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 Post subject: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Wed Jan 27, 2010 12:05 am Post Number: #1 Post
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I had a discussion on another board about how the RGs affect the RPMs. It had been my assumption that it is the difference in RPMs for a given force that creates the difference in reaction between a high rg drilling vs a low rg drilling (same ball). From my discussion and math it looks like the difference in RPMS between the two would be negligible, about 2- 4% or so..
350 rpm for a 2.8 rg ball vs 357.6 rpm for a 2.74 rg ball...

So if my math is correct I wouldn't think these 7 rpms would change the reaction like it does on the lane.. So what is going on with the ball/core that creates the angular jumpy backend hook on a high rg drill vs the smooth continuous hook on a low rg ball ??

Here is the link

http://www.bowlingcommunity.com/b/ubbth ... 128/1.html

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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Wed Jan 27, 2010 1:16 am Post Number: #2 Post
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J_w73 wrote:
I had a discussion on another board about how the RGs affect the RPMs. It had been my assumption that it is the difference in RPMs for a given force that creates the difference in reaction between a high rg drilling vs a low rg drilling (same ball). From my discussion and math it looks like the difference in RPMS between the two would be negligible, about 2- 4% or so..
350 rpm for a 2.8 rg ball vs 357.6 rpm for a 2.74 rg ball...

So if my math is correct I wouldn't think these 7 rpms would change the reaction like it does on the lane.. So what is going on with the ball/core that creates the angular jumpy backend hook on a high rg drill vs the smooth continuous hook on a low rg ball ??

Here is the link

http://www.bowlingcommunity.com/b/ubbth ... 128/1.html


Too many assumptions! I'll let Paul and Steve handle this, but remember that the only RG that matters to the motion of a ball is the RG of the bowler's PAP. The other RGs do not affect the motion of the ball.


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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Wed Jan 27, 2010 5:29 am Post Number: #3 Post
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that is what I am referring to.. the rg of the ball based on the PAP.. pin on the track or near the VAL would be higher RG. pin on pap would be low RG..

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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Wed Jan 27, 2010 2:17 pm Post Number: #4 Post
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J_w73 wrote:
that is what I am referring to.. the rg of the ball based on the PAP.. pin on the track or near the VAL would be higher RG. pin on pap would be low RG..


Not quite and allow me to explain while throwing a low RG ball you may see a slight increase in the Balls RPM rate, you will not see a difference in two balls with the same layout, same surface, same coverstock. It will only be about 5rpm (not even one revolution of the ball on the lane) between a 2.60" low RG ball and a 2.45" low RG ball.

Also, why would one want to put the pin on your pap or the pin in the track, just like throwing $ out the window. With dual angle layout techniques, we can create a vast range of motions that will span every shot one will possibly need.

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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Thu Jan 28, 2010 7:07 pm Post Number: #5 Post
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I was using the pin on track and pin on pap as a demonstration of two drillings with the max difference in RG.

back to your response.. so you agree that it would be about a difference of 5 rpm.. ?
so if it is only 5 rpm difference then why is the reaction on the lane so completely different between the two balls ??

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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Thu Jan 28, 2010 8:15 pm Post Number: #6 Post
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J_w73 wrote:
I was using the pin on track and pin on pap as a demonstration of two drillings with the max difference in RG.

back to your response.. so you agree that it would be about a difference of 5 rpm.. ?
so if it is only 5 rpm difference then why is the reaction on the lane so completely different between the two balls ??


On a symmetrical cored ball, you are not goign to see the difference in reaction, you have to remember though that the low RG of the ball does move depending on drilling technique and can move around with both drillings.

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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Thu Jan 28, 2010 10:43 pm Post Number: #7 Post
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So what is changing when you change the angle to the VAL on a symmetric ball? I think I see a significant difference in reaction from a ball that is 5.5 inches from my pap with the pin up near the VAL versus a ball with the pin at 5.5 inches from my pap at center of my grip...

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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Thu Jan 28, 2010 11:07 pm Post Number: #8 Post
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J_w73 wrote:
So what is changing when you change the angle to the VAL on a symmetric ball? I think I see a significant difference in reaction from a ball that is 5.5 inches from my pap with the pin up near the VAL versus a ball with the pin at 5.5 inches from my pap at center of my grip...


Changing the angle to the VAL changes the sharpness and angularity of the breakpoint on ALL balls, symmetrical or asymmetrical. The smaller the angle to the VAL, the sharper the break point. Minimum safe angle to the VAL is 20*.


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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Thu Jan 28, 2010 11:55 pm Post Number: #9 Post
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Mo Pinel wrote:
J_w73 wrote:
So what is changing when you change the angle to the VAL on a symmetric ball? I think I see a significant difference in reaction from a ball that is 5.5 inches from my pap with the pin up near the VAL versus a ball with the pin at 5.5 inches from my pap at center of my grip...


Changing the angle to the VAL changes the sharpness and angularity of the breakpoint on ALL balls, symmetrical or asymmetrical. The smaller the angle to the VAL, the sharper the break point. Minimum safe angle to the VAL is 20*.



yes.. I agree.. but WHY ??.. from my understanding changing the pin position in relation to to the VAL will change where the finger holes and thumb hole takes weight/mass out of the core.. I was under the assumption that this changed the rg of the core in relation to the PAP.. well if the change in RG's results in only a difference of about 5 rpms then what causes this extreme difference in reaction.. ???

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Book Average 220+


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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Fri Jan 29, 2010 12:06 am Post Number: #10 Post
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J_w73 wrote:
Mo Pinel wrote:
J_w73 wrote:
So what is changing when you change the angle to the VAL on a symmetric ball? I think I see a significant difference in reaction from a ball that is 5.5 inches from my pap with the pin up near the VAL versus a ball with the pin at 5.5 inches from my pap at center of my grip...


Changing the angle to the VAL changes the sharpness and angularity of the breakpoint on ALL balls, symmetrical or asymmetrical. The smaller the angle to the VAL, the sharper the break point. Minimum safe angle to the VAL is 20*.



yes.. I agree.. but WHY ??.. from my understanding changing the pin position in relation to to the VAL will change where the finger holes and thumb hole takes weight/mass out of the core.. I was under the assumption that this changed the rg of the core in relation to the PAP.. well if the change in RG's results in only a difference of about 5 rpms then what causes this extreme difference in reaction.. ???


I will give you credit. YOU ARE A UNIQUE INDIVIDUAL! When the pin is near the VAL, the holes remove mass from the ball much nearer the equator of the ball (the midplane of the ball perpendicular to the low RG axis-the pin). This flattens the RG ellipse on the y/z plane (the equator). The flatter the ellipse on that plane, the more asymmetrical the ball is. The degree of asymmetry is expressed using the term differential ratio (int. diff./total diff.) The larger the diff. ratio, the more angular the break point. Follow?


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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Fri Jan 29, 2010 5:45 pm Post Number: #11 Post
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Now we are getting somewhere... I guess I will take the "unique" comment as a compliment..

So this looks like it is moving towards my other post about why and how the mb placement does what it does for the reaction. The holes are creating asymmetry and a sort of MB/PSA spot.

So what is the next step?.. What is going on with the core out on the lane than creates the later more angular reaction? I am assuming this is moving into the "RG Contour" that I keep seeing.

thanks for the help.

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Book Average 220+


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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Fri Jan 29, 2010 6:08 pm Post Number: #12 Post
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I see there are alot of replies on the other post about the MB/PSA that I haven't read yet. Let me try to get my head around those and see if those answer my questions..

thanks again for the help.

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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Fri Jan 29, 2010 6:10 pm Post Number: #13 Post
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J_w73 wrote:
Now we are getting somewhere... I guess I will take the "unique" comment as a compliment..

So this looks like it is moving towards my other post about why and how the mb placement does what it does for the reaction. The holes are creating asymmetry and a sort of MB/PSA spot.

So what is the next step?.. What is going on with the core out on the lane than creates the later more angular reaction? I am assuming this is moving into the "RG Contour" that I keep seeing.

thanks for the help.


The drilled ball will display the motion caused by these three factors in order of priority:

1) Differential ratio
2) Total differential
3) The RG of the PAP


Remember, you must consider the complete ball, not just the core! The mass properties are of the complete ball system. You cannot separate the core from the ball. Cores do NOT roll well by themselves. They bounce!


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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Fri Jan 29, 2010 10:36 pm Post Number: #14 Post
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When I am using a ball and getting a great reaction during the first two games, sometimes the ball just won't go long enough 3rd game to get to that area I have been using. Often I will change to the old handshake release and get extra length and extra pop on the back end.

Am I moving my PAP (or changing the RG of my PAP) to get this reaction, or is it all just a change in axis rotation to something closer to 90*?

On edit: After reading other threads, I think the answer will be that release does not change RG and that the chage in axis rotation is the major cause of what I observe.

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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Fri Jan 29, 2010 10:56 pm Post Number: #15 Post
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RevZiLLa wrote:
When I am using a ball and getting a great reaction during the first two games, sometimes the ball just won't go long enough 3rd game to get to that area I have been using. Often I will change to the old handshake release and get extra length and extra pop on the back end.

Am I moving my PAP (or changing the RG of my PAP) to get this reaction, or is it all just a change in axis rotation to something closer to 90*?

On edit: After reading other threads, I think the answer will be that release does not change RG and that the chage in axis rotation is the major cause of what I observe.


Releases can't change RGs very much. The change in rev rate is probably the major factor. Axis rotation also contributes to the increased skid.


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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Fri Jan 29, 2010 10:58 pm Post Number: #16 Post
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Mo Pinel wrote:

I will give you credit. YOU ARE A UNIQUE INDIVIDUAL! When the pin is near the VAL, the holes remove mass from the ball much nearer the equator of the ball (the midplane of the ball perpendicular to the low RG axis-the pin). This flattens the RG ellipse on the y/z plane (the equator). The flatter the ellipse on that plane, the more asymmetrical the ball is. The degree of asymmetry is expressed using the term differential ratio (int. diff./total diff.) The larger the diff. ratio, the more angular the break point. Follow?


I understand.. So putting the pin up high creates more asymmetry and this asymmetry is like putting a PSA in/near the thumbhole/grip area.. so this creates a "pin to spin" line farther away from the initial PAP and thus stronger reaction later down the lane ? maybe some of my terms aren't correct but is this the general idea of what is happening on the lane?

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 Post subject: Re: How much does RG affect RPM.. and High RG vs Low RG balls
 Posted: Fri Jan 29, 2010 11:05 pm Post Number: #17 Post
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J_w73 wrote:
Mo Pinel wrote:

I will give you credit. YOU ARE A UNIQUE INDIVIDUAL! When the pin is near the VAL, the holes remove mass from the ball much nearer the equator of the ball (the midplane of the ball perpendicular to the low RG axis-the pin). This flattens the RG ellipse on the y/z plane (the equator). The flatter the ellipse on that plane, the more asymmetrical the ball is. The degree of asymmetry is expressed using the term differential ratio (int. diff./total diff.) The larger the diff. ratio, the more angular the break point. Follow?


I understand.. So putting the pin up high creates more asymmetry and this asymmetry is like putting a PSA in/near the thumbhole/grip area.. so this creates a "pin to spin" line farther away from the initial PAP and thus stronger reaction later down the lane ? maybe some of my terms aren't correct but is this the general idea of what is happening on the lane?


I'm on two large C C and waters so it's flowing. The sharpness of the break point is contributed to the diff. ratio. The distance down the lane is related to how much the ball has to flare before the PAP crosses the "pin to spin line". Separate cause and effect relationships.


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