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Author Topic: Larger thumb holes for IT system, does it...?  (Read 5801 times)

xrayjay

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Larger thumb holes for IT system, does it...?
« on: November 03, 2013, 12:43:59 AM »
With a much larger thumb hole, I'm sure it changes the dynamics of the ball in some way. But, I'm not sure exactly how. I'm assuming some balls gain more and/or less flare ??

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mnicholl

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Re: Larger thumb holes for IT system, does it...?
« Reply #1 on: November 13, 2013, 06:22:17 PM »
I was just coming on to look up the same kind of question and saw yours. Do any of the drillers on here know or have an opinion? I was just working in our local proshop and realized we drill out a 4 1/8“ deep whole 1 7/16" in wide for the IT system. Easily to the middle of the core of the ball. This has to affect ball dynamics right? Is there something Im missing here??

Mike

tburky

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Re: Larger thumb holes for IT system, does it...?
« Reply #2 on: November 13, 2013, 06:29:29 PM »
it sure does change the dynamics

Aloarjr810

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Re: Larger thumb holes for IT system, does it...?
« Reply #3 on: November 13, 2013, 07:34:36 PM »
Mo Pinel on Interchangeable thumb and ball dynamics:
Storm, MoRich, and the USBC did a study comparing balls drilled with the interchangeable thumbs, with different sized slugs, and balls drilled without slugs. The difference in ball dynamics (mass properties) were within one standard deviation. Therefore, interchangeable thumbs, or slugs, make NO difference to ball dynamics.

The study I referred to was an empirical study, not a theoretical study. The results were verified three times. In my opinion, the results are very accurate. No change in the drilled mass properties when using slugs or interchangeable thumbs. Good enough for me and the USBC Equipment and Specs. Dept., who did the actual work on the study.
« Last Edit: November 13, 2013, 08:19:28 PM by Aloarjr810 »
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Matt Fortney

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Re: Larger thumb holes for IT system, does it...?
« Reply #4 on: November 13, 2013, 08:38:43 PM »
For what its worth, and to support the info found in the study, I recently converted my Raptor Talon from a normal 1 1/4" slug to an IT 1 1/4...zero difference in reaction whatsoever.

Matt

tburky

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Re: Larger thumb holes for IT system, does it...?
« Reply #5 on: November 13, 2013, 09:53:29 PM »
i stand corrected

BallReviews-Removed0385

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Re: Larger thumb holes for IT system, does it...?
« Reply #6 on: November 14, 2013, 09:10:19 AM »
I believe the ball manufacturers have taken the issue into consideration as they design their cores.  If you have an older ball you may (or may not) remove enough mass to effect reaction.  Each ball would be different based on layout and it's individual core design.

It was about 4 - 5 years ago (when changeable inserts were new to the market) Brunswick had a few returns on a certain ball.  I can't remember which one, but as they tested "why" it was determined that with a certain layout, etc., enough mass was removed to adversely effect the reaction.  Most balls were fine, but now they had to plan for this possibility.

They immediately started tweaking things to accommodate the extra mass removed by drilling so deep and large a thumb hole.  I would bet that every major manufacturer has taken similar steps.

I would not disagree with the above mentioned study, but no study could possibly test every possible ball and layout options.  The study can only report on the balls it tested and not on the ones it didn't...





« Last Edit: November 14, 2013, 09:15:53 AM by notclay »

Matt Fortney

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Re: Larger thumb holes for IT system, does it...?
« Reply #7 on: November 14, 2013, 03:38:35 PM »
I thought it would affect reaction, and maybe it does, in some tiny way I'm not good enough to notice, because the way I look at it, I'm drilling a 1 5/16 hole 3 1/2" deep...if that doesn't affect reaction then how do weight holes that are a lot of times smaller?

Aloarjr810

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Re: Larger thumb holes for IT system, does it...?
« Reply #8 on: November 14, 2013, 05:05:40 PM »
I thought it would affect reaction, and maybe it does, in some tiny way I'm not good enough to notice, because the way I look at it, I'm drilling a 1 5/16 hole 3 1/2" deep...if that doesn't affect reaction then how do weight holes that are a lot of times smaller?

One thing to remember is that after you drill the hole, your adding mass/weight back into the hole when you put the interchangable into the slot. So theres not that big of a change in the mass/weight

As for the weight hole your not putting anything back into it, also the location plays a big part with it.

Plus they didn't say it didn't change anything, just that the change was so small. it didn't make a difference.
« Last Edit: November 14, 2013, 05:16:57 PM by Aloarjr810 »
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Matt Fortney

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Re: Larger thumb holes for IT system, does it...?
« Reply #9 on: November 14, 2013, 06:04:44 PM »
Yeah that makes sense. I figured location played the biggest part.

minimum bob

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Re: Larger thumb holes for IT system, does it...?
« Reply #10 on: November 14, 2013, 08:12:09 PM »
I thought it would affect reaction, and maybe it does, in some tiny way I'm not good enough to notice, because the way I look at it, I'm drilling a 1 5/16 hole 3 1/2" deep...if that doesn't affect reaction then how do weight holes that are a lot of times smaller?

One thing to remember is that after you drill the hole, your adding mass/weight back into the hole when you put the interchangable into the slot. So theres not that big of a change in the mass/weight

As for the weight hole your not putting anything back into it, also the location plays a big part with it.

Plus they didn't say it didn't change anything, just that the change was so small. it didn't make a difference.

Not exactly.  According to your first post, the study merely said that the difference in ball dynamics were within one standard deviation.  Presumably, this is based on a mean difference of zero (which is the hypothesis being tested).  However, depending on how large the standard deviation is, even a statistically insignificant difference of one standard deviation (presumably plus or minus) can translate into a significant difference on the lane.  Do you have a link to the USBC study so that we can see the results?

Bob

Aloarjr810

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Re: Larger thumb holes for IT system, does it...?
« Reply #11 on: November 15, 2013, 08:14:30 AM »
No I don't have link to the study, I just quoted what Mo Pinel said.

So you'll have to ask him and argue the math with someone else.



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tommygn

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Re: Larger thumb holes for IT system, does it...?
« Reply #12 on: November 15, 2013, 08:41:22 AM »
To say that a very large and deep thumb hole that changes the shape of the core doesn't change ball motion, but a balance hole placed in the P1, P2, P3 ,or P4 position, and DOES change reaction, is complete contradiction. I will say this. ANY hole in a bowling ball will affect it. It may not change the ball enough to see a noticeable difference, but it will change it none-the less. To what degree of noticeable change of ball motion would be based on the style of the bowler.

https://www.buddiesproshop.com/images/Drill_Sheets/Gradient_line_balance_hole.pdf
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