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Author Topic: Drilling angle for symmterical balls  (Read 5873 times)

1fife

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Drilling angle for symmterical balls
« on: February 04, 2016, 01:15:03 PM »
I know people have

what MB to use for symmetrical ball drilling angle

1-used a line from pin through cg   6 3/4 away to find mb
2-use center(to front edge) of the thumb hole for mb on symmetrical balls
3-use a determinator to find actual mb(which may change once thumb hole is drilled)


I would think 2 and 3 would be the most accurate way

it will probably be 2, but with weighthole 3 might be the best way to measure

and method 1 would be old school way-outdated

am I wrong in my thinking?

 

Aloarjr810

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Re: Drilling angle for symmterical balls
« Reply #1 on: February 04, 2016, 01:52:45 PM »
#1 is what you'd do on a UN-drilled sym. ball.

#3 is the best for the drilled ball

According to Mo:

The PSA almost always ends up 6 3/4" +/- 1/2" from the pin approximately on the centerline of the grip to 1" left (for right handers) of the centerline of the grip. The reason we go thru the cg for the base line is that the cg influences the size of the balance hole. A balance hole will move the PSA towards the balance hole after the hole is drilled, therefore moving the PSA toward its intended spot. What we can do as an approximation is use the thumb hole as the PSA when drawing the "Gradient Line" to locate the balance hole.



« Last Edit: February 04, 2016, 01:58:38 PM by Aloarjr810 »
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1fife

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Re: Drilling angle for symmterical balls
« Reply #2 on: February 04, 2016, 01:59:50 PM »
But

For number 1, if you Layed out a ball, the drilling angle will not be correct

As a weight hole will usually shift mb toward weighthole
« Last Edit: February 04, 2016, 02:01:57 PM by 1fife »

cory867

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Re: Drilling angle for symmterical balls
« Reply #3 on: February 05, 2016, 07:15:13 AM »
the MB moves on every ball once drilled whether its symetrical or asymetrical.  You drill it with the drilling angle on all balls pre-holes.  You do not drill it by predicting where the MB will move to.  Someone that thinks that way reads to much about drilling and has never done it themselves.
- Cory

1fife

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Re: Drilling angle for symmterical balls
« Reply #4 on: February 05, 2016, 07:45:13 AM »
BUT

in reality if you wanted to compare balls after drilling, wouldn't that be more accurate?

kidlost2000

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Re: Drilling angle for symmterical balls
« Reply #5 on: February 05, 2016, 08:21:20 AM »
1. listed above is for layout purposes only on a symmetric ball to make it easier to do while using the dual angle layout method. It's actual reference to the psa isn't a factor but more so on the cg location and the need for a possible weight hole later.

The point written above by Aloarjr810 about the ending location of the psa on a symmetric ball is your most accurate way of guesstimating. The end results is the psa will always be in the direction of the thumb hole on a symmetric core ball. Even when adding a large weight hole out towards the vertical axis line the psa will only move slightly.

Most cases the high rg axis and the low rg axis move in the area of 3/8" or less from undrilled to drilled. So on any symmetric core ball already drilled, take a prosect and draw a line 6 3/4" from the pin through the thumb and mark the area. You will be close enough.

A great way to see this in action and better learn for yourself is by down loading a free trial version of the blueprint software.


http://blueprintbowling.com/
…… you can't  add a physics term to a bowling term and expect it to mean something.

scotts33

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Re: Drilling angle for symmterical balls
« Reply #6 on: February 05, 2016, 09:11:33 AM »
Pic of my LM Ultimate Power with designation of how far the PSA moved before and after a P2 hole was drilled. 

Scott

1fife

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Re: Drilling angle for symmterical balls
« Reply #7 on: February 05, 2016, 10:25:10 AM »
but

look how far mb moved from

before drilling(through 6 3/4) and where it was after drilling(before weight hole)

scotts33

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Re: Drilling angle for symmterical balls
« Reply #8 on: February 05, 2016, 10:27:43 AM »
but

look how far mb moved from

before drilling(through 6 3/4) and where it was after drilling(before weight hole)

That's why I posted it.  Most can't picture the PSA moving much if at all.  The Ultimate Power was helped quite a bit in that it is a low end LM ball with low total diff.   A DeTerminator is a great tool for PSO's. 
Scott

1fife

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Re: Drilling angle for symmterical balls
« Reply #9 on: February 05, 2016, 10:50:23 AM »

how deep was the hole?

scotts33

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Re: Drilling angle for symmterical balls
« Reply #10 on: February 05, 2016, 11:35:19 AM »

how deep was the hole?

I believe if memory serves 5/8" x 3". 
Scott

1fife

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Re: Drilling angle for symmterical balls
« Reply #11 on: February 05, 2016, 11:39:11 AM »
figured it had to be pretty deep

JohnP

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Re: Drilling angle for symmterical balls
« Reply #12 on: February 05, 2016, 11:53:33 AM »
When drilling symmetricals I use the old pin to PAP and pin to cg method to locate the PAP, then the angle of the VAL to complete the layout.  The pin to cg used will position the cg for potential use of a balance hole.  The post-drilling psa location will be near the thumb hole, and will set the true drill angle, which will be always be the same for a given PAP unless a balance hole is added. --  JohnP