Master Luthier Otis Tomas

I start with the rib assembly. The rib material is roughly sized to 3 inches wide and about 2 millimetres thick. I will scrape them a little thinner in the area of the cutaway to make it a bit easier to bend without cracking but I have to be careful and use some judgement. Leaving them a little thicker will give me a bit more material for smoothing out any irregularities that come from bending this highly figured wood. Made thinner, and they will bend easier, but leave little room for correction.

The bending is done freehand on a simple electric bending iron. No other bending forms or aids but a sensitive eye and hand. I keep the wood dry, using moisture sparingly only if I think it needs a bit in the tighter curved areas.
I have chosen mahogany for the blocks and linings. Kerfed linings are prepared on the tablesaw, the blocks must be hand countoured to fit the curve of the mold. Here is the completed rib assembly on my workbench.

The top and back plates must now be prepared for carving. The large spruce billet must be resawn to yield the two halves that will make up the 16 inch wide top. For this, I will use my old bandsaw, which once belonged to Alexander Graham Bell, pioneer of the telephone.

Next, the edges are joined and glued together. For clamping, I use a rubber band cut from an old inner tube in a long spiral. Here, both the top and back plates are joined. Between the two halves of the back is a strip of ebony bordered by fine veneer lines. When finished, this back strip will tie into the ebony bindings of the guitar body. Then the bottom surfaces must be planed flat, ready for sawing the outline.

After cutting the outline, I start with the gouges to rough out the arching of the back. I have to be careful because this slab sawn quilted grain really likes to chip out, so after an initial quick removal of excess wood, I switch to the carving planes. Note the toothed blade that makes working with this figured wood a little safer.

I will make the height of the arch of the back just under 1 inch. After the initial roughing in, I set the long arch, looking for a smooth flow of line and gentle recurve at the ends. I will not be using a template for these arches. There is no prototype for this guitar, so I will be using my judgement, hand, and eye to determine its shape. To fair the convex curve of the arch, I use a flexible steel ruler as a spline to check for irregularities in the line. A fair curve will follow the shape of the bent ruler when the ends are held down to the wood.

The curve will reverse at the ends, turning from convex to concave. This is an important feature in the carving of a well arched plate. A single curve, rising right from the edge in an even arc can be quite stiff and strong; given an S shape, it acquires much more flexibility and freedom of movement. What is needed is a good balance of stiffness and flexibility for the response one is looking for. In this picture I have drilled a series of guide holes to mark the low point of the arch a little way in from the stiff outer edge and lining. The outside perimeter of the plate will stay at about 6 millimetres in thickness to provide a nice raised edge. For now, the low point in the channel will be about 3.5 millimetres in thickness. The edges and recurve area will not be finalized until the guitar goes together.

One of the best tools for located any irregularities in the curves of the arching is the hand and fingers. Often you can feel slight differences that go unnoticed by the eye.

The tranverse or cross arching is shaped after the long arch is established. The curves must blend and flow naturally, there is no substitute for the eye of a sculptor. When the planes are done their work and the flow of the lines seems correct, the scrapers will finish the work.

When I am satisfied with the overall shape of the arch, it is time to hollow out the inside. First, a series of guide holes is drilled using a depth stop on the drill press. These are just to help the initial roughing out, and should leave plenty of thickness for final graduating. I will leave about 8 mm in the center, tapering to about 4 mm at the low point of the arch, a little ways in from the edge. As in carving the outside of the arch, I progress from the gouges to the carving planes and end up with the scrapers. In this picture, you can see the inside of the back pepperred with guide holes. I will sometimes use the mallet on the gouge during the during the roughing stage; the long handled gouge is for the arms. It lets you get a lot of power behind it for quick removal of material.

The final thickness of the back will depend on the material, design, arching, and tonal considerations. All these factors are balanced in an intuitive manner. This wood is new to me, and so is the design. There is nothing to tell me what is too thick or too thin but my own judgement, based on my experience and objectives. This slab sawn big leaf maple seems softer and more flexible than the eastern maple I am used to, so I leave my graduations a bit heavier than I might otherwise. I stop when the center is 6.5 mm and the edges are 3.5 mm. It needs to be thick enough for stability and coherence of tone, yet thin enough to be easy and responsive. There is a lot of guesswork involved, but it should be educated and experienced guesswork. Once the instrument is together, I will revisit these graduations one more time with the scraper. I prefer to work the instrument as a whole as much as possible, rather than trying to finalize it as parts out of context.