Design and Construction of the 'Jomama

 

a fretless baritone banjo-sculpture

Built in 1992

 

I'd been dreaming for a long time about using the mask-making techniques I'd learned as a teenager to craft the body of a musical instrument. Finally, in 1992 I decided to set aside some time to get started on the project. I knew I wanted an instrument that I could use the old-time banjo playing styles I was already versed in to get a sound that was something like what the early ancestors of the banjo might have sounded like. And I wanted something low, perhaps an octave below the standard modern banjo tuning, in pitch.

I had had some exposure to an Ethiopian instrument called the krar, a surprisingly banjo-like instrument whose throaty, plunky tone had completely charmed me.

I saved the original drawing I made when determining parameters for the initial design. I wanted an instrument that would balance well in a banjo-like position, but with a body shape that wasn't circular like the banjo. To achieve this I got out my old Bruno open-backed banjo, sat in a chair in my favorite playing position and took some measurements to calculate the angle of the instrument relative to the floor. Then, I made this rough sketch of myself in playing position, holding a banjo, and then began to play with that circular shape, stretching and flowing it while trying to keep the mass balanced. Ultimately, this resulted in an instrument that is remarkably comfortable and balanced physically. And I'm amazed when I look at this photograph taken sometime after the instrument was completed, to see how closely I realized that first visioning.

 

I made the 3-dimensional sculpture that became the back-and-sides part of the body, first using clay to get a "positive" mold. I cut a piece of three-quarter inch plywood to the exact outline of the top of the instrument, and built my clay positive on top of that. The clay sculpture was then cast in plaster creating the negative mold that I built the shell in. The shell was made from recycled supermarket grocery bags, the heavy-duty brown paper ones, that my mother-in-law had been saving for years (she must have had some premonition!). After covering the plaster with a resist of plastic sandwich-wrap material, I ripped the bags into strips and dipped them in a mixture of aliphatic resin glue (Titebond) and water. I took old glue remnants, stuff too thick to be useful for general guitar-building, and thinned it enough with water to be able to soak the paper in it. I alternated layers of brown bag with layers of newspaper, to be able to keep track of how many layers I'd done. I think the total ended up being 7 or 8 layers, perhaps an eighth of an inch thick when dry. When this shell of industrial papier mache was thoroughly dried, I removed it from the mold and trimmed it. I applied a layer of lightweight latex spackling compound to the exterior surface and sanded that down to the paper again, filling uneven areas. I covered the entire exterior with a base coat of white paint, then settled down to the fun of painting in the colors. These are typical acrylic art paints, and the whole thing is sealed, inside and out, with a couple of coats of clear waterborne polymer finish.

 

 

I then cleaned up the plywood template that I'd formed the original clay on and cut away most of the interior with a jigsaw, following the perimeter to leave a narrow rim the shape of the outline. At the neck and tail piece ends I left more substantial mass . This rim-piece became both the linings that connect the top to the body, and also the structure that the neck is connected to. The walnut neck extends through the entire instrument body, as on the old banjos. The part inside the body, called the "pot stick" in banjo terminology, is glued to the rim-piece at both neck and tail (or in this case, nose) ends, and does not contact the top of the instrument. The shell was then epoxied to this rim/neck structure. The thin Engelmann spruce top received one diagonal brace, arched to put the top under a certain amount of tension. The very thin top and the highly arched brace were intended to simulate somewhat the condition of the stretched animal skin one would find on the instruments I was trying (tone-wise, at least) to emulate . The top was then glued to the body/rim assembly and the painting/finish touched up and "binding" painted on. The "mouthpiece", essentially similar to a lute (or classical guitar) bridge in the way the strings are attached to it, was glued on and painted to resemble lips and teeth. This is not actually the bridge, since there is a floating, banjo-like bridge; instead this serves the function of tail piece.

To backtrack a bit: the peghead was of course attached to the neck prior to neck/body assembly. It angles sharply away from the neck plane in almost lute-like fashion. The primary reason for this was one of physical balance. I determined that in order to achieve my ideal of an instrument that balanced perfectly on my leg, I needed to move the center-of-balance further toward the tail-end of the instrument. One way to help accomplish this was to shorten the overall length of the peghead/neck, which I did effectively by angling the peghead so steeply. The pegs themselves were originally of Vermont cherry wood. One has been replaced with rosewood and all are painted with little pink faces: Peg-People who sing along as you play, or make derisive comments, depending on their mood (usually they're quite jovial).

The 'Jomama was not built to be a "fine musical instrument" in the sense that we often associate with, for instance, handmade guitars. I've done plenty of that kind of work, which has its own deep satisfactions for me. But the 'Jomama was intended to be the joyful expression of a musical dream, and as such I consider it one of the finest musical instruments I've ever made.

 

 

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