For this guitar I wanted the bracing to be light enough to allow for a clear note when plucked with a fingertip, but firm enough to maintain its sustain and volume. I chose to follow Martin's standard X-bracing guidelines, with subtle modifications to the placement of the lower face braces.
I used AutoCAD software to try a few different layouts and then printed the one I liked best, transferring the line work to the underside of the soundboard. This way I could better control the symmetry of the bracing, as well as the open / closed relationship of the X-bracing.
According to the book, the next steps include dry fitting the X-brace (the most important one), gluing and shaping the remaining bracing and upper face brace (the one that bears the load of the fingerboard and soundboard torsion) and THEN gluing and shaping the X-brace. However, i chose to fit and glue the X-brace first, then attach the remaining braces. The X-braces are each carved first with a slight arch, so that when glued they impart a gentle arched dome to the soundboard. I felt that by installing this element first, I would then have established the arch of the top and could then make sure the other braces fit that curve, rather than compete with it.
(You can never have too many clamps, and get good ones).
LESSON LEARNED: Before carving the arches into both X-brace blanks, I mistakenly notched the lap joint first. Then I tried clamping one into a vice for carving, not thinking about the fact that I was bearing down on the end of the brace, and ultimately fractured it near the lap joint. I was able to wick superglue into the crack and clamp overnight, so it's fine now. In the future, I will arch first--fully supporting the length of the brace--then cut the lap joint.
LESSON LEARNED: Have a shape in mind, and stick too it. I began thinking I would "scallop" the X-brace a little (you can see my rough carving in the picture below). I introduced a slight scallop, then changed my mind and had to carefully feather my high points back into a gentle curve. I'm currently under the belief that scalloping creates dead zones at the peaks, and instead favor a more gentle parabola.
In the end I was very happy with my bracing. The top has a clean tap tone to it (but I really have no idea what I'm listening for...) and in general just looks freakin' cool. The 2 little diamonds toward the bottom are book-recommended seam patches to strenghen those regions. In the future I think I will omit them--I see no need for them there, so they probably only serve to deaden those spots a little...
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Below are just some more pictures of my bracing (you can never look at too many bracing photos. Check out this link for pictures of factory bracing).