Online Bowling Notes #01

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RG: Radius Of Gyration.
The RG of a bowling ball tells you how soon the core is designed to roll.
A Low RG ball (aka: a Center Heavy ball) is easier to "rev up", rolls earlier and tends to mean earlier hook, more midlane reaction,a more evenly arcing ball used on wetter conditions.

A High RG ball (aka: a Cover Heavy ball) is harder to "rev up", rolls later and tends to mean later hook, more backend reaction, tends to be more angular.

The Low RG axis is the pin and the High RG axis is the PSA.
Total Diff = High RG - Low RG
Int Diff = High RG - Int RG

Simple RG scale (there are others):
Low RG: 2.460" - 2.570"
Med. RG: 2.570" - 2.680"
High RG: 2.680" - 2.800"

Here's another:
Low RG = 2.430 to 2.540
Med RG = 2.541 to 2.690
High RG = 2.691 to 2.80

The RG Differential aka:The Differential:

Shows the difference between the low RG and the high RG.
The Differential indicates the potential for track flare.
The lower the differential the closer together the track flare rings are.
The higher the differential the further apart the track flare rings are.

Simple Differential scale (there are others):
Low Diff.-RG: .01 - .02 (low flare potential)
Med. Diff.-RG: .021 - .04 (med flare Potential)
High Diff.-RG: .041 - .08 (high flare potential)

Basic guide:
A lower RG ball with a low differential will produce an earlier rolling ball with a small arcing motion.
A lower RG ball with a high differential will produce an earlier rolling ball with a larger/stronger arcing motion.
A higher RG ball with a low differential will produce a later rolling ball with an angular backend motion.
A higher RG ball with a high differential will produce a later rolling ball with a strong, somewhat angular backend motion.

Suggestion for using the undrilled ball #s to help anticipate ball reaction.

1) Take the min. RG # and add 70% of the total diff to it. That'll give you the approximate RG of the PAP for about 80% of the layouts. The RG of the PAP is the only RG that matters to the motion of the drilled ball.

2) Divide the int. diff. of the undrilled ball by the total diff. of the undrilled ball. That'll give you the diff. ratio. That tells you the potential of the ball to respond to friction.

Diff. ratios (using the drilled diff.):
>.45 is strong reaction
.25 to .45 is medium reaction
<.25 is smooth reaction

Ball Motion:
There are 3 phases of ball motion, the skid phase, then the hook phase and finally the roll phase. The first and second transitions is what we call the points which seperates these phases. The skid and roll phases are linear in nature which means linear equations can be used to model the ball motion. The hook phase is modeled by a quadratic equation. The vertex of that parabolic curve coincides with the breakpoint. It occurs somewhere between the first and second transition.

Dual Angle Info:
The Dual Angle Layout Technique is made up of three measurements:
1. The Drilling Angle: Which affects the length of the skid phase of the ball.
Higher angles = A Longer Skid phase.
Lower angles = The quicker the transition into the hook phase.

2. The Pin to Positive Axis Point (Pin-to-PAP) distance:
The Pin to PAP distance affects the amount of the flare.

3. The Vertical Axis Line (VAL) angle: Controls how long the ball remains in the hook phase.
Smaller Angles to the VAL lowers the RG, and increases the total differential of the ball. This results in the ball reving up faster and transitioning faster from the hook into the roll phase of the ball.

Larger Angles to the VAL raises the RG, and decreases the total differential of the ball. This results in the ball reving up slower and transitioning slower from the hook into the roll phase of the ball.

The comparison of Drill angle and VAL angle is expressed as a Ratio... Drilling Angle:VAL Angle

Ratios determine the balls break shape.
1. The drill angle helps determine the length of the skid phase of ball motion.
2. The val angle helps determine the length of the hook phase of ball motion.
3. The drill angle + val angle = the total length of ball motion before the ball reaches the roll phase.

A. A higher ratio of the drill angle to the val angle = longer and quicker reaction to the dry. (more of a
skid /snap ball motion)

B. A lower ratio of the drill angle to the val angle = earlier and slower reaction to the dry (smoother &
more continuous ball motion.)

Some of the common Lane surfaces in order of decreasing friction are:

Guardian (most friction)
wood (different coatings change friction)
Brunswick Lane Shield
Original Brunswick AnviLane (if it has been polished)
new Brunswick Pro AnviLane (textured)
early Brunswick Pro AnviLane (least friction)

The hardness of the sub strait, the foot print that the ball produces on the surface, and the texture are the determining factors in determining the friction between the ball and the lane.

USBC specs a minimum of 35 Sward hardness for synthetic panels. Though the exact hardness is proprietary info to the manufacturer.

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Updated 07-26-2016 at 10:57 PM by bowl1820

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  1. bowl1820's Avatar
    The Exit Point Formula & Mo Pinels Breakpoint Formula:

    It's referring to Joe Slowinski's exit point formula (Pattern length - 31= Exit point)

    The exit point is just that, the point where you want the ball to come out of the oil, It's not where you hit the entry angle (breakpoint).

    Once it hits that exit point using various launch angles. Then the ball will travel distance X out of the oil and turn (at the break point) to line up with the desired entry angle.

    The problem with it is that doesn't work right on shorter patterns. (Mo said it's not accurate and shove it)

    Mo suggested on how to find the board the breakpoint is on. By looking at the composite graph of the oil pattern. (you can also find it by looking at the Lane Machine Settings chart)

    What you do is look for the highest corners of the red bars on the bar graph and subtract 3. That's the place to start looking for the breakpoint. (But this doesn't tell you how far down the lane it is)

    Remember that the loads are applied to the buffer brush, so ALL the forward loads affect the breakpoint.

    Here's a example: using Kegel's DEAD MAN’S CURVE 3043 Pattern
    Direct Download the pdf for the pattern here

    or see the webpage here and click on composite view

    In this example the highest red bar is on board 14, so 14-3= 11. That's where you start looking for your breakpoint.

    from the Lane Machine Settings chart

    Now my thought is not so much to shove the exit point formula, but to look at the situation and see if it would be beneficial if used (on The longer patterns).
    Like use the end of pattern minus 31 to give you a starting place, when the only info you have available is the length of the pattern.
    And if possible combine it with Mo's suggestion.
    Updated 07-07-2014 at 08:39 PM by bowl1820
  2. bowl1820's Avatar
    Change Ball Surfaces Every Time Your Bowl:
    Jayhawk found that a ball starting with a cover at 2500 became 3900 after just one game.
    Storm also has a similar finding with covers moving from approximately 1200 to 3000 after seven games.

    Bowlers also often make the mistake thinking that by simply using a pad at certain grit will make the ball that grit. To illustrate, 500 + 4000 is approximately 1200 while 500 + 2000 is the same as 1500 and 500 + 1000 + 4000 is approximately 2000

    To ensure you have the exact cover surface you want, start with a minimum of two grits down and work your way back to the that grit. For example, to achieve a true 4000 on the cover use 500 + 1000 + 2000 + 4000.

    When using a polish on the cover as well, be sure to use 2000. Grits lower than 2000 have more inconsistency, day-to-day, when trying to get the same exact grit. 1000 + factory finish is nearly identical to 2000

    Deep Clean Your Bowling Balls:
    Bowling balls can lose reaction significantly after 75 to 100 games of use. The pores of the cover become saturated with oil reducing the dynamic interaction between cover and the lane. When using bowling balls over 75 games without deep cleaning, a bowler will see between 2 to 4 boards less backend.
    Updated 07-08-2014 at 10:45 PM by bowl1820
  3. bowl1820's Avatar
    The 4 influences a bowler imparts to a bowling ball:

    1-Initial ball speed
    2-Initial rev rate
    3-Initial axis rotation
    4-Initial axis tilt

    The following are generalized descriptions of ball speed, Rev rate, Rotation.

    Ball Speed:
    The following is a generalized description of ball speed at the time of release

    Slower: Ball speed at time of release is typically 15.0 MPH or slower
    Average: Ball speed at time of release is between 15.1 MPH and 17.9 MPH
    Faster: Ball speed at time of release is 18.0 MPH or greater

    Rev Rate:
    Rev Rate is defined as the amount of rotation imparted to the ball at the time of release.
    The following is a generalized description of the balls rev rate at the time of release.

    Lower: Lower Rev Rate is when the ball speed is greatly higher than the rotation. Typically Rev Rates of 240 RPMs or less would fall into this category.

    Average: Average Rev Rate is when the speed of the ball and the rotation are matched. Typically Rev Rates would fall between 240 RPMs and 360 RPMs would fall into this category.

    Faster: Faster Rev Rate is when the rotation of the ball greatly exceeds the ball speed. Typically faster Rev Rates are greater than 360 RPMs would fall into this category.

    Axis Rotation:

    Axis Rotation is defined as the Direction the ball is rolling compared to the direction the ball is thrown.

    Up The Back: When the direction of rotation is "end over end" and the ball is rotating the same direction as it is rolled use this measurement.

    If the Axis Rotation measurement is known, Up the Back is considered to be 30° or less.

    In Between: When the direction of rotation is roughly 45° to the direction the ball is thrown use this measurement. The average bowler will fall into this category if the direction of rotation is unknown.

    If the measurement is known, In Between is considered to be any measurement between 30° to 60°.

    Off the Side
    : When the direction of rotation is roughly 90° to the direction the ball is thrown use this measurement.

    If the measurement is known, Off the Side would be any measurement greater than 60°.
    Updated 07-13-2014 at 08:08 PM by bowl1820
  4. bowl1820's Avatar
    From Low RG, Total Diff and Intermediate Diff, we can determine the missing information.

    To use the RipR's specs as example

    • Low RG: 2.545"
    • Total diff: 0.042"
    • Asymmetrical, or Intermediate diff: 0.013"

    From this we can determine the following: (New info in bold)

    • Low RG: 2.545"
    • High RG: 2.587" (Low RG + Total diff)
    • Intermediate RG: 2.574" (High RG - Intermediate Diff)
    • Total diff: 0.042"
    • Asymmetrical, or Intermediate diff: 0.013"
    • Diff ratio: 0.31 (Intermediate diff / Total diff)

    Unless otherwise stated, we're usually given the Low RG. Brunswick is one of the few that lists High (Max), Low (Min) and Intermediate (Asym) RG values, as well the Total Differential and the Intermediate Differential (Asym Diff).
  5. bowl1820's Avatar
    Some of the basic bowler information needed to help give recommendations on layouts, equipment etc.
    The more information you give, the better information others can give out.

    The pro-shop usually will fill out a form that lists this type of information:
    (note: not all forms look the same or list all or the same information)

    1. The actual span for each finger. (that's the measurement from the thumb to that particular finger.)
    2. The Forward/Reverse pitch used on each fingerhole and thumbhole.
    3. The Left/Right lateral pitch used on each fingerhole and thumbhole.
    4. The size of your fingerholes and thumbhole.
    5. The size and type of grips used (if any)
    6. Whether you have Round or Oval holes
    7. If using a Oval thumbhole, what angle is used.
    8. Positive Axis Point (P.A.P.)
    9. What hand is used.
    10. Ball Layout used (Dual Angle, Pin Buffer, other.)
    11. Location/size of weighthole (if used)

    Here's a example using my grip

    Bowler specific information

    1. What hand you bowl with
    2. Speed (Specify if its on the monitor or at the foul line)
    3. Positive Axis Point (P.A.P.)
    4. Rev Rate
    5. Initial Axis Rotation
    6. Initial Axis Tilt
    7. What surface you want the ball for (wood or synthetic)
    8. What lane condition you are bowling on most of the time
    Updated 09-04-2015 at 01:07 PM by bowl1820
  6. bowl1820's Avatar
    Intermediate Differential: Ball Asymmetry

    The intermediate differential values shown below are a basic guide to the amount of asymmetry in a ball.

    • .000 is a True symmetric, no PSA.
    • .000 to .007 (is treated as a symmetric because the PSA will migrate toward (not necessarily in) the largest hole in the ball, which is usually the thumb hole.)
    • .008 to .012 is a mild asymmetric.
    • .013 to .017 is a medium strength asymmetric.
    • .018 to .022 is a strong asymmetric.
    • .023 and above is a very strong asymmetric.
  7. bowl1820's Avatar
    Heres some info on the pin.

    A Pin-in ball (when the pin is located within two inches of the CG) is excellent choice for control and less hook a Pin-out ball usually can be made to hook more and flip more dramatically than pin-in balls they often give the driller more options in layouts.

    AFFECT OF PIN PLACEMENT (Symmetrical core)
    Pin to PAP distance: (PAP=Positive Axis Point)
    0" - minimum flare potential, core is in its most stable position, earliest roll with smoothest arc.
    1 1/8" - 1/3 of flare potential, stable core position, earlier roll with smooth arc.
    2 1/4" - 2/3 of flare potential, semi stable core position, early roll with strong arc.
    3 3/8" - max flare potential, most unstable core position, medium length with the most hook potential.
    4 1/2" - 2/3 of flare potential, semi stable core position, late roll with flip/arc reaction.
    5 5/8" - 1/3 of flare potential, stable core position, later roll with a flip reaction.
    6 3/4" - minimum flare potential, stable core position, latest roll with strongest flip.

    Remember : These reaction characteristics are all relative to the conditions they are being used on and may not perform as expected due to burning up too early or not setting up early enough.

    Pin to grip center (GC) distance: The higher the pin above grip center the more length you will get for given pin to PAP distance. The placement in relation to GC also affects where the tracks of track flare intersect (bow tie). Higher pin = Higher intersection. For this reason they suggest high trackers place the pin higher above GC to reduce the risk of flaring over the finger holes.
    Updated 07-20-2017 at 08:29 PM by bowl1820
  8. bowl1820's Avatar
    Flare Safe Zone Info: from a post I made before, it includes info from Ebonite and Mo about the Flare safe zone.

    I don't know that it's a set in stone rule, but it has been a general guideline for approximating the top bowtie location.

    This had to do with what was called the Flare Safe zone, if you had a high track and you put the pin too low. You ran the risk of the ball flaring over your finger holes.

    The old guideline on what you did was draw a line from your initial PAP through your Ring finger hole to the track. (This IMO showed basically where your release would cause the bowtie to be.)

    Then If you placed the pin above and to the right of that imaginary line (on high track players) it minimized the chances of the ball tracking (flaring) over the finger holes.

    If you placed the pin below that imaginary line you ran a greater risk of the ball tracking (flaring) over the finger holes.

    You would also see "draw a line from the PAP through the pin to the track. To approximate the top bowtie location." used in conjunction with it. (This IMO showed basically where the ball layout +release would most likely cause the bowtie to be.)

    This is a quote from Ebonite that relates to this also:

    "If you draw a line from the positive axis point, through the locator pin to your ball track, that spot would constitute the pivot for your track flare bow tie. When the track flares, it moves closer to the fingers and farther from the thumb so this causes your ball to roll over the fingers.

    You should ONLY drill a pin in the flare safe zone referenced in our documentation. That zone is above a line from your positive axis point to your ring finger. Anything below that line raises your roll especially in asymmetrical bowling products."

    According to a MO post he said that's more related to how older balls tracked, That with today's more dynamic cores the bowtie locations have been altered somewhat. He said:
    "On modern balls the top bowtie is usually about an 1 1/2" to 3" above the line(on the track) from the PAP through the pin. The bowtie(location?)is far less defined than it used to be because of the stronger dynamics of modern cores."
    Updated 07-20-2017 at 08:34 PM by bowl1820