Oval thumbholes

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Nsane
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Joined: June 15th, 2010, 5:01 pm
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Positive Axis Point: 5 3/16 - 7/8 up
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Oval thumbholes

Post by Nsane »

Can anybody explain me how to drill oval thumbholes. When i type the needed Datas in the Ovalcalculater i get numbers. Sometimes up to 5 cuts.

For example:

Thumb height : 13/16" thumbwidth: 29/32" holeangel 20°

The Oval-Calculator says: 2 cuts: 0.40 hori. 0.23 vert, final cut: 0.13 h, 0.06v


My questions;
Where to put the first Drill? On Centerline or shifted mayby left for righthanded to get the total hole centered?

What drillpit do i use in this case, 13/16?

And what is the diffrence between Ebonite and IBPSIA oval calculation.


kindly
Nsane
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The Kid
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Joined: July 30th, 2010, 5:26 pm
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Re: Oval thumbholes

Post by The Kid »

I must use the old school method. I use increments of .030 inches. At 45* that's .021 right and reverse (for a right-hander) for each cut. So I can't give an answer for your whole question.

However, I do know you use the smaller bit. In your case, that is the 13/16" like you thought.

From my experience (which isn't ages, but a couple of years), drilling the first cut slightly left of center is preferable to most bowlers. I normally just drill the first cut directly on the center line. Not sure which way is the "professional" way.

Hope this helps some! Here's a chart. Page 18. Sorry I couldn't find one easier to read.

-Steven
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Nsane
Certified Coach
Certified Coach
Posts: 650
Joined: June 15th, 2010, 5:01 pm
THS Average: 190
Positive Axis Point: 5 3/16 - 7/8 up
Speed: 17
Rev Rate: 300
Axis Tilt: 13°
Axis Rotation: 55°
Heavy Oil Ball: Brunswick Tenacity, Radical Tremendous
Medium Oil Ball: Guru mighty,
Light Oil Ball: Motiv venom cobra
Preferred Company: Radical
Location: Germany

Re: Oval thumbholes

Post by Nsane »

Super Steven it helps me a lot and the sheet gave me answers on questions i plant to make it here like "ajusting the Jig" and so on.

1000 Thanks for you. i´m always open for Sheets like this or for other tips´n tricks.

Mayby others can tell us theres way to drill ovals. I guess the more you read or hear the more you´ll know. Knowledge is the key to success!!!!
Again it is very important for me to be able to drill Ovals, because here in the closer Area (1 hour ambit ) is only one who can drill ovals. We are here in a Ovalhole "outback".

THX a lot


Nsane
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Ducati what else?
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