Weighty Problem

[David C. Stanwood]

Stephen Birkett Wrote: 

>Leverage is a consequence of geometry...i.e. they are the same thing.

Let me put it this way.  As I see it there are two aspects to geometry.
One is the relationship and efficiency of interacting arcs.  The other is
the total leverage that the finger exerts on the hammer, which is a product
of the key, wip, and shank levers.   

I've seen many technicians over focus on stuff like knuckle size and action
spread, shifting the stack, shimming the stack, etc., when the problem is
something more obvious like the key ratio.  For instance, I've measured Key
Weight Ratios on Steinways within a range from .46 to .62.   0.02 is a
significant change.  With this kind of variation, to assume that the total
leverage is anything is sheer madness!   

Typically the leverage part gets left out of the discussion. 


David C. Stanwood