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Making the Benetti Archtop Guitar
The design for this guitar had been in the can for a couple of years. Now it's time to build, so we print out the drawing of the body outline and tape it to a piece of 1/4" MDF. We traced the outline of the drawing with an Exacto knife leaving the MDF marked for bandsawing. The bandsawn outline is cleaned up with files, rasps, and sanding blocks to create a perfect template for the new guitar.
The first fixture to make is a form to hold the bent sides in place while the internal structural elements are constructed. The form is cut from a lamination of three layers of 3/4" plywood rough cut oversized. The joining faces are coated with yellow wood glue. We used sheet rock screws in the center area and clamps around the edge to hold it together until the glue dries.
After clamps and screws are removed, a centerline is chosen and marked. The template is aligned and traced onto the face of the laminated form blank. The inside of the form is removed carefully with the bandsaw. We want the blade to just touch the pencil line. The shape of the form must match the template perfectly.
We will need a holding fixture for carving the inside and outside arching of the top and back. This cradle will also be useful to hold the guitar body for certain operations later in the process.
Back Glue Up
The halves of the back are planed to an even thickness. Then the edges are cut perfectly square and straight using a jointer. If that work is done correctly, then gluing the halves together is simple. Not much clamping pressure is required. We use three bar clamps to close the joint and a C-clamp on each end (with plexiglass cauls to protect the wood and resist the glue) to keep the boards aligned vertically.
I am doing this project with Jim Sadler, a recent graduate of Kennesaw State University in jazz guitar performance. So we are building 2 guitars: one prototype, and one for Jim's professional use. For his guitar we are using master grade quilted maple for the back, sides, and neck. This picture of the body blank starts to show the beauty of this radically figured wood.
The quilted maple neck will be cut from this blank. It was cut from one solid piece except for a small block glued on at the end to accomodate the neck heel.
Except for the top, the prototype is made of plain woods that have been in our shop for several years. Two separate boards were selected and milled. A 3/4" board was planed flat leaving about 5/8" thickness. This was used to make the bookmatched sides of the body and the 2 outer sections of the 3-piece neck.
Flip Matched Back
A 1 3/4" inch thick board was resawn to a thickness of one inch and flip-matched, rather than bookmatched, to make the body blank. This and the sides will be dark stained. The top will be made of the quilted maple and finished in sunburst to highlight the natural figure. A piece was also cut from this board in an area of perfectly flat grain that when turned 90 degrees orients the grain vertically making a strong and stable center section for the neck.
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