Guitar 101: The sound hole and rosette

Now that the back and top had both been successfully joined and cut to shape, it was time to focus on the task of cutting the sound hole and inlaying the decorative rosette rings that surround the sound hole. This would be my first attempt at inlay and I was a little worried about this delicate process. I knew I would need an attachment for my router or my Dremel tool to cut the circle shapes. I did some research and found a variety of attachments were available for either tool. I found a really nice looking circle attachment from Stewart MacDonald to fit my Dremel and decided the smaller tool seemed like a better more controlable tool for this job. The sound hole/rosette routing jig from Stewart MacDonald was a well-crafted aluminum and brass jig that attached to their Precision Router Base attachment for the Dremel. I had purchased the router base earlier when I first started acquiring special tools to make the guitar. I had some 2" aluminum bar stock and after some consideration I thought I could fabricate a similar circle cutter attachment. I quickly sketched out some rough plans and consulted with Matthew about the construction. He also thought we could make this attachment, so we began. It was a fairly simple 2 piece device that used a sliding center pin to adjust the size of the circle. The hardest part for us was cutting the slot in the aluminum. Matt suggested that we try a straight spiral router bit chucked up in the drill press and mount the aluminum bar on a sliding machine head clamped to the drill table bed. This method was a little rough but worked. I used an old 3/16 drill bit and cut of the shaft to use as the center pin. A small thumb knob and bolt purchased at the local hardware store was used to secure the sliding mechanism at the fixed radius for the circle cuts. Two small flat head allen screws were used to attach the jig to the router base.

The aluminum base with slot and counter-sunk attachment holes.

The two aluminum pieces and the center pin.

The completed circle jig.

The circle jig with attached Dremel tool.

Close up of jig, center pin and Dremel attachment.

Now that I had a method of cutting circles I could start cutting the rosette rings around the sound hole and the sound hole itself. I thought that I could use a regular Dremel 1/8" router bit to cut these rings and the hole. I had one so I chucked it up in the Dremel and attached the new jig. I got a couple of scrap pieces of wood to experiment on and drew out the circle patterns with a compass. I adjusted the height or depth of cut on the router base to approximately 1/16" and made my first cut. It was horrible! The edges were soft and fuzzy and the bottom of the cut was not square. This would not work. The StewMac catalog recommended a down cut spiral, solid carbide bit for this but I thought surely I could find a suitable bit locally and not have to order another expensive bit and pay more shipping. So, I started searching. My first stop was the local lumber/home improvement store. The bit had to be a 1/8" shaft to fit my Dremel tool. The Dremel section at the home improvement center would surely have a bit that would work. As I suspected they had a ton of bits and accessories for the Dremel tool but very few actual router bits. They did have a 1/8" solid carbide spiral up cut bit rather than the recommended down cut bit. I thought to my self, this would work, it might even be better and it was half the price. NOPE! It was just as bad on the edges but it did have a flat bottom. Well, to make this story a little shorter, I tried several more bits all with no better results and ultimately ordered the bit from StewMac. It arrived and of course worked great. So, after a test cut, I began on the spruce top.

Routing the rosette circles with the Dremel and circle jig.

Detail of cutting the rosette rings.

Removing the cut sound hole.


The finished rings and sound hole.

The rosette rings around the sound hole are purely decorative. In my research and in the books that I am working with I found many different and beautiful examples. I decided that on this my first guitar I would try and keep it simple. Most steel string guitars have a series of very thin black and white stripes. These are usually made from either very thin wood strips or plastic strips. My first thought was to go with plastic strips that I could order from StewMac. These plastic strips are cheap and pretty easy to work with because they can easily bend and conform to the circle inlay. After calculating the amount I would need to go around the circumference, I checked the StewMac catalog. I found that it was going to cost more than I thought. I noticed that they sold a pre-bent set with a beautiful herringbone pattern for a lot less than the total cost of the plastic strips. That seemed a no brainer, so I ordered it and some plastic strips to later bind the body. They fit nicely in my routed rings. I learned that you start your cuts and later your inlay work on the top of the circles. This part will later be covered by the finger board if you make mistakes or if your inlay material runs short. This was the case with mine but the finger board will cover it when I attach it later in the construction.