The soundboard was completed "in the rough" earlier this month, after all the intermediate sections were glued together into the final assembly of 8 boards. After scraping all the joints and examining the trueness of the surface with a metal straightedge, I discovered, not with any great surprise, that the act of scraping had left little valleys at the joints between boards with higher areas in between. The correct way to address this would be with a large handplane, but we don't have a good one, and I'm too cowardly to try this for fear of doing something irreparable. So my father made a sanding block about 10" wide, and, starting with 80-grit sandpaper, he sanded both the front and back face of the board. Using a wide block ensured that the hills would be flattened without making the valleys any worse. Though time-consuming, this approach proved quite effective, and the resulting flat surface ensures that the bridge and ribs can be glued on securely when the time comes.
Here's a view of the soundboard in the rough, with the large sanding block visible in front:
With the off-cuts that came from my soundboard planks, I made a small sheet to cover the wrestplank:
Gluing this onto the wrestplank not only hides the fact that the plank is made up of a bunch of strips of walnut but also constrains the plank's cross-grain movements to a degree. A second sheet has to go on the underside of the plank, since veneering technique requires both faces of a board to be covered, otherwise uneven expansion and contraction would occur.
