Pin to cg distance

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poloidrogo
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Pin to cg distance

Post by poloidrogo » December 26th, 2018, 3:58 am

Hi guys I just got a new Roto Grip Idol as a Christmas present, but I notice that the pin to cg is around 1 inch distance, what is the reason some balls have 3 or 4 inches distance and this came to short. Do you think it will afect being to short ??

Thanks in advance

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EricHartwell
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Positive Axis Point: 4-3/4" and 1/2"up
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Re: Pin to cg distance

Post by EricHartwell » December 26th, 2018, 4:16 am

Pin in or short Pin to Cg balls used to be very limited in how you could drill them. With the rules today allowing more static weight imbalance allows for more drilling versatility with such balls.

What is the top weight?
Eric Hartwell

Right Handed
PAP 4.75" up 1/2"
45* rotation
12* tilt
330 rev rate
16 mph off hand

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bowl1820
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Re: Pin to cg distance

Post by bowl1820 » December 26th, 2018, 7:57 pm

poloidrogo wrote: what is the reason some balls have 3 or 4 inches distance and this came to short.
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.

There's a article wrote by Nick Siefers called "MANUFACTURING PROCESS VARIATION: THE SMALLEST of SHIFTS CAN ALTER PIN DISTANCE and TOP WEIGHT" that explains it in detail.

"MANUFACTURING PROCESS VARIATION: THE SMALLEST of SHIFTS CAN ALTER PIN DISTANCE and TOP WEIGHT"
http://www.itbca.bowlingknowledge.info/ ... top-weight
"REMEMBER, it isn't how much the ball hooks, it's where."

poloidrogo
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Re: Pin to cg distance

Post by poloidrogo » December 27th, 2018, 10:24 am

EricHartwell wrote:Pin in or short Pin to Cg balls used to be very limited in how you could drill them. With the rules today allowing more static weight imbalance allows for more drilling versatility with such balls.

What is the top weight?
Hi Erick the top weight is 2.55

Thanks

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EricHartwell
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Posts: 3637
Joined: April 5th, 2011, 12:24 am
Positive Axis Point: 4-3/4" and 1/2"up
Speed: 16 off hand
Rev Rate: 330
Axis Tilt: 12
Axis Rotation: 45
Heavy Oil Ball: Radical Tremendous
Medium Oil Ball: Motiv Villain, Hammer Nail, Brunswick True Motion
Light Oil Ball: Blue Hammer, Columbia Nitrous
Location: Michigan

Re: Pin to cg distance

Post by EricHartwell » December 27th, 2018, 10:00 pm

poloidrogo wrote:
Hi Erick the top weight is 2.55

Thanks
With 3 oz of imbalance to work with this will not limit layout choices.
Eric Hartwell

Right Handed
PAP 4.75" up 1/2"
45* rotation
12* tilt
330 rev rate
16 mph off hand

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