Today I am working on the back panel. Since I try to learn new techniques with every project, I am going to attempt to re-use the piece that I cut for the control cavity, as the cover itself. This will give me a perfect grain match, if I can do it right.
I already traced out the cavity walls onto my back piece of wood. In the past, I have made my cavity covers about 1/4″ larger, but I always seem to have problems countersinking holes in the panel, that close to the edge. This time, I am making the cover roughly 3/8″ to 1/2″ larger. The purpleheart loves to tear out, hopefully staying away from the edge will help avoid that.
The best way, that I can think of, to cut out the cover, is to use my scroll saw. It uses a fret saw blade, which is extremely thin. I used a 1/16″ drill bit to drill two holes, right next to each other. Wiggling the bit a little will break the wall between the holes and give me enough room to slip the blade through. Once the blade was inserted, I installed it into the scroll saw.
The purpleheart cut surprisingly well. I did push too hard, trying to cut the last curve though. Jacked my blade up pretty good.
Just a side note. The Excalibur scroll saws have a bunch of slotted holes in the side. They are just the right size for test tubes which are perfect for storing your replacement blades. If you have a different kind of scroll saw, I still recommend the test tube storage system. I would probably just drill a bunch of holes in a board, large enough to hold the tubes, and mount it to the wall, near the saw.
Once I replaced the blade, I was able to quickly finish my cut. There were two places where the cut is wider. The start point and the area where the blade got messed up. Hopefully I can sand in a bit of a relief to hide the wide spots.
The back piece has a lot of tear-out and about a 2″ diameter low spot, left-over from re-sawing the board. I want to glue the board on, but wood glue is not good at filling voids. Hollow spots may affect the sound of the guitar. For a good, solid bond, I am going to try my fast-setting, two-part epoxy.
I mixed up about an ounce or so and spread it out, along the entire back. I made sure that all of the voids were filled, then clamped the heck out of it. I wiped off all of the squeeze-out that I could see. I don’t want to have to sand that stuff down when it dries.
Since I can’t do much else, until the body dries, I decided to clean up the control cover. I started by working my way down from 80 grit sand paper to 220 grit. After that was as smooth as I could get it, I polished the surface with my mop sanders.
This was an experiment to see the best way to bring up the polish on the guitar body after I have finished. I would say that it worked pretty well. I am really looking forward to seeing what this looks like complete.
If it doesn’t rain tomorrow, I intend to take the body outside and try my hand at sculpting some angles onto the surface with a flap sander wheel, on my angle grinder. That will be very dusty, but it should be fun.