Official Luthiers Forum!

This is fascinating! Who knew there were so many approaches! I was familiar with Mr. Cumpiano's building board technique, and has read about the tapering and wedging of the upper bout, but the photo essays were quite illuminating. Thanks so much to all that took the time to so beautifully illustrate your techniques and equipment!

The approach used in the build/repair shop where I spend my spare moments differs a bit, but works well for scale lengths and bridge placements from 3/4 size guitar (~20.5" scale and 12 fret neck) to 12 fret-to-body dreadnaughts (and ABG's where the string height is 9/16"). In summary: the upper bout bracing radius and glue-up is directly modified to ensure an natural fit for the fretboard extension at 1/2" string height over the top at the saddle location. Other than a method to accurately radius top bracing at both 28' and 60', no other jigs or fixtures are used beyond the basic outside mold for the body shape and the 15' and 28' radius dishes common to the radius dish/go-bar approach to construction.

Preparation: The rim is radiused at 28' for the top and 15' for the back. X-brace, tone bars, bridge plate, and fingers are radiused at 28', with the upper transverse brace radiused at 60'. Any sound hole braces and any upper transverse graft are left flat.

Execution: X-brace, cap, tone bars, fingers, and plate are glued up in the 28' dish. When dry, the remaining bracing (UTB, UTG, sound hole braces) are glued up on a flat caul, resulting in a preload that resists further flattening of the upper bout.

We fret after the instrument is finished and assembled, but I'm not sure that is really necessary to success. No wedges or tapering of the fretboard is necessary - the extension lies naturally on the top, and the fretboard gluing area is nearly dead flat (no further flattening of the area is done to fit the extension).

Again, thanks for the discussion!