[pianotech] Point of contact between capstan and wippen heel

pianoguru at cox.net pianoguru at cox.net
Tue Mar 24 08:22:01 PDT 2009


---- Mike Spalding <mike.spalding1 at verizon.net> wrote: 
>  What shape and angle of capstan 
> and wippen heel did you use?  Got a drawing that shows them?

I used three different configurations.  In the first the capstan is perpendicular to the key.  The second orients the capstan and wippen such that the arcs of each are tangent to the magic line.  This results in about an 18 degree angle tilting toward the front of the keyboard.  That's a rather severe angle, but I wanted to test the notion that there might be some benefit to tangency to the magic line.  The third configuration has the capstan and wippen profile tilted 18 degrees in the opposite direct.  Again this is rather severe angle, and probably the most extreme that might be considered.  All other dimensions are derived from my 3D action model.  The attached file is a 2D JPG rendering of that 3D model.  Some basic dimensions derived from this model are:
Variables		mm
Capstan radius		11
wippen heel radius		14.25
key mid-range length		126.18
wippen mid-range length	66.51
Center to center horizontal dist.	183.7
Center to center vertical dist.	59.1

Frank Emerson
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