[Daryl]

Just to clarify, are you saying the amount of the spin is mostly caused by the Line of Compression? Does speed play a part? Does loft play a part? Is HK also assuming a centered strike?

He goes on to say in 2-C-0 that maximum compression is the ideal result. Where can I find his definition of compression?

HK Said:

The Principle of Golf is the “Line of Compression.” The Mechanics of Golf is the production and manipulation of the “Line of Compression.” Precision is recognizing and reconciling minute differentiations.

and

The ball is subjected to a violent deforming compression. The ball is actually distorted, not compressed – except for reduction of one dimension. Rubber is incompressible. Trapped air bubbles can be compressed – but not the rubber itself – it flows. It flows in two directions – but acts like a solid in the third. This third direction is the direction of the compressing force. The momentum of the violent return of flow after impact also distorts the ball by exceeding the normal dimension of the compressed point. The “kick” given to the ball by this action is an important factor in ball response. Roll of the ball on the face of an inclined striker does not account for all the action produced by such an impact, especially in imparting spin to the ball. When the direction of the compressing force does not pass exactly through the center of the ball, a spin will be imparted to the ball. It will rotate on the plane of a line drawn form the line of compression to a parallel center line.

and most Important is:

2-C-0 LINEAR FORCE The ball will respond to non-linear (angular) force exactly the same as to linear forces only if the application produce forces equally linear to the ball but not necessarily linear to anything external to the ball.

Briefly stated, it is necessary to find a way to compress the ball through a particular point along a particular line, and maintain this compression through the same particular point along this same particular line straight line, through the entire arc of the Impact Interval, and with geometrical precision for consistent control. Study 2-K and 2-N.

To maintain compression at a particular point that point, then, must rotate around the same center that the rotating force does. Not just the physical center of the ball nor the gravitational center – just the point of compression. In other words, the original contact points of the Clubface and ball must remain in contact throughout the entire Impact Interval. This is possible only if the motion – or arc – is uniform. Therefore there must be a perfectly centered action – or a compensating manipulation.

The Ball leaves the Clubface with a force proportional to the compression produced by Impact. Then the ideal result of the above procedures is maximum compression. But any Clubface imprecision during Impact will permit compression to leak away. Lost compression cannot be recovered. Between the precision Impact of 2-C-1#3 and the total loss of compression in 2-C-3#3, there can be every degree of Compression Leakage – some intentional (Back Spin) but mostly unintentional. Your main lines of defense are the Flat Left Wrist, Hinge Action and a Three Dimensional Downstroke – that is DOWNward (Attack Angle) AND OUTward (Plane Angle) AND FORward (Approach Angle) per 2-C-1#2A/B. Study 2-H, 2-N and 7-3.

And finally, to help further your understanding:

2-H SHOULDER MOTIONS The point may be made that it is impossible to inscribe perfect circles while the center is in motion – that is the turning Shoulder. The straight line requirements of the Compression Point are satisfied as long as both the Vertical and Horizontal Centers move precisely in unison. Direction control remains stable because both Centers are also moving in a circle – that is, the circumference of the Shoulder Turn.

Bold by Daryl to highlight points of interest.