when kicking a field goal where the football tumbles end over end is an example of that object being in a PSA on the vertical axis.

This same steady motion occurs when the core or weight block is either rotating while lying on its side or tumbling end-over-end, as shown below in Figure 6-17, Preferred Spin Axis. The introduction of an internal weight block will create an imbalance within the ball.

Figure 6-17, Preferred Spin Axis When placing an imbalance ball into motion, the ball will seek to move in a direction that offers the least resistance. When the weight block finds a spinning motion where it is not exerting a force that will change the direction that the ball is spinning, the ball has found its PSA





Understanding the concept of PSA will make it easier to explain the concept of differential. Determining differential requires placing the ball on a device known as an RG swing (as pictured in below photo). The RG swing is used to measure the energy required to rotate the bowling ball. Several readings are required to calculate the differential.

Differential

The first reading is taken with the ball placed on the RG swing with the weight block standing vertically on its end as shown below in the upper left in Figure 6-18, Determining Differential. A measurement is taken to determine how much energy it takes to rotate the ball with the weight block on its vertical axis, called the low RG axis.

NesidDito RG

SuasDi


Low RG Axis (pin 90° from axis of rotation)

High RG Axis (pin on axis of rotation)

RG Swing

Figure 6-18, Determining Differential

xt, the ball is rotated 90 degrees, laying the weight block horizontally on its e in the RG swing as shown on the right in Figure 6-18, Determining fferential. A second measurement is taken to see how much energy it takes rotate the ball with the weight block on its horizontal axis, called the high axis.

btracting the high RG axis from the low RG axis will yield the value known the differential. This value is used to determine “track flare” potential. scussion on track flare follows on the next page.


Page 6–31



As a bowling ball rolls down the lane it will only roll on a very small portion of the ball surface. The part of the ball that contacts the surface of the lane is known as the ball track.

Track Flare

The key to understanding track flare lies in understanding the concept of PSA. If the core axis of the weight block is in a position that is in line with the horizontal axis (0 degrees) or vertical axis (90 degrees) the ball will already be in its PSA. Placing the core axis of the weight block at a 45-degree angle off the horizontal and vertical axis, as shown below in Figure 6-19, Preferred Spin Axis, will place the weight block into a very unstable position. The weight block, will naturally seek to roll in a stable position or the PSA.

Figure 6-19, Preferred Spin Axis

As the ball seeks to find its PSA, the ball will roll on a different part of its surface. The rings of oil deposited on the ball are evidence of track movement known as track flare, as shown below in Figure 6-20, Track Flare.

Figure 6-20, Track Flare





The higher the differential, the greater the track flare potential. Conversely, the smaller the differential value, the less potential for the track to flare.

Controlling Track Flare: The key word in the previous paragraph is track flare “potential.” There are several factors that will determine just how much a ball will flare: the bowler’s revolution rate, friction on the lane, the strength of the ball’s PSA and how much of that strength is being used.

The strength of the PSA is determined by the construction of the ball by the manufacturer; however, the amount used is determined by the layout of the ball.

A ball drilled with the pin near to the bowler’s positive axis point (PAP) will have little to no flare because the ball will already be positioned on its PSA or at 0 degrees. (See Axis Rotation in 3 – Understanding Ball Motion for a further explanation of Positive Axis Point.) The same is also true of a ball drilled with the weight block 90 degrees (perpendicular) to the bowler’s axis. The table below shows how the angle of the core axis and the distance of the pin from the PAP affect potential track flare.

Core Axis Angle from PAP

Pin Distance from PAP

90 degrees 6 3/4” Minimal Track Flare Potential

75 degrees 5 5/8”

60 degrees 4 1/2”

45 degrees 3 3/8” Maximum Track Flare Potential

30 degrees 2 1/4”

15 degrees 1 1/8”

0 degree 0” Minimal Track Flare Potential

Track flare continued





The illustrations shown below in Figure 6-21, Core Axis Positions, demonstrate this track flare potential for 0” (0 degrees), 3 3/8” (45 degrees) and 6 3/4” (90 degree) from the PAP.

Track flare continued

Figure 6-21, Core Axis Positions

To this point most of the discussion has centered on the motion of the ball. There is another set of terms you will hear discussed from time-to-time around the pro shop. These include:

Static Weights

• Finger or thumb weight • Positive side or negative side weight • Top or bottom weight

These terms fall into an area known as static weight. Static weight is the measurement of forces at work in a system that is at rest.

Finger/Thumb Weight: “Finger weight” and “thumb weight” are determined by how the finger holes are drilled in relation to the center of static balance as shown below in Figure 6-22, Finger/Thumb Weight. If the finger holes are drilled closer to the center of gravity, the ball will have finger weight. Conversely, if the thumbhole is drilled closer to the center of gravity the ball will have thumb weight.

Finger Weight Thumb Weight

Figure 6-22, Finger/Thumb Weight





In today’s higher performance bowling balls static weights have little to no effect on the overall performance characteristics of the ball. However, the traditional three-piece ball shown in the high RG diagram, Figure 6-16, Cover Heavy Ball, will have the following characteristics because these balls are only made as Pin In and the core must shift with the static balance thus giving the effect of these weights:

Static Weights continued

A traditional three-piece ball drilled with finger weight will have a tendency to roll longer down the lanes before getting into a roll. The thumb-weighted bowling ball will tend to roll earlier and stop hooking. It will hook early, set and then continue to roll at that angle.

Right/Left Side Weight: As shown below in Figure 6-23, Right-Left Side Weight. A ball with right-side weight will have holes drilled to the left of the weight block’s center. In this configuration, there will be more weight on the right side of the ball. Conversely, if a ball were drilled with left-side weight, the holes would be drilled to the right of the weight block’s center, placing more weight on the left side of the ball.

Figure 6-23, Right-Left Side Weight

The same is true for Right-Left Side weight higher performance bowling balls static weights have little to no effect on the overall performance.

All balls can be drilled to have either right or left side weight. Bowling balls with right side weight also are known as balls with “positive” weight. In this configuration, for a right-handed bowler, the ball will tend to hook to the left slightly more aggressively. Conversely, a ball set up with left side weight for a right-handed bowler is called “negative” side weight. This promotes the ball rolling earlier more arcing hook.





Finger weight, thumb weight, positive side weight and negative side weight are very tightly regulated by USBC, the total weight movement from the center of the weight block can be no more than one ounce in any direction according to USBC specifications. These static weights only are used for the finest of adjustments today even in traditional three-piece core construction.

Static Weights continued

Top/Bottom weight: The final factor influencing static weight is top weight. As discussed earlier, the original reason for adding a weight block to a bowling ball is to compensate for weight loss when holes are drilled. Once the holes are drilled, a bowling ball that weighs 10 pounds or more may not have more than three ounces of difference between the top half and the bottom half of the bowling ball.

Of all the static balances, top-bottom weight has the most influential effect to the characteristics of the balls roll because in effect it is a function of RG values.

Although these forces have a negligible effect on the ball when in motion, these values are checked at some tournaments to ensure the integrity of the equipment used.



Section 3 – Understanding Ball Motion

Overview

One of the most important things coaches can do for their athletes is to watch their ball reactions and help them adjust to lane conditions either by making changes to the physical game or in equipment. It is necessary to discuss some of the terms (or the physics) that a bowling ball uses to move down the lane.

Introduction

There are several items that should be understood before discussing ball motion. Two forces must be present for a bowling ball to roll and hook: gravity and friction. Without these forces, nothing happens. As discussed under Coverstock – The Bowling Ball Surface in 2 – Bowling Ball Structure and Components, earlier in this chapter, the coefficient of friction (or the resistance to motion between two surfaces) must be present for the ball to have the potential to hook. Without friction, the ball will go straight.

This section provides a basic understanding of the four motions that a bowler may apply to a bowling ball, which include: ball speed, revolutions, axis rotation and axis tilt.

This section covers the following topics: In this Section

Topic Page

Ball Speed 6–38

Revs 6–39

Axis Rotation 6–40

Axis Tilt 6–47

Axis Tilt & Rotation Summary 6–52

Determining Ball Motion 6–54

Chapter Summary 6–56



Ball Speed

Linear motion is the direction the ball travels down the lane. Ball speed is the measurement of the rate the ball is traveling down the lane, as depicted below in Figure 6-24, Ball Speed. The faster the ball travels, the shorter the time the ball will stay on the lane. Friction between the ball surface and the lane will cause the ball to lose speed as it travels down the lane.

Linear Motion

Figure 6-24, Ball Speed

The table below shows the “average” ball speed generated for various times that it takes for the ball to travel from release at the foul line to the head pin (60 feet).

Ball Speed Chart seconds mph seconds mph

1.8 22.7 2.5 16.4

1.9 21.5 2.6 15.7

2.0 20.5 2.7 15.2

2.1 19.5 2.8 14.6

2.2 18.6 2.9 14.1

2.3 17.8 3.0 13.6

2.4 17.0 3.1 13.1

Average speed of ball from foul line to head pin



Revs

A revolution, or rev, is simply one complete turn or rotation of a round object on its axis as shown below in Figure 6-25, Revolutions. Spinning the sphere 360 degrees equals one revolution. The more revolutions that a bowler can impart to a bowling ball, the more potential energy a ball will have when it hits the pins.

Description

Figure 6-25, Revolutions

There is a direct correlation between the hand position at the point of release and the number of revolutions an athlete may potentially impart to the ball. The longer the fingers remain in the ball, once the thumb is released, the greater potential energy may be imparted to the ball in terms of number of revs.

How Revs Are Created

The relationship between wrist position and potential energy generated in the ball is explained in Section 2 – Components of the Physical Game, located in CHAPTER 7 – FINE TUNING THE PHYSICAL GAME, in this manual.



Axis Rotation

The axis is an essential component of understanding the dynamics of a bowling ball. All spheres in motion will revolve around an axis.

The Axis

An example of this concept is looking at the earth, which revolves around the North Pole and the South Pole. The axis runs through the middle of the earth and exits at both poles, as shown below in Figure 6-26, Earth Axis.

Figure 6-26, Earth Axis

The other concept to establish is that the direction of the sphere’s movement is 90 degrees from the axis, as shown below in Figure 6-27, Direction of Movement. Using the earth again as an example, the direction that the earth is turning on is the equator, which is 90 degrees away from either pole.

Figure 6-27, Direction of Movement

© 2005 USBC Coaching Updated – Feb 05 Page 6–40


Axis Rotation, Continued

When discussing axis rotation, we must first define what the positive axis point (PAP) of the bowling ball is.

Positive Axis Point

The PAP is one of the poles, or axis points, on the sphere. In this case, we’ll make the North Pole the PAP and the South Pole the negative axis point. Knowing the location of the PAP is a key element to understanding ball motion.

A quick way to find the PAP is to find the track on the bowling ball. If you cannot find the ball track, have the athlete roll the ball over the fourth arrow to pick up some fresh oil in the ball’s track area.

Determining the PAP

If there is track flare, you are looking for the oil ring closest to the thumbhole. Once you have determined where the track is, turn the ball and place it in a position where the track runs parallel to the ground.

NOTE: The track will be located below the thumb and finger holes in this position.

The PAP is located directly on top of the ball as shown below in Figure 6-28, Locating the PAP. To find the exact location, you may use a tape measure and measure the distance from the track by the thumb and finger holes, going over the top of the ball and to a point that intersects the track on the backside of the ball. One half of this total measurement will be the top of the ball and the location of the PAP.

Figure 6-28, Locating the PAP





As the ball rolls down the lane, the PAP will be measured along the horizontal plane as shown below in Figure 6-29, PAP on the Horizontal Plane. The horizontal plane is along the equator of the ball in an east-to-west direction.

Understanding Axis Rotation

NOTE: All examples will be for right-handed bowlers. The PAP will reside – as you watch the ball roll down the lane – on the left half of the bowling ball.

Figure 6-29, PAP on the Horizontal Plane

Friction must be present for axis rotation to become a factor in ball motion. Without friction the ball would continue to go in the original trajectory indefinitely. Friction between the lane surface and ball will cause a decrease in ball speed. The point at which the force that represents axis rotation becomes more dominant than ball speed, the ball will begin to hook. The degree of axis rotation is a factor that will affect the potential for a ball to hook.

The pages that follow illustrate axis rotations for

• 0 degree • 20 degrees • 45 degrees • 90 degrees


Page 6–42 © 2005 USBC Coaching Updated – Feb 05



When the positive axis point sits dead left on the bowling ball (right-handed bowler) as it rolls down the lane, it is known as zero degrees of axis rotation, as shown below in Figure 6-30, 0° Rotation (Straight Ball).

Zero Degree Axis Rotation (Straight Ball)

Figure 6-30, 0° Rotation (Straight Ball)

Understanding the fact that a ball’s rotational direction will be 90 degrees from its axis is an important concept to remember when studying ball motion. When the axis of rotation is 90 degrees from the linear direction of the ball, there will be little or no hook potential – a straight ball. To achieve this axis rotation the ball would be released with the thumb and fingers being in a 12 o’clock and 6 o’clock position.

In this position the PAP would be on the side of the ball and almost impossible to see.





When an athlete releases the ball with the thumb between 11 - 12 o’clock and fingers around 5 o’clock (right handed athlete), it will position the hand slightly to the right side of the bowling ball creating a difference in the direction that the ball is rotating versus the linear direction of the ball. The example shown below in Figure 6-31, 20° Rotation (Straight Ball) and photos represents approximately 20 degrees movement of the axis rotation from the zero degree depicted on previous page.

20 Degree Axis Rotation (Straight Ball)

Figure 6-31, 20° Rotation (Straight Ball) A ball with this axis rotation, in most cases, will possess a very slight potential to hook potential will be slight.





Adjusting the athlete’s hand to place the thumb between 10 - 11 o’clock and fingers between 4 - 5 o’clock (right handed athlete), it will position the hand further to the right side of the bowling ball creating a greater difference in the direction that the ball is rotating versus the linear direction of the ball.

45-Degree Axis Rotation (Hook Ball)

In this scenario, the direction the ball will be rotating around 45 degrees off the linear direction of the ball as shown below in Figure 6-32, 45° Axis Rotation (Hook Ball).

This angle of rotation will create adequate hook potential while giving the athlete the best chance to effectively play various lane conditions.

Figure 6-32, 45° Axis Rotation (Hook Ball)





Placing the positive axis point in a position where it is pointing straight back at the athlete represents 90 degrees of axis rotation. This 90 degrees axis rotation represents maximum potential to hook the ball. In this scenario, the ball’s directional rotation will be 90 degrees off the ball’s linear direction as shown below in Figure 6-33, 90° Axis Rotation (Hook Ball).

90-Degree Axis Rotation (Hook Ball)

Figure 6-33, 90° Axis Rotation (Hook Ball)

A bowler positioning the hand with the thumb at 9 o’clock and fingers at 3 o’clock at the point of release will achieve 90 degrees of axis rotation. While this rotation will create the greatest hook potential, it also affords the athlete the least amount of control in the back ends.



Axis Tilt

Axis tilt relates to the gravity that is applied to the axis that is tilted out of line with the horizon. If the lane where long enough all balls would end up rolling over the entire circumference of the ball after gravity pulled the axis back to parallel to the horizon.

Description

The axis tilt determines what part of the ball rolls on the lane – also known as ball track. The axis tilt determines the size of the track. The PAP remains the focal point when determining the axis tilt or type of ball an athlete rolls.

Axis tilt is measured along the vertical plane as shown below in Figure 6-34, Axis Tilt. The measurement of axis tilt may range from 0 degree at the equator of the ball to 90 degrees at the top of the ball.

Figure 6-34, Axis Tilt

As you study the concept of axis tilt, remember that the ball track is always 90 degrees from the axis. The size of the track will be measured across the bottom of the ball. This will be done by picking a point on the track and running a tape measure around the bottom of the ball to a point on the ball track 180 degrees on the other side.

The following examples of axis tilts are offered in the subsequent pages:

• Full Roll (Zero degrees tilt) • High Roll (3-10 degrees tilt) • 3/4 Roll (15-25 degrees tilt) • Low Roll/Spinner (30-45 degrees tilt)

• Helicopter (90 degree tilt)




Axis Tilt, Continued

A ball rolling in this position will have the PAP position on the equator as shown below in Figure 6-35, Full Roller (0° Tilt). With the positive axis point at this position, the ball will use its full circumference will measure at or near 13½" across the circumference of the ball.

Full Roller (Zero-Degree Tilt)

Figure 6-35, Full Roller (0° Tilt)





A ball rolling in this position will have only a slight amount of tilt as shown below in Figure 6-6-36, High Roller (3-15° Tilt). With the ball now rolling slightly on its side, less ball surface will touch the lane. The ball track will be smaller and will measure about 10” to 11½" in width across the ball’s circumference.

High Roller 3-15 Degree Tilt

Figure 6-6-36, High Roller (3-15° Tilt)

The axis of a three-quarter roller will tilt up towards the top of the ball. When the PAP moves from 1/8 to about 1/4 of the way to the top of the ball, the axis tilt will be between 15-25 degrees as shown below in Figure 6-37, Three-Quarter Roller (15-25° Tilt). With the ball now rolling more on its side, even less ball surface will touch the lane. The ball track will be smaller and will be about 9-10" in width across the balls circumference.

Three-Quarter Roller (15-25 Degree Tilt)

Figure 6-37, Three-Quarter Roller (15-25° Tilt)





The PAP for the spinner is closer to the top of the ball or at a 30 to 45 degree position up on the vertical plane as shown below in Figure 6-38, Spinner (30-45° Tilt). As the PAP moves closer to the top of the ball, less ball surface contacts the lane. A spinner’s track is about a 6-9” in width across the ball’s circumference.

Spinner (30-45 Degree Tilt)

Figure 6-38, Spinner (30-45° Tilt)

An example of this axis tilt, as shown below, has been included to show the affect of what maximum 90 degree tilt does to the track. Pacific Rim or Taiwanese-type athletes use this type of release, also known as the helicopter. The best analogy of what a ball is doing on this release is that of a top. The ball is spinning with the axis pointing north and south on the ball. A ball delivered in this manner will have a very small track.

Helicopter (90-Degree Tilt)

Figure 6-39, Helicopter (90° Tilt)





The chart shown below in Figure 6-40, Axis Rotation and Axis Tilt is a representation and summary of axis rotation with axis tilt.

Tilt and Rotation Summary

Figure 6-40, Axis Rotation and Axis Tilt Since the PAP used to identify both the axis rotation and axis tilt, a measurement must be made along the horizontal and vertical planes. Below is an example of a ball with 50 degrees axis rotation and 20 degrees axis tilt.



Axis Tilt & Rotation Summary

Below are charts that summarize what the position for axis rotation and axis tilt means in terms of actions to the ball or on the lanes.

Summary

Axis Rotation degree of rotation 0 45

Hook Potential Minimum Maximum

Ability to control ball reaction Most Least

90

Axis Tilt degree of tilt 0 45

Track Size Largest Smallest

Hook Potential Most Least

90

The idea is to adjust the four items described in this section so they work together. It is important to properly match these items to your athlete’s abilities.

The coach’s job is to begin to study these variables and match them to their athletes. The illustration shown below in Figure 6-41, Breakpoint, gives you an understanding of how some of these items and the force they exert work together. This example defines breakpoint.

Breakpoint

Ball Speed

Ball Revs

Figure 6-41, Breakpoint




Axis Tilt & Rotation Summary, Continued

Friction will reduce ball speed (decreased velocity). When this happens, ball revs will go up. Yes, revolutions go up; energy imparted to the ball as speed is converted to rotational energy.

Breakpoint continued

The point where the revs start to become more dominant than ball speed is when the ball will start to hook. Adjusting ball speed or rev rate will change the point where the ball reacts on the lanes. For example: Increased ball speed will result in the ball going further down the lane before the ball revs will become the dominant force and start hooking the ball. Increasing revs will cause the ball to hook sooner



Determining Ball Motion

Below is a summary of how the athlete’s influences affect the ball’s motion on the lane.

Athlete’s Influences

• Ball Speed Slower: The ball has more time to react. Athlete would need to

delay the roll.

Faster: The ball has less time to react. Athlete would need to create earlier roll.

• Axis Rotation Low amount (1-15 degrees): Athlete creates early even banana

shape roll. May have problem with ball stop hooking (hook out/rollout).

High amount (60-90 degrees): Athlete creates later strong ball reaction at breakpoint. Often difficult to control hockey stick shape hook of ball.

• Axis Tilt Low amount: Athlete creates larger track size and earlier type roll.

High amount: Athlete creates smaller track size and may need help creating roll.

• Revolutions High initial rev rate: Athlete creates larger potential for ball

reaction, more difficult to control, but very powerful.

Lower initial rev rate: Athlete creates lower potential for ball reaction, more easily controlled, not as powerful.

Although each of these forces that an athlete imparts to the ball have been discussed separately, in reality the motion of the ball is a by product of all four of these forces. You will need to study and understand the influences of each force in order to effectively make changes to your athlete’s game.




Determining Ball Motion, Continued

Once athlete attributes have been determined, a ball choice can be made keeping in mind the following (order of importance):

Putting It All Together

• Lane conditions- The amount and location of the oil on the lane will be the indicator first where the athlete should be playing the lanes, with abilities.

• Coverstock & surface preparation- The type of cover will be the first determination of which ball will be used. Then how will that ball be textured will closely follow.

• Core- Whether to use high RG or Low RG and should it flare or not.

• Ball layout- A layout of the core angle should be the binding force to tie it all together. This is simply the fine-tuning to get the cover and core design to work best for this athlete on this condition.

• Static weights- Have little to no effect on the balls motion potential and should only be considered for ABC/WIBC legal specifications.

Coaches should utilize this information with the information in CHAPTER 8 – LANE PLAY as to choosing the most appropriate ball for their athlete.



Chapter Summary

Following are key points presented in this chapter. Key Points to Remember

1. The process of improving an athlete’s physical game begins with having properly fitted equipment. When an athlete has equipment with an improper fit, the body will go into “survival mode” that will seriously hamper and negate the learning process.

2. Blisters, calluses, broken blood vessels and pain on the athlete’s hand are signs of an improper fit.

3. The span should not be so drawn out as to produce white or light-color knuckles because the fingers are stretched out tight like banjo strings. The fit for the fingertip grip introduced in this section should have a relaxed and comfortable feel.

4. Two items of consideration when drilling holes into the ball include:

• Pitch (or direction)

• Size of the holes

5. There are four pitches or distinct directions that a hole may be drilled into a ball:

• Zero

• Forward

• Reverse

• Right or left lateral

6. The reference point for determining hole pitches is the geometric center of the ball.

7. Snug, not tight, thumb and finger holes will allow the athlete to hold onto the ball with minimum finger pressure required for a loose free armswing.

8. Maintenance of a proper fit is important for young athletes who should have their ball fit checked frequently – monthly in some cases would not be unreasonable. Adult athletes should consider checking every six months or when there is a noticeable fluctuation in weight.

9. When purchasing additional equipment an athlete should be looking to expand the ability to play the lanes by acquiring equipment ranging from very aggressive to fairly tame.




Chapter Summary, Continued

10. A coach should make sure that the weight of the ball works for the athlete. It doesn’t have to be the heaviest but heavy enough to be effective.

Key Points to Remember continued

11. The amount of friction (or the coefficient of friction) between the lanes and ball surface affect how much a ball will hook. A total absence of friction between the ball and the lane surface will result in a straight ball.

12. There are four distinct coverstock types being used:

• Plastic (polyester)

• Urethane

• Resin

• Particle

13. An athlete may alter or change the surface to fit into several categories, which include:

• Sanded

• Benchmark (lightly polished or lightly sanded)

• Polished

14. The processes used to alter the surface of the ball are:

• Sanding

• Polishing

15. Terms and concepts introduced regarding components of the bowling ball include:

• Bowling Ball Math

• Pin

• Center of Gravity (CG)

• Pin-in/pin-out

• Radius of Gyration (RG)

• Center Heavy ball (low RG)

• Cover Heavy ball (high RG)

• Preferred Spin Axis (PSA)

• Differential

• Track flare

• Static weights




Chapter Summary, Continued

16. The four motions that a bowler may apply to a bowling ball include: ball speed, revolutions, axis rotation and axis tilt.

Key Points to Remember continued 17. A key component to find when studying the motion of an athlete’s

bowling ball is the positive axis point (PAP).

18. When making choices regarding equipment selection the following items need to be considered. These items are listed in order of importance.

• Lane conditions

• Coverstock & surface preparation

• Core/weight block

• Ball layout

• Static weights

Page 6–58 © 2004 USA Bowling Coaching

chapter 6 – bowling ball parts and dynamics...bronze certification bowling ball parts and dynamics...

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