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 Post subject: Effect of USBC's Rule Change Eliminating Balance Holes
 Posted: Wed Sep 19, 2018 2:37 pm Post Number: #1 Post
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The following quotes were taken from viewtopic.php?f=13&t=6000

kellytehuna wrote:
That's actually a common conclusion once people see that the drilling angle doesn't work quite the same on syms. However, the DA system is still effective for syms. The drilling angle on syms allows us to put the CG in favorable positions for balance holes we intend to use. More often than not, you will see us recommend a hole 2" down the VAL from mid line to help pull the PSA from the thumb hole toward the balance hole thus lowering the effective drilling angle getting us much closer to our intended drilling angle.


kellytehuna wrote:
I think the nomenclature is pretty clear. The problem is understanding the concept. You will notice that everyone who is comfortable with the concept of the PSA ending in the thumb hole (or very close to it) on syms before the use of a balance hole will ALWAYS make recommendations for a balance hole as well. It's rare to see a layout recommendation for a sym on these boards that doesn't include a balance hole placement as well.


MegaMav wrote:

The FINAL drill angle is relevant in symmetrics.
You will only find the final drill angle with a determinator, or by an educated guess based on experience with a determinator and hole depths.

6 3/4" Pin thru CG is merely a reference line, not the true drill angle.
"The PSA on a drilled symmetrical ball without a balance hole falls 6 3/4" from the true low RG axis about 1/2 from the center of grip line"




My questions are as follows:
Since the drilling angle on a symmetrical ball is chosen to put the cg in a favorable spot as to allow balance holes to be used to achieve the desired ball reaction will the drill angle now be less important in achieving desired ball reaction since balance holes will soon be illegal?

Will the drill angle now be used to determine where the first transition occurs only or is there a way to manipulate the drill angle specifically or dual angle method as a whole to take advantage of the increase in static weights?

With regards to the third quote I am curious as to what effect if any having neither a balance hole nor a thumb hole will have on the final location of the PSA on a symmetrical ball and how much of a change does it have on the true drill angle as opposed to the drill angle of an undrilled ball?

TIA Jason


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 Post subject: Re: Effect of USBC's Rule Change Eliminating Balance Holes
 Posted: Sat Sep 22, 2018 1:04 pm Post Number: #2 Post
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If there is a place where this can be found please direct me there.

Jason


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 Post subject: Re: Effect of USBC's Rule Change Eliminating Balance Holes
 Posted: Sat Sep 22, 2018 1:26 pm Post Number: #3 Post
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This should answer your question:

The PSA in a drilled symmetrical ball without a balance hole will be located 6 3/4" from the Low RG axis within 1/2" of the center line.
This is true before and after the rule change.
Contrary to even Mo & Radical, the PSA will not always end up in the thumb hole.
No idea why they're saying that, it isnt true, anyone with a determinator can tell you that.
Not that it matters, because you cant do anything to move it soon.

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 Post subject: Re: Effect of USBC's Rule Change Eliminating Balance Holes
 Posted: Sat Sep 22, 2018 1:59 pm Post Number: #4 Post
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Bluelobstor wrote:
My questions are as follows:
Since the drilling angle on a symmetrical ball is chosen to put the cg in a favorable spot as to allow balance holes to be used to achieve the desired ball reaction will the drill angle now be less important in achieving desired ball reaction since balance holes will soon be illegal?
Without a balance hole the Drill Angle will be about the thumb hole as MegaMav explained on Symmetrical balls. After this season gone are the days when you could manipulate the drilling angle on Symmetricals. Now you will have to adjust the surface to get the desired reaction. It make surface prep more important.

Will the drill angle now be used to determine where the first transition occurs only or is there a way to manipulate the drill angle specifically or dual angle method as a whole to take advantage of the increase in static weights? More research needs to be done on the affect of static weights. All the data so far only hints at the fact that static weight makes a difference.

With regards to the third quote I am curious as to what effect if any having neither a balance hole nor a thumb hole will have on the final location of the PSA on a symmetrical ball and how much of a change does it have on the true drill angle as opposed to the drill angle of an undrilled ball?
An undrilled truly Symmetrical ball will not have a drill angle or PSA. Many Symmetrical balls will spin up and show a PSA on a determinator but the spin time will be very high and the strength of that PSA is small enough the Manufactures are not required to mark the PSA.
I think it would be a good idea to spin an undrilled Symmetrical to see IF it has a PSA prior to drilling for a no thumber. Recommendations for the no thumb drillings was to drill the fingers deeper to help stabilize the PSA. The gripping holes need to go into the core to change its properties.


TIA Jason

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 Post subject: Re: Effect of USBC's Rule Change Eliminating Balance Holes
 Posted: Sat Sep 22, 2018 8:35 pm Post Number: #5 Post
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Thanks MegaMav and Eric this is what I was looking for.

Jason


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