Case work details

Cutting bevels at the joints between various case parts is a little trickier than it might seem. The Trasuntino has rather sharp corners and the required angles cannot be set directly on most power tools, which only go up to 45 degrees. Such tools are designed to help cut things square, or to make up angles that add up to 90 degrees (two 45-degree miters, for example).

To cut an angle of more than 45 degrees—and all the case bevels, except at the cheek-bentside corner, exceed 45 degrees—I built the following table saw jig, which stands the workpiece up on end instead of flat on the saw table. By changing the orientation with respect to the saw blade, the complementary angle can be cut, which will now be less than 45 degrees.


The jig slides along the saw fence, and the table is tilted to the appropriate cutting angle. A sacrificial piece of plywood keeps the blade from slicing into the jig, and a sample piece of yellow cedar is shown in the proper position.

I'm using a Shopsmith Mark V Model 510 saw system; with suitable accessories it can also operate as a jointer, sander, bandsaw and drill press. It's a good tool, but the tilting table makes angled cuts a bit tricky. Cutting the spine bevel was a real production: my father and I dragged the saw out of the garage onto the driveway so that the 92" long spine wouldn't hit the roof rafters during the cut.

The front edge of the cheek and spine are cut out decoratively on most Italian harpsichords. I glued two additional layers of wood against the inside face of each case piece, making a sandwich of two outer layers of yellow cedar and a thinner middle layer of walnut. The grain of the middle piece is at right angles to the other two. Below, some walnut is glued to the outer layer of cedar:


I made a plywood template from a tracing of the original Trasuntino cheek profile shown on my drawing. When the three-layer sandwich was ready, I traced the template profile onto it in pencil, cut most of the waste out with a jigsaw shy of the line, then attached the template with double-sided tape and ran the whole assembly against a piloted flush-trimming router bit to cut the exact final shape. Below are the spine and cheek cut-outs: the cheek has been sanded thoroughly while the spine is still rough from the router table:


I sharpened some of the corners of the profile on the cheek, which are naturally softened by the round router bit.

It's interesting to note that these layered cutouts not only look good but add strength to an otherwise weak area of the case: the sides are attached only along the baseboard at this point. Many cosmetic elements on Italian instruments turn out to have strengthening properties when one looks more closely at them.