The Hinge will be located at the Left Shoulder. But if this is annoying, use shorter dowels and locate the Hinge near the normal location of the Left Wrist. During training exercises, the Left Hand will hold onto the Long Dowel and help stabilize the Long Dowel during operation.
The Alignment of the Paddlewheel Motion of the Right Forearm Wedge will determine the Alignment of the Hinge (i.e. Angled, Horizontal).
If the Right Forearm/Hand Paddlewheels about an axis perpendicular to the Horizontal Plane, then the Hinge Pin will be Perpendicular to the Horizontal Plane. Horizontal Hinging.
If the Right Forearm/Hand Paddlewheels about an axis perpendicular to the Angled Plane, then the Hinge Pin will be Perpendicular to the Angled Plane. Angled Hinging.
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Hinge Training for the Right Hand Paddlewheel Motion
The following Illustrations show a device using two dowels and a simple clamp Hinge. The Longer Dowel (Axis Dowel) is held Perpendicular to the Associated Plane of your Hinge preference. The Short Dowel (Paddlewheel Dowel), is connected to the Axis Dowel. This device is used to learn the "Paddlewheel Motion" of the Right Hand/Forearm during the Stroke from Release to Follow-through.
The Paddlewheel Dowel rotates around the Axis Dowel. The design confines the Right Hand and Forearm to Paddlewheel Motion. Unfortunately, it lacks a Swivel Mechanism so Swingers will need to grip the short dowel with the right Hand pre-swiveled (nearly under the shaft with the #3 PP pressure at the Top of the Knuckle and Thrust moving Downplane to the Aiming Point).
I think that this device would be best used while practicing the "Basic Motion" Curriculum. The Axis Dowel is located near the Center of your Torso at the beginning of Release and remains perpendicular to its Associated Plane while rotating as it travels with the right Arm/Hand through the Interval. At Impact Location, the Axis Dowel will have moved laterally and become opposite the Left Shoulder. Hitters using the Angled Axis Dowel will need to shorten it to clear the Body during the Drill Stroke.