The Mandolino Bresciano Project:
I recently became fascinated with the bowl back mandolin known as the Mandolino Brescaino (MB for short). It is a four string instrument with gut strings and a 330mm scale.
I had wanted to build a lute for some time, and this smaller version of a lute seemed like a good place to start. Over the past few weeks I documented the building process.
The MB has a relatively short period of popularity (1880 to 1930). According to Alex Timmerman’s mandolin family tree, it is a cousin to the traditional mandolin. What interests me about this instrument is that it is the last in the line of gut-strung three and four course instruments dating back at least 800 years.
There is a wonderful YouTube example of the MB: Francesco Piccone (1685-1745) from his Divertimento di Mandola, Siciliana. Gary Payne, mandolin - YouTube
The process starts with a lot of internet research; piecing together as much information as possible, and assembling a photo album as a visual reference guide.
Everything is roughly based on the vibrating string length: The 10th fret position determines the length of the neck; the remaining string length is the location of the bridge; the bridge is set at 2/3 of the body length; the body width is a ratio of the body length; the depth is half the body width. So in this project with a 330mm scale, the body is 11 inches long by 8 ˝ inches wide by 4 inches deep.
The shape of the body is based on a geometric spiral. It is a simple shape that dates back to earliest lute designs:
All the dimensions for the bowl are taken from this simple shape. The bowl is a half circle with 9 ribs, so each rib is 20 degrees:
I apologize for the boring math, but a form for constructing the bowl must be precisely laid out in order for the ribs to fit tightly next to each other.
The building process begins with a form on which to assemble the ribs of the bowl back.
The first photo shows all the pieces that were cut from a single 12” by 36” board. Note: The neck block and tail block were made from the rectangular piece in the middle of the board, and the ribs from the long piece at the top:
There are five half-circles that make up the form. The center one is positioned at the widest point of the body. There are two closely placed semicircles toward the tail where the circular shape of the bowl tightens. The two toward the neck are spaced a little further apart. Note the flat facets that are cut around the form so that the ribs lay flat against it:
The platform is cut to the body shape and a block is added to the underside for clamping in the vice:
The neck block is added to the front of the form. It is a simple piece to make with the bandsaw table tilted to 45 degrees. It is held in place with a screw:
The tail block is a little more complicated. It is a rounded disc shape carved with a rasp:
With the form ready to go, it’s time to make a batch ribs (no BBQ sauce on these ribs).
There are nine ribs total; all identical because of the simple shape of this bowl.
A “pattern rib” is created by carefully transferring the width of each facet to the pattern rib.
The pattern rib is cut out and bent to shape on a hot pipe. It is checked to see that it is a perfect match to each of the facets along the form:
The nine ribs are cut and bent according to the pattern:
Assembly starts with the center rib, also known as the keel:
Now the real fun begins. The ribs are added to each side of the keel. The ribs have to be adjusted so that they match exactly to the previous rib. This is done by carefully removing any high spots along the length of the rib by shaving small slices off the edge, using a plane fixed upside-down in a vice:
It is necessary to make the ribs a bit larger than the pattern because he ribs get shaved down in the fitting process. Once the rib had a tight fit, it was glued to the keel and to the two end blocks. Note: Put scotch tape on the top of the form so the glue that gets squeezed out of the joint doesn’t bond to the form:
The rest of the ribs follow this process until all nine ribs have been glue in place.
The last rib glued in place:
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