According to Chris Foss, "The trouble with solid wood is it shrinks or swells across the grain with changes in humidity in the environment. It can move a lot. The rule of thumb in woodworking is not to glue wood cross grain over 8 inches wide. But we routinely do it in the hammered dulcimer world, gluing tops as wide as 24 inches to maple pin blocks. It is asking for trouble, but we all do it. If the top is not totally dry when glued to the frame, and it shrinks in winter, it can crack. If it is dry, but the humidity goes way up, it will swell and put stress on the overall instrument."
"The construction of the top for the Finch model is a completely new and novel way to eliminate this problem. They are composed of 7 individual narrow boards joined by tight fitting tongue and groove joints which are not glued. This allows each individual board to shrink or swell as it needs without causing problems. No more cracks, no warps, no having to keep your dulcimer in a specially humidified environment in the winter to avoid losing your warranty, no worries at all. Just play it and enjoy it. We believe this is the way solid wood top hammered dulcimers should be built. It works great! We have tested them, and they will take almost any environment and just sound good. No special care necessary. Sound holes all need to be in the back on these. Cutting sound holes on the top would compromise the structure."
For solid one board tops, builders are pretty much trapped with some version of mahogany or other, or a softwood like spruce because they are the most stable. But Songbird can now make dulcimers from any wood. Walnut and Curly Soft Maple are the standouts so these are the ones Songbird offers. But Chris says it would also be fun to build custom dulcimers for people. So if you have a piece of your grandfather’s old cherry tree or some other special piece of wood and have enough of it, let me know and I will see if Chris can use it to make you a custom dulcimer!. Jess@Dickinsondulcimer.com.
The standard Finch is Walnut with Curly Maple bindings, hard Maple sides, cherry bridges, and laminated Birch back.
OPTIONAL LAMINATED BRIDGES
According to Chris Foss, the biggest culprit to dulcimers going out of tune is the bridges shrinking and swelling with changes in the humidity of the environment. Wood shrinks or swells across the grain which in the case of the bridges is the height. Any change in the height of course changes the tension of the strings, and the dulcimer goes out of tune. This is the point behind lamination. Plywood is built up of layers of wood glued together with grain directions at 90 degrees to the layer above and below. This effectively stops wood movement, and the thinner the laminations, and the more plies, the better.
As an option, Songbird makes bridges with a core of birch plywood and solid walnut on the outside. You can see the ply core, but it isn’t objectionable. The ply core limits the shrinkage or swelling of the bridge, and really helps with tuning stability. While they don't completely eliminate the problem of dulcimers going out of tune, they really help.