Author Topic: why do drillers tend to taper thumb holes (Read 9417 times)

Neptune66 · « **on:** April 28, 2011, 05:21:45 AM »

Happens alot to me. I buy a ball or have one redrilled, and the driller (if he's not familiar with how fussy I am) drills the thumbhole so that it's bigger at the top of the hole than at the bottom.

Drives me nutz, cause when I want to add tape to firm up the fit at the top of the hole, the thumb is too tight further down. And when I take tape out, the ball is too hard to hold onto.

For years I had a driller who understood what Iwanted and drilled the hole and did very minimal bevelling. But that driller has since relocated and it's hit or miss with the successors.

Is there some kind of code word to signify to all drillers that I want the thumbhole to be a perfect cylinder? Not a cone shaped hole (it's not that severe, but that IS the shape).

milorafferty · « **Reply #1 on:** April 28, 2011, 01:25:40 PM »

I used to have the same problem. I now have the interchangeable thumb installed. It takes the drilling out of shaping the thumbhole.

The Ballreviews Ignore User feature, Learn it, Love it, Live it!

Dan Belcher · « **Reply #2 on:** April 28, 2011, 01:26:35 PM »

...just tell him exactly what you told us before he punches any holes in your ball? Just be as detailed as possible -- don't expect the driller to read your mind.

Also, molds or interchangeable thumbs are great if you are indeed "fussy" about how your thumb feels. I've been using the Vise IT system for a couple years now and love love love it.

Nails · « **Reply #3 on:** April 28, 2011, 01:29:07 PM »

Are you sure that's what's happening? Unless he's got a neat trick, they punch the drill bit the whole way down, so that the top and bottom should be the same diameter. I read a tip on here about tapering thumb holes because most people's thumbs are fatter at the base than at the nail, but it takes a lot more effort than simply punching the bit the whole way down.

Actually I re-read what you posted. If you're just talking about excess beveling at the very top of the hole, do what the others suggested and simply tell the driller to just gently tap the opening with the sander so that there's no sharp edge that could lead to cracking.

Telling it like it is.

Edited by Nails on 4/28/2011 at 1:31 PM

Cobalt Bomb · « **Reply #4 on:** April 28, 2011, 01:43:49 PM »

Are you getting an oval thumb hole or round hole drilled? Sometimes the drill bit will deflect when drilling ovals due to the side load.

12X · « **Reply #5 on:** April 28, 2011, 02:04:46 PM »

I told my ball driller just drill the thumb hole and I'll do the rest as far as beveling and oval opening.... I am using sand paper. I know it will take time but it worth it.

PrecisionFit46 · « **Reply #6 on:** April 28, 2011, 02:15:35 PM »

Either get a mold made of your favorite thumb and have inserts made for each ball or learn to work out and bevel your own equipment. Just tell the operator to only drill the hole and that you will finish it off yourself. If you are going with a mold I would ask the pro shop what kind of mold and plug material they are using.

The molding material from Exactacator (VISE) is terrible....it shrinks significantly over time and you will need to get new ones made. As for the slug material, the Ultimate Wizard Plug has oil added to it and will leave a residue or leak out of the insert creating a weird slippery feeling in the thumb.

There is a company called Pro Edge Bowling that makes longer lasting and faster setting mold material (15 minutes) and a urethane based plug for the inserts that always have the same texture.

Good Luck

Xx 12 X 300 xX · « **Reply #7 on:** April 28, 2011, 02:18:23 PM »

Learn how to bevel it yourself, that is the answer to your problems. It sounds to me your driller is opening up the top too much with the bevel and you do not like it. Bevel is a very fickle part of drilling a bowling ball, and the least amount of bevel should be used for a customer. Some drillers go overboard with it, because they span bowlers too long.

As a side note, a drill bit if sharp goes into the ball in a perfect round shape. If the bits are dull, the bit can move a bit and create areas where the hole is not perfectly round. Also if they drill to FAST you can get this. It's ideal to go nice and slow and peck drill holes so the bit does not wander off course and create a strange feel.

When making ovals, there are some techniques that cause the hole to get a slight taper. It's best to drill ovals with end-mills instead of using a regular drill bit. Same principle as above. The bit will wander some and create a slight taper. End-Mills are expensive and most drillers do not use them, or only have selected sizes in them.

Edited by Xx 12 X 300 xX on 4/28/2011 at 2:19 PM

Neptune66 · « **Reply #8 on:** April 28, 2011, 02:32:49 PM »

Thanks. I thought you were all going to say I was nutz for preferring no bevel.

I usually DO tell the driller that I do not want any bevel ----or almost none at all (just enough to smooth the edges). Unfortunately, I tend to forget that I am in the minority in that preference and forget to speak-up or remind the driller of this. I understand the default is to bevel it. I just find it very frustrating that this is the case and that the burden is on me to remember it.

I do not have the thumb hole ovalled. I actually turn the ball somwhat while my thumb is still in it, so this is another reason I want the whole to be perfectly round. And my thumb is unfortunately an apparent exception to the norm, in that the base of my thumb is quite a bit narrower than the middle of it. Course that's because of the callus built up around the middle. But even on my non-bowling hand the thumb is not any wider at the base....just the same all the way down.

I did go to a pro-shop today, and he used a power tool with a long stem and a little round cylinder at the end of it, slightly larger in diameter than the stem. He used that tool to widen the botttom of the hole somewhat. Won't know till tonight if it worked, but it appears to at least be on the right rack (vs the spinning wire thing that is used fro beveling that always messes up my fit, no matter how sparingly they use it.

Am curious if I could get one of those tools to use on the bottom of the holes myself, but don;t know what the proper name would be for it.

Xx 12 X 300 xX · « **Reply #9 on:** April 28, 2011, 02:44:19 PM »

Because it's wider at the top, your thumb now goes deeper into the ball, thus you feel what you call "taper". What he is doing is using a mandrel with a sanding sleeve it sounds like to open up the bottom of the hole to remove the taper feel. This might make the bottom of the hole too big.

It sounds to me like your getting deeper into the thumb and now that lower part of the thumb is too tight because your thumb is getting deeper in. Next time have your ball driller eliminate the bevel and any finish work and have him do it on site while your there.

Alot of the top rate drillers, who spend some time on education will drill the ball and carve it so your thumb seats deeper into the ball. This creates a new feel, that the bowler might not like if they are accustomed to a feel.

The way it is taught now is less bevel and more carving to create the exact shape of the thumb. You then either make a mold of that thumb or you have to have your driller do it exactly the same every time.

Neptune66 · « **Reply #10 on:** April 28, 2011, 03:18:43 PM »

Well.. even if the hole is a little too big, at least I'll be able to use tape to snug it up. Problem with the tapering is putting tape in, improves the fit at the top of the hole, and ends up pinching the nail part of my thumb, cause that part of the hole is smaller. Taking the tape out results in dropping the ball every 3rd shot or so. Putting it back in, causes discomfort or hanging up.

In the past, I have tried putting some tape just at the top of the hole, and this helped. But why should anyone have to resort to such a measure when simply drilling the hole and leaving it [mostly] alone accomplished the same fit.

Wilbert · « **Reply #11 on:** April 28, 2011, 05:05:42 PM »

I think a taper could be caused by runnning the sander just on the top of the hole. I agree, as previously mentioned, that it could also be caused by the drill bit moving when drilling an oval hole.

Another possible cause is that an taper predrilled insert was placed in the ball. (Do you know if it is solid insert or predrilled insert in your ball?)

Weaser · « **Reply #12 on:** April 28, 2011, 06:18:27 PM »

Ebonite sells a workout tool which you referenced. Bowlingball & Buddies (to name a few) offer it. A circular rasp is also available.

Gary
Proud Member of the Track Legion
Tag Team Coaching Success Story

Edited by Weaser on 4/28/2011 at 6:18 PM

solid9 · « **Reply #13 on:** April 28, 2011, 08:10:19 PM »

If the span and pitches are correct, you should be able to throw it, right off the press.

Bevels should only be used for comfort, not a a bad ball fit.

JohnP · « **Reply #14 on:** April 29, 2011, 07:34:44 AM »

The key here is communication. Tell your driller what you want every time. Don't assume he will remember from the last ball he drilled for you. He's done a lot of balls since then, and memories are not always reliable. I would want a customer like you present when I do the finishing touches on the holes so you can feel it as I work it out. -- JohnP

Author Topic: why do drillers tend to taper thumb holes (Read 9417 times)

Neptune66

why do drillers tend to taper thumb holes

milorafferty

Re: why do drillers tend to taper thumb holes

Dan Belcher

Re: why do drillers tend to taper thumb holes

Nails

Re: why do drillers tend to taper thumb holes

Cobalt Bomb

Re: why do drillers tend to taper thumb holes

12X

Re: why do drillers tend to taper thumb holes

PrecisionFit46

Re: why do drillers tend to taper thumb holes

Xx 12 X 300 xX

Re: why do drillers tend to taper thumb holes

Neptune66

Re: why do drillers tend to taper thumb holes

Xx 12 X 300 xX

Re: why do drillers tend to taper thumb holes

Neptune66

Re: why do drillers tend to taper thumb holes

Wilbert

Re: why do drillers tend to taper thumb holes

Weaser

Re: why do drillers tend to taper thumb holes

solid9

Re: why do drillers tend to taper thumb holes

JohnP

Re: why do drillers tend to taper thumb holes