Author Topic: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it? (Read 9170 times)

bgh · « **on:** July 31, 2007, 08:44:37 AM »

Article : USBC Equipment Specifications and Certification - Center of Gravity placement on a symmetrical bowling ball: How critical is it? - By Paul Ridenour, USBC research engineer

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Edited on 8/6/2007 6:43 PM

Fluff E Bunnie · « **Reply #46 on:** August 01, 2007, 12:45:01 PM »

quote:

Then to top it all off, we can't even have a decent discussion without the moronic kiddies like notclay and Fluff E Bunnie interjecting their childish remarks. Even now, half of the posts in this thread are irrelevant to the discussion.

Haha! Pleased to be of service! It's funny how many people on here can't take a joke. Of course there is a double irony there because my childish remarks are a reference to the earlier childish/mudslinging CG debate threads.

Here's an intelligent question for you. Why is it that in the first videos people said that they wouldn't trust anything until a robot threw the balls and then now the criticism is that only a robot could produce those results?

So here's the only way we can settle this debate. Take the poor robot and have him/her/it throw every single ball made and re-oil the lane in between each shot. Results should be available shortly so that everyone can argue again.
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qstick777 · « **Reply #47 on:** August 01, 2007, 12:49:20 PM »

quote:
quote:
the only substantial difference is that the positive CG ball has positive side weight of 1.25 ounces and the negative CG ball has negative side weight of 1.35 ounces.

I thought the maximum allowable "legal" sideweight was 1 oz. Therefore, the maximum allowable difference for this test should be 2 oz, but they themselves ( U.S.B.C. ) used balls that were, in essence "illegal", so the test results are still null and void.

1.25oz+1.35oz=2.60oz--- Out of tolerance by .60

If you are going to do the test, you should at least stick to the legal ruling you have made yourself. Swinging the CG out to 45 degrees should not be done if it put the ball outside of the "legal" limits. If it is outside those limits, the appropriate weight hole should have been used to bring it back within specs.

If you are going to arbitrarily test balls without regards for the "legal" limits, what good does that data do us in the "real world" environment? You would never be allowed to swing the CG that far, ending up with too much sideweight, and still be allowed to use it in sanctioned competition until the weighthole was applied to bring it back to "legal" specs.

How could they overlook something like that?
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Edited on 7/31/2007 6:15 PM

Your point has been asked multiple times, but nobody will respond. Some will say that the x-hole will affect the reaction, but according to Ebonite and Brunswick, you'll need a hole 31/32" x 2" deep or 1" x 3" deep to affect reaction. So, anything smaller than that will just remove weight. Shouldn't be any problem removing the .25 and .35 of weight to make the balls legal.

ebonite's view of balance hole:

The location of a balance hole is a method of manipulating primarily the differential or track flare potential in a drilled ball. By changing the differential with the use of a balance hole, a pro shop operator can increase or decrease the hook potential of a bowling ball. Note that in order for a ball reaction change to be noticed by most bowlers the balance hole must be at least a 31/32" bit and at least two inches deep.

According to Jayhawk's weight removal chart, 31/32" x 2" hole will remove 1.2 oz.

Brunswick:

Brunswick is recommending a simplified one-hole size / two-hole position technique that
covers the vast majority of ball reaction changes that can be accomplished by drilling an X-hole.
â€¢ Use a 1â€ drill bit, 3â€ deep, to both increase or decrease track flare.
Note: Larger and deeper X-holes result in only slightly greater increases or decreases in track flare. The one-hole size technique has
the added advantage of avoiding problems with illegal static weights. As long as the ball was originally laid out with at least Â¾ oz. of
positive side weight and a small amount of finger/thumb weight, the 1â€ X 3â€ hole using either of Brunswickâ€™s recommended X-hole
positions will keep you out of static weight trouble.

According to Jayhawk's weight removal chart, 1" x 3" hole will remove 1.95 oz.
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chitown · « **Reply #48 on:** August 01, 2007, 01:04:30 PM »

quote:

Your point has been asked multiple times, but nobody will respond. Some will say that the x-hole will affect the reaction, but according to Ebonite and Brunswick, you'll need a hole 31/32" x 2" deep or 1" x 3" deep to affect reaction. So, anything smaller than that will just remove weight. Shouldn't be any problem removing the .25 and .35 of weight to make the balls legal.

ebonite's view of balance hole:

The location of a balance hole is a method of manipulating primarily the differential or track flare potential in a drilled ball. By changing the differential with the use of a balance hole, a pro shop operator can increase or decrease the hook potential of a bowling ball. Note that in order for a ball reaction change to be noticed by most bowlers the balance hole must be at least a 31/32" bit and at least two inches deep.

According to Jayhawk's weight removal chart, 31/32" x 2" hole will remove 1.2 oz.

Brunswick:

Brunswick is recommending a simplified one-hole size / two-hole position technique that
covers the vast majority of ball reaction changes that can be accomplished by drilling an X-hole.
â€¢ Use a 1â€ drill bit, 3â€ deep, to both increase or decrease track flare.
Note: Larger and deeper X-holes result in only slightly greater increases or decreases in track flare. The one-hole size technique has
the added advantage of avoiding problems with illegal static weights. As long as the ball was originally laid out with at least Â¾ oz. of
positive side weight and a small amount of finger/thumb weight, the 1â€ X 3â€ hole using either of Brunswickâ€™s recommended X-hole
positions will keep you out of static weight trouble.

According to Jayhawk's weight removal chart, 1" x 3" hole will remove 1.95 oz.

Wouldn't Brunswicks weight hole suggestions make a ball illegal? I mean if your ball is originaly laid out with 3/4 oz of side and you drill a balance hole 1" in diameter, 3" deep, it would give you an ending static of over the 1oz negative! This makes no sense and why would Brunswick suggest this?

I will say this, you don't need to drill the balance hole that deep to get a difference in reaction from the use of the balance hole.
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J_Mac · « **Reply #49 on:** August 01, 2007, 01:10:25 PM »

quote:
According to Jayhawk's weight removal chart, 1" x 3" hole will remove 1.95 oz.

I wouldn't trust that chart anymore since most balls today are made with denser cores and light weight filler material between the coverstock and core. This chart might get close on L/LM equipment where the balls are mostly just coverstock on core.
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qstick777 · « **Reply #50 on:** August 01, 2007, 01:32:29 PM »

quote:
quote:
According to Jayhawk's weight removal chart, 1" x 3" hole will remove 1.95 oz.

I wouldn't trust that chart anymore since most balls today are made with denser cores and light weight filler material between the coverstock and core. This chart might get close on L/LM equipment where the balls are mostly just coverstock on core.
--------------------
"A word to the wise ain't necessary -- it's the stupid ones that need the advice." Bill Cosby
"Never argue with an idiot. They bring you down to their level and beat you with experience."

Possibly. I don't expect it to be 100% given different densities, coverstock thickness, ball weight (14-16), etc. I've found it fairly accurate when estimating size and depth.
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« **Reply #51 on:** August 01, 2007, 03:38:15 PM »

Quote:

Then to top it all off, we can't even have a decent discussion without the moronic kiddies like notclay and Fluff E Bunnie interjecting their childish remarks. Even now, half of the posts in this thread are irrelevant to the discussion.

Haywood

_____________________________________________________________________________

Dear Haywood,

Sorry you have zero sense of humor. We've heard this all before, and you're right, no one's convincing anyone with their arguments. Some of us like to have some fun once in awhile. This is not life or death, it's fricking bowling!

Go home. Kiss your wife and kids. Pet the dog. Relax with some incense. Do whatever you need. But remember, it's just bowling.

Sincerely, Your moron,

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notclay

Lane Carter, Strike Zone Pro Shops - Salt Lake City, Utah

"He who dies with the most bowling balls is still dead."

Edited on 8/1/2007 3:49 PM

qstick777 · « **Reply #52 on:** August 02, 2007, 10:34:40 AM »

quote:
Quote:

Then to top it all off, we can't even have a decent discussion without the moronic kiddies like notclay and Fluff E Bunnie interjecting their childish remarks. Even now, half of the posts in this thread are irrelevant to the discussion.

Haywood

_____________________________________________________________________________

Dear Haywood,

Sorry you have zero sense of humor. We've heard this all before, and you're right, no one's convincing anyone with their arguments. Some of us like to have some fun once in awhile. This is not life or death, it's fricking bowling!

Go home. Kiss your wife and kids. Pet the dog. Relax with some incense. Do whatever you need. But remember, it's just bowling.

Sincerely, Your moron,

--------------------
notclay

Lane Carter, Strike Zone Pro Shops - Salt Lake City, Utah

"He who dies with the most bowling balls is still dead."

Edited on 8/1/2007 3:49 PM

These threads are too funny!

I don't think the "half the posts" was accurate. I went through and counted both of their posts and they only have 1/3 of the posts - 18 out of 54!

If it really bothers you just put them on "ignore" while you read the post!

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« **Reply #53 on:** August 02, 2007, 10:44:06 AM »

And I promise to not joke around on this subject anymore... This is serious stuff.
Other subjects are still "open play".

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notclay

Lane Carter, Strike Zone Pro Shops - Salt Lake City, Utah

"He who dies with the most bowling balls is still dead."

Fluff E Bunnie · « **Reply #54 on:** August 02, 2007, 12:28:47 PM »

I also apologize for joking around. It won't happen again. Carry on.

Juggernaut · « **Reply #55 on:** August 06, 2007, 06:41:16 PM »

O.K., lets review

CG NOMADDAH in Brunswick balls due to the manufacturing techniques used to keep core orientation stable so that, despite the different pin/cg orientation, the core orientation stays static in relation to the pin ( I.E. No tilting of the core to create pin-out positions )

CG MAYMADDAH in balls produced by other companies that have differing manufacture processes and techniques than Brunswick, especially if core orientation is manipulated to produce differing pin positions in relation to the CG positions ( I.E. tilted cores )

I think I understand the concept of CGNOMADDAH. It doesn't matter due to the fact that there is NO DIS-ORIENTATION of the core in Brunswick balls, but I further contend that it doesn't matter no matter WHAT brand of ball you are throwing, due to the fact that, if it is shifted far enough to the side to need a weighthole, then drilling the weighthole moves the actual CG location back close enough to the grip of the ball that it become irrelevant. And, if it is in the palm to begin with ( the CG), then it was inconsequential to start with.

This is why I wasn't satisfied with the testing that Paul did. On the test balls, without appropriate weightholes to bring them into static "legal", the CG position would almost have to make some difference, albeit a small one, but if the weightholes had been drilled, the balls would have ended up with ACTUAL CG placements close enough to one another to have become inconsequential to the balls reaction as a whole.

I sent Paul a message saying that, if the tests had been done both without and with weightholes, I would have found that to be much more conclusive than the way it was done. He replied that there was much more testing to come in the future in this area.
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purduepaul · « **Reply #56 on:** August 06, 2007, 09:21:32 PM »

Juggernaut:

You are right, and we are going to be doing both legal and illegal side weights to see the difference if its linear or not. One of the absolute critical things was no weight holes. If you read Nick Siefers' article, one of the subtests he performs shows how the radius of gyration about the pap can change dramatically with a weight hole. We try to keep as many of the other variables as constant as possible. Honestly, no cg test we will perform will have weight holes because of the difference in performance with weight holes added.

CoachJim · « **Reply #57 on:** August 06, 2007, 10:10:41 PM »

quote:
You are right, and we are going to be doing both legal and illegal side weights to see the difference if its linear or not. One of the absolute critical things was no weight holes. If you read Nick Siefers' article, one of the subtests he performs shows how the radius of gyration about the pap can change dramatically with a weight hole. We try to keep as many of the other variables as constant as possible. Honestly, no cg test we will perform will have weight holes because of the difference in performance with weight holes added.

So Paul, you are saying that the cg placement in a ball doesn't effect ball motion as much as weight hole placement.

That being the case, there is no need to test any cg placements beyond 1oz pos or neg due to the fact that anything past that will require a weight hole to make the ball leagle and the weight hole will take presidence in ball motion over cg placement.

I would like to see the results of a series of tests: one oz pos cg placement vs. one oz. neg cg placement, then test one oz pos vs cg on grip center with one oz pos weight hole vs oz neg cg placement with 2oz positive weight hole vs two oz pos cg placement with one oz neg weight hole vs 3 oz pos cg placement with 2oz weight hole.

This kind of info would help me layout equipment for different reactions and prevent laying out some elaborate drill pattern when all I really needed to do would be to move the cg one way or the other. I am not sure how this reads, but I am not trying to be a smart @$$, I appreciate the hard work and look forward to your future tests.

Moon57 · « **Reply #58 on:** August 07, 2007, 10:11:57 AM »

My 2 cents as follows;

Back in the plastic ball era the CG meant alot more because there were no cores in the ball, only a weight block located right under the cover of the ball to compensate for the drilling of the grip. From what I understand, on a ball with a core, the core is tilted a very slight amount to make one side of the ball heavier than the other. This heavier spot is located at various distances from the center of the ball depending on the dia of the core. All the term CG means is somewhere on a line from the CG mark to the center of the ball is a heavy spot. The closer to the cover this heavy spot is the more of an effect it will have on the ball. I think this is the same principal that works for the weight hole. The cover weighs more than the filler, so the weight balance point of the weight hole would be closer to the cover thus having a greater effect on the ball, which it does.
In conclusion, I think the effect of CG is dictated to a small degree by the dia of the core.
Could be everything I've said here is a load crap, half right, who knows. I'm sure I'll be thusly informed.

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Dick
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Author Topic: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it? (Read 9170 times)

bgh

USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

Fluff E Bunnie

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

qstick777

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

chitown

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

J_Mac

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

qstick777

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

qstick777

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

Fluff E Bunnie

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

Juggernaut

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

purduepaul

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

CoachJim

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?

Moon57

Re: USBC Equip & Spec : Center of Gravity placement on a symmetrical bowling ball: How critical is it?