The outline of the Concert body shape was drawn on both sides of the Cedar top. On the exterior side of the Cedar I drew in the rosette channel and purfling lines on both sides of the rosette. The interior of the top will contain the bracing, perhaps one of the more important contributing factors to the sound of the guitar. I use a traditional X bracing design that was developed by CF Martin and perfected by James Goodall (in my humble opinion) and slightly modified by me! I drew the bracing outlines directly on the top and I will dimension the bracing to fit perfectly within these patterns.
Using triangles, square and rulers to draw the bracing outlines on the top.
The next step is to insert the rosette and purfling lines. I use a Dremel tool with a special circular base I obtained from StewMac, a major supplier of luthier tools. First I route out the rosette channel. I made a rosette from a wood called Bocote that has beautiful lines of browns, blacks and tans. It looks awesome against the Western Red Cedar! Next I route out two narrow purfling channels on both sides of the rosette. I will use purfling made of Koa/Maple/Koa to compliment the Bocote.
The Dremel tool with a StewMac circular base for routing the channels.
After routing out the channels, I test the rosette and purfling to make sure there is a snug, but not too tight fit. This time it is perfect and I do not have to re-route. I clean up the channel bottom and sides using 220 grit sandpaper.
Concentrating on getting the rosette and purfling channels routed for a perfect fit.
Now it is time to glue in the rosette. A thin film of luthier”s glue is spread on the bottom and sides of the channel. The rosette is inserted and pressed into place. The glue squeezeout is wiped off after rubbing a thin film on top of the rosette. I place wax paper over the rosette and I use a caul that applies equal pressure to the entire rosette.
The rosette fits perfectly in the channel.
The caul applies even pressure on the rosette. I keep the caul on overnight.
The completed rosette and purfling with the soundhole cut out.
The same process is repeated for the purfling lines: apply glue, position the purfling, press into place, clear excess glue and clamp with the caul. After the glue has set (over 24 hours), I use a sanding block with 220 paper to even the purfling and rosette with the top. It really looks beautiful with this combination of natural woods.
I really want to thank my wife for taking all the pictures. She prefers to remain nameless but she is a great help!
Next up is bracing the soundboard.
After the glue has set for over 24 hours, I remove the joined top from the jig. Using my favorite tool, the scraper, I micro plane the top to remove the glue squeezeout and level the top. To sand the middle of the top to the desired 130/1000″, I use a random orbital sander with 150 grit sandpaper. I frequently measure the thickness of the top using the caliper jig. The perimeter areas of the top will reach 110/1000″. With the middle of the top thicker than the perimeter, the top can act like a speaker cone – it has strength and elasticity. The next step is to draw the outline of the guitar on the Cedar and begin planning the rosette. I also have been squaring the headstock and I drew the headstock outline on the top of the neck. I am waiting for delivery of the Waverly tuners before I proceed any further with the neck.
Using the scraper to micro plane the Cedar top.
The outline of the headstock shape drawn on the neck.
Random orbital sanders are efficient tools – all you have to do is guide them.
The Master grade Western Red Cedar top is extremely stiff with very tight annular rings so I plan to bring the center thickness to 130 thousandths of an inch (130/1000″). I am using accurate calipers to measure the starting thickness. I will create a gradient from the center to the perimeter of the top, bringing the perimeter to 100/1000″.
Measuring the starting thickness of the Cedar top.
Using my Performax drum sander, I carefully remove thin layers from the top. It takes over 100 trips through the sander to arrive at 140/1000″. I will use a random orbital sander, a scraper, and sanding blocks to achieve the final thickness but this will happen after joining.
Thicknessing using the drum sander.
The bookmatched top pieces need to be joined using a butt joint. This is an extremely important join as the top radiates as a whole and the join should never fail with the continual stress exerted by the movements of the top. In order to ensure the stability of the join, I prepare each Cedar half using a trim router and 1/4″ straight bit. I run the router several times along the edge of each piece. To test the evenness, I hold the two pieces together in front of a bright light source to see if there is any “candeling” (any light showing through). Fortunately, the first candeling test is successful.
Using the trim router and routing jig to prepare for the top join.
Using rope to join the top pieces together.
To join the top pieces, I use a method developed by Spanish luthiers over 200 years ago. I built a jig that uses rope to pull together two thin pieces of wood while keeping them flat. I apply a thin line of glue on each side, place it in the jig, and wrap several runs of rope in four positions along the width of the top. I then insert Mahogany wedges under the rope to pull the tops together by tightening the rope.
Inserting Mahogany wedges under the ropes to tighten.
The Cedar top glued and drying in the joining jig.
The headstock outer veneer is Ziricote to match the back and sides. I sandwiched light Maple veneer between the Ziricote and deep green dyed Ash veneers and glued it to the headstock. The deep green veneer, although only 1/32″ thick, will help contrast dark Zirocote to the Mahogany. I often use Ebony for this but I feel the deep green will look beautiful behind the Waverly tuners.
Clamping the headstock veneers
Today I routed a channel for the truss rod and then fashioned a Mahogany spline to cover the rod and couple the spline to the neck. I then drilled two holes through the end of the neck to accommodate the two barrel bolts that will eventually assist in joining the neck to the body. Next I used the table saw and my neck jig to cut out the tenon. I cut a 5 degree angle at the neck end that will be parallel to the body end. Preparing the Ziricote headstock veneer is the next step.
Overhead view of the neck, bolt on tenon and truss rod.
Another view of the tenon.