Nicholas Simons wrote:
> The Watt's linkage consists of three pin-jointed links that create
> a straight line motion without any recourse to a straight edge.
Just to be nit-picky: It only creates an _almost_ straight line.
However, the small "S swing" can be made as small as one wants.
Harald M. Mueller
[ I am studying Watt's linkage right now as I am fitting a
[ replacement pneumatic action stack into a different piano.
[ I want to minimize the scrubbing motion of the vertical pushrod
[ where it contacts the tail of the whippen, which means that the
[ contact surface at the whippen must lie on the line through the
[ whippen fulcrum (pin joint). Naturally, the whippen construction
[ of the old piano action doesn't come close to the ideal geometry.
[ :-( -- Robbie