For some time I have relied on an outside mold to maintain the shape of a dulcimer during assembly.
This type of mold helps keep the body symmetrical. Recently I have desired more flexibility during construction. Sometimes I’ll be working with wood that asks for a slightly different body shape for both acoustic and aesthetic reasons. I am also currently working on a dulcimer that is an experiment in subtly departing from the usual goal of symmetry.
Traditional classical guitar makers often construct instruments on a work-board called a solera. The solera also serves as a jig providing references for the geometry of the instrument and allows for some flexibility when determining the shape of the body.
I’ve recently started using a solera. The geometry of a dulcimer is much simpler than that of a guitar. My current solera is simply a heavy piece of plywood glued and screwed to a brace. The brace keeps the solera flat and allows it to be mounted in a vise.
The flatness of the solera is my reference for keeping everything square and parallel during assembly of an instrument. The solera also provides a good surface for gluing and shaping braces. The elevation above the bench and the contoured outline of the solera help make various clamping procedures much easier to perform. The extra few inches of height above the bench makes working much easier on my back too!
I can control the shape of the dulcimer by using spacers both within and outside the perimeter of the instrument. My standard pattern is easy to set up using a few spacer blocks and one clamp at the waist. I have the pattern drawn on the solera in pencil to help me line everything up.
When using an outside mold I glued the soundboard to the top of the sides face up. With the solera I glue the soundboard to the sides by laying the soundboard face down and clamping the sides down from from above. Cauls placed around the edges of the top and back make simple work of adding arching if desired.
I enjoy the simplicity and the freedom of working without a solid form. I am thinking of making some simple add-on attachments to assist with other aspects of construction.