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Author Topic: cg locations for no weight hole  (Read 2274 times)

kleptic

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cg locations for no weight hole
« on: October 09, 2007, 08:08:26 PM »
I'm trying to decide on a layout for my blackwidow with 2 3/4 top weight.

anybody have an estimate of how far off grip center the cg can be and be legal without a weight hole.

thanks


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qstick777

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Re: cg locations for no weight hole
« Reply #1 on: October 10, 2007, 09:24:14 AM »
When it doubt, ask the bowler!

http://www.askthebowler.com/bill_taylor_shifter.html

You might be able to get a good idea from pic #3, but I'd say Ironhorse is right - keep it within an inch of grip center and you should be fine.

edit:  info from JohnP

quote:

JohnP
         Posted: 8/25/2007 10:36 AM    
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quote:
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 Is there a good rule of thumb for laying out a ball to know ahead of time how much side weight you will end up with?
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To estimate, figure that for 3 oz of beginning top weight, a 1" shift of the cg from grip center gives 1 oz of imbalance. For lower/higher top weights, simply use proportions. Same for less/more than a 1" shift. In the finger/thumb direction, drilling either deeper or shallower than normal influences the imbalance accordingly. In the side directions, drilling one finger hole deeper than the other changes the imbalance.

WARNING: This is just an estimate. And it is always safest to confirm the cg location and the amount of beginning top weight on a dodo scale. -- JohnP
 


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Edited on 10/10/2007 9:27 AM
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JohnP

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Re: cg locations for no weight hole
« Reply #2 on: October 10, 2007, 04:41:06 PM »
Read his post, he said he has 2 3/4 oz of top weight.  Actually, the distance you can go depends on the direction.  If you're moving toward either the thumb or fingers, you can probably go at least 2" and make it legal by drilling the appropriate holes deeper than normal.  If it's toward either side, the limit will probably be around 1 1/2", which can be made legal by drilling the appropriate finger hole deeper than normal.  With all normal depth holes, the 1" is a good limit.  --  JohnP
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kleptic

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Re: cg locations for no weight hole
« Reply #3 on: October 10, 2007, 06:29:36 PM »
so higher top weight is really only good when you are shifting the cg into the positive thumb quadrant for a large balance hole?

when i get a 3-4 inch pin ball and its closer to 3 than 4 i have a hard time keeping the cg below center of grip. limits my weight hole options quite a bit

so i should get balls with lowest top weight possible?

are 4-5 inch pin balls common? for example on buddies I see 3-4 as the highest option.

thanks


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JohnP

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Re: cg locations for no weight hole
« Reply #4 on: October 10, 2007, 09:49:32 PM »
BO -- Did you confirm the top weight and cg location with a dodo scale before you drilled it?  If not, I'll bet either the top weight was less than the box said or the cg was mismarked.  --  JohnP
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qstick777

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Re: cg locations for no weight hole
« Reply #5 on: October 11, 2007, 10:43:45 AM »
Is the Black Pearl a ball with no filler, only coverstock to the core?

Might have something to do with it - coverstock tends to weigh more than filler, so you would be removing more weight with the finger and thumb holes.

I don't know if cover is twice as heavy as filler, but that may explain the ability to do almost double the normal CG shift without needing a weight hole (just estimating from BrunsNick's picture. )
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qstick777

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Re: cg locations for no weight hole
« Reply #6 on: October 11, 2007, 02:15:52 PM »
quote:
quote:
Is the Black Pearl a ball with no filler, only coverstock to the core?


qstick, yes.....Also on Legends balls with no filler, they reduce the weight of the ball by reducing the weight of the core. Thus a 14# ball's core is 2# lighter than a 16# ball. I don't know if this has any thing to do with it or not. My ball is a 14# ball.


I think I remember reading that about those balls.

I had an AMF Titan that cracked and I was able to get the core.  On a 14lb balls, the core weighed 5lbs - that was with finger and thumb holes hitting the core.  I didn't weigh the other parts (mainly because I  tore the thing into hundreds of pieces!), but the cover was heavier than the filler material.

I would guess maybe the cover was twice as heavy as the filler material - so I would guess maybe 5 lbs of core, 6 pounds of cover and 3 pounds of filler.  

I'm not smart enough to do the math on how much of difference that would make when drilling out a 31/32 finger hole.

I have a full Columbia Bully core and that only weighs 3 lbs, so I guess the density of the cover and filler will be different for each ball.
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