Construct New Soundboard
February 16, 2010

I've been constructing the new soundboard, which will consist of a solid spruce panel and 11 stiffening ribs.  The panel was furnished by Central Michigan PIano, a rebuilding operation which is equipped (as I am not) to join Sitka Spruce boards into a panel 5 feet wide, and thickness it to a uniform 5/16".  It arrives generously oversized, so I trace the outline of the piano onto the panel and trim it to fit. 

The ribs begin as 1/8" thick slices of Sitka spruce, which are then laminated in a curved form to make arched beams.  Here's a laminated slab:

And here's the completed set of 11 ribs.  No two ribs are the same - the curvature, length, width, and thickness of each rib is calculated to achieve the desired shape and stiffness of the completed soundboard assembly.

 

The ribs are glued to the panel, using " go bars" to clamp the pieces together, and backed up by the same radiused form that was used to laminate the ribs.