Hey me too!
I've posted a little below(in drilling) on a concept I call release point spanning.
But here I'll be more direct. (None of the below is for the Kings of the mill or any other drilling gurus) it is intended for non drillers who like to read or to give ideas to discuss with your driller. Or it is intended for other guys who have the simplest jigs around(like me) and never thought they could drill ovals!(like me). TILL now!
THE PROBLEM
I always liked round thumbholes and then just add tape to turn the round into oval. Problem I needed about 6 to 7 pieces to turn a 31/32 round hole into an oval that was snug enough.
Then everytime I got an oval it seemed that the ball wanted to get off my hand early! In my relaease point spanning post I talk about how the release point which is in the right upper corner for a lefty(straight under middle finger) or upper left corner of the thumbhole for a righty(straight or near straight under middle finger) is shortened when one just puts in an oval insert.
Also this distance is shortened when one has a driller do what is called a symmetrical oval, the process a small bit that covers ones front to back distance of the thumb is drilled under the t grip center of the span and then a drill bit drills at the upper left corner for the righty and then also drills out the lower right hand corner for the righty. Driller also then puts these additional drills along a line that is for your proper thumb rotation in relation to the t grip line. 45 degrees seems to be a simple and common angle used by drillers. As it is easy to enter into the digital read out drill presses.
The symmetricly drilled oval I believe also shortens ones middle finger to release point span. And the greater the angle of rotation and the greater the amount of ovaling necessary the more the middle finger to release point span shortens.
The Solution
I then ran into a driller that drilled rear of hole ovaling only!
This concept is that the release point area of the thumb is left alone(no ovaling applied to the upper left hand corner of the righties thumbhole.
No instead we are going to only oval out the back of the thumb(the lower right hand corner of thumb for righties, lower left hand for lefties), thus getting the fit nice without screwing up the bowlers release!
Well this is it: fit with very little tape for the oval thumb. No change in the feel of the release point or need to change pitches if they are already good for you and the span is staying the same!
Types OF Drill Presses
I had always been told that to do ovals with a drill bit one needed the very top of the line equipment!! Ovalmatics, digital readouts etc.
I believed em.
Then the other day a guy did an oval for me and he and I were rushing in opposite directions quickly and I left without feeling it!
Got home not so good!
I said you know I'm going to try to fix this with my old fashioned manual jig with no digital readout. I was concerned immediately about a broken bit etc.
Suppossedly I don't have the right drill bits. Nor did I have a digital readout to get the table shifted perfectly they said.
But instead I found my standard carbide tipped drill bits had no problem biting right thru urethane slugs just like butter as long as the jig table was tightened very strongly. I would not try this on the ball surface (instead of a urethane slug nor would I try on a vinyl slug. Urethane ONLY with a standard jig!
The Simple Jig manual method to a beautiful oval!
Anyway I get home and I notice that the oval I have is a 45 degree angle to my T grip. Well I don't really like that. The front of my thumb seeks less angle than that(I notice from looking at the tape of my old round grips). In fact I realize my thumb front seeks an angle of about 33 degrees.
(This is a figure that Bullred that Luckylefty bustin son of a gun often talks about). Oh well I have to give him credit. I decide to go with that.
So on the next ball I go to drill. Oh yeah my thumb is about 55/64 from front to back and about 15/16 to 61/64 from side to side!
So I start under the grip center with a 56/64 bit or what we sometimes call 7/8!
Now I go to the backside of the oval(lower left corner for this lefty) and decide were gonna oval this surface up. Now if I switched my 56/64 drill bit 1/16 straight left into the ball, and then 1/16 straight down towards the bottom of the hole I will end up getting another 45 degree angle. (some out there might remember their sine tables from trigonometry(rise over run = 1 = 45 degree angle) For the really advanced a sine that equals .5 creates a 30 degree angle, ah...........soooooooooo, that is what those sine table rise over run tables were good for). Oh yes for you non builders of roofs!
So since I want a 4/64+ widening of the thumbhole at near a 30 degree angle I'm going to shift the ball so that the bit moves into the ball 1/16 left and 1/32+ downward. + is because I want slightly more than 30 degrees. Surprisingly easy to see!
Voila plunges with the drill bit and voila! As long as urethane a carbide tip cuts thru like butter!
A very interesting point! The way to know what your angle is going to be BEFORE one drills is easy! Even with this manual method. You see as one centers the drill bit slightly off center with the 1 to 1 or 1 to 1/2 move of the ball or table depending on angle wanted between 30 and 45(most common area of oval angle). All one has to do as one has ball in position where they think they are ready and have lined up perfectly is bring the drill bit down and almost touch ball holding it there with the little blue thingy(that is a technical term). NOW rotate the drill bit. Note the point where the drill bit covers the MOST deeply into the ball. In other words at one point the drill bit will cover more distance into the ball than at any other point!
STOP at this point and draw a line with your grease pencil extend a line from the flutes of your drill bit! This is the angle your oval is going to be created at. Is that what you want? If not go back and tweak the movement of the ball or table till a line extended from the flute of your carbide tip is at the exact angle you want at the point where it is covering the most distance in to the ball!! Oh yeah remember that distance is to be the maximum extension of your width extension of your first hole(in my case 1/16 of an inch or as we don't usually say in public 4/64s).
AWESOME. If you have a ball protractor you can dead zing this thing perfectly.
NOW we are done!
Oh not really. In my case I have a strange thumb and for some reason the back surface of my thumb wants the 45 degree angle. Simple. I go back and start at original hole(in my case the complete right border of the original hole is still there and make the appropriate 1 to 1 moves to act as though I am going to create a 45 degree oval.
NOW it is awesome!
33 degrees in the front, 45 degrees in the back 1 piece of tape front and back and the exact same release point span!
Second hole I did!
REgards,
Luckylefty
PS Now that's a meataball, er um I mean an oval!
Edited on 10/3/2004 1:41 AM
