evaluating sdbd. crown & bridge downbearings in a new piano

[Richard Moody]

On the side of all this.. I have always wondered about something that perhaps
some of you can answer for me. What is "wrong" with the idea of "heat shaping" a
board into crown. Much like boatmakers apply heat and humidity to bend planks,
or for that matter as piano techs do to twist hammer shanks and the like? Could
not a soundboard be crowned and ribbing in this fashion ? Would it be strong
enough ??  Just curious.

Richard Brekne

Then it wouldn't be under "tension"  One of the ideas of crowning a sb is because
bent  wood seems to "amplify" the sound.   There used to be a demonstration model
consisting of a piece of soundboard between two pieces of wood with a tuning fork
mounted in the middle.  The blocks of wood could be screwed closer together thus
forcing the soundboard wood to bow.  When the fork was sounded on the bowed board it
 was much louder than sounding on the flat board. How much this really has an effect
in the piano is hard to determine, one of the considerations being the board is
bowed across the grain in the piano instead of with the grain as in the model. Also
if the piano sound board were bowed as much as the demonstration model, it would
probably have a two inch arch.  ---ric