The first step in building the Dreadnought Guitar was to start assembling the body. This involved the two sides of the guitar, the tail block, the neck block and the kerfed linings that run around both the top and bottom edges of the sides and serve as a gluing surface later.
Assembling the sides
The two Rosewood guitar sides are connected with to two Mahogany blocks. One block for the tail of the guitar and one for the neck location. The neck block has a mortise for a bolt on neck (some guitars may use a single large dovetail joint here). The tail block is just a raduised solid block to match the curvature of the sides. These two blocks must be glued to the the sides precisely at the center of the body and as square as possible to the edges of the sides. This is especially true of the neck block because this setup determines the eventual set of the neck on the guitar. Because the neck block must eventually be glued to the guitar back and top, it must match also the angles formed by back and top. So, it is machined with a 5 degree bevel to match the back and a 1.5 degree bevel to match the top.
The two guitar sides are machined flat on the top edge and have a radius on the back edge. To start the assembly, the centers of both the neck and tail blocks were marked with a pencil. The pattern of the top of neck block was outlined with a knife through just the top layer on a piece of cardboard. This relief was created so that the 1.5 degree bevel of the neck block could extend below the cardboard surface allowing the block to sit square to the workboard. The sides were placed flat side (top) down on the cardboard and the blocks were aligned to match up with the seams created by the sides. It took a few dry fits to align the seams as well as the top and bottom edges of the blocks with the sides. After these dry fits it was time to do the glue up. This started with weighting down the sides so that they would remain stable during the glue up.
The tail block was glued first (with the neck block just dry clamped to the sides). As you can see this took quite a few clamps in a small space – two of these needed extra deep capacity as well (it looks like some creative clamping solutions may be necessary before this project is completed). Gluing the neck block followed once the tail block assembly was dry. Again, a lot of clamps and extra attention to detail were required to get the neck block set as precisely as possible so that the eventual neck set on the guitar will go smoothly. We’ll have to wait until later in the project to see how well I did in that department! In the picture you can see the completed glue up of the neck block, the tail block and the sides. Also in the background are some parts of the cardboard form which I’ll talk about next.
Building the cardboard form and waist clamp
Often, guitars are built using a specialized workboard or custom wooden form. The kit that I started with has a very economical way of creating a workboard and form. This was done with a flat workboard, two cardboard cutouts that mirror the shape of the guitar body, a couple of wood blocks and a shop made waist clamp.
The two cardboard pieces were cut to match the shape of the guitar body. The first piece was inserted into the body over two scrap pieces of 3/4″ material. This was done to elevate the cardboard so that there would be room to attach the kerfed linings to the edge of the sides later. I made a couple of wooden blocks to stand off the second piece of cardboard from the first. One block in the upper bout of the guitar (the smaller section of the body) was 2″ high and the second block in the lower bout was 2 1/2″ high. This offset is because the body actually has a taper – the body is deeper at the bottom than at the top. The blocks were glued to the lower piece of cardboard and then the top piece of cardboard was inserted and glued to the blocks as well.
The second part of the form is a shop made clamp that slides over the waist area of the guitar body to keep things stable. I built this clamp from some scrap MDF. I simply cut the shape out on the band saw and then radiused the inner edges so that it would slide snugly over the waist without cracking the sides. With the inner cardboard form and the waist clamp installed, the assembly was fairly rigid. At least, rigid enough for the next step.
Attaching the kerfed linings
The top and bottom edges of the sides require some material to be applied to both support the guitar body as well as to add a gluing surface for both the top and back of the guitar later. Because of the curves in the sides of the guitar, these linings are kerfed with a narrow saw cut at even intervals so that they can bend with the shape of the guitar. The linings were not long enough to make it around an entire side of the guitar so they were installed in two pieces.
The kerfed linings needed to be attached about 1/32″ of an inch above the guitar sides. This was done so that they can be sanded flush to the top and bottom at the appropriate angles later. It does not require much pressure to clamp these linings to the sides. So, as you can see they were clamped using ordinary clothes pins – though, there were a lot of them! This was done by simply applying a sparing amount of glue to the backside of the lining and then applying the clamps one by one, carefully aligning the edges (1/32″ proud) and making sure that there were no gaps between the lining and the guitar sides. As I mentioned, two kerfed linings were required for each side (top and bottom) for a total of eight linings. In the photo you can see the the glued up body with the completed linings.
Just a note about glue. As you can see in the picture, I am using original Titebond I for this project. Traditionally a luthier would use Hot Hide glue for an instrument. This is done both for its strength as well as its reversibility (i.e. the ability to take a joint apart later if necessary). It is also important to use a glue that creates a very rigid glue line and does not exhibit any creep while making an instrument. Hot Hide glue has all of these properties. Liquid Hide glue is kept in a liquid state by adding Urea and as a result looses some of its strength making it useless for an instrument project. I do not typically work with Hot Hide Glue so I chose the next best choice, Titebond I. Titebond I is the best choice of the aliphatic resin glues for instrument making. It is not nearly as reversable as Hot Hide glue but, it can be reversed. Where Titebond I is better than other versions of Titebond is in the glue joint it produces – it is very rigid and does not exhibit creep. This will ultimately result in a stronger and better sounding instrument.