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http://www.lynnblakegolf.com/forum/s...+compressio n

Originally Posted by Jim Cook

Yoda said: "Then, repeat it from memory: 1-L #4 -- The Hinge Assembly controls the Clubface alignment. " So in the office I yelled at the top of my lungs: The Hinge Assembly controls the Clubface alignment. The Hinge Assembly controls the Clubface alignment. The Hinge Assembly controls the Clubface alignment. The Hinge Assembly controls the Clubface alignment. The Hinge Assembly controls the Clubface alignment. It was funny watching all the heads pop up from the cubicles. Like groundhogs.... does that mean there will be 6 more weeks of winter? But the Hinge Assembly does not control the Clubface alignment. With the hinge pin verticle to the horizontal plane, the hinge blade horizontal plane the little club face stays verticle to the horizontal plane. The face of the little club is open to the intended target line, then square to the line and finally closed to the line. Is this "open, square then closed" what you mean by "The hinge assembly controls the clubface alignment? Does the hinge pin represent my shoulder/arm joint? And the bolt at the hinge arm/plate represent my fixed Wrist?

I missed that first part, Jim. What did you say? Oh! I hear you now!

1-L #4 -- The Hinge Assembly controls the Clubface alignment!

You are right!

But then you say, it does not control the Clubface alignment, and Yoda is confused. The Clubface's circular, horizontal ('closing' only) motion is the direct and inevitable result of the identical motion of the horizontal blade rotating about its vertical pin. If this is not controlling the Clubface alignment throughout the motion, then what is?

And surely you did not mean that the Clubface should stay 'square' to the Line, did you? Because if so, that would be Steering, the No. 1 Snare in the Game -- attempting to hold the Clubface square to the Line of Flight. And we learned in Lesson One that you cannot make the blade of a hinge move in a straight line. It only moves in a circle!

Remember, in G.O.L.F. we are dealing with a Force moving in a circle --the Clubhead Orbit (2-N-0). And because you measure the circumference of a circle in terms of angles from its center, we call that force Angular Force. Force moving in a straight line -- like a pool stick through a cue ball-- is Linear Force. The problem we have in golf is to produce the same effect as a Linear Force -- a point of contact between Ball and Clubface that remains welded until separation -- while our Clubhead force is moving in a circle. And the way you do that is through this Horizontal Motion of the Clubface through Impact.

At Impact a Line of Compression (2-C-0) is constructed through the Ball-- like a bullet hole through a baseball. This is a Linear Force. Now, if we can keep that point of contact -- the Compression Point, from slipping on the Face, then we will have 'sustained' the Line of Compression.This maintains the Linear Force in relation to the Ball, even though the Ball has now joined the Orbiting Clubface in its circular, centrifugal journey.

This is the goal of every Golfing Machine: To sustain the Linear Line of Compression as the Orbiting Clubhead is Arcing through Impact. And it all begins here with an understanding of the horizontal motion the Clubface must make through Impact. Then we must train our Flat Left Wrist to reproduce its motion on demand.

So, the Horizontal Hinge Assembly is producing a pure 'opening and closing'-- ONLY! -- Motion of the Clubface. THERE IS NO LAYBACK! If Impact occurred with the Clubface in the 'slightly Open' alignment, and if separation(of Ball and Clubface) occurred with the Clubface Square to the target line,then the result would be a perfectly Straight Shot and Maximum Compression.

The 'Closing Only' Motion produces the Ideal Application of Linear Force(2-C-1) because the Angled Clubshaft and the Closing Clubface are rotating about the same center. Thus, there is no glancing force (except for backspin). This 'Closing Only' Motion of the hinge blade produces the exact same motion in the Clubface. And because the Clubface does not Lay Back, the true loft of the Club is maintained throughout the Impact Interval]. Further, since there is no 'tilting under' of the Clubface, the Ball and Face stay welded, and the Compression Point -- the 'point of contact' between Club and Ball -- is maintained until they separate.

Hinges whose blades duplicate the remaining two planes of motion -- vertical and angled -- do Lay Back, and this causes the Clubface to made an identical 'Layback' motion through Impact. With Vertical Hinging -- the 'Layback Only' Cut Shot (2-C-2) -- as in Horizontal Hinging with its 'Closing Only' Motion -- the Point (and Line) of Compression is sustained. However, the Layback of the Clubface effectively increases the Clubface Loft and therefore produces higher, softer Shots than the Ideal Application of the Horizontal Hinge. This characteristic Ball Flight may be exactly what the player intends to produce -- out of a greenside bunker, for example. On the other hand, it is doubtful the player would deliberately employ this technique off the tee of a long Par Four!

The Lob Shot (2-C-3) is the Low Point application of 'Layback Only.'This results in a 'tilting under' of the Clubface through the Ball and a total loss of the Compression Point. This loss of the original contact point is termed 'Compression Leakage,' and in this application produces the Lob Shot, the high no-spin floater. This is the Shot Mr. Mickelson often uses greenside, but again, has probably never used off the tee.

The Angled Hinge also results in Compression Leakage. Here, we have simultaneous 'Layback' and 'Close' and thus an 'uncentered' motion and Slicing tendency. There are compensations for this deficiency, but the Angled Hinge application of Linear Force remains inferior to the pure 2-C-1 Ideal Application of the Horizontal Hinge.

So, the Hinge Assembly does indeed control the Clubface alignment, and tomorrow we will re-orient the hinge pin to see exactly how that occurs.

I'll be back tomorrow to complete our 'mechanical' stuff. Then we'll get on to educating our Flat and Vertical Left Wrist to duplicate the Three Planes of Motion on the face of one Inclined Plane.