bcoak said:
So, a bent plane line would be swinging down the TSP and up the ???
...and up the TSP. The problems come when you change the
baseline of the plane.
For example, let's say a player starts their downstroke perfectly on-plane. The butt-end of the club is pointing at the plane line. Now, at some point during the downstroke, they start pointing that butt-end somewhere
other than at the plane line. Maybe a little inside of it or a little outside of it.
Imagine a laser on the butt-end of the club. It will, in an on-plane stroke, inscribe a perfectly straight line right on top of the plane line. If you bend the plane line, it'll inscribe an angle at some point. Maybe you get most of the way to the ball and then your laser line veers left or right. Now your ideal "perfectly straight line" is no longer straight. It may curve, it may change at an acute angle, anything. If you deviate from tracing the straight base line of the plane (the Plane Line) you've bent the Plane Line.
Maybe I'll make a drawing...