To Oval or Not to Oval

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MrTweener2u
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To Oval or Not to Oval

Post by MrTweener2u »

I have been seeing a lot of people lately with really flat thumbs. It seems everytime the weather and seasons change I get this influx of thumb issues and its to be expected. But I want to know for the general bowler who is really flat, can they come out of a ball easier from a 45* thumb angle? I'm talking about people who are using oval thumbs for the first time.

Here is my oval technique and appreciate any and all corrections and comments.

1. I use digital calipers and measure the widest part of the thumb. example - .937

2. I then measure the flat part of the thumb to get my pilot hole. i.e. .867

3. I would use a 55/64 bit and cut at 45* using right and down for right handers until I achieved 15/16 width or .937

if I move the table 1:1 @ .021 it will .030 at a time. so I would need to make up .078 divide it by .030 = 2.6 cuts @ .011 .032 and .053

So for a first time oval thumb would 45* be appropriate? Of course using proper pitches. First timers have a hard time with ovals for obvious reasons.

But I'm concerned about the wiggle room the skinny thumb necks cause.

4.
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stan
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Re: To Oval or Not to Oval

Post by stan »

Although, most bowlers may fall into the 45 degree oval, some do not. I would suggest you check each bowler for the exact degree of oval they will need. There are various methods for doing this.

As far as drilling the oval, I use a Ovalmatic machine. I feel this is the best out there and doing ovals is extremely easy. Hopefully, some of the other guys that drill ovals like you will post back with any other suggestions that might be helpfull.
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MrTweener2u
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Re: To Oval or Not to Oval

Post by MrTweener2u »

I check the thumb angles and I use a sheet that is trigged out alread and then factor it.

Its the first timers that are the most problematic as they don't come out of the ball the same way everytime and oval requires you to do.
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Vendetta
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Re: To Oval or Not to Oval

Post by Vendetta »

For first time ovals we determine the appropriate "degree" and then measure the thumb with the calipers as you have stated to establish the pilot hole and width of oval. Our shop has a vacu-jig with a digital read-out. We set the pitches and drill the thumb pilot hole (we drill thumb hole first). We then set the digital to .000 for both pitches. Using the WIKI oval thumb chart we set the vertical and horizontal numbers for our required oval. We usually make two cuts for the oval:

A 45 degree oval at .030s for a right hander would be (+).021 vertical (y axis) and (-).021 horizontal (x axis) for one cut and then (-).021 y axis ... (+).021 x axis for second cut. For a left hander our vertical & horizontal values would both be positive for one cut and both be negatiove for the second cut.

For wide ovals (.090 - .120) we use multiple cuts, but in one direction (right hander: (+) x axis; (-) y axis) to "smooth out" the ridges in the hole.
militant02
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Re: To Oval or Not to Oval

Post by militant02 »

not to rehash this topic but i was about to post a similar question. i use a 55/64 thumb hole in the winter but need a 7/8 round thumb hole to clear my thumb in the summer. my shop lets me drill my own equipment and i would like to try an oval thumb for a better fit.

how do you determine the angle of the oval that is needed?. also, is .030 the normal amount that i should move the press because i'm not sure if they have calipers anymore.
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Re: To Oval or Not to Oval

Post by StrikeTheory »

You need to put your thumb in the ball, and look at how it lies in the hole.

A quick and dirty on doing it with limited tools:

Draw your center grip line on the ball, draw one perpendicular do this line through the center of your thumb hole. Now you have 0 degrees, and 90 degrees marked on the ball.

Put your hand in the ball, and draw a line on each side of the thumb. Line up a flexible protractor with your 0 and 90 degree lines to see where your oval angle lies in that range.
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Re: To Oval or Not to Oval

Post by militant02 »

ok, i understand that part. another question, is it normal for to try to oval the back of the thumb in addition to the x and y axis? i had someone do that without actually measuring the height of my thumb.
StrikeTheory
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Re: To Oval or Not to Oval

Post by StrikeTheory »

If you are taking more out of the back of the thumb, then you are changing the pilot hole size.
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Re: To Oval or Not to Oval

Post by militant02 »

ok thanks. i'll see how it goes later on this week.
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Re: To Oval or Not to Oval

Post by Nsane »

the easiest way to get the perfect coordinates for a oval thumbhole is to use the ovalcalc. Downloadable from http://bowlingtrainer.topschi.de/compon ... erial.html.
poor english Sorry, but works perfect!!!

Thomas

PS:
is it normal for to try to oval the back of the thumb in addition to the x and y axis? i had someone do that without actually measuring the height of my thumb.
its not possible to drill a accurate thumbhole without measure the height oif the thumb.
Tha datas you need are: width, height and angle.
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Ducati what else?
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