[O.B.Left]

IMO , in regard to the human golfer as opposed to the model or machine of 1-L , rolling the entire Primary Lever (left arm and club) with a Flat Left Wrist places the Hinge Pin at the connection point between left arm and body..... the left shoulder. The hinge pin is at the end of the lever , the end of the radius. If the lever breaks in half , the hinge loses control of the clubface .

Also, while the left hand (as clubface) is moved in a manner so it remains in a perpendicular alignment to one of the three basic planes (vertical, horizontal or somewhere in between aka angled) it is not moved by the left hand. Its a left hand alignment , but its not created, motivated , powered by the left hand . Something a lot of guys get wrong when attempting , manipulating various hinge actions.

Talking full shots here. When putting you could place the hinge pin at the hands (Arnie style, Zone 3 only putting) or at the Pivot Centre (zone 1 only putting) ...... or misguidedly or more likely out of ignorance , in some combination of Zones , 1,2 and 3 (Michelle Wie's putting used to look zone 1 and 3 ish to my eye, pivot stroke with a breaking left hand). But for full shots with a straight left arm through the ball , the hinge pin is in the left shoulder, given a flat left wrist. If the left wrist breaks , the club face goes with it.

Speaking of old school Zone 3 only putting ....didnt some of those guys anchor their hands? Hmmmm...... need our rules official Kev Carter to come in and make a ruling.