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Author Topic: Drilling core upside down  (Read 4121 times)

Keith Frye

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Drilling core upside down
« on: November 18, 2005, 05:14:54 AM »
In another post, someone is selling a blem ball with a 7" pin out.  He said that his driller told him that the core could be turned upside down and it would be like a ball with a 2-3" pin out.  

Maybe I am not looking at this correctly.  I am thinking that the pin would need to be a few inches further out in order to flip the core and end up with the new theoretical pin within "normal" distance from the CG.  Since the circumference of a ball is 27", the new pin would be 13.5" away from the marked pin (exact opposite side of the ball).  13.5 minus 7 leaves a 6.5" distance from the "new pin".

So, wouldn't one need about a 9.5" or more pin for this to work?  Or am I not looking at this in the right way.  Of course the top weight (which will become the bottom weight) would need to be pretty low as well so that the drilled ball does not end up with more than 3 ozs. on the bottom.

 

CORDOG

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Re: Drilling core upside down
« Reply #1 on: November 19, 2005, 09:27:15 PM »
that is why it would have to be 7" pin instead of a 9.5", that difference in distance makes up for the difference in top/bottom weight.

Keith Frye

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Re: Drilling core upside down
« Reply #2 on: November 21, 2005, 07:22:46 AM »
I don't follow why the difference in pin distance would have an effect on the top/bottom weight.  If you start with a ball that has 3.5 oz. top weight, when the finger/thumb holes are drilled the ball will then have less than 3 oz. and be within USBC limits.  If you turn the core upside down, you will then have 3.5 oz. of bottom weight.  After drilling fingers/thumb, the bottom weight will increase making the ball even more over the limit.  That is why a low top weight ball would be needed.  The starting pin distance doesn't change that.  Or am I again missing something?

shelley

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Re: Drilling core upside down
« Reply #3 on: November 21, 2005, 07:44:24 AM »
You're on the mark, Keith.  A low top weight ball would be needed.  However, to create a ball with a 7+ inch pin, you'd probably have pretty low top weight anyway.  Especially with a 9" pin, which you'd really need to make drilling it upside down worthwhile.

SH

Keith Frye

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Re: Drilling core upside down
« Reply #4 on: November 21, 2005, 07:48:49 AM »
Thanks shelly.  That's what I thought.

tjj300

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Re: Drilling core upside down
« Reply #5 on: November 21, 2005, 11:55:52 AM »
Wait a minute.  Top weight is based on CG position, not pin. A 9"+ pin is 9"+ from the CG which is where the static weight is based from. So you treat the top weight listed on the box like you would for any ball. You mark your new pin 13.5" from the original pin and go from there.

mrbowlingnut

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Re: Drilling core upside down
« Reply #6 on: November 21, 2005, 12:00:45 PM »
I am the seller my driller johnny debendetta has drilled thousands of ball, he told me that he flip the core and reweigh statics and drill a new layout with ball flipped over. I am not a driller so i do not know exactly what he means and do not claim too i was told it could be used and still work. I am going to drill it up since you guys state it cant be done and see what happens.

btw the way it is low top weight

Edited on 11/21/2005 12:53 PM

Keith Frye

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Re: Drilling core upside down
« Reply #7 on: November 21, 2005, 12:08:19 PM »
mrbowlingnut,
I am certainly not saying that the ball can not be drilled upside down.  I am only questioning that the new effective pin would be only be 2" to 3" out when the starting pin was only 7" out.  I have never drilled a ball this way and was just interested in finding out more.  Your driller may set up a great reacting ball for you.

mrbowlingnut

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Re: Drilling core upside down
« Reply #8 on: November 21, 2005, 12:19:34 PM »
Keith no problem he started rattling off different layouts to me, i understand some of it and some was over my head to be honest. We looked up the core on the net and the ball will be early, flipping the core upside down. Luckily Johnny who drilled at the ABC nationals for years has done every layout in the world you can imagine. It was my fault getting this ball in the first place but i had good success with ebonite blems on ebay, i can tell you that those balls even with mb 180 degrees off still roll well for me with standard pin positions.

This ball the high energy will have a much shorter core flipping it over, i hope the cover is still pushes it down the lane being half pearl/ soild like it is.

Keith Frye

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Re: Drilling core upside down
« Reply #9 on: November 21, 2005, 12:23:01 PM »
Good luck with it.  Maybe you can post some pics showing the pin in relation to the cg and another showing the final layout.  Then, let us know how it rolls for you.