Cutting the inlay channels will be one of the most demanding jobs you will have outside of actually cutting the pearl pieces themselves. While this as a multi-step process, we will go over each of the steps carefully here.
Step #1 – Free Hand Routing:
Prepare your work carefully and get the guitar supported solidly so there is not any play or rocking going on.
Use a dental bit that is tapered to a point and use the Dremel Moto Tool free handed to complete this first pass. Hold the Dremel like you would hold a pen and cut. Cut down about 2mm or so and be sure you stay inside your lines. You will get a lot of dust flying around and if at any time you cannot see perfectly, stop and clear the surface.
This is a very slow process and take your time to get the cuts perfect. Vary the speed of the tool for optimal cutting of the wood. With experience you will improve you cutting technique.
Finish cutting the entire pattern and inspect your work carefully. Make any touchups as needed.
Step #2 – Routing With The Router Base:
Next chuck up a small down-cutting carbide bit and adjust the Dremel in the Router Base so that it cuts down to about 90% of the thickness of the inlay material.
Completely clean out all of the channels, going very slow while routing. Again, if at any time you loose your way (and this is very easy to do, especially with a complex design), just stop and clean the dust away, expose your lines and continue.
If you get tired or very bored, take a break. After a few minutes gain your composure again and you will find you have renewed energy to finish the task.
Step #3 – Undercutting The Channels:
Now we want to undercut the channels just a bit to hold the inlay in place, much as a dentist holds a filling in place. This also helps to keep the inlay from binding when it is inserted into the channel.
The ideal bit is a ball tipped one that will allow just a bit of undercutting, while at the same time utilizing the bit shank as a ‘guide’ so you can easily trace around the pattern. Also the best condition is if the ball cuts flush with the bottom of the channel floor, but not too close to the top of the wood piece. This is kind of tricky to find just the right bit to accomplish all of these things.
Refer to the diagram at the top of this article for a graphic representation of what I am talking about.
If you run across areas that are too tight to admit the ball to undercut the channel, use the pointed dentist bit and undercut in these areas.
Carefully inspect each channel for roughness and completeness. Inspect your scribed line to be sure there are not any tight areas. If so, rout them out and again, inspect the channels very thoroughly.