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 Post subject: Re: The core hitting the pocket...
 Posted: Wed Oct 10, 2018 5:36 pm Post Number: #21 Post
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stevespo wrote:

The pin rarely stands perfectly vertically, but the ball is generally trying to do this, it just doesn't have enough time. That's why I said "somewhat".

I also think it depends on the bowler and the ball. When I use a long pin to PAP and with my lower tilt and forward roll, the pin is standing pretty tall at the pins. Contrast this with people who spin the ball. For most people that low RG axis is somewhere between horizontal and vertical, but anything above horizontal should have more gyroscopic inertia. Core shape and asymmetry also factors in. Or so my simple mind likes to think.

Steve


The location of the Low RG axis (riser pin) to the bowling lane, i.e. vertical, horizontal, in-between, will be entirely dependent on what RG contour the PAP of the bowler throwing the ball starts on and how far the PAP precesses, which will depend on the bowl speed/rev rate relationship.

The location of the Low RG axis at pin impact is essentially a pointless marker. You could just as easily look at the location of the thumb hole and gather the same amount of useful information.

The reason people want the ball in the roll phase when entering the pins is because at that point the ball is on a straight line path and will have less deflection. It has maximum traction.

You can think of the three phases like this:

The skid phase it's like driving on ice with ice tires. You can turn the wheel any direction and it won't impact the direction of the vehicle. A bump will easily change your direction. The hook phase is like driving in the rain with good tires making a turn. You're steering the vehicle, but not as well as in good weather. If you hit a bump, it is harder to recover than in good weather, but easier than on ice. The roll phase in like driving on a nice dry road with good tires. Bumps in the road don't as easily effect your direction.

Hitting the pins is like hitting a big bump in the road. If the ball is skidding it will have a big deflection, if it's hooking it will have less, and will have minimum deflection when in a roll.

Of course, where you hit the pins has a dig impact on deflection as well, but the above scenario is an all other things constant type of scenario.

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 Post subject: Re: The core hitting the pocket...
 Posted: Thu Oct 11, 2018 12:10 pm Post Number: #22 Post
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stevespo wrote:

Nice video.... i think we are describing different things, or we interpret them differently. For example in this video, if the black light green dot is the pin, what i see is that it STARTS standing up at release (the circle it makes is huge almost the total circumference of the ball), and at the pins the same "circle" has become much smaller/tighter. This, in my mind, can only mean that the core and the pin is now more horizontal than vertical to the lane. So no matter how it looks or how it is described, to me the core always lays down to a more stable position at the pins. As i understand it, the pin represents the low RG axis of a ball. So when o ball rolls in the 3rd phase of motion, it will probably roll on or near that axis. So how could that core and pin be vertical then? Maybe i am missing something...


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 Post subject: Re: The core hitting the pocket...
 Posted: Sat Oct 13, 2018 5:54 am Post Number: #23 Post
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TheJesus wrote:
Nice video.... i think we are describing different things, or we interpret them differently. For example in this video, if the black light green dot is the pin, what i see is that it STARTS standing up at release (the circle it makes is huge almost the total circumference of the ball), and at the pins the same "circle" has become much smaller/tighter. This, in my mind, can only mean that the core and the pin is now more horizontal than vertical to the lane. So no matter how it looks or how it is described, to me the core always lays down to a more stable position at the pins. As i understand it, the pin represents the low RG axis of a ball. So when o ball rolls in the 3rd phase of motion, it will probably roll on or near that axis. So how could that core and pin be vertical then? Maybe i am missing something...


This is how I've always interpreted it as well. I've put tape on the pin and watched it begin with a large circumference off my hand, and as it travels down the lane, the pin slowly migrates to the left (right handed bowler) and makes smaller and smaller circles, approaching what I believed to be, the core laying flat/horizontal, and spinning on the axis of the pin.

Years ago, I recall Mo saying physics dictate that a ball, or the core, if you were to think of it as a football, or rolling pin, only wants to rotate on 1 of 2 axis', and will always migrate (or attempt to) to one of these positions; End over end (Like a football that was kicked) or Spiral (Like a football that was thrown) That is what 'balance' and the laws of physics dictate.

I've always wondered if there would be a benefit to a ball rolling end over end vs one that was spinning, in regards to hitting power, carry, energy transfer etc. I've always assume the core 'lays down' and 'spirals' because the end over end motion is more 'lope' like, and as the rotational mass because a tighter circle, the ball can 'appear' to pick up speed, or revolutions, and gain more energy as it moves towards the pocket. I have no clue if this is true, nothing to back it up etc, but to my eye and ear, and common mind, it makes sense.

To ensure I'm illustrating my 'opinion' I offer the following:
This is the 'spiral' of the core. This is the way I perceive and assume the ball is migrating towards, as it moves towards the pocket. I don't believe it ever reaches this position, but it seems like it works towards it... although that brings up another question, what does the 'roll phase' really mean, if the ball is still migrating to a different axis.
Image

And here is the 'end over end' of the core.
Image

Having said all that... a Determinator essentially rotates on the axis of the thumbhole, which means the pin is rolling end over end, or standing up. Which pretty much contradicts everything I just said.
Sooooo I don't have a clue.

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 Post subject: Re: The core hitting the pocket...
 Posted: Fri Oct 19, 2018 2:43 pm Post Number: #24 Post
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I'm not disagreeing with anything that has been said here. I'm just not sure there is a scenario that is 100% correct all the time. My experience with the determinator, and my own particular ball roll has definitely colored my opinion, but my data points are few.

The determinator is a useful tool, but it's not a real world scenario because it's constantly energizing the ball. As long as there is a small differential, there is a low RG axis, a PSA/MB, and (eventually) the ball stands up and tumbles end over end. On the determinator, the core is like a "weeble". Remember those? It wobbles and doesn't fall down.

In the real world, where the ball is rolling down the lane and losing energy, the trend will be different. The axis will generally migrate along the RG of the PAP, and settle into a lower energy/RG position.

Most of the time, it does look like the axis is moving/tightening closer to the fingers/pin. In others, I still believe there is a point where it gets closer and then appears to visually move away. Wish I could find a great example, but it may take a bit of time. A few of Nick Siefer's examples (Pics 2 & 8) do seem to support this.

Marketing vs. Physics: The truth about axis migration and core dynamics

"The migration of axis points can be plotted on the ball and, depending upon certain characteristics, will yield different shapes (curved vs. straight line) due to the drilling pattern used. The plots will be at different distances away from the pin of the bowling ball."

"The test ball loses energy and migrates toward a lower energy and lower RG values. Also as in Test I, the on lane migration does not seek a higher RG state or the mass bias spot (the highest RG of the ball)."

"While on the lane, the bowling ball did not migrate to an axis that had a higher RG value (ball did not end up rotating about the mass bias spot or high RG axis)."

Steve

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 Post subject: Re: The core hitting the pocket...
 Posted: Fri Oct 19, 2018 3:15 pm Post Number: #25 Post
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stevespo wrote:
In the real world, where the ball is rolling down the lane and losing energy, the trend will be different. The axis will generally migrate along the RG of the PAP, and settle into a lower energy/RG position.

Steve


This is not accurate. From the study you linked to, "While on the lane, RG values of the migratory path remained approximately constant at each migratory axis point for all core geometries and drillings."

The RG of the migratory path is set at release and will be approximately that of the PAP. It will neither go up or down. If you look at the attachment you see the PAP stays on the same RG band, between the green and yellow bands, as the ball flares down the lane. It doesn't have enough time to change while on the lane. If the lane were longer and not oiled, it would eventually migrate to the low RG axis.


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 Post subject: Re: The core hitting the pocket...
 Posted: Fri Oct 19, 2018 3:58 pm Post Number: #26 Post
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I may have over-stated that it "settles into a lower energy/RG position". I was attempting to paraphrase the direct quote from the article.

"The test ball loses energy and migrates toward a lower energy and lower RG values."

I can see what you're saying from the simulation. I'm not trying to split hairs. Nick outright says that it migrates toward a lower RG value - so it must be moving away from the RG of the PAP. No? It does look to be moving towards the green. It might be very slowly, and it will never get there because it runs out of lane - but it is slowly moving.

I don't see a contradiction here and I wish I had access to the software. It would be interesting to look at a larger data set. It's a reasonable test and would be worth repeating.

Steve

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 Post subject: Re: The core hitting the pocket...
 Posted: Fri Oct 19, 2018 4:32 pm Post Number: #27 Post
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That looks like a lower-flaring control layout on a higher RG sym, medium-high diff (2.56/.047).

Can you run a Black/Blue Paradox, OOB at 60x4x40 with my sig specs. Span is 4.875", typical finger pitches, thumb 1" left and 3/8" reverse pitch (ADT). Add a double thumb or P3.5.

Always curious. Thanks!

Steve

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 Post subject: Re: The core hitting the pocket...
 Posted: Fri Oct 19, 2018 4:45 pm Post Number: #28 Post
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stevespo wrote:
That looks like a lower-flaring control layout on a higher RG sym, medium-high diff (2.56/.047).

Can you run a Black/Blue Paradox, OOB at 60x4x40 with my sig specs. Span is 4.875", typical finger pitches, thumb 1" left and 3/8" reverse pitch (ADT). Add a double thumb or P3.5.

Always curious. Thanks!

Steve
I think what you are looking for was posted by MathIsTruth here: viewtopic.php?f=13&t=69&start=40 (see #50 and #52)


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 Post subject: Re: The core hitting the pocket...
 Posted: Fri Oct 19, 2018 8:16 pm Post Number: #29 Post
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Thank you. Glad to see that my personal observations are consistent with what Mo and MathIsTruth have documented in the thread.

It might take a high diff core and particular release characteristics, but there are conditions where the elliptical axis migration path moves the pin towards the axis, and then away (stands up) before the ball hits the pins.

Steve

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 Post subject: Re: The core hitting the pocket...
 Posted: Mon Oct 22, 2018 2:40 pm Post Number: #30 Post
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stevespo wrote:
I may have over-stated that it "settles into a lower energy/RG position". I was attempting to paraphrase the direct quote from the article.

"The test ball loses energy and migrates toward a lower energy and lower RG values."

I can see what you're saying from the simulation. I'm not trying to split hairs. Nick outright says that it migrates toward a lower RG value - so it must be moving away from the RG of the PAP. No? It does look to be moving towards the green. It might be very slowly, and it will never get there because it runs out of lane - but it is slowly moving.

I don't see a contradiction here and I wish I had access to the software. It would be interesting to look at a larger data set. It's a reasonable test and would be worth repeating.

Steve

That quote is referring to a test with a ball that had three times the maximum allowable differential. From the same section, "If this test ball flared within USBC specifications, the path would start on the green axis point and end up down lane approximately on the red axis point. After looking at the data, the green axis and the red axis point exhibit the virtually same RG value, which directly matches the trend results of Test I."

MathIsTruth confirms the RG of the PAP remaining constant in the thread elgavachon linked to. From post 52 in that thread, "The spin axis will migrate and maintain an RG value which is equal to the RG value of the original PAP."

As far as the Blueprint scenario you mentioned, I don't own the software. I just downloaded the picture.

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 Post subject: Re: The core hitting the pocket...
 Posted: Tue Oct 23, 2018 4:38 am Post Number: #31 Post
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Arkansas wrote:
MathIsTruth confirms the RG of the PAP remaining constant in the thread elgavachon linked to. From post 52 in that thread, "The spin axis will migrate and maintain an RG value which is equal to the RG value of the original PAP."


Right. I understand that particular test is not within spec and that the RG value of the PAP is maintained regardless. For some people and some equipment, the pin will be more horizontal at impact and for others, the pin will be more vertical.

That's really the thing I've been trying to put my finger on. It's just an attempt to learn something. My confusion was based on my personal observations which is a small sample for sure.

Steve

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 Post subject: Re: The core hitting the pocket...
 Posted: Tue Oct 23, 2018 7:53 am Post Number: #32 Post
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Adrenaline wrote:
Years ago, I recall Mo saying physics dictate that a ball, or the core, if you were to think of it as a football, or rolling pin, only wants to rotate on 1 of 2 axis', and will always migrate (or attempt to) to one of these positions; End over end (Like a football that was kicked) or Spiral (Like a football that was thrown) That is what 'balance' and the laws of physics dictate.

I've always wondered if there would be a benefit to a ball rolling end over end vs one that was spinning, in regards to hitting power, carry, energy transfer etc.


I actually brought this up with Mo in 2010. His reply was "That kind of question about the difference in carry would require an exhaustive study to be accurate, so we're left with only opinion. The two balls will hit differently, but which one hits better at any given time is purely trial and error."

This is the link to the discussion: viewtopic.php?p=11578#p11578

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