Building a Mountain Dulcimer - Part 2

The two plates (top and back) shouldn't be dressed until they are glued together. The dulcimer is only a little over eight inches wide, so why use two pieces glues together? bookmatching makes a pleasing grain pattern, for one thing, and you'll get a higher percentage of good splits resawing four and a half inches than you will at eight and a half. 

 

In order to make a good joint, the edges have to be trued. I do this by clamping the two pieces together in the vise, with the two "good" faces together and the joint edge upward. Then I use my longest plane (a "fore" plane, which is one class shorter than a "jointer" plane) and take slow, careful shavings. The fingers curled under the plane's sole help to keep it square to the boards, by feeling along the side of the board as the stroke is taken.

The best reason for doing both boards together and in exactly the alignment they will have when glued is that slight errors in squareness won't matter. As in the diagram at left, if the plane is tilted slightly, the error in one board will compensate for the other one when they are flipped open and butted up. Even if the plane wobbles as it goes down the boards, the error at each point will be compensated.

 

Here's an alternate way to get a tight seam: a big piece of plywood with sandpaper glued down to it. The diagonal of this setup is just about as long as the boards here. Note, I'm still holding the two boards together in book-folded orientation.


There are numerous ways to clamp the two boards together for edge-gluing. Here's one of the simplest. First one board is laid down on a large sheet of flat plywood, and nails are driven into the plywood all along the edge of the board. Not through the board -- just touching the edge of it. Then that board is lifted, and with its edge still up against the nails, a small stick, here 1/4" square, is placed just under the free edge so that half of it is visible. The other board is laid on the stick and snugged up along the joint, and nails are driven into the plywood all along the edge of this second board as well. 

When the stick is removed,  and the boards pushed down against the plywood base, the nails exert just enough pressure to close the joint. Between the boards and the plywood, I've place a sheet of "freezer paper", plastic-coated side up, to prevent the seam from gluing itself to the plywood. You can use waxed paper or any kind of material that the glue won't stick to. One of the edges is coated with just enough glue to cover the whole edge with a thin film, and the boards are pressed down. Then two sticks are clamped down along next to the seam to keep the boards flat.


The biggest problem with this process is keeping the boards flat against the base. I've got two maple sticks that are slightly "sprung", i.e., their bottom edge is curved to be thicker at the center. One of these goes on each board right near the seam (but out of the glue squeeze-out!). When they are clamped down at the ends, the spring in them assures that pressure is exerted all along their length. Here another piece of scrap is used to distribute the pressure of one clamp to both sticks.

Once the sticks are clamped down, the whole assembly can be set aside for half an hour to dry. After half an hour, pull the nails from one side, release the clamps and take the glued-up board out to dry further; the plastic-coated paper keeps the glue from dying out on the inner side. Let it cure for a few hours before doing any heavy planing on it. If you don't remove the nails first, relieving the inward pressure, the board can buckle up and crack when the clamps holding it down are taken off. 

While the front and back plates are drying, you can make the scrollhead and the tailpiece. The scrollhead is where the tuners go, and it's glued up out of three blocks. You can see the outline on the top slab here. Some makers carve this part out of a single block. The scrollhead has functional and decorative purposes. It can take many forms. Click here for Jerry Rockwell's site: he makes some of his dulcimers with guitar-like heads (On Jerry's home page, click the button on the left labeled "Mountain Dulcimers"). Cripple Creek Dulcimers makes custom dulcimers with scrollheads carved into decorative shapes (Click "custom dulcimers"). This one will have a simple scroll. 

On this scrollhead, the part on the right attaches to the main body of the dulcimer, and the part on the left is a moderately decorative scroll. I think of this as the handle! The tuners are mounted in the middle section and the strings are attached inside, between the "cheeks" of the scrollhead.

Did I say you need a lot of clamps to be an instrument-maker? It's important to clamp this glue-up thoroughly, because the scrollhead is a visual focus of the instrument, and you don't want any gaps to be showing. Because three-layer glue-ups always slide around on me, I like to do this in two steps, first the two inner blocks to one of the sides, and then the other side glued to the resulting assembly. There is plenty of space for guide pins, and I could do that, but it just seems easier to do it this way. Well, a lot of glue has to dry, so it's on to the next day.

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Copyright 2003 Stephen Miklos