Guitar construction basics
The guitar construction follows traditional Spanish assembly techniques although Mr. Beltrán uses modern technology where such technology yields results that are superior to traditional methods.
One example of modern technology is the use of vacuum gluing to glue the soundboard bracing and the bridge to the face of the guitar. The even clamping pressure and low humidity at the glue line as a result of the high vacuum make this method superior to the traditional mechanical clamps.
The woods used by Mr. Beltrán in the construction of his classical guitars are the finest available. The wood is stored in a controlled environment, as is each guitar during its construction.
Top woods include Englemann Spruce, Redwood, and Western Red Cedar. All brace wood is selected from billets and then hand split.
Wood for the back and sides is generally select East Indian Rosewood or Cocobolo. Brazilian Rosewood, that is over 90 years old, is available by special order. Some of that wood can be seen in the pictures.
Mr. Beltran considers the finish to be as important as the other considerations in guitar construction. All guitars are finished in French Polish. The entire finishing process takes approximately six weeks.
The guitar rosette design is made from wood, and then inlayed into the guitar. A new pattern begins with a large drawing of the design as shown in photo 1. Initially, brown was going to be used for one of the colors. Later, it was decided it would blend in too much with the color of the top. Instead, red was substituted for brown. Once the design is laid out, then thin strips of wood are glued up to form the “log” as shown in photos 2 and 3. Each of the flat panels is made up of about 9 strips, representing each column of the rosette. Those panels are then glued-up into the square as shown in photos 5 and 6.
Once the slot for the rosette is made in the top, pieces, about 1.5 mm thick will be cut from this log like slicing up salami.
Slicing the rosette into 1.5 mm pieces (see photograph at left)
Photographs 1, 2 and 3 show the construction of a guitar top. This top was a replacement. The guitar, waiting to receive the top is shown in the background of photograph 2.
Photographs show how guitar sides are made.
The sides are bent on the tool shown in photograph 1, which originally was made to bend cello sides. The side bender is heated up to about 200 degrees, and the sides are bent. You can see the pitch that has come out of the wood during bending. Once the sides are vent, the rosewood sides are laminated with Spanish Cypress. Once the sides are assembled, beech linings are installed, that serve to increase the side thickness to give a gluing surface for the back of the guitar.
“Twinos” – There are small wooden blocks that hold the guitar top to the sides. This picture shows those blocks being glued in. Maestro Schneider called them “twinos.” Most call them “tentelones.”
“Binding” The purflings and bindings, which is the wood that goes around the perimeter of the guitar, are glued to the guitar using rope. There is a function in that they seal the end-grain of the top or back, slowing the transfer of moisture, and also, the bindings guard against a split if the guitar is banged against something.
“Brace_wrk.” The braces are carved after gluing them on. There is a process of tuning the guitar top, which involves selective thinning of the top and carving of the braces, while tapping and listening to the guitar top.