The core hitting the pocket...

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The core hitting the pocket...

Post by ballspoint » August 25th, 2018, 5:31 am

In what position is the core when hitting the pocket best to get max results?
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Re: The core hitting the pocket...

Post by GrumpyCatFace » August 25th, 2018, 6:50 am

Even if you got a coherent answer to this, would it matter? Lol

Probably the position it’s in during roll-out.

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Re: The core hitting the pocket...

Post by EricHartwell » August 25th, 2018, 7:16 pm

GrumpyCatFace wrote:Even if you got a coherent answer to this, would it matter? Lol

Probably the position it’s in during roll-out.
It Matters

Roll out would be in a declining state of energy.

A ball rolling with some tilt and rotation will be at its highest state of energy.
In an example of a bowler that hast Zero tilt and what ever rotation...
When the rotation reaches zero the ball is at its maximum hitting power. The instant the ball reaches 0/0 tilt/rotation the hitting power begins to decline this is now in the roll out position.

At the other end of the tilt spectrum, high tilt lets say 30* tilt and 45* rotation. Rotation is going to equal tilt way before it reaches zero, but to hit the pocket with too much tilt will cause deflection and poor carry.
So, the position of the core is important.
ballspoint wrote:In what position is the core when hitting the pocket best to get max results?
Max results... I interpret this as to mean the best chance to carry. This is the premise behind the Dual Angle method for layouts. Properly applied you can have the core in a position that will Maximize the its gyroscopic properties to give you the best chance to carry.

The exact position of the core starts with the Rg of the PAP. The migrating axis follows the Rg contour defined by the position of the PAP in relation to the Pin. After so many revolutions the rotating axis will cross what is referred to as the pin to spin line. At this point the core is going to "rev up". The layout helps determine when this takes place. Smaller drilling angles rev up sooner, while larger drilling angles and lower flaring pin positions rev up later.

So the best position depends on many different variables including release specs, lane condition, angle of attack, ball surface and the bowlers ability to repeat shots and get it to that point.
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Re: The core hitting the pocket...

Post by MegaMav » August 25th, 2018, 8:20 pm

ballspoint wrote:In what position is the core when hitting the pocket best to get max results?
The simplest answer:

A ball in the roll phase will have maximum hitting power.
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Re: The core hitting the pocket...

Post by ballspoint » August 25th, 2018, 10:49 pm

Some very informative answers thank you.
But not exactly what i am after.
To make it simple...the pin is at the top of the core, depending on the bowler, sometimes i see the pin almost on its side facing left (right handed), so the core is now laying sideways.
I know it will be different because of releases, but is this the basics of where the core position should/could be in the roll to the pocket.?
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Re: The core hitting the pocket...

Post by TonyPR » August 26th, 2018, 3:21 am

No, it will be different for every bowler depending on their release specs and PAP. We need to see the three phases of ball motion. First the ball will skid, this phase will be dominated by coverstock chemical composition and surface prep. When the cover starts “grabbing” the lane this will “activate” the core which will start looking for it’s “balance” (hooking, which is the second phase of ball motion) in doing so it will start to “burn” the axis tilt and axis rotation applied by the bowler at release, this is called axis migration. Finally when axis tilt equals axis rotation the ball will begin to roll forward (this is the third phase of ball motion), in this phase the ball will hit the hardest. Hope this oversimplification helps.

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Re: The core hitting the pocket...

Post by GrumpyCatFace » August 26th, 2018, 6:21 am

ballspoint wrote:Some very informative answers thank you.
But not exactly what i am after.
To make it simple...the pin is at the top of the core, depending on the bowler, sometimes i see the pin almost on its side facing left (right handed), so the core is now laying sideways.
I know it will be different because of releases, but is this the basics of where the core position should/could be in the roll to the pocket.?
I think I see what you’re getting at now.

You already know that a “symmetrical” core has a rounded shape, with a bit of extension toward the pin. It stands to reason that during a roll-out phase, the ball would have max geometric stability - the pin would be on a 90 degree angle from direction of travel.

Curious if there’s been any study of where it actually ends up, but that’s my guess.

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Re: The core hitting the pocket...

Post by delbowler » August 26th, 2018, 9:02 pm

GrumpyCatFace wrote:
I think I see what you’re getting at now.

You already know that a “symmetrical” core has a rounded shape, with a bit of extension toward the pin. It stands to reason that during a roll-out phase, the ball would have max geometric stability - the pin would be on a 90 degree angle from direction of travel.

Curious if there’s been any study of where it actually ends up, but that’s my guess.
Yep, here's one I found in a USBC white paper about axis migration: http://wiki.bowlingchat.net/wiki/images ... _cores.pdf

When they tested on a completely dry lane the axis did indeed end up at the minimum Rg position, but it didn't get there for the normal shots.

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Re: The core hitting the pocket...

Post by todvan » August 31st, 2018, 11:59 pm

I think he is talking about a ball rolling on the high rg axis vs the low rg axis.
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Re: The core hitting the pocket...

Post by MeNoRevs » September 1st, 2018, 2:18 am

todvan wrote:I think he is talking about a ball rolling on the high rg axis vs the low rg axis.
The ball doesn't roll on the low RG axis or the high RG axis. The ball rolls on the rg of the pap. Since the lane is 60 feet it will never get to the low RG. Now if the lane was infinite, it would eventually migrate to the pin.

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Re: The core hitting the pocket...

Post by ballspoint » September 1st, 2018, 6:41 am

Some of your answers i dont understand, too technical for me.
But what i think iam getting from the answers is... every bowler has a different release, so their ball will have its own core axis spin position when hitting the pocket.
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Re: The core hitting the pocket...

Post by J_w73 » September 6th, 2018, 5:01 pm

Check out some of the intial MOtion hole discussions. Mo talks about gyroscopic inertia and how that helps go through the pins and carry. I believe he talks about the core position at impact and what is beneficial for carry.

On a side note, Earl Anthony always wanted the ball at its maximum rpms when it went into the pocket. Maybe not so important with today's cores and covers, but it does make a difference in hitting power , , deflection (lack of) going through the pins, and carry.
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Re: The core hitting the pocket...

Post by ballspoint » September 6th, 2018, 7:09 pm

J_w73 wrote:Check out some of the intial MOtion hole discussions. Mo talks about gyroscopic inertia and how that helps go through the pins and carry. I believe he talks about the core position at impact and what is beneficial for carry.

On a side note, Earl Anthony always wanted the ball at its maximum rpms when it went into the pocket. Maybe not so important with today's cores and covers, but it does make a difference in hitting power , , deflection (lack of) going through the pins, and carry.
I have a motion hole ball, its like everytime its hitting the pocket it will probably strike. We in NZ follow World Bowling rules, but they are making that decision very soon if they are to follow USBC rules...of course they will. No balls...pun intended.
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Re: The core hitting the pocket...

Post by TonyPR » September 9th, 2018, 7:26 pm

J_w73 wrote:Check out some of the intial MOtion hole discussions. Mo talks about gyroscopic inertia and how that helps go through the pins and carry. I believe he talks about the core position at impact and what is beneficial for carry.

On a side note, Earl Anthony always wanted the ball at its maximum rpms when it went into the pocket. Maybe not so important with today's cores and covers, but it does make a difference in hitting power , , deflection (lack of) going through the pins, and carry.
Earl was correct, the ball is at it’s maximum rpms in the roll phase.

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Re: The core hitting the pocket...

Post by TheJesus » September 17th, 2018, 3:21 pm

Question : Ok, so if tilt=Axis rotation, so...roll phase, we are told that the ball has the highest % for better pin action, ...because of ....what? Why is this? What are the gyroscopic properties exactly? And does it have less deflection in the roll phase, or does it have less deflection while still hooking? Is deflection accounted for when we talk about "gyroscopic properties" ? Or do we only say it is better to hit the pins in the roll out phase because of the RPMs being at the max? Doesn't also the speed (which is at the lowest when the ball rolls out) play a role here ? (kinetic energy transferred to the pins)?

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Re: The core hitting the pocket...

Post by stevespo » September 17th, 2018, 4:29 pm

TheJesus wrote:Question : Ok, so if tilt=Axis rotation, so...roll phase, we are told that the ball has the highest % for better pin action, ...because of ....what? Why is this? What are the gyroscopic properties exactly? And does it have less deflection in the roll phase, or does it have less deflection while still hooking? Is deflection accounted for when we talk about "gyroscopic properties" ? Or do we only say it is better to hit the pins in the roll out phase because of the RPMs being at the max? Doesn't also the speed (which is at the lowest when the ball rolls out) play a role here ? (kinetic energy transferred to the pins)?
Eric's earlier description is very good. In physics, when breaking down movement, they often teach vector notation. This is essentially magnitude and direction. A moving object may have multiple vectors which interact and influence motion.

A bowling ball has a translational vector, which is the energy used to move it forward (change position). It also has a rotational vector, which is the energy it uses to hook (when it encounters sufficient friction).

We know the translational energy is essentially the speed/direction off the hand. The rotational energy is the RPMs, tilt/rotation you impart at release.

The rotational energy doesn't begin to influence motion until the hook phase. As the ball hooks, some rotational energy is converted to translational, some is lost to friction, etc - the trajectory changes and you've got this additive effect happening. All the translational and rotational energy are combined into a single vector, with max speed and a new direction. The forces are now lined up. This is why we'd like to see it roll out just in front of the pocket.

The gyroscopic properties are more complicated, but I personally do think it has to do with the position of the core at the point of impact. It stands to reason that if the low RG axis (pin) is standing tall and rolling (somewhat) end over end - the ball not only has maximum momentum (speed x mass) it also has a core that is tumbling (somewhat) near the high RG axis. It stands to reason that the core has a longer moment arm and more gyroscopic inertia, more torque, as it goes through the pins.

I haven't done the work to measure/simulate/prove this - it's just a simple mental model I fall back on.

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Re: The core hitting the pocket...

Post by TheJesus » September 18th, 2018, 11:09 am

stevespo wrote: All the translational and rotational energy are combined into a single vector, with max speed and a new direction. The forces are now lined up. This is why we'd like to see it roll out just in front of the pocket.
Ok i understand this, but do we know why this is desired? Does it create less delfection for the ball? Does it achieve better energy transfer to the pins?
stevespo wrote:The gyroscopic properties are more complicated, but I personally do think it has to do with the position of the core at the point of impact. It stands to reason that if the low RG axis (pin) is standing tall and rolling (somewhat) end over end - the ball not only has maximum momentum (speed x mass)
...wait. When the ball rolls out...isn't the core more on it's side, "parallel" to the lane surface?

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Re: The core hitting the pocket...

Post by stevespo » September 18th, 2018, 1:51 pm

TheJesus wrote: Ok i understand this, but do we know why this is desired? Does it create less delfection for the ball? Does it achieve better energy transfer to the pins?
Yes, I think so. A more energetic ball (M=mv) and increased gyroscopic inertia means less deflection. Energy transfer to the pins is a function of total energy and coefficient of restitution, which is something else.
TheJesus wrote:...wait. When the ball rolls out...isn't the core more on it's side, "parallel" to the lane surface?
No, not based on my observations - but like many things in bowling "it depends". Axis migration follows a path of "near constant" RG of the PAP, not the low RG axis as marked on the ball. If the pin is located on/near the PAP, then the core might be on it's side. Most of the time, it's not.

Every PWBA telecast Kelly Kulick says "watch the pin stand up as the ball enters the pins". 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.

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Re: The core hitting the pocket...

Post by TheJesus » October 7th, 2018, 5:34 pm

stevespo wrote:No, not based on my observations - but like many things in bowling "it depends". Axis migration follows a path of "near constant" RG of the PAP, not the low RG axis as marked on the ball. If the pin is located on/near the PAP, then the core might be on it's side. Most of the time, it's not.

Every PWBA telecast Kelly Kulick says "watch the pin stand up as the ball enters the pins". 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
I am curious about this. I watch slow mo videos of balls, and, i dont see the pin "stand up" in pretty much any of them. What DOES stand up is the PAP however. The pin seems to be already pretty inclined when we release the ball. So i am assuming (as i understand it), that when a ball nears its roll phase, the core must be reaching a more stable position. So either horizontal or vertical.

Also, these videos :

[youtube][/youtube]

[youtube][/youtube]

As you can see in the 2nd video clearer, the pin is pretty much "up" at the start, and makes large circles as the ball turns. And the PAP of course is stationary. And they slowly switch : the Pin makes smaller and smaller circles, and the PAP larger.

So,...i am not sure what Kelly meant to be honest. Maybe someone can explain it to me.

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Re: The core hitting the pocket...

Post by stevespo » October 9th, 2018, 9:11 pm

TheJesus wrote: As you can see in the 2nd video clearer, the pin is pretty much "up" at the start, and makes large circles as the ball turns. And the PAP of course is stationary. And they slowly switch : the Pin makes smaller and smaller circles, and the PAP larger.

So,...i am not sure what Kelly meant to be honest. Maybe someone can explain it to me.
I'm not claiming that Kelly (or I) know what we are talking about. Just expressing my opinion and trying to improve my understanding.

I'm seeing something different than what you're describing in the 2nd video. The pin migrates left, the radius tightens up and then gets larger. The PAP radius seems to gradually enlarge. The pin and original PAP appear to be almost (but not quite) vertical as the ball goes through the pins. The fingers might be vertical, but it's hard to tell for sure. Go through it frame by frame and see if you aren't seeing the same thing?

That simulation is using a pin down layout with a generic looking core. Greater/lesser differential and/or different layouts are going to change the outcome.
axis-migration.png
The Gary Faulkner videos where he highlights the pin show it in different positions as it enters the pins. Pin moves left, the axis migrates between the thumb and fingers and the pin generally does "stand up". Not always, not completely - too many variables to talk in absolutes here. See 2:11.

[youtube][/youtube]

In a system where the ball is consistently energized for a longer period of time (ie. Determinator) the pin will always stand up. What it does on the lanes is going to be different, the real world is more complicated.

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