BubbaRay
11-08-2007, 05:53 AM
http://www.currahee-usbc.org/korner/layouts/layout.png
Finding the PAP
Laying the ball out can be a tough venture, especially if you do not know the PAP (Positive Axis Point) of the bowler you're drilling a ball up for. The best method to finding a bowler's PAP is to use a low-flaring ball. If the bowler does not have any low-flaring ball, use the lowest flaring ball possible (one with the lowest differential). If you use a higher flaring ball, you won't find your true PAP, but it'll be close. If memory serves, I believe you should add a quater-inch (1/4") to the measurement you get from the center of grip to the PAP.
I might do it differently than others, but here's my method. Trace out your grip centerline and your grip midline. Draw a line connecting your grip center to the PAP. This is your axis of rotation line. I use this as my horizontal (h) number (even though it looks diagonal). Now, draw your VAL (Vertical Axis Line which is perpendicular to your axis of rotation line). Note the distance from your PAP to where the VAL intersects the grip midline. I call this vertical (v) number.
I've known some ball drillers to use the grip midline as their horizontal and the perpendicular line from the PAP to the grip midline as the vertical, and that's fine. As long as you know how you obtained those figures, it's fine. I prefer my method because it makes for laying out the ball much easier.
Once you find your PAP, write it down.
Other factors
Now that we know the location of the bowler's PAP, we now have a little more information to lay out the ball, but not enough. We still need to get a grasp of the bowler's factors: rev rate, speed, axis rotation and axis tilt, and we also need to know what kind of line they play, what sort of conditions they face, etc. For the last two factors, unless you bowl at the same place they do, some carefully crafted questions need to be asked. I'll go into those a little later.
Without an idea of what the bowler brings to the table in terms of his/her phyiscal attributes (revs, speed, rotation and tilt) and without an idea of what kind of conditions they face, you're drilling blind. Having the wrong layout is almost as bad, if not worse, than having the wrong ball for the conditions. there are essentially 3 different groups of bowlers; speed dominant, which essentially means a bowler's revs are not enough to match their speed, rev dominant, which basically means that a bowler's revs are too much for their speed, and balanced, which is exactly what the word implies - their speed and revs are in balance. You don't need to sit there with a stop watch and a high-speed video camera to figure out that a bowler's revs are wrong or right for their speed, at least not for the majorty of bowlers (the exceptions might be PBA members, high-stakes amateurs, or Team USA bowlers). For most of the bowlers, recognizing whether they're speed dominant, rev dominant, or balanced will do just fine.
Now we need to understand the other 2 factors - axis rotation and axis tilt - and how they factor into the equation. Let's start with axis rotation. A bowler with more forward roll (lower axis rotation) will have a smoother rolling ball that the bowler with more side roll (more axis rotation). Think of a car hydroplaning on water or skidding on snow. If you keep the wheels fairly straight, once they hit the dry pavement, the car will remain pretty straight on course. If you crank the wheels to the extreme left or right, once the wheels hit pavement, the car will quickly turn to the side the wheels were cranked. This is just as true with a bowler with more forward roll (straighter wheels) and a bowler with more side roll (turned wheels). The bowler with forward roll doesn't rely as much as the bowler with side roll does on friction to get their ball to the pocket. The forward rolling ball will still be powerful enough to carry even on wetter or carrydown conditions. The ball with side roll depends on friction to get it to the pocket and a drilling to get it into a roll.
As far as axis tilt is concerned, this is just as important as axis rotation. A bowler who has a higher tilt (more spinner release) needs help getting their ball into a roll. These bowlers have a natural "skid" because of their higher tilt. A bowler with a lower axis tilt will need less help getting their ball into a roll because they're using more of the ball's circumference.
Now that we've gathered information about the bowler's factor's on the ball itself, we need to find out what they face and what they want out of a ball. To find out what kind of line they play and what kind of shot they're on, you have to be thinking for quite a few of them. Some people are knowledgeable enough to give you the information, but for those who aren't, you either need to watch them bowl (recommended) or guess (not recommended). If you can watch them bowl at the bowling center they normally bowl at, do it.
Using PAP to layout the ball
I will explain how you can use the PAP to come up with your grip layout.
Once you've decided on the kind of layout , it's time to put the grease pencil to work. The first thing I normally do is draw a line through the pin and CG or mass bias (use the mass bias if it's there because that's a more important point on those balls). If you have a ball with a mass bias, don't be surprised or upset if the CG isn't on the line you drew. In fact, it's not too often when the CG is on that line.
Next, figure out at what point your axis of rotation is going to cross this line (it's not really an exact science, at least for me, and sometimes it takes more than once to get it dead on) and mark that spot. This spot depends on where the pin is to be located. If it's on the line that runs from the PAP to the ringer finger (a stable, even rolling core), then I basically use the rule of less than one-half the grip length 1/2") to start minus a fraction more depending on the layout type, pin to PAP distance, and the vertical value (v). You might have to redraw a few times to get pretty close. Once I'm set on my layout type, I mark the axis of rotation line.
The next step is to determine where you're going to place the PAP on the axis rotation line. Hopefully you've decided on a pin to PAP distance before you drew your axis of rotation line. Measure out your pin to PAP distance and mark it on the axis rotation line. While you're at it, mark back along the axis rotation line the value of your h distance. This mark will be at the center of your grip.
After you've marked your PAP, you can draw your VAL and determine where your GML is. Draw a line perpendicular to your axis rotation line and measure down the VAL the value of v. Mark that spot. Now, connect the mark on the VAL and the mark on the axis of rotation line and you now have your GML. Draw a line perpendicular to the GML to give your GCL. You're almost done!
Lastly, mark out your finger and thumb holes with the specs you have. If your specs are "cut-to-cut" you won't have to adjust for any inserts or slugs. If your specs are "hole-to-hole", then you'll have to adjust your hole markings accordingly. Now, other than physically drilling the holes, you're pretty much done.
Balance holes
A note about balance holes; some layouts will need them, especially axis drillings and even some stacked drillings. The general rule of them for balance holes are draw a line from your center of grip through the CG (not the mass bias) and note the location where it hits the VAL. Use larger, shallower holes for minor adjustments and to take the most amount of "insignificant" mass away. Use deeper, smaller holes to take more core mass out and to adjust the breakpoint, backend, and/or overall reaction of the ball. Ebonite has an excellent piece written on balance holes, so I will not reinvent the wheel here. Read what they have to say about them. Drilling balance holes are not just about removing weight. You must do them with thought and properly else you could ruin how the ball reacts and when it reacts.
Finding the PAP
Laying the ball out can be a tough venture, especially if you do not know the PAP (Positive Axis Point) of the bowler you're drilling a ball up for. The best method to finding a bowler's PAP is to use a low-flaring ball. If the bowler does not have any low-flaring ball, use the lowest flaring ball possible (one with the lowest differential). If you use a higher flaring ball, you won't find your true PAP, but it'll be close. If memory serves, I believe you should add a quater-inch (1/4") to the measurement you get from the center of grip to the PAP.
I might do it differently than others, but here's my method. Trace out your grip centerline and your grip midline. Draw a line connecting your grip center to the PAP. This is your axis of rotation line. I use this as my horizontal (h) number (even though it looks diagonal). Now, draw your VAL (Vertical Axis Line which is perpendicular to your axis of rotation line). Note the distance from your PAP to where the VAL intersects the grip midline. I call this vertical (v) number.
I've known some ball drillers to use the grip midline as their horizontal and the perpendicular line from the PAP to the grip midline as the vertical, and that's fine. As long as you know how you obtained those figures, it's fine. I prefer my method because it makes for laying out the ball much easier.
Once you find your PAP, write it down.
Other factors
Now that we know the location of the bowler's PAP, we now have a little more information to lay out the ball, but not enough. We still need to get a grasp of the bowler's factors: rev rate, speed, axis rotation and axis tilt, and we also need to know what kind of line they play, what sort of conditions they face, etc. For the last two factors, unless you bowl at the same place they do, some carefully crafted questions need to be asked. I'll go into those a little later.
Without an idea of what the bowler brings to the table in terms of his/her phyiscal attributes (revs, speed, rotation and tilt) and without an idea of what kind of conditions they face, you're drilling blind. Having the wrong layout is almost as bad, if not worse, than having the wrong ball for the conditions. there are essentially 3 different groups of bowlers; speed dominant, which essentially means a bowler's revs are not enough to match their speed, rev dominant, which basically means that a bowler's revs are too much for their speed, and balanced, which is exactly what the word implies - their speed and revs are in balance. You don't need to sit there with a stop watch and a high-speed video camera to figure out that a bowler's revs are wrong or right for their speed, at least not for the majorty of bowlers (the exceptions might be PBA members, high-stakes amateurs, or Team USA bowlers). For most of the bowlers, recognizing whether they're speed dominant, rev dominant, or balanced will do just fine.
Now we need to understand the other 2 factors - axis rotation and axis tilt - and how they factor into the equation. Let's start with axis rotation. A bowler with more forward roll (lower axis rotation) will have a smoother rolling ball that the bowler with more side roll (more axis rotation). Think of a car hydroplaning on water or skidding on snow. If you keep the wheels fairly straight, once they hit the dry pavement, the car will remain pretty straight on course. If you crank the wheels to the extreme left or right, once the wheels hit pavement, the car will quickly turn to the side the wheels were cranked. This is just as true with a bowler with more forward roll (straighter wheels) and a bowler with more side roll (turned wheels). The bowler with forward roll doesn't rely as much as the bowler with side roll does on friction to get their ball to the pocket. The forward rolling ball will still be powerful enough to carry even on wetter or carrydown conditions. The ball with side roll depends on friction to get it to the pocket and a drilling to get it into a roll.
As far as axis tilt is concerned, this is just as important as axis rotation. A bowler who has a higher tilt (more spinner release) needs help getting their ball into a roll. These bowlers have a natural "skid" because of their higher tilt. A bowler with a lower axis tilt will need less help getting their ball into a roll because they're using more of the ball's circumference.
Now that we've gathered information about the bowler's factor's on the ball itself, we need to find out what they face and what they want out of a ball. To find out what kind of line they play and what kind of shot they're on, you have to be thinking for quite a few of them. Some people are knowledgeable enough to give you the information, but for those who aren't, you either need to watch them bowl (recommended) or guess (not recommended). If you can watch them bowl at the bowling center they normally bowl at, do it.
Using PAP to layout the ball
I will explain how you can use the PAP to come up with your grip layout.
Once you've decided on the kind of layout , it's time to put the grease pencil to work. The first thing I normally do is draw a line through the pin and CG or mass bias (use the mass bias if it's there because that's a more important point on those balls). If you have a ball with a mass bias, don't be surprised or upset if the CG isn't on the line you drew. In fact, it's not too often when the CG is on that line.
Next, figure out at what point your axis of rotation is going to cross this line (it's not really an exact science, at least for me, and sometimes it takes more than once to get it dead on) and mark that spot. This spot depends on where the pin is to be located. If it's on the line that runs from the PAP to the ringer finger (a stable, even rolling core), then I basically use the rule of less than one-half the grip length 1/2") to start minus a fraction more depending on the layout type, pin to PAP distance, and the vertical value (v). You might have to redraw a few times to get pretty close. Once I'm set on my layout type, I mark the axis of rotation line.
The next step is to determine where you're going to place the PAP on the axis rotation line. Hopefully you've decided on a pin to PAP distance before you drew your axis of rotation line. Measure out your pin to PAP distance and mark it on the axis rotation line. While you're at it, mark back along the axis rotation line the value of your h distance. This mark will be at the center of your grip.
After you've marked your PAP, you can draw your VAL and determine where your GML is. Draw a line perpendicular to your axis rotation line and measure down the VAL the value of v. Mark that spot. Now, connect the mark on the VAL and the mark on the axis of rotation line and you now have your GML. Draw a line perpendicular to the GML to give your GCL. You're almost done!
Lastly, mark out your finger and thumb holes with the specs you have. If your specs are "cut-to-cut" you won't have to adjust for any inserts or slugs. If your specs are "hole-to-hole", then you'll have to adjust your hole markings accordingly. Now, other than physically drilling the holes, you're pretty much done.
Balance holes
A note about balance holes; some layouts will need them, especially axis drillings and even some stacked drillings. The general rule of them for balance holes are draw a line from your center of grip through the CG (not the mass bias) and note the location where it hits the VAL. Use larger, shallower holes for minor adjustments and to take the most amount of "insignificant" mass away. Use deeper, smaller holes to take more core mass out and to adjust the breakpoint, backend, and/or overall reaction of the ball. Ebonite has an excellent piece written on balance holes, so I will not reinvent the wheel here. Read what they have to say about them. Drilling balance holes are not just about removing weight. You must do them with thought and properly else you could ruin how the ball reacts and when it reacts.