Building Without Stress

From the moment strings are fitted, a guitar’s structure is subjected to forces that determine its behaviour. Understanding and controlling those forces is one of my motivations for research.

“My approach to guitar making has been to build with zero stresses.”

When I speak of zero stresses, I mean avoiding unnecessary strain in the parts during assembly.

Imagine removing the glue: the guitar should remain assembled. The parts must reach their position and fit together without depending on the pressure applied while gluing.

The solera and assembly stresses

In some construction methods, the solera is used to give the soundboard a particular curvature. The part is placed, pressed and glued in that position. Once the clamps are removed, the wood retains a tendency to return to its original shape.

From my point of view, assembling the guitar in this way already introduces a stress into the structure.

Taking this observation to the guitar led me to a question: if string tension already has an effect on the soundboard, why force that curvature during assembly?

My way of working is to prepare the parts beforehand with the shape they need, so that they settle into place without being forced. It is not about eliminating the forces that will act on the guitar, but about preventing the structure from accumulating unnecessary stresses.

What old guitars reveal

Restoration allows me to observe how guitars have responded over time. In the workshop I find sunken soundboards, displaced braces, detached joints and other deformations. Each one shows the combined effect of tension, humidity and the behaviour of the wood.

A guitar built in 1856 came to the workshop after a significant change in humidity while the strings were still fitted. The wood softened and the structure collapsed. The soundboard had bent and many joints had come apart, although its main parts were not broken.

Restoring it required taking it apart, recovering its shape and assembling it again. All the original material that could still perform its function was kept, and only the elements that had disappeared were replaced.

Cases like this make it possible to study where and how a guitar deforms after years under string tension. What I observe in old instruments inevitably influences the way I build new ones.

A guitar continues to evolve

String tension acts on every instrument, and materials respond according to their own characteristics. A newly finished guitar is therefore not an object that will remain exactly the same. The wood will continue to adapt and the structure will seek its balance.

For me, building with zero stresses means allowing that evolution to begin from a structure that has not been unnecessarily forced during assembly.

Research from the workshop

I do not come from a family of guitar makers. What I have achieved in construction comes from research and observation.

My experience as a carpenter taught me to understand the behaviour of wood. Restoration allows me to see the deformations produced over time. Guitar making gives me the opportunity to apply that knowledge and test other solutions.

Building without stress is part of that process. It is a way of asking why we do each thing, and of not accepting a solution simply because it has always been done that way.

Francisco Sánchez · Estepa, Andalusia