Hello all,

We have an Innovative Drill with the suction cup to hold the ball and digial scales for the pitches.

We also have flat headed mill bits.

However, we have yet to find a good way to figure out how to mill the holes, usually make them too big.

A friend of mine just gave us a couple of micrometers to use.  When I measure the width of my thumb |------| I get .900, but could get away with being as low as .885.  The other measure of my thumb thumb nail side to pad side is around .790..  So, with those measurements, and an oval degree of 35 or so..  I cannot remember exactly, I am not in the proshop..    What do I do with those numbers?  

Also, someone sent us an oval chart for interchangable thumbs, According to those numbers, which do I use to get the oval size?  An example is a size 57 is 0.890 and 0.796 (the width and height of the thumb)

What we do is take the two measurements and subtract them from each other. The number you get is the amount that you need to move the mill to cut that part off the oval. You need to mill out .110 off the thumb. Im not sure how your press works, but with my press (Oval-Matic, no Vaccu suction) we drill out the regular circular hole, then rotate the jig to 35 degrees to the right. Then i would move the lateral (left/right) gauge one full turn and then .01, which would be going from 1 to 2, or 2 to 3, etc. Then you mill out that much and off you go.
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Bowler, I understand that, we use a VaccuJig, cannot rotate the ball like you describe..

my thumb is not shaped normal from alot of bowling..its 3/4 at nail or pad and is 1 inch at widest pt from side to side..it is 5/8 measuring from front to back at pad and 1 inch right past knuckle at widest pt(from squeezing a callus)..i would love to find a way to drill my thumbholes where it doesnt feel like there is so much play down in my thumbhole where the pad of my thumb sits..
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You have to dril the oval based on the largest size of your thumb.  That is front to back and side to side, not at the nail.  The measurement should be around your middle crease.  This may be a bad assumption, but I assume the calus on your thumb is probably near the side to side measurement.  You may have to include this size as your side to side measurment, unless it is in a different spot.  I have an ovalmatic and not the type of jig that you do.  Use your inside calipers to measure the circle hole.  Then using the conversion chart, as someone alreay mentioned, get your oval coordinates and drill it to you side to side measurement, again checking with the caliper.  when you are done, the hole front to back should equal your front to back measurement and the oval part should equal your side to side measurements.

do not make the oval to tight, you will hang up especially if this is your first oval.  Once your calus goes down, modify your side to side measurements accordingly.  Get use to using the inside caliper, this is the only way you can accurately drill out an oval.

Good Luck

I should have assumed the numbers were the fraction for the drill bit..  Duh...  


But what size do I use for the pilot and which do I use for the mill?

I am totally clueless...  Which is why I usually just drill my own stuff  

Edited on 7/31/2007 8:23 PM

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