[12 piece bucket]

Mr. Bucket,

What is the geometry of Shaft Lean? I mean, what causes the lean or why does the shaft lean, or under what alignments does the shaft lean more or less, or what is the purpose of shaft lean??

Shaft lean is potentially a dynamic component of the "manipulating the line of compression" equation.... it has a large degree of influence on loft, angle of attack (depending on other variables), where the face angle thingie is pointing, rate of release (or not release) of the accumulators....also can be a function of grip type...

the purpose of lean is defined ideally consciously by the player hitting the shot required given the playing conditions and the adjustment and/or compensations of his individual machine.