Before we can start carving out this guitar body, I need to finish up my design on the computer and convert everything into vectors that can be imported into my carving software for my Carvewright CNC router.
A lot of detailed planning is involved in this step. I need to lay out lines for tool paths, and I use different colors to indicate different cut depths. Then I import the lines, one color at a time, into my carving software and model up my simulated guitar body. The software is fairly accurate at showing the finished product but you still need to rely on a bit of experience and imagination to know how things will turn out. I am not looking for the machine to give me a finished product. That would require a lot more time, and probably a much more expensive CNC, but this little hobby machine can easily turn out a guitar body that can be finessed, with some hand and power tools, into a nice guitar.
With all of my programming done, I am starting with the back plate covers.
I found an interesting looking piece of hard maple and planed it down to 1/8″ thick.
Look at that grain. Usually Maple is fairly plain, but this piece was cut at just the right angle to expose an interesting pattern.
Next I attach this thin piece to a much thicker piece of wood, with double-sided tape. This will trick the CNC into thinking it is cutting out a larger piece that will stay attached. It doesn’t like cutting out parts completely, I have had pieces break loose and jamb up the cutter or rollers and mess up the carve completely.
This way, the parts are cut free, but stay in place until I separate the tape.
In case you were wondering, the recessed holes, in the plates, are for magnets, not screws. These plates will be easy to remove without any tools.
My walnut boards are just wide enough to fit the guitar, but the CNC requires 1/2″ on either side of the carve. To achieve this width requirement, I attach some extra strips to the outside, again with double-sided tape.
Then I load it up and start the 4 hour carve of the back side of the guitar.
I have used this trick before without any trouble, but I failed to notice that one of my attached side strips was about 3/32″ shorter than the body. The tracking roller did not notice this problem and kept on cutting, shifting each successive pass 3/32″ to the right as it carved, resulting in a stepped carve. All I managed to create here is a guitar-shaped piece of scrap walnut…
So to prep the replacement board and the front, I decided to glue on over-sized strips and cut them down to match the sides exactly.
I used my drum sander to match the thickness of the boards.
The next carve was significantly more successful.
And with a little sanding, the back plates fit perfectly.
To save time carving out the holes in the top of the body, I just carved their outline, all the way down to the last 1/32″ and stopped. This left the big piece in place and I just cut through the last little bit with a knife to release them.
The top and bottom were held in place with a small 1/4″ tab which I cut away by hand, and the body was free.
I did a bit of sanding to clean up the edges, and set it aside for later.
The front half of the guitar is a double-sided carve and it will take about 8 hours, with me paying attention to when it needs to be flipped, and when I need to change the cutter to a different bit. So while I wait, I am prepping another piece to be carved.
The neck Vicenç bought seems to be made of mahogany, but the top is painted black. We want to veneer it with walnut and carve the guitar’s name into it for a small inlay detail. To find walnut to match the body, I only have to look at my newly created piece of scrap.
I trimmed off a 2″ wide piece of the sapwood, that has some really nice coloring, then re-sawed it in half.
By cutting the length of those two strips in half, I created four pieces that could be book-matched together.
They are currently about 1/8″ thick, and I glued them to a 1/8″ thick piece of that maple from the back plates.
Then clamped them to a backer board to keep it straight while it dried.
I plan to carve this piece really thin. Thin stuff can easily break if I use my double-sided tape, then try to pry it apart. So, for this, I am using painter’s tape on both my veneer, and the plywood backer board, then I use CA glue to attach them.
The CA glue holds everything together firmly, but to release the veneer, I only need to peel away the painter’s tape.
I trimmed the veneer to match the backer board exactly. Now this piece is ready to carve for the head stock.
After about 8 hours of carving, the top is done.
Here is what they look like put together.
And this is why you should pay attention in Geometry class. When it asks you for the “Radius” of a circle, you don’t give it the “Diameter”… The holes for the tone and volume knobs are far too large. Everything else worked out perfectly though.
This is very frustrating for me, since I do not have the wood or the time to carve another front half. If I did, it wouldn’t look the same as this piece either. So I have to repair this one.
I grabbed the off-cut from the bottom of the carve, and made some 1/2″ plugs from an area with similar grain and color.
I cut the plugs away on my band saw, then lined them up with the grain to make sure they would work.
I drilled the holes slightly larger to match the 1/2″ plugs and did a test fit.
Then I mixed up some clear epoxy and inserted the plugs, and rubbed some sawdust in to fill any gaps.
After the epoxy dried, I used my sanding block to sand the plugs down flush to the guitar body.
I flipped the body over and used a larger forstner bit to cut the plug down flush to the surface.
Then I used a 1/4″ forstner bit to drill a much smaller hole through the plug, then used the correct size drill bit to ream the hole out to the correct size. It is not a perfect match, but the glue line should all but vanish when the finish is applied, and everything will be completely covered by the knobs when they are installed.
While that was being repaired, I completed the carve on the headstock veneer.
I used a 2″ wide chisel to gently separate the tape’s connection.
Then I was easily able to remove the painter’s tape.
I used the drum sander to thin the walnut side of the veneer down to 1/16″ thick, and set it aside for us to do the inlay before attaching it to the head stock.
The last thing I need to do before Vicenç comes over tomorrow to finish working on the body, is to glue the back to the front. I use a thin piece of veneer to spread the wood glue around evenly, making sure to work quickly. If you move too slowly, the glue starts to dry out and won’t hold.
Then I used 26 clamps to hold every possible place I could manage.
Oops, I mean 27…
And when the glue was dry, I pulled all the clamps and test fit the neck.
Looks pretty good. Now I can hand all of the sanding and shaping over to Vicenç tomorrow, so he can customize the shape to suit him.