My neighbor is working on his doctorate at NC State University in industrial education. He asked me to be a guest lecturer to a 100-level industrial education class on the processes of guitar making. The processes I discussed included; the design plan, joinery, dimensioning, bending, routering, inlay, and finishing. I prepared a PowerPoint presentation and gave a lecture to two classes yesterday. I brought a finished guitar, a braced top, and a set of plans. There were a lot of photos. The lectures were well received and I had a great time. No pictures of me lecturing, but here's a shot of shop time after the lecture...
I haven't posted in a while but it's not because I'm not doing anything. I'm actually working on three builds at a time, including working on my first carved top (or archtop) guitar. This is in the style of a Gibson CS-336. It is sorta like a shrunken ES-335, with the exception that the construction is quite different. An ES-335 has bent ribs (or sides) and the top and back are pressed laminated wood. The CS-336 is constructed by hollowing out a slab of mahogany and the top is carved. In order for the top to be able to be carved it must be thick enough. I am starting with a 5/8" nicely figured maple top.
Before beginning the top carving, I initially used a forstner bit to hog out most of the insides and that was followed by a router. In addition, I had to rout the channel for the binding (I didn't take any photos of that procedure). Also, I had to plane the appropriate angle for the fingerboard (and neck) to ensure that the strings are the right height at the bridge. After this is done, I can begin the top carving.
I have placed the maple top on the body with only screws at this time. I will need to remove the top and carve out the inside of the top. The objective is to have the top approximately 1/4" thick. Once that is achieved, I will be able to rout the mortise for the neck , cut in the f-holes and complete carving the top.
I started carving by hogging off a large amount of maple using an attachment to a grinder. That is followed by using a small concave bottom hand plane. Of course all of this will be followed by a lot of sanding... To access the electronics I installed an access hole in the back. This is accomplished by using various routing templates. There is a lot of work ahead...
Many pieces of different types of woods are used to construct a mosaic rosette. In this case, these woods are spalted tamarind, lacewood, and red heart. Small sheets are sanded to the same thickness and then cut into strips and the edges are sanded level. Each piece is then glued together separated by a thin piece of black fiber, cut again, and then positioned such that a circular rosette can be cut out. The design is random in this kind of rosette and so every one is unique. This one will be used in an upcoming build.
After the top has been tested for deflection, the location of the rosette is determined and the "micro" router jig is used to route out the channel for insertion of the rosette ring. At this point I had already pieced together the wood mosaic and cut it out.
The rosette and black fiber purfing in dry fitted to ensure fit and the channel and surrounding area is wiped with shellac. I intended to use thin Cyanoacrylate (super glue) to glue in this rosette. Shellac seals the spruce top and prevents the glue from staining the top. The rosette is placed into the channel dry and then flooded with Cyanoacrylate. Once the glue dries the black fiber purfling can be leveled with a finger plane.
Here's how it came out...
Today I am continuing the finishing of two guitars, a grand auditorium w/ Florentine cutaway and a tele style electric. At this point I have put on several coats over the course of a few days. Each day before I start a new round of spray applications I level sand w/ 400 grit sandpaper. Level sanding removes a fair amount of finish, so it takes several days to build up enough coat to make sure I don't sand through the finish during final wet sanding and buffing. The trick is to make sure you don't sand through, but not make the finish too thick. It comes with experience.
I have constructed a spray booth using dense foam insulation. The wings are hinged so it can be collapsed and stored easily. A simple 20"X20" box fan is placed behind the booth w/ a 20"X20" opening that accommodates a furnace filter to capture overspray. The window behind the booth is open to the outside. I don't need an explosion proof fan because I am using water based finish.
My finish is Target Coatings EM 6000. I have been very pleased with this finish and after a few guitars I have become accustom to it's characteristics. It has excellent properties that are conducive to application and the end result is a pleasing nitro-like appearance. I use a Fuji Q3 HVLP (High Volume Low Pressure) spray system. The spray gun is retrofitted to accept a smaller finish reservoir which is more conducive to guitar finishing.