The Basic structure of all Thomas Guitars, are made by employing the old Spanish method of using a solera to glue the unfinished neck with the intended angle to the soundboard. Then the bent sides are glued with individual wooden blocks to the top, and finally the back is fitted.
This method has some really great advantages both tonally and structurally.
We make laminated quarter sawn necks, and a flat sawn block to connect the neck and foot. This block prevents the foot from being pressed out of the back over time due to wood shrinkage and expansion from varying temperature and humidity changes.
Before gluing the Fretboard we glue a 6mm high wedge and a carbon rod into the neck, the steel string guitars additionally get a stainless steel truss rod. The carbon rod simply stabilizes the neck and prevents the neck to rise and bend too much over the years. The wedge has some great advantages. Such as the fretboard is lifted up in the area of the Soundboard, providing easier playability of the upper frets and at the same time the fretboard could be way thinner, reducing the weight of the neck giving the guitar better balance.
The Fretboard is made of a quarter sawn piece of African Ebony.
The Slots including the nut, and the shape are cut by CNC. That guarantees the perfect position, hides the fret ends and allows the nut to become part of the fretboard for better sounding open strings.
We use solid shells, different kind of bones, metals and recon. Even our Abalone or MOP purfling is cut from solid pieces and glued in position. We don't use laminated shells or ZipFlex.
We sometimes use different woods but we still favor Alpine Spruce from our area. Since 2010 we chose the trees in the summer and cut them at a particular time in the winter considering the phase of the moon, following the rules of the old grand masters. The wood is directly cut in pieces and naturally dried. The spruce cut after these simple rules becomes harder and lighter and tends to move less than ordinary cut spruce.
Each model has a particular bracing we use for sake of sound and stability. All braces are split for maximum rigidness and weight ratio. After gluing, the braces are shaped to a certain tone and stiffness.
Classical and Flamenco both have the same bracing, but are worked to a different tone. We use five fan struts and three additional shorter and thinner bars to control the frequency of the Soundboard.
The Contra Octave Guitar has a double X bracing to resist the extra hard tension of its thick strings.
The Steel String Guitars have a traditional scalloped X-bracing and two tone bars.
We bend our sides on a self-made bending machine with a very accurate temperature limit for each different kind of wood and "bake" them until they become harder and stay in shape. One advantage of using a Solera for construction is the tension free assemble of the Sides and Soundboard. After being bent the Sides are trimmed and glued into the slots in the heel, and then fixed to the top with small individual blocks.
Our backs are spherically domed with a 4m radius. After the sides have been tapered, we glue a reverse kerfed cedar lining and fit the back. As the Back affects the timbre of the guitar, we work every back a little bit different to interact as good as possible with the Neck and Soundboard. In the case of bracing, we stick to 3 to 5 individual scalloped back bars.
We make very traditional quarter sawn 12 and 18 hole bridges with a 3mm bone or mammoth saddle for our classical and flamenco guitars. The Advantage of an 18 hole bridge is that the string is clamped better and cannot slip, damage or crack the top. Both types provide a better break angle on the saddle compared to a 6 hole bridge where the tie lifts the string and flattens the break angle. Especially for Flamenco guitars with a very low string height the angle is very important to assure enough pressure on the saddle.
The steel string bridges are cut of a quarter sawn piece of ebony. The radius of the Bridge concurs with the fretboard. The bridge is slotted in a way that the string is held even if you remove the Pin and ramped that the string is guided to the Saddle with a soft break angle. It will never happen to any of our Guitars that the string will pop a Pin out. You could play our guitars even with no Pin in the Bridge. We use the Pins as fine-tuning like different materials for nut and saddle, not for fixing the strings in place.
We've invented this unique Cutaway for structural and esthetical reasons. The idea is to change the angle formed by the slot in the heel to the central axis from nearly right angled to obtuse angled, and at the same time switched the position of the slot about 25mm on the top side facing the sound hole. As a result the heel is extended, due to its shape and the angle in a very special and ergonomically way. The advantages are that the heel cap could be normal sized, but the side is still straight and does not have to be bent in a 3rd degree. This simple trick keeps the normal sized and shaped heel, removes any tension of a twist-bended side and at the same time provides great access till the 20th fret.