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 Post subject: Okay, just where is the pocket????
 Posted: Sun Oct 13, 2013 8:37 pm Post Number: #1 Post
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Okay a disagreement with another poster (MWhite).

I said this (that the pocket is on the 17.5 board and included these images0:
In regard to the pocket.

A 2.5 inch offset is basically the perfect strike hit for all entry angles and all ball weights. The strike pocket is approximately 17.5 boards in from the right, or the same from the left for left-handers.

Image

Here's the pocket showing 0°-2°-4°-6° entry angles
Image

This is based on USBC info and some info/article from John Williams (BTBA National Coach).

MW say:
Quote:
I don't know where you got your info and images but i'd question it's validity.

First off, lets not confuse inches and "boards".

The lane is 41.5 (+- 1/2 ) inches wide, and consists of 39 "boards".
That means each board is approximately 1 1/16" inch wide.

The head pin while sitting on the 20 board, is more accurately centered at 19.5 boards from the edge of the lane, or 20.75" from the edge of the lane.

The pin diameter at point of impact is about 4.72".
The ball diameter is about 8.595"

This means at impact, the vertical center line of the pin is about 6.66 inches from the center of the ball.

Since we want to drive the head pin directly towards the 7 pin we need to impact the pin on a line 30 degrees counter clockwise thru the center of the head pin.

This puts the offset from the vertical center line of the head pin to the center of the ball at 3.33" (6.66*sin(30)) in the cross lane direction.

20.75 - 3.33 = 17.42, 17.42 / (1 1/16) = 16.4 So the true pocket is approximately the 16.4 board



So my question is wheres the pocket??

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Last edited by bowl1820 on Thu Oct 17, 2013 1:16 pm, edited 1 time in total.

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 Post subject: Re: Okay, just where is the pocket????
 Posted: Sun Oct 13, 2013 9:09 pm Post Number: #2 Post
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Around the head pin left of it right of it and we have all seen 2 or 3 pin strikes....somewhere around there. :mrgreen:


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 Post subject: Re: Okay, just where is the pocket????
 Posted: Sun Oct 13, 2013 9:54 pm Post Number: #3 Post
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Interesting post. I was told from a few sources that I would consider credible that the pocket is between the 17 and 18th board. Then again I was also told that 1 board was 1 inch. Apparently that is wrong. So I learned something new today.

So the question is where is the pocket? I think the pocket changes from pattern to pattern ball to ball and bowler to bowler. The author of this posts signature is "its not how much the ball hooks, it's where" I think that is fitting for this conversation. Bowling at the highest level is all about micro adjustments. Great players develop a skill to read the lanes, get the ball rolling through the 3 phases correctly combining that with the proper entry angle. Lots of variables if you ask me when it comes to the *pocket*.

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 Post subject: Re: Okay, just where is the pocket????
 Posted: Sun Oct 13, 2013 10:14 pm Post Number: #4 Post
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I believe the pocket moves as entry angle changes. All you have to do is consider the line of pins 1,2,4,7 to visualize that this is true. A different entry angle will require the ball to hit the headpin in a different position in order for the 1,2,4,7 to line up perfectly so they hit each other on center. If entry angle gets too extreme then one of two things needs to happen: The ball must hit light and shred the rack to carry or the ball must be at the end of the roll phase and losing energy so it will deflect and not leave a solid 8 or 9 pin.

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 Post subject: Re: Okay, just where is the pocket????
 Posted: Sun Oct 13, 2013 10:54 pm Post Number: #5 Post
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Here's the John Williams info if it helps, the other is from the USBC Pin Carry Study. Now if there is some updated info to change this okay.

by John Williams
(BTBA National Coach)

"Technically, the strike pocket is measured by 'offsets', that is the distance between the centre of the ball and the centre of the head pin.

If the centre of the ball was in direct line with the centre of the head pin, then this would be called 'zero offset'.

A 2.5 inch offset is basically the perfect strike hit for all entry angles and all ball weights. If you remember my article of last December about the 'Basic Adjustment' for getting your ball into the pocket, there is 12 inches between the centre of the head pin and the centre of the 3-pin and also between the centre of the head pin and the centre of the 2-pin. There are normally 39 boards in a lane and the width is between 41.5 and 42 inches, so each board is more or less 1.076", so the strike pocket is approximately 17.5 boards in from the right, or the same from the left for left-handers."

Every website I've checked that talks about where the pocket is, says it's at the 17.5 board.

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 Post subject: Re: Okay, just where is the pocket????
 Posted: Mon Oct 14, 2013 12:57 am Post Number: #6 Post
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Location -
Geographically/positionally the pocket is the 17.5 board. It is point halfway between the headpin and the companion pin in "the pocket" (i.e. the 3 for rhb and the 2 for lhb).

Headpin Zones -
In his book "Weber on Bowling" , for the sake of analysis,
he illustrated "Headpin Zones", i.e. Brooklyn, Nose, Pocket, Bucket.
Sub Zones of the Headpin Pocket Zone -
He further subdivided the Pocket Zone of the Headpin into 3 zones, Light, Middle, High.
He also called attention to the sub-triangle of the rack he dubbed "The Deflection Zone" as a clue area.
Deflection Zone -
The Deflection Zone for the 1-3 being the 3 - 8 - 10 triangle.
The outer or main triangle is a barometer for location, the aforementioned sub-triangle for reading deflection (too much, too little, just right).

Deflection and drive play a role in which part of the pocket will work best on a given shot.
There are various reasons for deflection and drive, the weight of the pins is also part of the equation, what phase of precession your ball is in.

Mo-ism
"The object of the game is to hit the pins between the place where the ball loses rotation and where it loses tilt"
My source, the soon to be defunct Bowling This Month, in an article by Palmer Falgren on Tilt and Rotation

That tilt has a vital role as it is a reason for secondary torque, i.e. a source of opposition to oppose gravity and deflection.

It ain't over 'til it's over. The shot that is ...
Just one more reason to post your shot keeping an eye on the ball meander through the pins noting it's course, how it makes the pins dance, and where it falls into the pit. The shots over when the ball enters the pit, don't stop watching and posing at the line until the curtain falls.

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https://m.youtube.com/watch?v=ih-HTtMtwek
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 Post subject: Re: Okay, just where is the pocket????
 Posted: Thu Oct 17, 2013 11:51 am Post Number: #7 Post
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sprocket wrote:
I believe the pocket moves as entry angle changes. All you have to do is consider the line of pins 1,2,4,7 to visualize that this is true. A different entry angle will require the ball to hit the headpin in a different position in order for the 1,2,4,7 to line up perfectly so they hit each other on center. If entry angle gets too extreme then one of two things needs to happen: The ball must hit light and shred the rack to carry or the ball must be at the end of the roll phase and losing energy so it will deflect and not leave a solid 8 or 9 pin.


It is my opinion that if you hit the head pin in a position that it would head directly towards the 7 pin, you have hit THE pocket.

Entry angle comes in to play when considering deflection, and the ability have the ball reach a second position to drive the 3 pin directly towards the 10 pin.

http://www.bowl.com/Equipment_Specs/Equ ... entations/

Looking at the videos labeled solid pocket, in each example, the head pin is driven directly into the 2 pin, which is driven into the 4 pin, and the 4 into the 7.

In the other examples, Light, and High pocket, the head pin is not driven directly into the 2 pin.

Using the specifications of the ball, pin, and pin spots:

The head pin needs to be driven on a line 30 degrees left of straight back to go directly into the 2 pin.

The radius of the pin at the height were the ball makes contact is 2.36", the radius of the ball is 4.30"

That puts the center of the ball 6.66" from the center of the head pin at the point of contact.

At 30 degrees, the right offset would be 3.33" (6.66" * sin(30))


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 Post subject: Re: Okay, just where is the pocket????
 Posted: Thu Oct 17, 2013 1:21 pm Post Number: #8 Post
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Yes I see that now, your correct mike. Well done.

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 Post subject: Re: Okay, just where is the pocket????
 Posted: Thu Oct 17, 2013 1:46 pm Post Number: #9 Post
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Good job Mike; that makes perfect sense. I stated that the perfect board would be different depending on the entry angle but I can see how that is not true if the goal is to gt the head pin to move directly towards the 7 pin. It WOULD be true at any point EXCEPT the exact point of cantact. At that point, if you took a freeze frame you would not know where the ball came from, you would just know whether or not it was striking the headpin at the perfect position.

Now all that being said, imagine the ball coming in at the shallowest angle imaginable that can still get the ball to contact the head pin at the theoretically perfect spot. That ball has very little if any momentum towards the five pin so although it should in theory clear the 1-2-4-7 and 3-6-10 perfectly, one would think it would leave a weak 8 pin. The funny thing is you seldom see just a weak 8 pin. Usually the 10 pin is with it. That doesn't make sense if the ball is contacting the head pin at the perfect spot. It tells me that perhaps the position of the ball changes instantaneously when it contacts the headpin from that shallow angle, and before the 3 pin can move directly towards the 10 pin the ball is already deflecting towards the 3 pin and moving WITH the 3 pin. So it maintains contact with the three pin for a little longer period of time, effectively pushing the 3 pin off its perfect line....and an 8-10 is the result.

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 Post subject: Re: Okay, just where is the pocket????
 Posted: Thu Oct 17, 2013 2:22 pm Post Number: #10 Post
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Just so everybody knows here's some info posted about offsets and entry angles and how they did the Pin Carry study. Which sheds light on some of this.

Quote:
Mike White:
Back in early August I was at a trade show, talking to one of the ball reps from either Storm, or Motiv. If it was Storm it would have been Boomershine.

The topic of that angle of entry test came up. The testing method was described as a ramp delivery system to control the angle, "offset", and speed of the ball.

The "offset" is related to the probability of getting the 7 pin out.

The deflection is related to the probability of getting the 10 pin out.

Since a ball on a ramp has no axis tilt, it effectively has rolled out.

When a ball has rolled out, it has to hit higher (less offset), to carry the 10 pin, but too high and you leave a 7 or 4 pin.

The graph only focused on the strike and ten pin.


Here's the graph being referred to:
I sure didn't know the USBC just used ramps for that study and the balls were rolled out.
Image

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 Post subject: Re: Okay, just where is the pocket????
 Posted: Thu Oct 17, 2013 5:16 pm Post Number: #11 Post
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sprocket wrote:
Good job Mike; that makes perfect sense. I stated that the perfect board would be different depending on the entry angle but I can see how that is not true if the goal is to gt the head pin to move directly towards the 7 pin. It WOULD be true at any point EXCEPT the exact point of cantact. At that point, if you took a freeze frame you would not know where the ball came from, you would just know whether or not it was striking the headpin at the perfect position.

Now all that being said, imagine the ball coming in at the shallowest angle imaginable that can still get the ball to contact the head pin at the theoretically perfect spot. That ball has very little if any momentum towards the five pin so although it should in theory clear the 1-2-4-7 and 3-6-10 perfectly, one would think it would leave a weak 8 pin. The funny thing is you seldom see just a weak 8 pin. Usually the 10 pin is with it. That doesn't make sense if the ball is contacting the head pin at the perfect spot. It tells me that perhaps the position of the ball changes instantaneously when it contacts the headpin from that shallow angle, and before the 3 pin can move directly towards the 10 pin the ball is already deflecting towards the 3 pin and moving WITH the 3 pin. So it maintains contact with the three pin for a little longer period of time, effectively pushing the 3 pin off its perfect line....and an 8-10 is the result.


By the same reasoning that the ball has to hit the head pin with a 3.33" offset to drive the head pin into the 2 pin, the ball also has to hit the 3 pin with a 3.33" offset (on the left) to drive the 3 pin into the 6 pin.

The 3 pin is offset right 6" from the center of the head pin. and 10.4 inches back. (6*sqrt(3))

The path the ball needs to take after contacting the head pin is to a point 2.67" right of the center of the head pin, and 4.62" back.

To be complete, the center of the ball at impact with the head pin would be 3.33" right (lateral direction), and 5.77" in front (linear direction) of the center of the head pin.

At the point the ball correctly impact the 3 pin, it would be 3.33" left and 5.77" in front of the center of the 3 pin.

That location in reference to the head pin is 2.67" right, 4.62" behind the head pin.

(6-3.33) = 2.67
(10.39-5.77) = 4.62

10.39 is the linear distance from the head pin to the line between the centers of the 2 and 3 pin.
sqrt(12*12-6*6) = 10.39

The ball will have to travel 0.66 left, and 10.39 back between the impact with the head pin, and the impact with the 3 pin.

atan(0.66/10.39) = 3.63 degrees

I have to refresh my physics on elastic collisions to include Coefficient of Restitution of both the ball, and the pin to determine the relationship between angle of entry, ball speed, and weight.

In addition a ball has rotational momentum that can alter the path after impact.


So a ball that hits the pocket, but at a weak angle. (take a left hander crossing over as an extreme example) will not magically deflect back to the left to be in the proper place to drive the 3 into the 6.

By watching the 1-2-4-7 pins you can tell if you are hitting the head pin correctly, then you observe the 3, 6, 10 to determine if the angle, deflection, and speed combination are correct.


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 Post subject: Re: Okay, just where is the pocket????
 Posted: Thu Oct 17, 2013 10:20 pm Post Number: #12 Post
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viewtopic.php?f=3&t=7783&hilit=+pin+comparison

There is a good video of strikes with slo-mo to show the pin action

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