Oval thumb drilling

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Positive Axis Point: 5 5/8 up 3/4
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Oval thumb drilling

Post by ads » November 1st, 2020, 3:18 pm

Came across this chart

http://wiki.bowlingchat.net/wiki/index. ... gguide.PNG

What do X and Y mean?

There are some references from this old post but not quite understand.

viewtopic.php?t=2709


Thanks.
Adrian
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PAP: 5 1/8 up 3/4
Speed: 15.5 mph (Kegel Specto)
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Axis rotation: 60*

MineralitePaul
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Re: Oval thumb drilling

Post by MineralitePaul » November 1st, 2020, 4:28 pm

“X” & “Y” are the mill table’s coordinates. X being the side-to-side and Y the front-to-back movements of the mill table and thus the ball jig mounted on it. The X & Y chart represents increments in thousandths of an inch, that must be added to the X & Y settings you made to the mill to achieve the pilot hole pitch, to get the ball to move under the bit to achieve the desired oval axis angle & width upon second drilling. Z represents the additional material thickness that needs to be cut at the oval angle to achieve the desired oval width.

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bowl1820
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Re: Oval thumb drilling

Post by bowl1820 » November 1st, 2020, 5:48 pm

heres a little graphic of the xyz axis directions
xyz.jpg
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Re: Oval thumb drilling

Post by MineralitePaul » November 1st, 2020, 11:50 pm

In that Chart, “Z” does not represent hole depth; it, unfortunately, is used to denote the oval width minus the first hole diameter - an unfortunate misuse of nomenclature

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Posts: 657
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Positive Axis Point: 5 5/8 up 3/4
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Rev Rate: 300
Axis Tilt: 15
Axis Rotation: 60
Location: Hong Kong

Re: Oval thumb drilling

Post by ads » November 3rd, 2020, 2:50 am

Thanks MineralitePaul and bowl1820.

See if I understand correctly. The thumb hole will be drilled twice, one with -x+y and then +x-y, or vice versa.
Adrian
Right handed
PAP: 5 1/8 up 3/4
Speed: 15.5 mph (Kegel Specto)
Rev: 350 RPM
Axis tilt: 18-20*
Axis rotation: 60*

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bowl1820
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Re: Oval thumb drilling

Post by bowl1820 » November 3rd, 2020, 3:23 am

This might be useful, Here you can see a oval thumb hole being drilled:

(They have this system here)
Jayhawk Tri-Oval System Demonstration
This is a short demonstration of how to drill a ball using the Jayhawk Tri-Oval including how to use the built in ovaling program.
"REMEMBER, it isn't how much the ball hooks, it's where."

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