This is the first time that I am building a guitar with the truss rod adjustable from within the soundhole. It is a little tricky, so watch your step. While you learn to build a guitar, it is one of those variables that keep cropping up. There are pluses for both styles of truss rod insertion. The advantage of having the adjustment at the soundhole end of the neck, is that the neck/head area will be stronger.Unfortunately, a small section of the soundboard has to be removed to accomodate the truss rod.
I am mentioning this now, because we will need a hole through the first cross brace that we will glue on. This cross brace is 1/2″ x 1/2″, and depending on the size of the truss rod adjusting nut, this will determine the size of the hole.It should be in the middle of the brace, and when the brace is glued on, the hole should line up with the soundboard centerline.
I use a curved template to mark a 15ft radius on the gluing side of the brace. Go to the disc sander and fashion this curve. Place a thin flexible gluing caul under the soundboard, and clamp the brace down. Look at the photo to see this in action.Use at least 5 clamps to secure the brace. Leave to dry at least 2 hours if you live in a warm climate. While this is drying, you can be cutting the other main ‘x’ braces to length, and mark and sand the curve to the underside. If you have one of the 20ft dishes that the luthier supply places sell, then you would use the dish to fashion your bracing curve. I use a single 15ft template to draw my curve. I use the measurements at the end of the braces to help with the curve drawing. The longest brace will subtend the biggest vertical distance (about 3/16″) at its end. When drawing the curves on the back braces, you will see these vertical end measurements of the 4 braces will vary according to their length.
Tags: acoustic, build, clamps, guitar, learn, luthier, soundboard