Don't really have a link to any articles, but have studied many aspects of bowling and ball construction + some drilling techniques, so I feel comfortable with the information I want to share here.
RG is a reference to the term Radius of Gyration. It simply means the distance from the center (radius) of a rotating object that the weight
seems to rotate (gyrate).
Anytime you can alter the shape of the weightblock, either the heighth OR the width, you can have an influence on the ending RG numbers.
You may see a ball that has a rating system using an RG min and an RG max, but not to fear. This is only a reference to the maximum RG drilling ( pin in track ) and the minimum RG drilling ( pin on pap). SOmetimes they will also list an RG Differential number. This is only the difference between the RG min and RG max. The higher the differential number, the more flare POTENTIAL a ball has, and thusly, the more you can influence the amount of flare created by manipulating the balls ending RG numbers.
Lower RG balls TEND to be ball types that read the lanes both earlier and smoother than balls with the same coverstock and higher RG numbers.
You can also calculate how much to move the pin position to influence the ending RG of a ball before adding any extra holes. Simply put, you divide the RG differential number by the distance from your track to your pap, I.E. differetial = .050 and distance from track to pap = 6 3/4 inch. The number .050 tells me there are 50 points of differential available to me in this ball so 6.75 ( distance ) divided by 50 ( points available ) gives me the answer of .135. .135 inches is how far to move the pin position relative to the drilling to affect ending RG by one point.
If you know what ending RG number you are after, you can calculate which ball, with what RG numbers, is going to allow you to build the ball with proper ending RG numbers and proper pin position to help give you the reaction that you are looking for.
Much more simply, if you are looking to only lower the RG number of an already drilled ball, you must calculate the spot on the ball to drill an extra hole to help move the rotating mass closer to the center of the ball, but, don't misinterpret these terms. By saying the center of the ball, I DO NOT mean the center of gravity, but the actual center of the ball. Example would be, if the weightblock is a tall, slim one, the extra hole would have to be placed at one end or the other of the weightblock to effect a shortening of it, thusly reducing the ending RG numbers.
I am not sure, but on second thought, you might be able to find some useful info at
www.rollriteproshop.co.uk under the coaching tab. Highlight the coaching tab and look under Mario's secrets. Lots of good info there.
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"The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
Albert Einstein
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