A couple days ago, I got an email from Scott asking me to come on here and try to help out with some explanations on the Mixed Breeds, and possibly some of the other balls in our current line. Sorry for the delay, but right now I have been extremely busy.
There are two types of asymmetric bowling balls on the market, Y spin and Z spin. Y spin bowling balls have the MB located on the preferred spin axis (PSA). This is also the point located approximately 6 3/4" from the pin, through the CG (providing they are in line). Z spin balls have the PSA located 90 degrees off of the the MB and pin, or approximately 6 3/4" from both the pin and MB. On a DeTerminator or other device used to locate the high RG axis
, the PSA is the axis in which the ball wants to rotate around. Given the time, every ball will migrate to rotate around the PSA, and the higher the differential and lower the RG, the faster it will get to this point.
Now, to explain the MB location marked with a V on the Mixed Breed. Z spin bowling balls, will spin to a point using a DeTerminator or other device made for finding the high RG axis. When you flip the ball, it will spin to a point directly opposite the first point marked. Half way between these two points is where the MB is located, and it should be almost directly in line with the pin and CG. This is where we mark the MB with the V.
Locating the PSA points on the Mixed Breed is extremely simple. If your pro shop has a DeTerminator, the ball will spin to the PSA points. If they don't, they can simply place the 0" mark at the top of the quarter round on the pin, and run the middle rib down to the V. Each end of the quarter round should now be on the PSA points.
Next, lets define what symmetric vs asymmetric balls are.
Dynamically, a symmetric ball does not have a definite high RG axis or intermediate RG axis. The Y and Z axis will spin at the same rate on the RG swing, and create nearly identical or identical RG results. In fact, any axis around the equator of the bowling ball (using the pin as a pole) will have nearly the exact same RG.
An asymmetric ball will have a well defined high and intermediate RG axis, and will find one point to rotate around (the PSA).
Symmetric - Intermediate differential at or near 0"
Mild Asymmetric - Intermediate differential between .002" and .007"
Moderate Asymmetric - Intermediate differential between .008" and .014"
Strong Asymmetric - Intermediate differential greater than .015"
Core dynamics are very complex, and manufacturers numbers and marked locations are only true prior to drilling. Once you start putting holes in the ball, you not only change the RG, RG Differential, and static weights, you can also change where the PSA is located.
When you drill a hole in the ball, the RG is typically raised slightly on the axis that runs through the center of the hole. However, the biggest impact comes from the fact that the RG is lowered on the axes (plural for axis) that are perpendicular to the hole. In reality it is a little more complex than this, but this is the basics. Now depending on the shape of the core, the density of the material drilled out, and the size and depth of the hole this can be fairly minor, or pretty significant.
How do the holes affect the ball?
Here are some data results from one of my early tests with the Mixed Breed Solid:
Take a Mixed Breed, which starts out with an RG of 2.520" on the X axis, 2.557" on the Y axis, and 2.572" on the Z axis. The ball has a total differential of .052" and an intermediate differential of .015".
First, we put a thumbhole directly into the MB location (also the Y axis and is marked with a V), which lowered the RG on the X and Z axes, and raised the Y axis. This was a normal size thumbhole (1" diameter and 3" deep), which brought the RG's to 2.514" on the X axis, 2.565" on the Y axis, and 2.566" on the Z axis. After the thumbhole, the total differential is still .052", but the intermediate differential is now down to .001" instead of .015".
Next we drill the fingers 1" below the pin (which is the X-axis), and used normal fingers (size and depth for inserts). This raises the X axis and lowers the Y axis and the Z axis. So now after the thumb and fingers are drilled, we have an X axis of 2.521", a Y axis of 2.558" and a Z axis of 2.557". This means the ball now has a total differential of .037" and an intermediate differential of .001". Dynamically, this is significantly different than the ball that we started with.
Now here is where the interesting part comes in. Because this ball has virtually no intermediate differential, there is NO PSA! This ball is now dynamically symmetric, and will be more than happy to rotate around any spot that is 90 degrees off of the X axis (again on the DeTerminator or similar device). Bowlers with a high rev rate and a fair amount of side rotation will likely love this ball. Bowlers who are high trackers and come up straight behind the ball will likely hate it. But the great thing about this, is you can now generate a PSA in a variety of different locations on the positive side of the ball with proper weighthole location and size. If you place a weighthole near the thumb (a double thumb), you will create a PSA that will be in or right next to the weighthole. If you migrate the weighthole towards the Z axis, the PSA will follow.
In this instance, I placed a 1" weighthole just right of the thumbhole, approximately 2.5" deep with the hole pitched to where it would not intersect with the thumbhole. The end product was an RG of 2.520" on the X axis, 2.568" on the Y axis, and 2.550" on the Z axis. This gave the ball a total differential of .048" and an intermediate differential of .018", and a PSA located in the center of the weighthole (just right of the thumb). Dynamically this is fairly strong, and gave the bowler a strong midlane, with pretty aggressive backends and great continuation. His only complaint is that he leaves more 9 pins now than before, but very rarely leaves a 10 pin anymore.
What effect does moving the mass bias away from the thumb have on a Z spin bowling ball?
As you move the CG and MB towards the positive side of the ball, you slowly remove the effect of eliminating the intermediate differential, and the PSA not only gets closer to the thumbhole because of the drilling placement, but also because of the dynamics created by the hole. The dynamic effect on the ball actually pulls the PSA from it's original location towards the thumbhole, so from this point on, the original PSA location is no longer accurate.
For example, a Mixed Breed with the thumbhole 3 3/8" from the marked mass (with the mass bias on the positive side) and the fingers 1" under the bridge with a weighthole 1" above and 2" right of the thumbhole, ends up an RG of 2.527" on the X axis, 2.557" on the Y axis and 2.576" on the Z axis. This gives you a total RG differential of .049" and an intermediate differential of .019" with a PSA located just to the left of your thumb. As you can see, the total and intermediate differentials are almost identical to the above example, but the RG's on the Y and Z axes are inverted.
As you can continue moving the MB further right you will increase the total differential and intermediate differential to the point where you can have a total differential over .070" and an intermediate differential over .030". I typically do not suggest a layout like this for most bowlers because it can cause the ball to flare extremely fast and burnout, especially under today's lane conditions and the coverstock strength of this ball.
Drilling scenarios are a little different with Z spin balls than Y spin or symmetrics, but it should not be too complex for most pro shops. RG's are affected by hole locations on every ball, and knowing how these holes affect the RG and differential is something most pro shops should know and understand.
Visionary Bowling Products
Edited by VBPadvertising on 1/6/2012 at 8:45 AM
Edited by VBPadvertising on 1/6/2012 at 2:13 PM
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