We will start with the Center of Gravity, because it is the easiest to understand.  First off, the static weights resulting from CG placement only control about 5-10% of a ball's reaction.  This number used to be much greater, however, the dynamics of bowling ball cores and the friction generated by new ball coverstocks have given much more precedence to core positioning and surface than ever before.

The CG is usually marked on the ball with a punchmark, a small punched dot on the ball.  Underneath this punch mark, there are a couple of extra ounces of weight to make up for the roughly 2.5 ounces that are removed during drilling.  This way, the ball retains its balance and doesn't wobble down the lane because of the top of the ball being lighter than the bottom of the ball.  However, over the years bowlers realized that they could drill the holes on other places on the ball thereby shifting the CG to the side.  This changes the reaction characteristics because now one side of the ball is heavier than the other side, so the ball will want to lean more in that direction.

There are six (6) types of static weights that result from shifting the location of the CG away from the center of your grip:

1. Positive Side Weight
2. Negative Side Weight
3. Finger Weight
4. Thumb Weight
5. Top Weight
6. Bottom Weight

Positive side weight means that the CG is shifted towards the side of the ball that is hooking into the pins.  If you're right-handed and throw a hook, it's the right side of the ball as you look at your grip with the fingerholes up and thumbhole down.  It is also the opposite side of your ball from where your track is.  This is the side of the ball where your PAP is located.  

Positive and negative side weights have effects on when and how much the ball will hook.  A ball with positive side weight will hook later and hook more.  A ball with negative side weight will hook sooner and hook less.

ABC/WIBC regulations place a limit of one ounce of side weight, either positive or negative.  This is measured by weighing the ball on a "dodo scale."  You compare the weight with the ball facing in one direction to the weight with the ball facing in the other direction.  The center of the grip faces up and for one measurement, the fingers are above the thumbhole and for the other measurement, the thumbhole is above the fingerholes.

Finger and thumb weight mean the CG is shifted up or down towards the finger or thumb holes.  Finger weight will make the ball go longer down the lane and have a snappier backend reaction.  Thumb weight makes the ball roll sooner and have more of a smoother arc when it starts to hook.

ABC/WIBC regulations place a limit of no more than one ounce of finger or thumb weight.  Again, this is measured on a dodo scale by comparing two sides of the ball.  The center of the grip again faces up, but this time, the finger holes face left on one measurement and right on the other measurement (you're comparing the finger half of the ball with the thumb half of the ball).

As mentioned previously, bowling balls come with extra weight placed under the center of gravity punch on the ball to balance out the weight taken out by drilling holes.  This weight is called top weight because it is located in the top of the bowling ball.  Bowling balls generally are manufactured with anywhere from two to four ounces of top weight although it is possible to find balls that fall outside that range.  Lightweight balls are made with less top weight generally for two reasons.  Light balls generally are drilled for children so the holes are smaller, meaning there is less weight removed that needs to be balanced out.  Also, since the ball has less total weight, an ounce or two of top weight will have more effect on the ball's dynamics and throw them "out of whack."

Top weight has a similar effect as finger weight: the ball will go longer down the lane and snap a bit more on the backend.  Likewise, bottom weight is like thumb weight in that it makes the ball roll earlier and arc more.

Unlike other static weights, ABC/WIBC regulations allow up to 3 ounces of either top or bottom weight.  This is measured on the dodo scale by comparing the drilled side of the ball (top) to the non-drilled (bottom) side of the ball.

Top and bottom weight are not necessarily caused by shifting the CG away from the center of your grip.  They are more a result of how much extra weight the manufacturer placed in one side of the ball and how much weight is removed from that side during drilling.  However, you can alter top weight and bottom weight by shifting the CG.  Because top/bottom weight are measured by comparing the grip side of the ball (the top) to the non-grip side (the bottom), if you shift the CG away from the center of the grip, you are moving it around the circumference of the ball towards the bottom.  You would be removing top weight (and/or adding bottom weight depending on how you look at it) by shifting the CG.  Therefore, the most top weight you can have in any particular ball after drilling (and before drilling any extra holes) would be if the CG is directly in the center of the grip.

When bowling balls are manufactured, the core of the ball is suspended in the mold by a plastic colored rod.  The coverstock is then poured around the core.  The plastic rod is then sliced off at the ball, leaving a bright colored dot on the balls surface about one-half inch in diameter.  This dot is referred to as the Locator Pin, or just the "pin," and represents the location of the center of the core.  By putting this pin in different positions when drilling a ball, you can achieve different ball reactions because the core will be aligned and will rotate in a different way.  As stated at the beginning of this document, the location of the pin controls what the ball does in roughly the first 40 feet of the lane.  It controls when the ball will change direction, how much the ball will flare and how much hook potential it will have when it does change direction.

There are generally four directions you can place the pin: high, low, towards the PAP and towards the track, or combinations thereof.  

A "high" pin position means that the pin is located up towards the top of the ball.  The higher the pin is placed, the longer the ball will go down the lane before it changes direction.  One must be careful, for if the pin is placed too high, the ball will go too long and will change direction too late, if at all.

A pin located towards the midline (horizontal line midway between thumb and fingerholes - use to locate PAP), or even lower, will make the ball change direction earlier.  It is also important to note that if the pin is placed too low, the ball might flare or track over the middle finger.  There is something called "the safe zone" which is located above an imaginary line from the PAP to the middle finger.  If the pin is placed below this line, there is the danger of the flare hitting the middle finger.  If the pin is above this line, the ball is "safe" from this result.  Generally, this is only a problem for higher-track players and for high flare potential bowling balls.

The closer the pin is placed to the bowler's positive axis point, the earlier the ball will change direction.  Please note this does NOT necessarily mean the ball will hook more - only earlier.  There are ways to drill balls involving this method where balls will change direction earlier than most other equipment, but cover less total boards than most other equipment.

Also, a pin on the PAP will generally make the ball have zero flare potential.  This is because the core is in a very stable position.  Flare is caused by the core "realigning" itself in order to find a stable position to roll in.  A ball with the pin on the axis means that the core is laying exactly on its side and rolling much like a rolling pin that a chef would use to flatten out dough.  Again, this is a very stable position so the core has no work to do to find stability.

The closer the pin is placed to the bowler's track, the later the ball will change direction.  This is essentially the opposite of the previous description of the pin near the PAP regarding when the ball will hook.

However, this is very much like the pin towards the PAP regarding flare potential.  Pin on the track is also a very stable position.  The core is standing straight up and down relative to the axis on which it is rotating.  Because of this stability, the ball again will not flare much because it has no reason to find a more stable position...it is already in a very stable position.

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