Monday, March 11, 2002

Mandolin #1: Headstock

Dogs smell each others butts. Mandolin players look at each others headstocks. You can tell what they're doing as they approach you with their heads cocked to one side, eyes squinting, struggling to read the tiny mother of pearl script in an angled scrawl about a foot and a half to the left of your head. And you can read the response in their eyes. Having played a hand-made instrument made by a master builder for a company that later became known for banging out inexpensive factory instruments, I'm sure people make assumptions when they read "The Kentucky" across the headstock. Hopefully, they are then impressed by the sound of the instrument and maybe even the player. At the same time, I've recently played a Monteleone and a Gilchrist that failed to impress me. Okay, they were both very easy to play and looked and sounded great but did not strike me as worth $10,000 more than my '84 KM-1500.

Installing the Truss Rod
Before the headstock overlay could be glued on, the truss rod had to be dropped into the precut channel and the wood stock that comes with the kit needed to be fitted over it. Some sanding on a flat sanding board removed enough with for a tight fit and a thin layer of Titebond (being sure none would drip down on the threads of the truss rod) made it permanent. The same process was used to close off the end of the channel below the rod "barrel." The excess wood protruding from the channel was then leveled using a flat sanding stick.

Leveled truss rod channel 

Headstock Overlay
The headstock overlay is a thin piece of ebony glued to the maple headstock of the neck. I started by tracing a general outline of the headstock onto the ebony using a clear plastic template created from the blueprint. More important than the outside contours of the headstock (which would just be trimmed down to the maple) was the outline of the truss rod slot access cavity. With the cavity outlined, a pilot hole was drilled and the coping saw used to create the rough opening which was then filed smooth. This opening was used to line up the overlay on the headstock for gluing. Note that the ebony that comes with the kit does not completely cover the headstock. Fortunately, it doesn't have to because the ebony is trimmed back to accommodate the binding.

Trimming headstock overlay 2 Trimmed headstock overlay 

Speaking of the binding channel, that was another job for my special Dremel/Stew Mac routing base with one modification. Instead of using the edge guide, I used a smaller bit with a pilot tip that rides along the maple sides and can get into some of the smaller areas of the headstock scrolls. The MacRostie video explains that the binding channel on the headstock is angled to match the angle on the sides of the headstock and this can be accomplished by angling the flat base of the jig to match the angled angle on the angle of the angle of the headstock. Well, anyway, that's about as much sense as it made to me. Anyway, I just rode the router base long the top of the headstock and cut the channel at 90 degree to the face figuring that I would just sand the binding to the angle of the sides (according to the angle of the angled headstock side angle, of course). The pilot bit could not get into the tightest parts of the headstock scroll and the little dongle on the opposite side so they had to be cut with a chisel.

Headstock overlay binding ledge 2 

With the ledge cut and painstakingly cleaned with a chisel (which MacRostie later points out could be avoided to some degree by drawing with a waxy colored pencil on the outline of the maple headstock so the ebony overlay wouldn't stick), I could proceed with binding. On both the body and headstock, MacRostie outlines a sensible sequence for gluing binding that allows you to keep moving around without ever needing to wait for glue to dry. His process also sets you up to best cut mitres. It was still rather tricky to figure out how to wrap the patient in rubber bands without covering a binding ledge you were going to want to work on next. In the picture on the left, some of the rubber bands were holding binding and some were holding the neck in my cheapo bench vise. I found that I was really stretching the rubber bands and had had a few scares when the rubber bands acted like a sling shot with a sharp mandolin headstock as ammo aimed directly at my face.

Headstock binding 

With the binding installed and the glue dry, I leveled the binding to the ebony using a increasing grits of sandpaper stuck to a flat board. With one hand applying downward pressure on the back of the headstock and one hand on the neck heel, I slid the headstock face back and forth across the sandpaper until everything was flush.

Leveling headstock binding 

Inlay Cavities
I had decided that I wanted to inlay a howling wolf (well a coydog) on the headstock. While messing around with designs on a white board, I realized that the mouth/nose of the howling coydog would fit perfectly in the top point of the headstock. I then realized that if I modified the tail a little, it could continue right up into what I think of as the "little pinky" on the left side of the headstock. I briefly considered modifying the left slope of the headstock point to mirror (or become) the curve of the coydog's back but decided to keep it simple. Maybe next time...

With a print out of the howling coydog I used for the label cut out and glued to a thicker piece of clear plastic, I cut a template using the coping saw. In anticipation of cutting the abalone I created a basic coping saw base by drilling a hole in the middle of one end of a long board and cutting a thin channel from the end to the hole. The coping saw was then slipped into the hole via the thin channel. With the blade in the middle of the board, the piece I was cutting could be completely supported as it was guided into the blade. The template was used to create an outline on the headstock in some bright yellow pencil for me to follow while routing. Now that I think about it, I probably could have cut out an inverse template and used it as physical router guide.

To cut the inlay cavity, I again used my trusty Dremel/Stew Mac router base. I had read somewhere online about someone asking their dentist for small bits (used for drilling teeth of course) that would fit in a Dremel tool. I'm a little ashamed to say that that was what it took for me to go see my dentist about a loose filling that had been bugging me for a couple months. Of course, I spent the whole time in the chair listening too closely to the drill in my mouth thinking, "I wonder if this bit has a rounded head or straight. Carbide tipped? Hmm..." When I brought the subject up as I walked past the receptionist, my dentist perked up and led me to one of those nail and screw organizers with the little plastic drawers and proceeded to give me one of everything. He even showed me the dental supply catalog with about every conceivable variation of mini bits perfect for inlay work. I left with plenty of things to try and eventually settled on a small round headed bit set in the router base to cut a slight undercut just below the surface of the ebony overlay. I definitely had to clean up the edges and try to smooth out the bottom of the cavity quite a bit.

Routing inlay cavity Routed inlay cavity

I then laid out and cut the inlay cavity for the script. As you may be able to see in the picture at left, I ended up blowing out the dots in the centers of the "O's" but figured I could fill them in later.

Routed script cavity Laying out script inlay

Cutting the Inlay
Perhaps another one of those cases where a special tool would have been a good idea, I elected to cut my inlays using my coping saw rather than a jewelers saw. I had ordered some "AbaLam" from StewMac which was created by laminating several layers of abalone together to create regularly sized sheets. I had been told that AbaLam was less expensive than natural abalone shell blanks and thought it a better choice for my first attempt.

To strengthen the inlay pieces, I glued my thick plastic templates to the blanks with Titebond and fed them into my coping saw on my saw base. While the coping saw left a rather rough edge, I found that filing along the edge using the plastic template as a guide cleaned everything up nicely. In fact, for the tight curves of the script, I probably removed more material with the file than with the saw.

Once the inlay pieces were cut, there was extensive fitting to be done before they would drop into the cavities I had cut. Because of the roughness of the edges of the cavity and the inability to get all the way into some of the tight curves of the plastic templates, I had to go back and forth between inlay and the cavity making small adjustments until they matched. Finally, erring on the side of making the cavities too big knowing that they could be filled in later, I filled the cavities with superglue and dropped the inlays in place. Then, with ebony dust made from leftover scraps of the overlay and sandpaper, I created a goopy filler with Elmer's glue to pack around the inlay. I apparently did not cut the cavities quite deep enough because the inlay material stuck up quite a bit. This was not really a problem in that it would be sanded down flush to the headstock, but within the laminated layers of the AbaLam, the quality of the material seemed to decrease as the top layers were sanded away. Sanding was done the same was the headstock binding was leveled, using a flat board with adhesive sandpaper and sliding the headstock face back and forth. Once the face was leveled, I clamped the headstock in my bench vise and leveled the sides of the binding to the wood.

Gluing inlay 1 Gluing inlay 2 Leveling headstock binding sides

Index of Project


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