In this part of the series, we’ll look at making and installing the back braces, making the back, and prepping the sides for the big glue-up.
In this guitar, I put in four back braces. These braces were made from 7×15 mm strips of Spanish cedar ripped on a bandsaw. The braces were given a rounded profile on the side facing up when you look through the sound hole.
After cutting the braces to length, the ends of each brace on the rounded side were chiseled flat. This would be the side glued down onto the kerfing.
The back of this guitar will be slightly rounded to a 15’ radius. So before installing the back braces, the kerfing on the sides were radiused using a 15’ radius sanding dish.
In this photo, you can also see that I have already leveled the kerfing on the top with the sides and notched the kerfing to receive the cross braces on the top. This was a painstaking process because you want the top of the sides to be dead flat when you glue on the top. It involved many iterations of flipping the guitar upside down on a dead flat surface, looking for gaps, flipping the guitar back right side up, and shaving material off to reduce the gaps. Occasionally, I would break off a piece of the kerfing and have to glue it back in and wait for the glue to dry.
With the back kerfing properly radiused, I notched the kerfing with chisels to receive the back braces.
The first brace was placed at the waist and then one brace was placed to roughly divide the upper bout in half. The last two braces were placed to divide the lower bout into thirds.
I chose to place the braces so that the notches fell on full kerfs. This made the braces not perfectly parallel, but I figured I wouldn’t be able to see that anyway in the finished product. This picture is also nice because you can see what the inside of the guitar would look like with the back removed. Kinda neat!
The braces were glued in without any clamps, just placed in the notches. The braces now had to be properly radiused. A block plane was used to remove most of the material.
Then, the sanding dish was used to arrive at the final radius.
The back panel can be glued up in the same way as the top. The only wrinkle is the added center strip. We actually glued the panel up with a technique that involved eight hands, CA glue, accelerator, and frustration. I think I prefer the simple wedge jig and yellow glue.
My back was made from a bookmatched pair of East Indian Rosewood. This LMI kit came with some great looking wood!
The final piece of the back was the center strip which was glued in using the go-bar clamping system that we saw in the last post on the top.
After scraping and sanding the inside surface of the back, I laid out where the center strip had to be notched to receive the back braces, heel block and tail block.
Here is the back after notching these areas out with a chisel and scraper. The final step before gluing up is rough cutting the outline of the back slightly oversized on the band saw.
Next time, the big glue up!