Bowling Ball Information

06Oct06

Axis tilt and axis rotationAxis tilt and axis rotation deal with the angle at which the ball is revolving. The ball revolves on two planes: 1) horizontal, and 2) vertical. The angle of the ball’s revolutions dictates the resistance to forward roll. Resistance to forward roll is synonymous with skid, delaying the breakpoint of the ball. The breakpoint is the point on the lane where the ball starts to make its move to the pocket. Axis tilt is the vertical angle at which the ball rotates. Axis tilt is what is commonly known as spin. Axis tilt is determined by the position of the thumb during the release. If the hand turns too early, the thumb exits on top of the ball. Bowlers with a high degree of axis tilt will be able to see the top of their hand during the release and follow through. Being able to have the thumb exit at the bottom of the down swing minimizes axis tilt. Axis tilt will induce skid and reduce the amount of backend hook potential. With the core rotating in a more vertical fashion, oily lanes will be the enemy, drier lanes its friend. Axis rotation is the horizontal measure of the angle of the ball’s revolutions. It is also determined by the release. It is the release position of the fingers that dictates the amount of axis rotation. Axis rotation is commonly known as side roll. When the fingers exit the ball in a 6:00 position, the ball is sent into an end-over-end roll. This is known as 0 degrees of axis rotation, the absolute minimum. This ball will have no chance of hooking, regardless of the amount of revolutions, ball speed, and lane conditions. The ball will have immediate forward roll. Think of it as being behind the wheel of a car with the steering wheel straight. The tires will face in a north-south direction. The car will go straight, not being able to negotiate a curve in the road. off the fingers exit the ball in a 3:00 position, caused by a rotation of the hand in a counter-clockwise direction, 90 degrees of axis rotation will result. This will give the ball a tremendous hook angle when it encounters friction. This is similar to being in that same car. However the steering wheel is now turned so that the tires are angled to the left. When the accelerator is engaged, the car will jerk violently to the left. (For lefthanders, the fingers will exit the ball at a 9:00 position, the hand rotates in a clockwise direction, and the car wheels would be pointed to the right).Most players have a finger exit somewhere in between 0 and 90 degrees. The halfway point, 45 degrees, will see the fingers exit the ball at 4:30 at the release point (7:30 for lefthanders). This is the most versatile release position. Please consult the Surface Friction Guide, True Grit, for pictures of axis rotation and axis tilt. Axis rotation also will cause the ball to skid further but, unlike axis tilt, will cause a dramatic hook angle at the breakpoint. 90-degree axis rotation is often quite uncontrollable at the breakpoint. High degree of axis rotation players will also tend to like drier lanes; minimal axis rotation will tend to like more oil. The ball, as it is rolling down the lane, will lose axis rotation due to encountering friction. The rate at which the ball loses axis rotation (side revolutions turning into end-over-end revolutions) will be determined by the initial axis rotation, the amount of ball speed, the amount of axis tilt, and the amount of oil on the lane. For the best carry percentage, we want the ball to lose axis rotation (enter into an end-over-end roll) just as it enters the pocket. This will give a strong angle of entry into the pocket and the proper amount of deflection. Your pro shop technician will be able to assist you in determining your axis tilt and axis rotation. While it is not necessary to know the exact angle, knowing whether you have low, medium, or high amounts of each will make understanding your ball’s reaction easier.Balance holesBalance holes are non-gripping holes drilled into the ball to adjust the static weights and to create dynamic influence. As mentioned in an earlier tip, the effect of static weights is extremely minimal on the ball’s reaction. So the major influence in the effect of a balance hole lies in the effects that it has on the ball’s dynamics, those forces affecting the ball when it is in motion. The location of a balance hole with regard to the distance from the pin is the primary tool for altering the dynamics of the ball’s core. From the past tips, we know that the strength of the core is measured by the difference of the RG of the height of the core and the RG of the width of the core. This is called Differential. The greater the difference between the height and the width, the higher the Differential. Higher Differential results in more track flare potential, and will induce the ball to release energy quicker when the ball encounters friction. The breakpoint will be stronger and will increase the hook potential. On the ball’s surface, the distance from the height of the core to the width of the core is 6 3/4 inches. It is within this range that we can alter the flare potential of the ball’s core by drilling a balance hole. The height of the core is represented by the pin, or the colored plug on the ball’s surface. This is where the core is pressed and suspended in the mold during the pouring of the coverstock. Should we choose to drill a balance hole into the pin, we would be drilling into the tallest part of the core. This would result in a shorter core and lower the flare potential of the ball. While this is not desirable for the vast majority of bowlers, it will be effective if the overall hook of the ball is excessive. Jason Couch won the 1993 Tums Classic with a Crush/R drilled in this manner. Reactive balls first were in their infancy and the lane conditions had not caught up to their power potential, nor Jason’s. If drilling a balance hole into the pin reduces flare potential, we know that drilling a balance hole 6 3/4 inches will increase flare potential. This balance hole will remove mass directly into the side of the core, decreasing the width, and increasing the differential. 6 3/4 inches from the pin will be the maximum strength position for a balance hole, regardless of the pin’s position relative to the PAP. Drilling a balance hole halfway between the pin and 6 3/4 (or 3 3/8 inches from the pin) will have little effect on the overall flare potential of the ball. It is located halfway between the height (pin) and the width (6 3/4 inches from the pin) and will remove relative equal amounts of height and width. With today’s higher flare core designs, we must be cognizant of the location of a balance hole with regards to the ball track, especially with a bowler’s medium to high rev rate. Balance holes past the PAP, which is where a hole 6 3/4 inches from the pin would be located, will most often fall within an area where the ball track flares into. To ensure that a balance hole location will be flare safe, stack several pieces of tape on top of each other and place them on the location of the intended balance hole. Throw the ball down the lane. If the ball hits the tape pieces and starts to “rumble”, you will need to choose another location closer to the PAP. As a rule of thumb, you can assume that 4 1/2 inches or more away from the pin will increase flare potential

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