Soundboard: Selecting boards

At long last I am ready to begin work on the soundboard.

The wood, as you will recall, was purchased back in October and has been sitting around for about two months. Vogel sent me something like 2 square metres, which is almost twice as much as I need, but the material only comes in increments of 1 square metre. It's good to have some extra in case something goes wrong; perhaps I'll build a smaller instrument someday with the remainder.

I spent several hours recently going through all the wood again, thinking about how to put it to best use. There are a number of considerations to balance in selecting the planks:

• It would obviously be wasteful to cut a long board into short pieces for use in the treble, especially since Vogel specifically sent me a variety of lengths. So the longest boards should ideally remain in the bass.
• The boards are sounded out by rapping them with one's knuckle. The idea is that "ringier" boards are better suited for the bass, while duller-sounding ones should go higher up. This is complicated somewhat by the fact that the boards are mostly of different lengths and sound different by virtue of that alone. I gave it my best shot by aiming to have some sort of gradation of "ringiness" as I arranged my boards from left to right.
• I've heard suggestions that coarser-looking grain should go in the bass and finer grain in the treble. One of my books says that there shouldn't be wild changes in grain density from one board to the next. My boards seem pretty good in this respect, except for one that has a patch of very wide rings right in the middle.
• My friendly harpsichord maker says that if boards want to bow, they should be arranged so they all bow upwards. The soundboard in a finished harpsichord is slightly crowned anyway, so any natural tendency of this sort should be noted and taken advantage of.
• Grain runout must be accounted for. Wood fibers don't run perfectly horizontal in sawn lumber but come up to the surface at an angle. On rough lumber, these little whiskers can be stroked with the fingertips: one direction feels rough, while the other is smooth (like a cat's fur). This must be noted when planing, otherwise the blade can catch the whiskers and start ripping fibers out of the surface like a loose thread being pulled on a garment. If the boards are properly oriented, however, the blade simply trims the fibers harmlessly.

After examining my collection of boards with all these factors in mind, I chose the requisite quantity, arranging them suitably from left to right, decided which face might end up as the visible upper surface—though it's a bit early to be completely sure, as the boards are still rough—marked down the grain runout on each face and made a note of defects such as chips and knots. Although the wood is of good quality, most boards have some knots or pitch pockets (near the edges, fortunately) that will have to be cut out. The exception is the left edge of the lowest board, which will be glued to the spine liner, so any modest defects there are unlikely to have an impact on the sound.

Today I did some preliminary straightening of one edge of each board. Since the wood is rough-sawn, all four surfaces will need attention, but everything must start with one straight edge to place against the table saw fence. The two longest boards were not that straight—one of them was out by about half an inch in the middle—so I had to attach a long straight board with double-sided tape to each of these in turn and run the whole package through the router table to get a half-decent straight edge. I was impressed by the gigantic splinters that flew all over the place as I did so: the wood is quarter-sawn, so the router bit was basically splitting the edge off along a growth ring. Still, no damage was done, and at least I can now take all this lumber to the table saw. Here it is, waiting for tomorrow: