Author Topic: Why do balls have varied pin-to-CG distances? (Read 3506 times)

BenLeong · « **on:** March 01, 2019, 06:54:25 PM »

I've never really understood this, and can't seem to find any answers.

To be clear, I'm not asking what options are available for ball drillers with longer pins versus shorter pins, nor am I asking what effect a pin distance might have on ball motion. I'm just specifically wondering why balls with the same core don't have the exact same pin-to-CD distance right out of the box. If it's all the same core, and they're all placed in the middle of the sphere, why would there be variances of inches between where the pin is set and where the CG of the core is?

mrwizerd · « **Reply #1 on:** March 01, 2019, 07:08:10 PM »

My 2 cents....not everyone throws the same, so a 3 inch pin might work for one bowler but not another. Bowling ball manufacturer's probably realized this and that is why the pin lengths are varied.

SVstar34 · « **Reply #2 on:** March 01, 2019, 07:21:18 PM »

It's a byproduct of the manufacturing process and the cores shifting slightly while the molds cure. I'll have to search to find it but I saw someone mention that fractions of an inch shift the cg 1+ inches

BrunsNick · « **Reply #3 on:** March 01, 2019, 08:08:28 PM »

1/10th of an inch core offset is the difference between a 2â€ pin out and a 4â€ pin out.

BenLeong · « **Reply #4 on:** March 01, 2019, 08:14:12 PM »

Quote from: mrwizerd on March 01, 2019, 07:08:10 PM

My 2 cents....not everyone throws the same, so a 3 inch pin might work for one bowler but not another. Bowling ball manufacturer's probably realized this and that is why the pin lengths are varied.

I wasn't asking why ball manufactures allow for it... I was just trying to figure out why the variances exist naturally.

BenLeong · « **Reply #5 on:** March 01, 2019, 08:16:32 PM »

Quote from: SVstar34 on March 01, 2019, 07:21:18 PM

It's a byproduct of the manufacturing process and the cores shifting slightly while the molds cure. I'll have to search to find it but I saw someone mention that fractions of an inch shift the cg 1+ inches

Interesting. Yeah if you can find some technical info that I can look at to see for myself, that would be great.

When I try to think about it in my own head, the distance between where the pin is to where the CG of the core is, seems like it always stays the same... and that variances of 1-5" or so seems impossible. Obviously I know it's not impossible, but I'm just not getting how it could be.

Aloarjr810 · « **Reply #6 on:** March 01, 2019, 09:18:26 PM »

Quote from: BenLeong on March 01, 2019, 08:16:32 PM

Quote from: SVstar34 on March 01, 2019, 07:21:18 PM
It's a byproduct of the manufacturing process and the cores shifting slightly while the molds cure. I'll have to search to find it but I saw someone mention that fractions of an inch shift the cg 1+ inches

Interesting. Yeah if you can find some technical info that I can look at to see for myself, that would be great.

When I try to think about it in my own head, the distance between where the pin is to where the CG of the core is, seems like it always stays the same... and that variances of 1-5" or so seems impossible. Obviously I know it's not impossible, but I'm just not getting how it could be.

Quote

If it's all the same core, and they're all placed in the middle of the sphere, why would there be variances of inches between where the pin is set and where the CG of the core is?

It's do to manufacturing variance, Basically all the parts used to make a ball ( have tiny variations in them (densities ,size etc.) and each step in making it has slight variations/errors in them.

They all add up and they cause the cg (which the center of gravity is not the actual geometric center of the ball) to move some and you wind up with different pin to cg measurements.

here's a article that explains it:

MANUFACTURING PROCESS VARIATION: THE SMALLEST of SHIFTS CAN ALTER PIN DISTANCE and TOP WEIGHT

Written by Nick Siefers, Senior Design Engineer, Global 900

http://www.itbca.bowlingknowledge.info/index.php/fall-2012/78-manufacturing-process-variation-the-smallest-of-shifts-can-alter-pin-distance-and-top-weight

stormed1 · « **Reply #7 on:** March 01, 2019, 09:49:07 PM »

As it was explained to me years ago. The core is positioned on a pin within the mold. over time pin bend slightly due to wear or the size and weight of the core. this causes the core to be positioned slightly off from straight up and down and that's what causes the different pin to cg distances

BenLeong · « **Reply #8 on:** March 02, 2019, 07:56:52 PM »

Thanks for the info, everyone. I appreciate it.

BenLeong · « **Reply #9 on:** March 02, 2019, 08:00:19 PM »

Quote from: Aloarjr810 on March 01, 2019, 09:18:26 PM

Quote from: BenLeong on March 01, 2019, 08:16:32 PM
Quote from: SVstar34 on March 01, 2019, 07:21:18 PM
It's a byproduct of the manufacturing process and the cores shifting slightly while the molds cure. I'll have to search to find it but I saw someone mention that fractions of an inch shift the cg 1+ inches

Interesting. Yeah if you can find some technical info that I can look at to see for myself, that would be great.

When I try to think about it in my own head, the distance between where the pin is to where the CG of the core is, seems like it always stays the same... and that variances of 1-5" or so seems impossible. Obviously I know it's not impossible, but I'm just not getting how it could be.

Quote
If it's all the same core, and they're all placed in the middle of the sphere, why would there be variances of inches between where the pin is set and where the CG of the core is?

It's do to manufacturing variance, Basically all the parts used to make a ball ( have tiny variations in them (densities ,size etc.) and each step in making it has slight variations/errors in them.

They all add up and they cause the cg (which the center of gravity is not the actual geometric center of the ball) to move some and you wind up with different pin to cg measurements.

here's a article that explains it:

MANUFACTURING PROCESS VARIATION: THE SMALLEST of SHIFTS CAN ALTER PIN DISTANCE and TOP WEIGHT

Written by Nick Siefers, Senior Design Engineer, Global 900

http://www.itbca.bowlingknowledge.info/index.php/fall-2012/78-manufacturing-process-variation-the-smallest-of-shifts-can-alter-pin-distance-and-top-weight

Awesome article--perfectly answers my question. Thanks!

Author Topic: Why do balls have varied pin-to-CG distances? (Read 3506 times)

BenLeong

Why do balls have varied pin-to-CG distances?

mrwizerd

Re: Why do balls have varied pin-to-CG distances?

SVstar34

Re: Why do balls have varied pin-to-CG distances?

BrunsNick

Re: Why do balls have varied pin-to-CG distances?

BenLeong

Re: Why do balls have varied pin-to-CG distances?

BenLeong

Re: Why do balls have varied pin-to-CG distances?

Aloarjr810

Re: Why do balls have varied pin-to-CG distances?

stormed1

Re: Why do balls have varied pin-to-CG distances?

BenLeong

Re: Why do balls have varied pin-to-CG distances?

BenLeong

Re: Why do balls have varied pin-to-CG distances?