Self-Righting Core

“Self – Righting Core (SRC)”:

Merging a Unique Shape with Technological Research to Enhance Innovative Motion

Written By: Nick Siefers

Senior Design Engineer

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Throughout the years many different core designs have been placed inside the bowling ball to aid and influence its path to the pins. Designs started with no weight blocks, to simple pancake top weight slugs, then evolved into two-piece shapes followed by the addition of flip blocks and then all the way through the complex asymmetrical shapes that are currently on today’s market. Each new progression in design often led to increased dynamic effects on how and when the ball expended its energy while traveling down the lane. At 900 Global we have been researching and testing what is to be the next generation in core design. The new “Self-Righting Core (SRC)” design merges a unique shape with the latest technological research to enhance innovative motion.

Initially the design and concept of the three-dimensional core shape was to maintain a convex shape (the shape does not bulge inwards), be homogeneous, and the defining trait was that it has only two points of equilibrium. One point is “stable” and the other is “unstable”. An object having this trait is defined as being mono-monostatic. In short, if you place the object on its “stable” spot the object will remain at rest until an outside force acts upon it. If the object is placed on its other “unstable” equilibrium point in theory it could balance on this point but the slightest movement or force will cause it to move off of that particular spot and roll around maneuvering itself until it finds the “stable” spot. Likewise, if trying to rest on any other surface or spot the object will automatically move and seek the stable point of equilibrium. It is because of this automatic moving and maneuvering that the phrase “Self – Righting Core” was coined. The core design seeks to find it stable point on its own through a series of orchestrated maneuvering without any outside forces.

The design itself was strategically challenging to develop because no shape existed in two dimensions that was both convex and contained only two points of equilibrium (one stable and one unstable). For example, the square can balance on the center of its four sides (stable) and the intersection points of the sides (unstable) giving it a total of 8 equilibrium points. Having multiple stable and unstable equilibrium points can be proven for all two dimensional shapes thus violating the definition of being mono-monostatic. In three dimensions, however, there are other points of equilibrium that exist. At these new points an object can balance unstable in infinitely many directions but only stable in one direction. The quantity of these new points depends upon the quantity of original stable/unstable points. In simpler terms and without going into extensive mathematical detail, it was ultimately the relationship and integration of all of these concepts that allowed the true three dimensional shape with the previously discussed mono-monostatic properties to be created.

The “SRC” core design by 900 Global is shown below in Figure 1 and was designed to maintain these mono-monostatic properties. The three dimensional single density mass is so unique simply because it is stable on only one facet. These concepts have never been tried in the bowling industry. The core will seek to “right itself” from any position that it is initially placed.

Bank Core

Figure 1: 900 Global "SRC"

Our research and on-lane testing verified that this shape inside “The Bank” increased the overall imbalance forces on each migratory axis point as the ball flared traveling down the lane compared with imbalance forces from typical core designs (asymmetrical and symmetrical) that are on the market. These imbalance forces enable the ball to transition through axis migration and the three phases of ball motion by resisting hesitation without using unnecessary extra energy that other core shapes must use to migrate through the many stable/flat spots that they have (see core video by selecting link at the end of this article). In effect, the “SRC” core enables the ball to have increased changes in the angle per foot of lane traveled. Basically, the “SRC”, once set in motion will try and seek its stable position quicker than any other ball on the market. By setting the core position through drillings one can allow “The Bank” to release its energy quicker and most efficiently with little or no core resistance giving the bowler maximum benefit of core dynamics.

In an additional step to push the design and technology envelope we have also optimized this design to enhance the overall “moment of force”. The moment of force, or moment arm, is simply the measured likelihood of a force to rotate and twist an object about any given axis. In this example and analysis we looked at four different core designs. Each core design was split into two halves using the center of the bowling ball as the axis line. Based upon typical drill patterns and the migratory axis migration from the initial PAP the analysis determined how easy the top half of the core would rotate around the horizontal axis line versus the bottom half of the core. The illustrations in Figure 2 below show the split lines with the corresponding mass of each half along with each half’s center of gravity location with respect to the horizontal rotational axis line.

The following Figure 3 shows the calculated moment arm forces and also shows the differences or imbalances between the moment arms of the top versus bottom parts of each design. Greater imbalance in moment arms is equivalent to greater amounts of loping as the core rotates traveling down the lane. The “SRC” having the greatest imbalance, in conjunction with its little to no resistance described previously, when rotating gives this core maximum dynamics, performance and efficiency in energy usage.


A	B

C	D Self Righting Core
Figure 2: Mass Distributions of various core designs

Tech Matrix

Figure 3: Moment Arm and imbalance calculations

In conclusion, using shape contours, stable/unstable equilibrium points, precise center of gravity placements, and moment arm concepts 900 Global has once again taken the next step in innovative motion. The new “SRC” helps give “The Bank” unprecedented reaction on the lane by releasing energy most efficiently and effectively to gain optimum ball reaction per bowler. Integrating new technological advancements 900 Global has been able increase the overall mid-lane read and back end continuation in this product versus other products on the market today.