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Oval thumb drilling

Posted: November 1st, 2020, 3:18 pm
by ads
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.

Re: Oval thumb drilling

Posted: November 1st, 2020, 4:28 pm
by MineralitePaul
“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.

Re: Oval thumb drilling

Posted: November 1st, 2020, 5:48 pm
by bowl1820
heres a little graphic of the xyz axis directions
xyz.jpg

Re: Oval thumb drilling

Posted: November 1st, 2020, 11:50 pm
by MineralitePaul
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

Re: Oval thumb drilling

Posted: November 3rd, 2020, 2:50 am
by ads
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.

Re: Oval thumb drilling

Posted: November 3rd, 2020, 3:23 am
by bowl1820
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.