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Author Topic: PBA Span Measurements  (Read 2500 times)

Aloarjr810

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PBA Span Measurements
« on: June 11, 2012, 08:24:43 AM »
While researching info on spans, I ran across this on a pic. of Norm Dukes layout
"The PBA measures the span 5/16" off the center line at the finger holes."


So why doe's the PBA measure the span 5/16" off the center line at the finger holes?

and is that span measurement the same as what you would have measuring from hole to hole.



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Bowling 300 900

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Re: PBA Span Measurements
« Reply #1 on: June 11, 2012, 09:18:50 AM »
I believe it's just a standard reference point when measuring and drilling the finger holes.

From my experience with a few guys who drilled on the PBA truck,  they like to drill the thumb hole 1st and then drill the fingers.   They measure out the lines ahead of time and use the 5/16th or some other reference intersecting point for the finger holes.

For instance when I drill my own balls, I like to use 1/2 of the finger size from the bridge line.  This would put the span line right in the center of the finger hole. 

Some guys do it different.  Not sure where the 5/16ths came about, but somebody else maybe able to explain that better.

Russell

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Re: PBA Span Measurements
« Reply #2 on: June 11, 2012, 12:52:17 PM »
It has more to do with keeping the finger pitches true to the angle the hand is sitting in the ball.  Some shops do this and refer to it as a Center Line Transfer.  In all reality to every bowler on the planet it doesn't really matter (IMO).  It's just a way to keep things uniform for those guys.

Bowling 300 900

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Re: PBA Span Measurements
« Reply #3 on: June 11, 2012, 01:06:24 PM »
The CLT would be the 1/8Left offset and the 5/16th measured off the center line?   I guess the 1/8th L and the combination of spanning the fingers at 5/16th from the center line makes the CLT.


Maybe it's just a Norm Duke thing.   The article is a bit miss leading as it implies that the PBA drilling truck uses the 5/16th reference point on all of the balls they drill.

It must be a Duke thing, because non of the other articles in the series mention a 5/16th measurement.   
« Last Edit: June 11, 2012, 01:15:41 PM by Bowling 300 900 »

Russell

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Re: PBA Span Measurements
« Reply #4 on: June 11, 2012, 01:43:33 PM »
Huh....you're right didn't notice that at the bottom....I'm not sure what that is exactly then.  The span is just that...the span...the distance between whatever holes you are measuring from.  If there is an "offset"...the geometry would still put the holes in a certain location...or at least I would think.

The CLT would be the 1/8Left offset and the 5/16th measured off the center line?   I guess the 1/8th L and the combination of spanning the fingers at 5/16th from the center line makes the CLT.


Maybe it's just a Norm Duke thing.   The article is a bit miss leading as it implies that the PBA drilling truck uses the 5/16th reference point on all of the balls they drill.

It must be a Duke thing, because non of the other articles in the series mention a 5/16th measurement.   

sabman

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Re: PBA Span Measurements
« Reply #5 on: June 11, 2012, 09:51:13 PM »
It just creates a consistent span measurement regardless of bridge width.  Nothing more.  The picture illustrates that very well.  Notice the span lines aren't touching the actual finger hole edges, but instead the horizontal tangent line to the finger hole edges 5/16th from the center line.

Aloarjr810

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Re: PBA Span Measurements
« Reply #6 on: June 11, 2012, 09:59:12 PM »
Thanks for the replies, I'm going to keep looking to see if I can find anyplace where they mention doing that other than this example.

Somehow I get the feeling it doesn't have to do with a center line transfer it might but...
Aloarjr810
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