[pianotech] problem in mating hammers to strings

[George F Emerson]

> if a hammer is tilted, the whole hammer moves in the path of the end of 
> the shank, which is straight up and down unless the flange is tilted or 
> the center pin is not parallel to the hammer rail.  Right?  Or what am I 
> missing?

Wrong.  Nothing moves straight up and down in a piano action,  It rotates on 
an axis. True enough the shanks have to be traveled, but even with perfectly 
traveled shanks, the center hammer of three at the low end of the tenor 
section will move closer to the hammer to its left as it rises.  It looks 
like an optical illusion, because it seems to defy all we think we know 
about the geometry of the thing, but it is not.  As the hammer rises, it not 
only moves up, but the tip of the hammer moves forward, toward the keyboard. 
Again, while dry fitting what would happen if you deliberately move the 
center hammer further down the shank by 5 mm or so?  Because of the angle of 
the bore, and the side faces of the hammers being essentially parallel, the 
center hammer will necessarily become closer the the hammer on the left and 
further from the hammer on the right.  This approximates what happens when 
the center hammer rotates; the "fat" part of the hammer move forward (as 
well as upward) between the two hammers remaining at rest.  Don't try to 
visualize it.  Dry fit three hammers on shanks and watch what happens.

Frank Emerson