Building my 1852 Torres replica - top bracing and inside the box
Updated: Jan 19, 2019
Working strictly from photographs of the outside of the 1852 Torres, I had no idea as to what it looked like inside. In fact, I became extremely confused. Reading the accompanying text of Alberto Martinez' Orfeo issue, it stated, "Four strut bracing under the top and two thick braces on the back". Text on the Musée de Musique website, translated from French - "internal structure consisting of a table dam with 2 bars on either side in a dam of the bottom comprising 2 thick bars in the part of the crate between the mouth and the easel" (Microsoft translation) and, "Internal structure composed of a table having two hand dam bars and other in a barrage of the bottom including 2 thick bars in the part of the box included between the mouth and the bridge" (Google translation). Huh? What? First, unless it was ladder braced, I had never seen an instrument with four (fan?) braces, and obviously had zero experience with such. And secondly, it sounded like both the top and back had two harmonic/transverse braces. I was okay with the two harmonic bars on the top, but only two back braces? Where were they located? In the end, I chose the path of least resistance - FE18 bracing, something I knew about and could do. I already knew that I would have to adjust the position of the upper harmonic bar due to the increased size of the soundhole (that also necessitated lengthening the soundhole stiffening pieces located on either side of the soundhole). As it turns out I repositioned the upper harmonic bar ~15mm towards the neck, the trailing edge of which ended up being located almost exactly under the 17th fret, and I lengthened the soundhole stiffening plates accordingly. Everything else stayed the same as the FE18 bracing.
The fan braces, the soundhole stiffening plates, and the harmonic bars on the top are all European spruce, while the back braces, the kerfed linings and end block are all Spanish cedar. Note the linen tape reinforcement on the sides.
With the rosette already inlaid, before gluing on the braces I thickness sanded the top to a uniform thickness (thinness?) of ~2.4mm (certain parts of the top around the perimeter of the lower bout were eventually thinned to as little as 1.65mm). I cut out the soundhole, signed and dated it to memorialize the date - July 6, 2018 - just as I do with every guitar I build, and then glued on the fan bracing and harmonic bars using my FE18 solera.
To accommodate the wide purflings on the soundboard, I needed to make my own kerfed linings. Most commercially available kerfed linings are a maximum of 6mm wide. For this replica, my top purflings were 9+mm wide. That meant I would need kerfed linings of at least 12mm wide in order to allow a 3mm "safety ledge". I made my linings from Spanish cedar ~12.5mm wide...over twice the "typical" width of commercially available kerfed linings. For the back it was no problem as there was no purfling, just the 1.5mm thick maple binding, the same thickness as the sides. Shown below, the linings I made for the top compared with "standard" linings.
I sure hoped that I had properly calculated the necessary size for the kerfed linings on the top. As you can see below, I had to rout a very wide rebate on the soundboard to accommodate both the maple binding and the purfling. Even though I was confident I had sized everything correctly it was still scary.