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Author Topic: cgnomaddah debate  (Read 2442 times)

BallsDeep

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cgnomaddah debate
« on: July 07, 2007, 05:35:24 AM »
Rather than posting my question on that long line of argument in the lane 1 forum I figured that I'd put it here.  I understand the manner in which the mass bias effects ball reaction as far as the placement with reference to the bowler's pap.  What I don't understand is the true dynamic of the mass bias.  I have been told that all balls have a mass bias.  Moreover I have seen that most balls have a mass bias that is in line with the pin and cg.  Yet with the no mercy series, hammer was able to manipulate the ball so that the mass bias and cg were offset.  Thus allowing one to drill a ball with the mass bias in the strong position without the cg preventing the ball from meeting static weight requirements (without a weight hole).  How they do this I do not understand.

This question also touches the other debate.  Assuming that the Gforce or whatever ball was drilled for the test has a mass bias (however weak) and that mass bias is in line with the pin and cg, then how come there is no difference in reaction between the negative and positive ball.  Is the mass bias that weak in a symmetrical ball that it has no effect.

Two easier questions to understand may be.  How weak is the mass bias of a symmetrical ball with reference to the brunswick asyms or some other asymetrical ball?  If the cg is the heavy spot on the ball, then wouldn't the mass of the ball have to be greatest in that direction, creating a mass bias in line with the pin and cg?
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kmanestor22

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Re: cgnomaddah debate
« Reply #1 on: July 07, 2007, 03:44:17 PM »
Go to a MoRich seminar if you are this interested in understanding its effect.  It is very technical.

And the No Mercy DOES NOT MARK THE MASS BIAS!!!!!, it marks the intermediate diff, which is the opposite of the mass bias in terms of resistance to revolution.

In physics class, have you seen the experiment where a guy spins in a revolving chair with two weights in his hands?  As he spins with his arms extended, he spins slowly.  As he pulls the weights in, he revolves faster.  This is basically the idea behind a mass bias.

Draw a line from the pin to the mass bias.  As your PAP migrates towards this line, it is like spinning with the weights extended.  Once your axis crosses this line, it is like spinning with the weights pulled in.  Moving the mass bias position changes where down the lane it takes effect.  Put it too far away from your axis, and the bias never takes effect.
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BallsDeep

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Re: cgnomaddah debate
« Reply #2 on: July 07, 2007, 05:10:03 PM »
Thats a pretty good example.  I know that the no mercy doesn't mark the mass bias, rather it marks a point 90 degrees from the mass bias, thus when the pin cg and hart are inline, the cg is also 90 degrees from the mass bias.  Though you make alot of sense, I still don't see how hammer does this.  Lets say they make an asymetrical core by putting weight away from the center of the core, this would make the mass bias in the direction of the displaced weight, but shouldn't the heavy spot or cg also move in that same direction?

This is moving away from the debate however, if all pin out bowling balls have a mass bias then why does the cg not matter as it would seem to indicate the direction to which mass is biased away from the core?
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four fried chickens and a coke[/size=4]

Let me say something, let me say something...
AAAAAAAAAAAAAHHHHHHHHHHHHHHHHH
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kmanestor22

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Re: cgnomaddah debate
« Reply #3 on: July 12, 2007, 09:40:41 PM »
quote:
Thats a pretty good example.  I know that the no mercy doesn't mark the mass bias, rather it marks a point 90 degrees from the mass bias, thus when the pin cg and hart are inline, the cg is also 90 degrees from the mass bias.  Though you make alot of sense, I still don't see how hammer does this.  Lets say they make an asymetrical core by putting weight away from the center of the core, this would make the mass bias in the direction of the displaced weight, but shouldn't the heavy spot or cg also move in that same direction?

This is moving away from the debate however, if all pin out bowling balls have a mass bias then why does the cg not matter as it would seem to indicate the direction to which mass is biased away from the core?
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four fried chickens and a coke[/size=4]

Let me say something, let me say something...
AAAAAAAAAAAAAHHHHHHHHHHHHHHHHH

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the cg placement always matters.  whether or not you can see a difference in reaction is the debate.

Where is the bait?  I'm goin' to jail!!! - Chocolate GAYzer

Edited on 7/12/2007 9:40 PM
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HamPster

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Re: cgnomaddah debate
« Reply #4 on: July 12, 2007, 10:40:25 PM »
Cg placement doesn't matter.  You can change the cg location drastically using weighthole placement.  Pin position and mass bias, if the ball is asymmetrical, is all that matters.  If the ball is symmetrical, you can put the cg anywhere.
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dizzyfugu

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Re: cgnomaddah debate
« Reply #5 on: July 13, 2007, 04:37:21 AM »
As far as I can tell... The difficulty in the discussion lies IMHO in the grey mist to decide whena mass bias has enough significance to "override" the PSA effect created to the CG position, relative to the pin.

Any ball/core "wants" to rotate/migarte towards a stable end position. On a low mass bias ball (either with a symmetrical or asymmetricla core), the CG defines this axis - its influence is weak, and you can approximate this with a drawn line of 6.75" from the pin through the CG - and that's why the PSA is not marked. Hammer did it on some balls with a LMB marker, as well as Ebonite, but IMO rather for marketing than true necessity for the driller.

Once the mass bias becomes strong "enough" in the core design - which means the core has a design that supports its migration tendency towards the PSA - it overrides the weak CG effect. The asym. RG diff. is a measure for this, and we can discuss when it is strong enough to be significant for drilling. IMO opinion, it might be between 0.01-0.015" - but this is the grey area. Symmetrical cores, but also low MB asymmetrcial designs have an asym. RG diff.
in the 0.005" area (Check Ebonite's website, they publish this number on some balls). A huge pin-out (say 4") might add a little, but it will be marginal.
Strong PSA balls start IMO at a asym. RG diff.of 0.015" and more (Brunswick's Zones have 0.017" and the new BZ 0.02", strong current cores touch 0.03").

Neverthless, since the CG can be off-line with the pin and the mass bias and its relevant PSA, it is important to check the PSA's position for the drill and go for this indicator instead of the CG - "CGnomaddah" for ball reaction, just for static weights to get the ball legal.
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