Binding the Body (Pt. 2)
Once the glue has dried, the tail graft is scraped flush with the sides of the guitar.
I use a router with two different size rabbet bits to cut the channels into the body where the binding and purfling will sit. The purfling lines are only about 0.060″ deep, so that channel is cut separately from the binding channel, which will be about 1/4″ deep. The reason it is done this way is to keep the top and back plates as strong as possible. If the purfling was the same depth as the binding, a great deal of the top and back plates, as well as the kerfed lining supporting them, would have to be removed to make the channel. The result would be that neither the top nor the back would be supported by very much wood and the bindings/purflings cannot be counted upon to provide any structural support.
Here is a picture of the two-stepped binding channels. As you can see, I don’t rout the binding line right to the tail graft. That last little bit is done by hand to make a clean looking joint.
The black-white-black purfling lines along either side of the tail graft are cut at 45 degrees. The same cut will be made where the side bindings join the tail graft to (hopefully) form a sharp 90 degree miter.
Now the bindings and purflings are glued to the body. The raw materials aren’t long enough to run a continuous strip, so there are two pieces for the top and two for the back. I can glue one top piece and one back piece in a day, but I can’t go any faster than that because I want to be sure the acetone-base glue is completely cured before I start trying to make the clean cuts necessary to join the opposing pieces together at the seams.
After gooping the body channel, the binding strip and the purfling strip with glue, everything is carefully positioned and then held in place with strapping tape until dry.