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Author Topic: Drilling a Gryo Urethane  (Read 2316 times)

Bowling Barista

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Drilling a Gryo Urethane
« on: April 22, 2011, 04:19:19 PM »
To satisfy my nostalgia, I purchased a Gyro to replace the one that I had as my first bowling ball. Unfortunately, I don't remember how I had it drilled. All I remember is that I rolled it straight over the second arrow from the right, and it gradually turned toward the pocket. I'm a stroker with low revs, and the lanes are dry (no oil track left on the ball). I know very little about drilling, but I have a feeling that the rules are different for a urethane coverstock with a pancake core.
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charlest

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Re: Drilling a Gryo Urethane
« Reply #1 on: April 23, 2011, 01:50:38 PM »
I suspect the Gyro Urethane had a simple pancake core.
If so, then you have two options.
1. Use static weights to control the ball. Example, the good old:1/2 oz side, 1/2 oz finger weight
and maximize the top weight.
2. Have the driller shift the CG (acting as the pin does in modern 2 piece balls, with a true dynamic core) to half way between the grip center and your axis point and put a weight hole, either 9" over or 3" below your PAP/axis point. This will increase flare.
 
There are couple of other esoteric options, like Mo Pinel's drill to max out the plastic ball (also pancake core) for the PBA Mark Roth tournament.
 


"None are so blind as those who will not see."
"Some bowlers are crazy as pickled cats."
 
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"None are so blind as those who will not see."

DON DRAPER

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Re: Drilling a Gryo Urethane
« Reply #2 on: April 23, 2011, 04:17:41 PM »
Unless you have a very high track I'd simply place the heavy spot in the center of your grip. You'll see a bigger difference in the reaction of the ball by adjusting the surface on the ball instead of where you place the heavy spot.

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Bowling Barista

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Re: Drilling a Gryo Urethane
« Reply #3 on: April 23, 2011, 08:42:25 PM »
Thanks, here is a picture of the same logo of Gyro that I bought. http://cgi.ebay.com/Brand-new-still-box-16lb-Gyro-Ebonite-/260772181108?pt=Bowling&hash=item3cb73bb474. I suppose the pro-shop owner will know how to find the heavy part of the ball. I thought that would be the mass bias, but I could be wrong, and am not sure if it is marked on a Gyro. My first Gyro, if thrown straight at the head pin would turn slight left, then turn right, and then left again right before hitting. I'd never seen a ball change directions 3 times before...probably never will again. Anyway, thanks for the ideas. Please keep them coming.


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charlest

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Re: Drilling a Gryo Urethane
« Reply #4 on: April 25, 2011, 08:11:57 AM »
That Ebay picture is a Gyro urethane. Ebonite's web site say s it's a pancake core. So, no pin-CG distance, no mass bias. CG is the "heavy spot". Every driller should find it in minimum amount of time. As LBHS1979 says, the surface will be more important than the drilling.
 
AS for the multiple moves to the pocket, static weights do affect the ball's path in pancake cores. Bottom weight or negative (finger & thumb) weights  can make balls appear to do what you saw. Not really a good thing for carry.


"None are so blind as those who will not see."
"Some bowlers are crazy as pickled cats."
 
 
Edited by charlest on 4/25/2011 at 8:13 AM
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