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Author Topic: Pin Up vs Pin Down drilling  (Read 27495 times)

EL3MCNEIL

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Pin Up vs Pin Down drilling
« on: September 25, 2014, 06:47:01 AM »
Could any one help and give me a run down of the differences in Pin up/Pin down drilling's on balls. Any help is appreciated.
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J_w73

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Re: Pin Up vs Pin Down drilling
« Reply #16 on: October 01, 2014, 02:39:14 PM »
Where the pin is in relation to the gripping holes (Angle or distance to the VAL) very much affects the dynamics of the ball and the reaction.   If the pin is lower (example: middle of grip), the holes will take mass out of the top of the core, make the ball more symmetric and lower the overall differential. This is why you usually get a smoother more rolly reaction.   If the pin is above the fingers, the holes will take more mass out of the side of the core, create more asymmetry, and increase the differential.  This is why you usually get a more angular and flippy reaction.

This is an example for any given pin to pap distance that would put the pin within or above the gripping holes.  With short pin to paps you won't see as big of a difference in reaction between different VAL angles (or distances from the VAL).  This is because the holes are taking mass out of the same general area of the core regardless of the VAL angle.

I don't see this at all.  I mean, the pin is the top of the core, correct?  So drilling with the pin above the fingers (within an inch or two), or drilling with the pin below the fingers (within an inch or two), should take mass out of the top of the core.  How can that be wrong?  Drilling out of the middle of the core would come from drilling  about 6.75 inches away from the pin, anywhere around the ball.

I mean look at this picture.  The finger holes are taking out the top of the core:

http://blueprintbowling.com/images/slideshow/Powerhouse_Blueprint.jpg

And if the yellow pin was just below the fingers, it would be taking weight out of the top as well.


yes. just above and just below the fingers you will not see much difference, but there will be some difference.  You will see a bigger difference from say a pin at the center of grip vs a pin 2 to 3 inches above the fingers (both at the same pin to pap distance).  The fingers and thumb hole take out a mass that is say averaged around the center of grip(provided the thumb and fingers take out the same amount of mass)  The farther you shift this mass removal to the side of the core the more asymmetry you will create and thus more flare and more angularity.  The more the mass removal is shifted to the top of the core the more it will reduce the rg differential, reduce flare and smooth out the reaction.
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J_w73

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Re: Pin Up vs Pin Down drilling
« Reply #17 on: October 01, 2014, 02:42:38 PM »

I don't see this at all.  I mean, the pin is the top of the core, correct?  So drilling with the pin above the fingers (within an inch or two), or drilling with the pin below the fingers (within an inch or two), should take mass out of the top of the core.  How can that be wrong?  Drilling out of the middle of the core would come from drilling  about 6.75 inches away from the pin, anywhere around the ball.

I mean look at this picture.  The finger holes are taking out the top of the core:

http://blueprintbowling.com/images/slideshow/Powerhouse_Blueprint.jpg

And if the yellow pin was just below the fingers, it would be taking weight out of the top as well.


I think you need to consider the thumb also.  Most of my equipment have shallow finger holes, yet, deep thumbholes.  Plus, thumbholes are bigger.

I would imagine on a lot of balls the finger holes barely contact the core.  Taking out filler doesn't seem like much of a change.  However, drilling a thumbhole will take out core material (dense) thus affecting the dynamics of the core. 

So in your example, I would assume the thumbhole being directed toward the middle of the core will raise the rg.  If the pin was below the fingers, then the thumbhole would take out more at the top of the core, thus lowering the rg.

Makes sense.
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jls

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Re: Pin Up vs Pin Down drilling
« Reply #18 on: October 01, 2014, 05:26:43 PM »
IMO...and in my area...Pin down drillings are not that popular anymore...

Houses don't put down enough oil for them...

And with today's strong covers...Pin down drillings may cause the ball to burn up
faster...