Here's how I explained this to many customers: (usually with a core in my hand or a half ball on the counter, to get the visual effect, and watered down)

There are two stable positions (happy places) for the weight block to be in.  Pin on your track, flip the football end over end for visual.  Pin on your axis, roll the football perfect spiral for visual.  Every where else the weight block is in an unstable (unhappy) position.

If the lane is long enough, the core is going to move itself to happy, it's just physics.  Trying to get happy the pin "migrates" towards your PAP (spiraling football).  As the the weight block moves toward happy, this is causes your track to flare instead of track over the same place all the way down the lane.  Because of the flare, the ball rolls over more fresh clean surface causing the ball to grip the lane more and hook more.

Generally speaking, more flare usually means more hook.  There are many other factors to consider when talking about hook.  

Now comes in the JohnP part with the mass bias/PSA.  I usually talked to people while watching them bowl, and was able to place this point where I thought it should go to get the desired hook shape that worked well for the customer with his/her game and the conditions they usually bowled on.  The position of the MB will help determine the shape of the balls hook down the lane, how snappy or smooth it will be.

JW73, you will get a lot of differing opinions on this site, which is good.  In my professional experience, I feel that the MB/PSA is a factor that too many bowlers put too much emphasis on.  I don't feel that most bowlers are good enough to really worry about this factor as much as they do, myself included.  Far too many bowlers have a hard enough time trying to pry the ball off their hand the same way twice.  Many bowlers will improve their game more/faster by worrying about fundamentals and making sure their equipment fits properly so they can learn to repeat shots more often.

Please know, that I am not calling you or anyone in particular stupid or terrible or any thing of the kind.  I'm glad that you want to learn more about the physics of bowling balls.  I tried to give a simplified view, as I tried to spend more time with beginners and lower average bowlers that really wanted to improve.  

Hope this helped ya, sorry for rambling, ate too much dinner tonight,, uggg

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Edited on 12/24/2008 9:02 PM

quote from Mike Austin
"Now comes in the JohnP part with the mass bias/PSA. I usually talked to people while watching them bowl, and was able to place this point where I thought it should go to get the desired hook shape that worked well for the customer with his/her game and the conditions they usually bowled on. The position of the MB will help determine the shape of the balls hook down the lane, how snappy or smooth it will be."

I understand why a ball flares.. I am more interested in this "point" that you put the mass bias and why you put it and how it does what it does at that point.  I want to know why "The position of the MB will help determine the shape of the balls hook down the lane, how snappy or smooth it will be."

Also, from your description you go with the thought of "on a long enough lane the pin will want to migrate to the axis point"   Makes sense.. on an actual lane what happens.. does the axis migrate to this pin... to the mass bias.. to the prefered axis point... to 6 3/4 from the pin??

looking at the morich determinator instructions I noticed this.. this could be a completely different topic or related..i'm not sure..


"Y-Spinning Versus Z-Spinning Balls
This manual mentions that a ball with a mass bias has either
a Y-Spinning core or a Z-spinning core. The difference
between the two is where the ball’s preferred spin axis is on
the ball. The ball can be imagined to have three axes (see
Figure 7). The X-axis goes directly through the pin and the
center of the ball. The Y-axis runs perpendicular to the Xaxis,
and goes directly through the mass bias mark on the
surface of the ball and through the center of the ball. Hence
a ball that spins around its mass bias has a Y-Spinning core.
The Z-axis also goes through the center of the ball, and runs
perpendicular to both the X and Y-axes. A Z-Spinning core
spins 90° from both the mass bias and the pin."

So according to this the Mass Bias is a different "thing" than the PSA? They can be the same point on the ball but they are a different "thing". On most balls is this spot the same??  If it isn't wouldn't the 2 types of balls have to be drilled completely different?  Are ball manufactures marking the PSA? Are they marking the MB?  Are they marking the High RG axis?

When we layout a ball and it says put the MB in the strong position.. are we putting the high rg axis in the strong position or are we putting the actual mass that is biased in that direction ...

2)

about High rg axis / PSA.
From what I know the PSA when found on a determinator is the high rg axis. The High RG axis has the most mass 90deg from this point.  This is called the PSA/ Preferred spin axis.  The ball will want to migrate to this axis point on the detmerinator.  Makes sense.. when under constant spinning force or increased spinning force the weight of the ball (mass) will want to be as far away from the axis do to centrifugal force (I know it is not a real force)

but what about in the real world?.. all the energy the bowling ball has is given to it at the point of release.  It can not get more so therefore it is always losing energy.  For the ball to go to a higher rg state than it started it would require more energy.  So can the ball go to a higher RG ??

It might.. I'm not sure.. assume that the ball is thrown with no rotation at 15mph down a hypothetical no friction super slick 40ft pattern.  When the ball hit the dry, friction (assuming 100% friction) would occur and force the ball into a rotation.. In fact the ball would go from 0 rpms to (if my math is correct) almost 590 rpms.  A version of this happens on a real lane condition but only with a slight RPM increase.  Would this increase in rpm send the ball to a higher RG state?  Or is this what is even happening on the lane..

I'm sure you all hate me for my rambling and pointless-ness.  If you aren't interested please don't read.  I am looking for answers and for other people that are interested in what is really physically going on with the bowling ball.

Edited on 12/30/2008 6:43 PM

Edited on 12/30/2008 6:44 PM