Now that the ribs are bent and glued into the form along with the top side of the linings it's time to cut the top and bottom plates. I preformed a lot of test cuts in order to find a process that would give me the results I desired . I'm very happy with the way these both came out. If you would like to follow along with this project follow/subscribe on
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Step 1: Carving the Top
I made a bunch of test cuts until I could refine this process. I didn't plan on cutting the purfling channels with the CNC but the test cuts came out better than I expected. I decided to cut them on the CNC and I was very pleased wit the results. My order of operations differs slightly from the way a traditional luthier would carve a plate. First I rough cut the inside and cut the outline with .1" stock to leave. Next I made the inside finish cuts. I choose a Fusion 360 scallop tool path for the finishing passes and it worked out great. Next I flip the part and rough cut the outside shape and then I cut the purfling grove. I then removed the part form the CNC and by hand bent and glued in the purfling. Finally I cut the finish passes through the purfling followed by the final outline bringing the part to dimension.
Step 2: Purfling
Instating the purfling was relatively easy. First the C bout corners are cut to points. Next the purfling is moistened slightly and bent on the Iron to fit the channel. The points are trimmed to form sharp points and finally they are all glued in. I also mixed in a bit of salt in with my hide glue to give it a little more open time while installing the inlay.
Step 3: Carving the Back
The back is cut in the same way as the top but without a brace on the inside. both of theses plates came out great and I can't wait to get them glued onto the ribs.The careful choice of tool path and test cuts paid of with final plates that exactly the amount of finishing work I anticipated. One of the challenges with CNC cut parts is removing any tool marks left from the milling process. Choosing the right tool path and feeds/speeds makes this process much less difficult.
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