Picture of hinge action?

[O.B.Left]

Nice one Bucket. The word "Perpendicular" works nicely too.

I agree Jerry , pictures are best when it comes to describing geometry. Words often make matters seem more obtuse. Imagine studying high school geometry but in words only, no diagrams. If I could ask Yoda for one thing this christmas it would be for more diagrams.

Take for instance 1-L-21:

The relations of all Machine positions and motions can be described by a geometric figure.

That would be a nice wiki post for guys to add geometric figures to. Even if its pencil sketches.

Homer gave us a few diagrams, but I do wish he'd given us more. Even the geometry of the circle was not illustrated in the book. By the way, there's one right there....... the geometry of the circle , in 2D can lay flat against the Inclined Plane. Somebody could draw that easily. How 'bout the law of the triangle? Or how the bending right elbow cocks the left wrist or Single Horizontal as a non planar, cone shaped motion or or ....

Perhaps Homer thought it was all obvious?

[jerry1967]

Nice one Bucket. The word "Perpendicular" works nicely too.

My next question was going to be, can I substitute perpendicular for vertical?

thanks everybody- I am not giving up on this hinge concept.

[Yoda]

My next question was going to be, can I substitute perpendicular for vertical?

thanks everybody- I am not giving up on this hinge concept.

No problem, Jerry.

In fact, when I choose to discuss these things with students . . .

I use the term perpendicular (relationship of the Flat Left Wrist to one of the Three Associated Planes) all the time. But, only after I've used the term Vertical, and then only because students relate more easily to perpendicular than to vertical. And then I explain the difference.

Now, why all the bother?

Assuming an intelligent golfer who wants to know -- indeed needs to know -- the answer is simple . . .

In the constructive vocabularly of The Golfing Machine, the term Perpendicular relates to the Wrists' overall up-and-down plane of Motion (Level, Cocked and Uncocked). The term Vertical relates to the mid-condition of the side-to-side Rotational Motion (Vertical, Turned and Rolled).

Then, answering your question here, when we relate the Left Wrist to a given Plane of Motion -- Horizontal, Vertical or Angled -- we can do so in its Rotational frame of reference. Namely, Vertical, i.e., neither Turned nor Rolled.

Hence, Vertical to the Ground (a Horizontal Plane) describes the mid-condition of a Rotational Motion, not Level, the mid-condition of a Perpendicular Motion.

Screwy stuff, I know. But when you're a teacher helping your student get results . . .

Precision matters.

The Wrists have Three Planes of Motion (Horizontal, Perpendicuar and Rotational). Within these are three sets of three -- Flat, Bent and Arched; Level, Cocked and Uncocked; Vertical, Turned and Rolled -- with the first term indicating the mid-condition within each Plane.

Most of the time, except as he needs to on this particular day, the student never knows.

But, the teacher knows.

And, so does the Ball.

That's a good thing!