I’ve tried a new method for cutting purfling channels, this uses Roger Hargrave’s interpretation of the Stradivari method. Among Strad’s artifacts, now in the Museo Del Violino in Cremona, Italy, are two single bladed purfling cutters. Roger believes that Strad used these to cut independently the outside and inside edge of the purfling groove.
I used this method on my most recent violin and found it worked well on the back, but was especially useful on the top, where year growth rings can cause a freely held knife blade to be pulled into the soft summer wood.
To do this I re-ground two of the blades from an Ibex-style purfling marker to be double edged (pointed) so they could cut in both directions. A narrow taper ensures the blades won’t over-widen as they cut around the turns and corners. I then mounted each blade in its own purfling marker. I added a small brass ‘L’ to act as a depth stop which meant less checking of my depth of cutting. The cutters worked well, but I did occasionally use my knife.
To setup the cutting position, test with a scrap of wood with the purfling you plan to use for the instrument under construction. Also in the pictures above you’ll see a file which i converted to purfling picker.