Mo Fact Sheet

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These are some quick facts posted by mo on various parts of the forum.

  •  For low tilt bowlers, on asyms., use pin to PAP distances of 2 3/4" to 4" to get the ball to change direction and read friction. Use 4" to 5" pin to PAP distances when you want to play straighter.
  •  For high tilt bowlers, don't use 3" to 4" pin to PAPs on asyms. unless there's lots of friction, or you're using a ton of surface with a big, strong balance hole. Use 4" to 5" pin to PAPs to read friction and 5" to 6" pin to PAPs to play straight. Another example of the need for accurate delivery specs.
  •  In reality, the coverstock, surface sanding, ball total diff., and pin to PAP distance control the length of the first transition. The layout and balance hole location, which affect the strength of the PSA affect the distance from the first transition to the second transition. That's basically the intermediate diff. of the drilled ball.

 The smaller VAL angle increases both diffs., but it increases the intermediate diff. much more than it increases the total diff., thereby increasing the diff. ratio. The smaller diff. ratio causes the longer hook zone (slower transition).

 Lowering the pin towards the midline lowers both diffs., but lowers the intermediate more than the total diff., thereby decreasing the diff. ratio.

 60x20 to 60x50 is a big change. I usually make 10* changes. P4 balance holes change diffs. more than small angle changes. Try to get it a close as possible with the layout and, then, tweak it with the balance hole. That's the best system.

 (For symmetrical balls): You're getting pretty good. Put the balance hole on the VAL 2" below the midline, if needed. Drill it 2 3/4" deep. As you make it bigger, it will pull the PSA towards it and reduce the drilling angle to get the ball to start up a little sooner. Also:

taken from: viewtopic.php?t=5781 (Again, for symmetrical balls)

"The P3 gradient line hole will make the ball reaction stronger because it will increase both diffs. The VAL balance hole will only affect the first transition by making it start up sooner as you make the hole bigger. This is because that hole will move the PSA closer to the VAL as you make it bigger."

 For balance holes close to the thumb hole: The pitch of the balance hole plus the distance that the center of the hole is from the edge of the thumb assembly must equal 2 1/2" plus whatever lateral pitch toward the balance hole the thumb hole has. Voila!

 When the fingers are over 3" deep, don't go any deeper than 2 3/4" on the balance hole! The holes will meet, if you drill the balance hole too deep.

 Staying behind the ball causes it to track high. Specifically, lack of axis tilt. Staying in the thumb too long causes it to track very close to the thumb. That's the real skinny.

 Reply to a two handed bowler who was clipping the edge of his thumb hole: Stop chasing your tail! Let's adjust your finger pitches since you don't use your thumb. Drill your fingers 7/16" left by 1/4" forward on your middle finger and 7/16" right by 3/8" reverse on your ring finger, if you're right handed. Now measure your initial axis tilt and your PAP and post that info. We'll go from there. No more hand grenades at 20 paces! Use your normal thumb hole location.

ALL bowling balls with migrate along the RG contour of the Bowler's PAP. That's governed by the laws of the universe. Therefore, in order to create a unique migration path, you must create a unique RG contour for that ball. ALL balls have RG contours that use the low and high RG axis as the centroid for the RG contours. The higher the differential ratio, the more of the RG contours that are centered around the high RG axis, and the flatter those ellipses. That's just pure science and math.

  • Don't worry about the cg. No problem. CGs don't mean a thing (to) ball motion as long as the ball has legal statics. .... NEVER put balance holes below the thumb. Too much of a chance of flaring over it.
*With Scotch Brite pads, it's all about the pressure you use with the pad.
Burgundy results in 400 to 800 depending on the pressure.
Grey results in 800 to 1500, again, depending on the pressure used.

Using scuff pads is not an exact science, but this is usually done during practice when the ball you want to use is not reacting enough. After the bowling is done, I always recommend using a spinner to return the ball to its' normal surface.

On a symmetrical ball drilled without a balance hole, the PSA (high RG) axis ends up very near the thumb. That puts the PAP near the intermediate RG axis on a vast majority of bowlers. Putting a balance hole in the PAP, which is near the int. RG axis, raises the RG of the int. RG axis. That decreases the int. diff., which makes the ball more symmetrical. That's what blueprint's excellent attachment shows. This explanation is for those who have math phobia.

Increasing the reverse in the middle finger actually helped to lower your tilt. Changing pitches changes the resulting ball motion. If you have to change the grip to accomodate issues like this, CHANGE THE SPAN FIRST TO RELIEVE THE PRESSURE, NOT THE PITCH, UNLESS YOU WANT TO CHANGE THE ROLL!

Sand 4 ways thoroughly with the first grit and sand two ways quickly with the second grit to do the "skip a grit" procedure.

Stretching spans tends to decrease tilt as does reverse in the fingers.

Stop chasing your tail! Let's adjust your finger pitches since you don't use your thumb. Drill your fingers 7/16" left by 1/4" forward on your middle finger and 7/16" right by 3/8" reverse on your ring finger, if you're right handed. Now measure your initial axis tilt and your PAP and post that info. We'll go from there. No more hand grenades at 20 paces! Use your normal thumb hole location.

Why is it that Mo doesn't recommend pin to pap distances of anything past 5.5 ?

Here's the real reason. The low RG axis can move when the ball is drilled. Using a pin to PAP distance of > 5.5" might result in the real low RG axis moving to a pin to PAP distance > 6 3/4". That may cause the ball to flare in bad places, causing the ball to flare over some drilling holes. NOT GOOD!

I'll try to make this plain. All balls are delivered with more axis rotation than tilt. Cannot be any other way. The laws of physics dictate that. The ball loses both rotation and tilt. The ball loses rotation faster than it loses tilt until tilt = rotation. That occurs at the second transition. FACT! During the roll phase (after the second transition) the ball loses rotation and tilt at the same rate until the ball hits the pins. That should keep your mind busy for a while.

Phasing is a function of porosity. Change in temperature causes it to absorb moisture. I light wipe with a little acetone, or a hair dryer will get rid of it. BALLS THAT PHASE EASILY HOOK!

This is what a vast majority of low tilt players don't understand. This is the magic. Fingers on the inside hemisphere of the ball at the top of the swing. Fingers move across the back of the ball until the hand reaches the "Nike Swoosh" position at the end of the follow thru. If the wrist is cupped at the top of the swing, it MUST be unloaded by the time of the release.

The reason we use a higher angle ratio for symmetrical balls is that drilled symmetrical balls lose tilt at a rate almost double the rate that asymmetrical balls lose tilt as both types of balls go down the lane.

You're very close. With a symmetrical ball, the PSA will be very near the thumb hole after drilling until the balance hole is drilled. We can change the mass properties of the drilled ball about 40% with layout and balance hole. With an asymmetrical ball, we can put the PSA whereever we want, and change the mass properties of the drilled ball by as much as 84% with layout and balance hole.

Conclusion: Syms are easier to drill and less versatile, making ball selection a premium. Asyms are more versatile and can provide stronger motion, but are dependent on the skills of the ball driller because they are more sensitive to the layout and balance hole.

The higher the diff. ratio, the more the ball displays gyroscopic properties because the PSA is stronger with a higher diff. ratio. In fact, that will help it retain tilt longer. I've been measuring it for years and syms lose tilt about twice as fast as stronger asyms.

The ability of the ball to retain tilt is related to the strength of its' PSA.

Blueprint has done a great service here. the difference is instantaneous direction as opposed to a fixed point rotation is measured against. Since the bulk of my research is from a fixed camera position, this difference can occur. Very educational!

Axis tilt is in relation to the horizon, so it's the same in either system. True "roll out" occurs when the ball has 0* instantaneous axis rotation and 0* of axis tilt. Using Blueprint's system of measuring axis rotation, a ball stops hooking when the instantaneous axis rotation is 0*, the second transition! the ball will have effective hitting power as long as it still has axis tilt. The ball stops hitting when axis tilt reaches 0*.

Good work, Blueprint!

Q. Just wondering if using p3 and p4 balance holes for low tilt players could cause the ball to lose tilt too quickly because of the increase in differential/flare, the same way as using max flare pin postions does. Should there be any concerns? Thanks.

A. Unless they're strongly speed dominant, be cautious with strong balance holes for low tilt bowlers.

  • This one is from Elgavichon, from: viewtopic.php?f=15&t=4992

The PSA on symmetrical cored ball without a balance hole ends up 6 3/4" from the low RG axis (primary pin), within 1/2" of the centerline of the grip.

  • From: viewtopic.php?f=15&t=4735
Your discussion of the movement explains why the "flare safe" zone, that I've recommended for two decades, goes from pin to PAP distances of 3/4" to 6 1/4". After seeing that the low RG axis can move as much as .6", I'm now going to reduce the flare safe pin to PAP distances to 3/4" to 6". I use 5 3/4" as my max. pin to PAP distance on the balls I personally layout. Balance holes near the high RG axis can be,and are, extremely effective, but balance hole near the intermediate, or low, RG axis can be dangerous because of the movement they can cause in ALL of the primary axis. I've do have some ancient engineering training, but have had to use empirical research to develop most of the techniques that I recommend and teach. Thanks for confirming that I didn't waste my time.

On a symmetrical ball drilled without a balance hole, the PSA (high RG) axis ends up very near the thumb. That puts the PAP near the intermediate RG axis on a vast majority of bowlers. Putting a balance hole in the PAP, which is near the int. RG axis, raises the RG of the int. RG axis. That decreases the int. diff., which makes the ball more symmetrical. That's what blueprint's excellent attachment shows. This explanation is for those who have math phobia.

The problem is simple!!!!!! This is a good time to address the cause, since you've asked. GOOD BALL REACTION OCCURS WHEN A BALL IS ROLLED IN ONE DIRECTION AND ROTATED IN ANOTHER! THE ANGLE BETWEEN THE DIRECTION OF TRAVEL AND THE DIRECTION OF ROTATION IS MEASURED IN TERMS OF AXIS TILT AND AXIS ROTATION! NOT ENOUGH OF EITHER AND THERE'S NOT ENOUGH BALL REACTION! As the ball travels down the lane the forces of gravity and friction reduces those angles. As those angles are reduced, the ball tracks higher. When it tracks too high, it hits holes.

Q. When laying out balls for specific conditions (long/heavy/short/dry) is it best to adjust ratios or sums (or a combination of both)? What range (in terms of ratio changes or sums) are generally useful, and how bowler specific is this? I guess I'm trying to get a handle on how far from the benchmark ratios/sums it is safe to venture when laying out balls for specific conditions.

A. You adjust the sum of the angles to move the transitions on the lane. You adjust the ratio to change the shape of the ball motion. You adjust the pin to PAP distance to mainly control the flare, which strongly adjusts the distance of the first transition.

Q. But my original question still remains: what is the reason why we keep ratios the same when looking to delay the first transition with a (close to) identical hook shape? Are the ratios themselves affecting the ball motion? Or are they a useful tool to manage more difficult to measure variables?

If the second, how does a ratio change affect the variables (perhaps the differentials)? Why is a change in drilling angle not preferable to a change in both angles?

A. Either one is useful. Changing the drilling angle delays the first transition and leaves the second transition the same distance from the new first transition. Changing both angle delays the first transition and increases the distance from the first transition to the second transition. This keeps the proportions the same (for example, 20ft first transition, 10ft hook zone becomes 25 ft first transition, 12.5' hook zone).

Sounds like your fit is close. My check, as always, is to place your fingers in the finger holes and, then, place your thumb ALL the way into the thumb hole by pressing down on the back of the knuckle above the thumb. If your finger nails press against the back of non Vacu inserts, your span is too long on either finger you feel the pressure on. Vacu grips, as traditionally done, allow too much movement for the fingers in the inserts IMO.

To allow for swelling, drill a hole 1/32" larger than the hole for the insert 1" deep (3/4" deep for short finger tips) at the cut span distance, then change the bit to the correct size for the insert and flush the bit against the front wall of the hole and drill it the desired depth. This will allow for the knuckle to swell and still keep the tip of the finger at the correct place at the bottom of the hole. I call these fake Vacu grips.

  • Taken from context: viewtopic.php?f=13&t=431

For Asymmetrical balls:

For bowlers that come up the back, I prefer to use pin to PAP distances of 3" to 5". Closer to 3", if I want them to cover boards. Closer to 5", if i want them to play parallel.

  • From: viewtopic.php?f=15&t=5119

Your very accurate! You must use balance holes to get true smaller drilling angles in symmetrical balls. What you've proved is that symmetricals transition very similar unless you use a balance hole. Use balance holes on the VAL below the midline to decrease the drilling angle. Use balance holes on the Gradient Line to alter the diffs. of the drilled ball to change the intensity of the ball reaction.

"For bowlers who get around the ball, I prefer to use pin to PAP distances of 4" to 6". Closer to 4", if I want them to cover boards. Closer to 6", if i want them to play parallel."

Q. Is it possible to lay out a ball to lower or raise the track of a bowler?

A. Not consistently, or effectively. Changing the track is related to changing the release, not the layout. Sorry!

Drilled asyms maintain their PSAs pretty well. Symmetrical balls end up with the PSA near the thumb, no matter where the cg is. Drilling the balance hole on the Gradient Line changes the intensity of the ball reaction on all balls. Balance holes on the VAL, below the midline, is the only way to reduce the drilling angle on a symmetrical ball.

  • From: viewtopic.php?f=15&t=5222

Densities, my man. Inner cores average 2.6 g/cc, outer cores average 0.9 g/cc, coverstock is 1.10 g/cc.

Ancient bowling mythology often gets in the way of the true science of ball drilling. This is the US of A, so everyone has the right to be wrong. My detailed thoughts on layouts are expressed in the article by me on the Dual Angle Layout System in the Wiki. I don't think I can be any plainer.

As a rule of thumb the PSA on a drilled symmetrical ball without a balance hole will be 6 3/4" from the pin approximately 1/2" negative of the centerline. The balance hole will pull the PSA towards it

  • Taken from viewtopic.php?t=5485 (see #8)

Timing is related to three things:

1) Grip pressure 2) The length of the hinge 3) The half period of the pendulum

"That's all Folks!"

Intermediate diffs of .008" or more, I treat as asyms. The Pursuits just make it, but without a balance hole, the PSA of the drilled ball will move more than half way towards the thumb hole. Check me, if you'd like.

  • Dealing with a low axis tilt player. Taken from:


Finger pitches are designed to increase your tilt. If you're not feeling the ring finger, the fit is doing the job. Ring finger dominant players are usually low tilt players. I need to see the original thread to comment on the thumb pitch because of the adjustments I made.

Also, from viewtopic.php?f=13&t=5542:

Hitting the ball with the ring finger will DECREASE tilt, not increase it.

On higher track (lower tilt) players, I try not to use pin to PAP distances in excess of 4 3/4" because it can pull the track up on the holes. It doesn't happen all the time, but it happens often enough for me to avoid it.

Note - in a subsequent post Mo says that applies to both symmetric and asymmetric balls.

If you describe it accurately, the transition is too short. That is altered by changing the mass properties of the drilled ball, thus, the balance hole is the answer. Surface changes the first transition.

I'm not versed enough on that math to comment, but have experience with abrasives and smoothing of surfaces. Regular surface scratches can create harmonics and tend to promote smooth, continuous motion. Irregular scratches tend to interrupt motion and can be used to increase the rate that balls transition. This is the basis for my "skip a grit" finishing technique used to promote earlier transitions and, therefore, help the ball read friction by helping to interrupt the skid phase. I keep recommending "true" grit sequences to promote smooth, continuous motion and "skip a grit" grit sequences to encourage the ball to transition faster.

Q. What layout does everyone use for the THS when they get real wet/dry ?

A. Use a larger VAL angle than normal and a longer pin to PAP distance than your benchmark layout.

Speed, or rev dominance, affects the sum of the angles and the pin to PAP distance. Tilt and rotation affect the ratios.

  • By Kelly Tehuna, confirmed by Mo.


This bowler has high axis rotation, which means we need to get the ball to roll forward as soon as we can. In asyms, longer pins promote more forward roll, while the opposite is true of syms. So, if we need the ball to roll forward off the end of the pattern, long pins will be the order of the day for asyms, and short pins for syms.

Here's how it works. When the lane transitions and you lose your reaction, make small physical adjustments (hand positions, ball height, eye distance) to regain the reaction. If that takes you out of your game, switch to the ball in your arsenal that gives you that good reaction with your "A" game. Not too bad! That just requires you to have a well developed, versatile physical game, an eye for ball reaction, and a well thought out, effective arsenal. Simple, heh?


Q. I have a question regarding Gradient line balance holes on balls on which PSA ends 1/8" - 1/2" past VAL line (I drilled few balls with larger VAL angles and smaller horizontal pap coordinates where this happened). I wanted to know does everything stay the same in those situations (6-3/4" up the VAL from PSA-to-PAP and PAP-to-PSA line divided in 4 points)? Will this cause any issues with flaring over balance hole if I drill P4 holes?

[color=#FFBF00]In this situation, P1 remains the same. You are right about the guidelines for positioning the P4 hole. Balance holes should not be placed below the thumb or past the VAL to prevent the ball from possibly flaring over the balance hole. We use the "Double Thumb" position when the P4 hole position is below the thumb hole. In the case where the PSA is past the VAL, use the intersection of the pin to PSA line and the VAL as the P4 position to keep the balance hole flare safe.[/color]

  • Taken from: viewtopic.php?f=13&t=6086

"Flare management is mainly used to help determine the length on the lane of the first transition when it is used properly. That's about the jist of it."

  • Some bowlers were saying that as long as flare rings were hitting a fresh surface, anything else was overkill. see viewtopic.php?f=13&t=6086

Mo's correction: "Stop using the distance between flare rings to measure flare! Try using the total distance that the precessing PAP moves in relation to the major and minor axis of the RG contour to accurately evaluate the amount of flare necessary for good ball motion. Now we're discussing reality, instead of just looking for things to talk about."

  • How many degrees do you add to sums for low tilt & low rotation? Found in discussion:

10* for tilt and 5* for rotation are the approximate guidelines that I personally use.

The quote below is by Mathistruth. See the thread for discussion and explanation by Mo and others.

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.

Here's the real answer about reverse oil. Reverse oil controls the amount of oil in the front part of the lane. Forward oil controls the shape of the pattern at the end of the pattern. The more reverse oil in relation to the forward oil, the longer the pattern last and the smaller the transitions. Read the pdf and find the corner of the red bar. Subtract 3 and that's where your breakpoint should be to start. Take the length of the pattern minus 31 rule and shove it. Not accurate. Do your homework!

  • from discussion of a Double Thumb layout for low tilt/high rotation bowler:

viewtopic.php?t=354 (see #6)

The P3 hole will make the difference as opposed to the "Double Thumb" balance hole location.

The key factor is your 70* of axis rotation in conjunction with 7* of tilt. We're getting into PDW territory. The P3 hole will help control possible overreaction and make the ball more controllable, but still very strong.

Mo's answer to a request for a definition of a performance fit.

[color=#FFFF40]A performance fit is a fit adjusted off a good basic grip that changes the natural effect of each of the fingers and the thumb on the ball motion that results from the bowler's basic (Wiki) grip. The purpose of the performance fit is to adjust the axis tilt, axis rotation, and speed, or rev, dominance of the bowler's natural delivery in order to improve the effectiveness of the ball motion. Basically "training wheels".[/color]

[color=#FFFF00]No reason it shouldn't work! I set the 10* minimum drilling angle to make sure the migrating PAP had to cross the pin to PAP line. Just a safety feature.[/color]

[color=#FFFF00]I try to make sure the PAP of the migrating axis goes past the pin to PSA line. This helps the ball to rev up more easily on the back end of the lane[/color]

  • from: viewtopic.php?t=6719

[color=#FFFF00]"Over/under with I prefer to call wet/dry is cured either of two ways. One by lengthening the hook zone, which is accomplished by lowering the angle ratio, to slow down the ball's response to friction. Second by creating a "hook/stop" reaction. This is accomplished by lowering the angle sum and the angle ratio and by using lots of surface to get the ball into the roll phase early."[/color]

The amount of movement of the PSA will depend on the intermediate diff. of the undrilled ball. Here are some estimates. If the ball is symmetrical (.000 int. diff.), use the thumb hole as the PSA for Gradient Line Placements. If the int. diff. of the undrilled bal is between .008 and .020, use a spot half way between the marked PSA and the thumb hole as the real PSA for Gradient Line Placements. If the int. diff. is over .020, use the marked PSA for Balance Hole Placements. These are good estimates and will produce good results. A DeTerminator is still the most accurate way to do it. Remember, the larger the volume of the balance hole, the more it will have an effect on the ball motion of the drilled ball.

  • Taken from: viewtopic.php?t=6710 (see #8)

In response to the question about the "flat spot", the flat spot is equal to the length of the slide and the distance the knee travels after the foot stops. Lengthening the flat spot can be achieved by lengthening either the slide or the knee continuation, or both. I suggest starting with knee continuation as the best way to increase the "flat spot". Increasing knee continuation tends to slightly increase the length of the slide at the same time.

  • From: viewtopic.php?f=13&t=7374&p=59667#p59667 (see #230)

"I word of caution on balls that use the "It" interchangeable thumb. There is no problem, if the collar on the drill is set to the position it comes from the manufacturer. Drill the 1/2" hole in the bottom to exactly the recommended 1" depth. That will always work without needing the pitch the MOtion hole. If you want a bigger margin of error, just drill the MOtion hole only 3 3/4" to the tip of the bit. There will be NO appreciable loss of performance because of the added depth of the hole for the hole for the "It"!"

  • Taken from: viewtopic.php?t=3088 (see #3)

"When a ball flares, it follows the RG contour of the drilled ball. IT IS NOT SEEKING ITS STABLE AXIS. Where the ball is is relation to it's first and second transition will determine where in the phases of ball motion that the ball is."

  • Taken from:

Those numbers may need to be adjusted for a small amount of bowlers to remain flare safe. The ideal location for the MOtion Hole ends up being 1 1/4" from the initial flare ring at least 10" from the pin avoiding the bowtie.

Note: Mo clarified in a later post that the 1 1/4" is measured from the center of the bit.

  • From Topic: viewtopic.php?f=3&t=7448&start=20

Here it is in a nut shell:

A Double Thumb Layout will cause the ball to read the friction harder and earlier because it causes the ball to lose axis rotation and tilt earlier.

A MOtion Hole will cause the ball to stay on it axis longer and, therefore, read the pattern late and hard. It hits harder because it reduces deflection.

  • viewtopic.php?f=6&t=7817&p=62380#p62380
Daily maintenance is the key to good coverstock performance. The most important step is to clean the ball thoroughly by hand with a good bowling ball cleaner immediately after each use before the oil can get deep into the coverstock. Preventing deep penetration of the oil into the coverstock is better, easier, and cheaper than trying to remove the oil after it gets deep into the coverstock!
  • Taken from: viewtopic.php?t=8096

According to the USBC award winning Ball Motion study, coverstock is the most important aspect in ball motion. Followed by core dynamics with static weights dragging up the rear. Coverstock means the nature of the coverstock and the surface used. This was settled in 2007.

P. 28, Post #550

I don't suggest MOtion Hole drillings for asymmetrical balls. I suggest using the latest expanded Radical asymmetrical drilling instructions for ALL asyms. They are attached to this post.

  • Outlines of the criteria to get a bowler's proper layout.: viewtopic.php?t=278 (see #9)

1) Determine the sum of the angles by analyzing the bowler's ball speed/rev rate ratio. 2) Determine the angle ratio by analyzing the bowler's axis rotation and axis tilt. 3) Adjust the angle ratio based on the design of the ball. 4) Adjust the numbers for the pattern the bowler wants to use the ball for. 5) Drill the ball and use the surface you choose. 6) Watch the bowler throw the ball and decide the balance hole size and location that will perfect the reaction. 7) Shake the bowler's hand and collect the money knowing you have done the job correctly

also from viewtopic.php?t=8564

[#1 Choose the pin to PAP distance to determine the resulting flare.

  1. 2 Determine the sums of angles to determine the distance of the 2nd transition (Ball speed to rev rate ratio is the primary factor.
  2. 3 Determine the ratio of angles to determine the shape of ball motion.
  3. 4 Add a balance hole where chosen for layout/needed for reaction.
  4. 5 Change the surface to fine tune the reaction.

Note: This tip applys only to symmetrically cored balls. -- JohnP

Placing a balance hole on the VAL 1 1/2" below the midline will cause the PSA to move toward the balance hole reducing the drilling angle. This will result in the symmetrical ball starting to transition sooner. The bigger the hole the sooner the ball will transition.

  • Let's talk issues in plugging:

Taken from: posting.php?mode=quote&f=7&p=69955

1) Control environment temperature and humidity. 2) Eliminate moisture as much as possible. 3) Use the little caps on the pumps all the time. Moisture control 4) Urethane ball plug is always susceptible to bubbles. CO2 is a by product of the reaction. 5) Stir until plug reaches body temperature.

6) added by ballspinner: Accurately measure the components! Do not rely on the pumps to give an accurate ratio.
  • The following is Mo's response to the question: "If the amount flare on any asymmetric with a pin to PAP distance between 2 3/4 and 6 3/4 is the same, then is it safe to say that regardless of that distance it will hook the same amount overall?"


The Dual Angle System is accurate. People's decision making is NOT always as accurate. The system is only as good as the person making the decision. My track record is pretty legendary. I use the principles that I teach.

Just because the flare is the same doesn't mean the shape is the same. 2 3/4" to 3 3/4" pin to PAP distance results in the ball covering the most # of boards. 3 3/4" to 4 3/4" pin to PAP distance covers less boards. 4 3/4" to 5 3/4" pin to PAP covers the least amount od boards and rolls forward the soonest.

  • Taken from: viewtopic.php?f=6&t=8892

Breaking down the high flare zone for asyms:

2 3/4" to 3 3/4" pin to PAP distances will cover a lot boards. 3 3/4" to 4 3/4" pin to PAP distances will cover a medium amount of boards. 4 3/4" to 5 3/4" pin to PAP distances will play more direct. They will all have all the flare will ball will offer before you choose the balance hole location to affect the flare.

  • Same topic (specifying 3" pin to PAP v.s. 5" pin to PAP asymmetrical): viewtopic.php?f=6&t=8892
Both balls will transition at the same points on the lane. The 3" pin to PAP ball will cover more boards and have a bigger change of direction at the breakpoint. The 5" pin to PAP ball will cover fewer boards and have a smaller change of direction at the breakpoint. That's about the most exact I can be in explaining it. I believe that should be completely understandable. 
  • Balance hole question "should you use a smaller diameter deep hole or one that is larger in diameter and maybe not as deep?"

Removing inner core material is more effective when altering ball reaction by using a balance hole.

  • From:


You all have different methods, but they are all inaccurate. Layouts have so much to do with the #s of the drilled ball that all approximations are not accurate. Refer to the latest Radical drilling suggestions. There is a chart on the front page of both the ReaX version 2 and the Yeti drilling suggestions that show the mass properties of the balls drilled with the six different layouts, a tremendous difference. That's reality!

Here's my best 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.

Asyms (> .011" intermediate diff.) will retain tilt longer with pin to PAP distances of 3" or less (dynamic Gimbal effect). Use 1 1/2" as a minimum pin to PAP distance as a guide. The smaller the pin to PAP distance in that range the later the breakpoint because of the reduced flare.

  • Question about Double Thumb layouts & high tilts. Taken from: viewtopic.php?t=544

On players with that high a tilt, I put the PSA 1 1/2" right of the right edge of the thumb (for right handers) and figure out the drilling angle. The 4" pin to PAP distance and the 30* VAL angle don't change. This puts the balance hole into the PSA and decreases the drilling angle to compensate for the added tilt.

High rev bowler will hit balance holes, taken from: viewtopic.php?f=15&t=9201

As a rev dominant player, I can understand it happening. I've seen it many times. Just draw the gradient line on the ball and mark the P3 and P2 positions. Make a decision as to what gradient line position you want to use. Now mark that position on the gradient line. Draw a line through that point perpendicular to the gradient line. Place the hole on that line at a distance closer to the grip that you feel will allow for the increased flare (not hitting the hole). Start with a small hole and increase the size, if you'd like, monitoring the flare.

Taken from viewtopic.php?t=793 (see #6)

To get an angular backend on dry lanes, you want a large drilling angle and a small VAL angle with reduced flare. Precisely, 75 to 90* drilling angle with a 20 to 30* VAL angle. Use a pin to PAP distance of 1 3/4" to 2 1/2" on asyms. depending on your style; 4 1/2" to 5 1/2" pin to PAP distance for syms., again, depending on your style.

  • viewtopic.php?t=9238 (see #3)

Core density, inner core volume and especially core shape have everything to do with how drillings and balance holes affect ball motion.

CORE SHAPE DETERMINES BALL MOTION!!!!!! An axiom of Radical Ball Technologies!

As the developer of Radical's "finger scoop" and being listed on the US Patent application as the inventor, I guess it's appropriate for me to comment.

The finger scoop was developed to increase the versatility of drilled balls. If one of these balls is drilled with the pin above the fingers, the fingers holes will only minimally penetrate the core, allowing the core to maintain it's undrilled core height. This produces a sharper, shorter breakpoint for the drilled ball. If one of these balls is drilled with the pin below the fingers, the fingers holes will substantially penetrate the core, reducing the height of the core compared to the undrilled ball. That results in a ball with a smoother, longer breakpoint.

That should sum it up!

Mo's response to a question about where a 24* axis tilt track would be located compared to a 14* axis tilt track.

[color=#FFFF00]The real answer is that it could be almost anywhere. It's only the distance across the track on the surface of the ball that really matters.[/color]

  • From: viewtopic.php?f=13&t=9406&view=unread#unread

Note: I've made an exception with this quote, it's from Math is Truth instead of Mo, and responds to a question about the PBA Plastic Ball Layout. -- JohnP

You want to use the balance hole to push the Low RG axis down so it ends up closer to 3 3/8" from the PAP. Use the smallest balance hole to make it statically legal. Larger balance holes will cut the diffs! I spent hours studying the changes in principal axes and diffs when Mo started developing this technique. Exciting times watching this layout win that Plastic Ball tournament!!

  • Taken from: viewtopic.php?f=6&t=9491

An intermediate diff. on the undrilled ball of <.010" makes the ball a symmetrical ball because when you drill it, the PSA of the drilled ball will move to the area of the thumb hole until a balance hole is added.

  • From: viewtopic.php?f=15&t=9567&view=unread#unread

On symmetrical balls without a balance hole, use the PAP as P1.

Regarding use of low differential balls for bowlers with low axis tilt.

[color=#FFFF00]I hadn't seen that, but here are some guidelines for low tilt bowlers (3*-11*). First of all low diff. balls, as long as the total diff. >10*, should help the breakpoint to get down the lane with more continuation. Always use pin to PAP distances < 5" for low tilt bowlers. Longer pin to PAP distances can cause the ball to pull the track up on the holes. Use angle sums > 90* with the drilling angle at least 1.5 time the VAL angle. Hope that helps.[/color]

  • From: viewtopic.php?f=15&t=9852&view=unread#unread

The pin placement on a full roller layout is designed so the ball doesn't flare over thew holes. Every company has their own way. When we did the aggressive full roller layouts, we used CAD program to analyze the drilled balls to maximize the diffs. of the drilled ball. That's accurate. There are two, one for asyms. and one for syms. Those layouts are in the Wiki. I guarantee the accuracy of our suggested layouts. They are entitled to their positions. That the jist of it.

  • from: viewtopic.php?f=15&t=9960

With no thumbers I use a pin location just above the fingers as a 1st drill. Using pins out to the right can sometimes pull the track up onto the finger holes. Safety first, and I can still use a balance hole to influence the reaction if there is no thumbhole drilled.

  • taken from: viewtopic.php?f=13&t=10266

Hook/Set reaction is ball motion with a medium skid phase, a short hook zone and a longer roll zone.

  • MOtion hole with no thumb & new rules: viewtopic.php?f=15&t=10306

Follow the instructions and start with the center of the grip as the center of the inserts. Measure from there through the pin. Measure 10" on that line. Make sure the center of the MOtion Hole is at least 1 1/4" for the 1st oil ring on the bottom of the ball. Start small. There can be NO thumb hole in the ball if you use a balance hole under the revised rules.

  • taken from: viewtopic.php?f=6&t=10315 (see #19)

Plugging and re-drilling a ball is specific to each event. The amount of change is related to which part of the ball (inner core, outer core, or shell) the holes hit. The changes are almost always minimal.

  • Taken from: viewtopic.php?f=3&t=10425 (see #17)

The first transition (skid to hook) is related to flare (pin to PAP distance) and the drilling angle.

  • Taken from: viewtopic.php?f=15&t=1118&hilit=CLT&start=20

This link takes you to a thread where Mo discusses the use of the fan chart in the fitting procedure and compares it to the Center Line Transfer (CLT) process. -- JohnP

Regarding: Layout for a no-thumb, two handed bowler

In regards to this remark : Also the pro shop just wants to put the cg center and just below fingers and then just set the pin to pap without drilling a thumb. Is this an ok method or is it very imprecise?

That's a good method. I just recommend pin to PAP distances between 4 1/2" and 5 1/4". Closer to 4 1/2" to get the ball to corner and closer to 5 1/4" for smoother roll.

Time to understand the effect of both cores and covers on the ball gooing down the lane. It's a sliding scale. The closer to the foul line the ball is, the more the coverstock (including surface) dominates. The closer to the ball going off the pin deck, the more the core dominates. In the pin deck (going thru the pins), the cover is mostly insignificant. In the heads (the front of the lane), the core is mostly insignificant. As the ball travels down the lane the coverstock becomes less important and the core becomes more important. Hitting the pocket is mostly related to to the coverstock, but pin carry is mostly related to ball dynamics (core).

That ought to start something!

  • Taken from: viewtopic.php?f=15&p=85622#p85622 (see #14)

There are only 2 ways to get the ball to flare the wrong way:

1) Please the pin (low RG axis),past the VAL. 2) Place the low RG axis of the drilled ball (post drilling low RG axis) more than 6 3/4" from the bowler's PAP. Because of the movement of the low RG axis after drilling, I use 5 3/4" pin to PAP as max.

Drilling high track bowlers with pin to PAP distance > 4 3/4" can pull the track up on the holes, but won't reverse the flare until you exceed 5 3/4".

  • From: viewtopic.php?f=15&t=11116&view=unread#unread

Regarding: Balance holes for no-thumb bowlers

Balance hole size and location is the most critcal factor to ball motion on a symmetrical ball because it moves the PSA of the drilled ball around so much. On no thumb drillings, the balance hole can cause wild swings in the PSA location because the drilling holes remove so little mass from the ball. I recommend drilling the finger holes at least 3" deep on no thumb balls to help stabilize PSA movements when adding a balance hole. I've been tracking the movement of the PSA on no thumb balls with a DeTerminator to learn more about the PSA movement. No solid determinations, yet. My 13 year old son, Levi, is a no thumb bowler because I wouldn't let him use his thumb when he started. So I get plenty of practice on these layouts.

  • Taken from: viewtopic.php?t=845 (see #9)

"Interchangeable thumbs are an important part of ball drilling today. We included demos on both the Vise IT and the Turbo Switch Grip in our advanced class this year. Both systems work well when installed properly and DO NOT negatively affect ball dynamics. USBC Equip. and Specs. did a study to prove that they don't negatively affect ball dynamics."

  • Taken from: viewtopic.php?f=15&t=11215

Re: Variation in PAP location on different balls

Let's do some confirming of the measurements. Put a piece of tape on your measured PAP and see if the ball rotates about that PAP as it hits the lane. You'll have to have someone watch it as the tape will move as the ball flares. Another way to confirm the PAP is to find the center of the ball track and measure 13 1/2" from that in any direction to find the PAP. I use that method when an Armadillo is not available.

  • Taken from: viewtopic.php?f=6&t=11274

To straighten out what seems to be confusion, double thumb layouts maximize both the differentials of a drilled ball. By scientific definition, strong ball motion is ball motion that turns translational energy into rotational energy the soonest. For lay people, that means the ball will hook "early and often". There's nothing in there that says there's any delay in the breakpoint. Depending on the axis rotation and axis tilt of the bowler, it will be perceived as either early roll or complete continuation. Some people think strong ball motion means flip on the backend. If you use the scientific definition of strong ball motion, that's NOT it. We can provide "flip hook" in the ball design anytime we, at Radical, want with our core technology. The double thumb technique is the way to turn that ball into a massive hooking monster

  • From: viewtopic.php?f=6&t=11278&start=20 (see #26)

Nope. Once the ball hits the pins, the motion is dominated by the rotational inertia of the ball assembly. Created by the core structure!

  • From: viewtopic.php?f=6&t=11274 (#10)

Response to "How do the double thumb and motion holes compare?"

DT is early and often while the MOtion Hole is late and hard. MOtion Hole delays the breakpoint and increases the severity of it. A must for ALL high track, slower speed bowlers. Like many of those who were born before the advent of color television. Opposite motions!

  • Taken from: viewtopic.php?f=13&t=6086 (#86)

Correct! If the bowler does NOT rotate the axis the ball will not hook no matter how much it flares. When a ball enters the roll phase it stops hooking, but it still continues to flare. You'll see it on every shot thrown that enters the hook phase at the correct time.