Question about symmetric drillings and pins close to PAP

Which layout is right for me?

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infinitbrandon
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Question about symmetric drillings and pins close to PAP

Post by infinitbrandon »

When drilling symmetric balls, the PSA ends up near the thumb hole. Also, I know that after drilling, all balls are asymmetric. So my question is, why does the recommendations in the wiki, say that symmetric balls should be drilled in general with pins past 4"?

I'm thinking from this standpoint, if you assume that the PSA ends up dead in the middle of the thumbhole, based on the VAL angle, PAP location, pin distance and your span dimensions, you can calculate an approximate actual drill angle. For me, my sweet spot is 120* and my benchmark ratios are 2:1, which means for my control/long and strong, the drill angles need to be high/90*. So a control layout might look something like 90X2.25X50 on a asymmetric piece.

Now, I've calculated that if I do a 2" pin to PAP, using the same 50* VAL on a symmetric ball, I end up with the same drill angle. Assuming similar RG numbers, diffs and covers, how different would their reaction be. Would they both allow straighter play through the front with a slow continuous response? Would there be much difference in tilt retention?

I'm thinking maybe most haven't done this math, but with all the knowledge on here that doesn't seem likely. I'm thinking the only reason is that for a particular drill angle, and VAL angle combination, a symmetric will only give a single pin distance that fits the criteria for those angles. As you move the pin further, for a given VAL angle, the drill angle always decreases.

The other thought I had is just that for the average person who isn't rev dominate like me, the longer pin distances on symmetric balls give lower drill angles that allow the ball to start up in the right spot for those who are better speed/revs matched.

So in summary, why aren't symmetrical balls recommended with short pin-to-PAP distances?
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EricHartwell
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Re: Question about symmetric drillings and pins close to PAP

Post by EricHartwell »

infinitbrandon wrote:I'm thinking from this standpoint, if you assume that the PSA ends up dead in the middle of the thumbhole, based on the VAL angle, PAP location, pin distance and your span dimensions, you can calculate an approximate actual drill angle. For me, my sweet spot is 120* and my benchmark ratios are 2:1, which means for my control/long and strong, the drill angles need to be high/90*. So a control layout might look something like 90X2.25X50 on a asymmetric piece.
The PSA will end up approximately 6-3/4" from the Pin and 1/2" left of the centerline not dead in the middle of the thumb.
infinitbrandon wrote:Now, I've calculated that if I do a 2" pin to PAP, using the same 50* VAL on a symmetric ball, I end up with the same drill angle. Assuming similar RG numbers, diffs and covers, how different would their reaction be. Would they both allow straighter play through the front with a slow continuous response? Would there be much difference in tilt retention?
Yes they will both play straighter but the Symmetric will have a very quick response to friction at the end where the Asymmetrical will have the slow continuous response.
infinitbrandon wrote:The other thought I had is just that for the average person who isn't rev dominate like me, the longer pin distances on symmetric balls give lower drill angles that allow the ball to start up in the right spot for those who are better speed/revs matched.
The problem with this is the longer pin to PAP on Symmetricals are lower flare and this delays the core from helping the ball reaction.
with my PAP a Symmetrical layout with a 5" pin to PAP and 35* VAL produces a drilling angle of ~ 75*. Not what I would consider as lower. It is a low flare layout that needs a dull surface on a strong coverstock or lots of early friction to get started up in the right spot.
infinitbrandon wrote:So in summary, why aren't symmetrical balls recommended with short pin-to-PAP distances?
In short they loose tilt too fast and the carry suffers.

From personal experience the only success I had with short pin to PAP Symmetricals was playing the lanes very straight with low rotation.
You think it would be different for a high tilt bowler, but the length of the skid phase is counter productive with the skid phase being too long for them.
Eric Hartwell

Right Handed
PAP 4.75" up 1/2"
45* rotation
12* tilt
330 rev rate
16 mph off hand
infinitbrandon
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Re: Question about symmetric drillings and pins close to PAP

Post by infinitbrandon »

Eric thanks for the response. All your points were what I was anticipating/but couldn't find anything specific in writing anywhere.

However, when I mentioned longer pins produce lower drill angles, I didn't necessarily mean they produce low drill angles. However, I did assume the PSA stayed constant in the middle of the thumbhole for my ballpark calculations. I was essentially getting to the point that with that assumption, as you move the pin to the up and/or to the left, your drill angle starts to narrow. So longer pin distances, produce lower drill angles in symmetric than shorter ones with my assumption and the assumption both are using the same VAL angle.

I've been wondering if it would be a good idea for me to do because I'm a rev dominant, low rotation, high track bowler. However, it seems if it burns tilt too fast, it will just produce a hook/set reaction for me, since my tilt isn't that high to begin with.
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EricHartwell
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Re: Question about symmetric drillings and pins close to PAP

Post by EricHartwell »

infinitbrandon wrote:Eric thanks for the response. All your points were what I was anticipating/but couldn't find anything specific in writing anywhere.

However, when I mentioned longer pins produce lower drill angles, I didn't necessarily mean they produce low drill angles. However, I did assume the PSA stayed constant in the middle of the thumbhole for my ballpark calculations. I was essentially getting to the point that with that assumption, as you move the pin to the up and/or to the left, your drill angle starts to narrow. So longer pin distances, produce lower drill angles in symmetric than shorter ones with my assumption and the assumption both are using the same VAL angle.

I've been wondering if it would be a good idea for me to do because I'm a rev dominant, low rotation, high track bowler. However, it seems if it burns tilt too fast, it will just produce a hook/set reaction for me, since my tilt isn't that high to begin with.
So, yes you are understanding the how the resultant drill angles are being affected by the pin to PAP and VAL angles.

I would recommend going with a weaker coverstock ball over trying the short pin to PAP on a Symmetrical ball.
Eric Hartwell

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Re: Question about symmetric drillings and pins close to PAP

Post by Arkansas »

infinitbrandon wrote:When drilling symmetric balls, the PSA ends up near the thumb hole. Also, I know that after drilling, all balls are asymmetric. So my question is, why does the recommendations in the wiki, say that symmetric balls should be drilled in general with pins past 4"?
Where did you see this in the wiki? All of Mo's Simple Symmetrical Layouts use less than 4". As well as the Radical Suggested Symmetrical Layouts are mostly in the 3-5" range.
http://wiki.bowlingchat.net/wiki/index. ... trical.jpg" onclick="window.open(this.href);return false;
http://wiki.bowlingchat.net/wiki/images ... ayouts.pdf" onclick="window.open(this.href);return false;
infinitbrandon wrote:Now, I've calculated that if I do a 2" pin to PAP, using the same 50* VAL on a symmetric ball, I end up with the same drill angle. Assuming similar RG numbers, diffs and covers, how different would their reaction be. Would they both allow straighter play through the front with a slow continuous response? Would there be much difference in tilt retention?
A 2" vs 2 1/2" pin-to-pap won't have much difference on the lanes. The 2 1/2" pin ball will flare more, so it may be slightly earlier, but if you drill 2 balls like that expecting to see a difference you will be disappointed.

infinitbrandon wrote:I'm thinking maybe most haven't done this math, but with all the knowledge on here that doesn't seem likely. I'm thinking the only reason is that for a particular drill angle, and VAL angle combination, a symmetric will only give a single pin distance that fits the criteria for those angles. As you move the pin further, for a given VAL angle, the drill angle always decreases.

The other thought I had is just that for the average person who isn't rev dominate like me, the longer pin distances on symmetric balls give lower drill angles that allow the ball to start up in the right spot for those who are better speed/revs matched.
Keep in mind that it's really easy to make the drill angle smaller on a sym ball. The initial drill angle on a sym is mainly used for balance hole planning.

infinitbrandon wrote:So in summary, why aren't symmetrical balls recommended with short pin-to-PAP distances?
They would be recommended if you wanted an early, smooth, urethane-type reaction. I'm pretty sure that's how they've been recommended on here in the past.
James Talley
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