[pianotech] Measuring Crown Radius

[John Delacour]

At 12:16 -0700 14/07/2011, David Love wrote:

>...As I said, I believe the differences between CC boards and RC&S 
>boards are, on a practical level, one of degree not of kind and the 
>differences are characterized by where the bulk of the load is 
>focused....

In "compression crowning", from what I have gathered from repeated 
mentions on this list of this extraordinary practice, the whole 
board, with bars (ribs) and bridge (?) already attached is dried 
down, then cut exactly to size and clamped and glued to the rim, to 
which the case is already attached.  I presume that at least the 
barred side of the board is also varnished beforehand.  As the board 
takes on moisture and expands (mainly across the grain) it is forced 
to arch because it has nowhere to expand to.

Before I go on, is that roughly what takes place?  Please tell me if 
I've got things wrong.

JD