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Author Topic: symmetric drill question  (Read 3778 times)

Trackoholic

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symmetric drill question
« on: January 22, 2008, 03:09:33 AM »
Assuming the pin is in the same place (example, 5 inches from pap and above bridge) what is the difference in the placement of the cg?  Lets compare pointing it towards the bowlers track and pointing it towards the bowlers pap.  I understand when it's aimed towards toe posative side this will most likely allow for a balance hole, and I know when it's stacked this usually means angular or strong.  I'm just not quite sure what the difference is between the pos and neg sides.  I have read that when aimed to the track=arcing, and when aimed to pos side=controlled.  Can anyone give a more detailed description?
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Strapper_Squared

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Re: symmetric drill question
« Reply #1 on: January 22, 2008, 11:31:19 AM »
Oh man... asking asking for it....

My belief is that reaction-wise there is no perceivable difference between having the cg located in your track versus in your palm versus on your PAP, providing the pin is in a constant place.  The shifting of the cg does however bring in the issue of legality with the static weights.. which gets into the use and placement of a weight hole (which does have an effect on the reaction).

Factors effecting reaction:
Bowlers Style/release
Surface
Pin Placement
Mass Bias (if applicable)
Weight Hole


S^2
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Trackoholic

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Re: symmetric drill question
« Reply #2 on: January 22, 2008, 12:53:06 PM »
I know the debate and I'm not trying to rehash, but does the cg location have more of an effect when on a very low diff cored ball?
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Moon57

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Re: symmetric drill question
« Reply #3 on: January 22, 2008, 01:21:10 PM »
My own opinion has always been that the cg has the most effect on a ball with no real core thrown end over end at a slow speed. Once you get away from that the cg doesn't matter much except for using it to make use of a balance/tuning hole possible.

I think it's been said on here that even symmetrical balls have a slight mass bias which is located 6 3/4 from the pin on a line drawn thru the cg. So on symmetrical balls, by swinging the pin to cg line, you are determining where this very slight mass bias is placed.
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Edited on 1/22/2008 2:23 PM

Edited on 1/22/2008 2:28 PM

Trackoholic

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Re: symmetric drill question
« Reply #4 on: January 22, 2008, 01:53:58 PM »
Ok, so lets rephrase this question.  With the pin location same, whats the difference in the slight unmarked mass bias in the two places. one being in the ball track and the other kicked out to the posative side.  One is arcing and one is controlled?  Whats the difference?
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Doug Sterner

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Re: symmetric drill question
« Reply #5 on: January 22, 2008, 03:23:21 PM »
What many people forget here is that when you swing the cg in or out you are not just moving 2-4 oz of the ball....you are changing the tilt of the core within the ball.

The tilt of the core is what makes the difference in ball reaction, not the cg itself being moved.

Laying the core down (pin on PAP) will reduce the effect the core has on the ball motion. Putting the pin further from the PAP typically forces the ball longer since the core has further to go to lay down and hit it's PSA.

Just a quickie reminder from your helpful staff here at Doug's Pro Shop :-)
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Trackoholic

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Re: symmetric drill question
« Reply #6 on: January 22, 2008, 03:57:07 PM »
ok, lets rephrase the question again.  What difference in reaction do you get when you "tilt the weight block" with the cg placement, to the track area and to the posative side, when the pin is in the same position.  assume no other variables (balance hole etc.)
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Doug Sterner

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Re: symmetric drill question
« Reply #7 on: January 22, 2008, 05:11:52 PM »
Again my experience is that if you perform a traditional "cg out" drilling (where the pin is further left than the cg) the ball tend to roll up sooner and you get a longer smoother hook. When you do a "cg in" drill (the pin is further right than the cg) you get a more angular reaction.

To repeat these are generalizatoins and may not apply to all weightblock designs.
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REvans284

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Re: symmetric drill question
« Reply #8 on: January 22, 2008, 08:40:18 PM »
quote:
Again my experience is that if you perform a traditional "cg out" drilling (where the pin is further left than the cg) the ball tend to roll up sooner and you get a longer smoother hook. When you do a "cg in" drill (the pin is further right than the cg) you get a more angular reaction.

To repeat these are generalizatoins and may not apply to all weightblock designs.
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I agree.  Though being a lower speed and slightly rev dominant person.  I feel as though a stacked layout seems to be the most angular off the break point.  When the CG is negative of the pin, the ball still gets similar length, but the reaction off the break is slightly more tame and not as sharp (CG left of pin = length/hard arc, CG stacked = length/snap, CG right = early roll/arc * for me).  This may not be the same for all people though..

Later,

REvans284

Mark T. Trgovac

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Re: symmetric drill question
« Reply #9 on: January 23, 2008, 12:46:02 AM »
quote:
My own opinion has always been that the cg has the most effect on a ball with no real core thrown end over end at a slow speed. Once you get away from that the cg doesn't matter much except for using it to make use of a balance/tuning hole possible.

I think it's been said on here that even symmetrical balls have a slight mass bias which is located 6 3/4 from the pin on a line drawn thru the cg. So on symmetrical balls, by swinging the pin to cg line, you are determining where this very slight mass bias is placed.
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Moon
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So many questions, so little time but I'm having fun.

Edited on 1/22/2008 2:23 PM

Edited on 1/22/2008 2:28 PM


This has no affect on what mass bias there is because once you drill the ball, the mass bias moves because it is not strong enough of a number to be stable in this spot. The only way you can find it again on a "Symetrical" ball is with the use of a deTerminator. Then you may still never find it because the ball can spin forever and never get to its PSA, or it can spin right to the biggest hole on the ball that is normaly your thumb.

Then you also come into the idea of what you call a "Symetrical" ball is not symetrical after you drill it. I love that one, LOL.
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T-GOD

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Re: symmetric drill question
« Reply #10 on: January 23, 2008, 08:45:43 AM »
Generally, the ball will go longer and react stronger down the lane with the CG in the positive quadrant with no balance hole and ending with positive weights.

Generally, placing the CG in the negative quadrant without the need of a balance hole will get the ball into an earlier roll with a smoother reaction down the lane when ending with negative side weight.

Normally a CG out layout will roll sooner with less backend than a layout with the pin out farther than the CG. But, because there are 2 factors working in opposite directions here, A layout that should go longer and snap more (but it has negative weight) vs. a layout that should roll earleir (but is has positive weight) they tend to equal each other out a bit. =:^D