The FretBoil Ukulele
February 20, 2014
I got this idea when we were Canoeing the Boundary Waters with my sister and her sons (my nephews). I brought along an inexpensive ukulele so we could have some music while in camp, and it was nice to have but inconvenient to carry in the canoe since it was too bulky and too fragile to fit in my backpack. My eldest nephew Josh and I each have the same model of JetBoil backpacking stove with a 1.5 liter cooking pot and I thought it would be cool to have a thin and easily packable ukulele that would use the cooking pot as its body, so one could just snap them together in camp and start playing. This year I finally got around to making one as a birthday present for Josh, and here's the result:
I did most of the machining using my Shark HD 2.0 CNC router. I made the body and neck from laminated quarter sawn white birch, with two of the inner laminations having the grain running at 45-degree angles to the neck to strengthen the area where the neck blends into the body. The top lamination is curly maple and there are five layers total, each 1/8" thick so the main body is only 5/8" thick. I made the soundboard from western red cedar, and I made it 1/8" thick which is quite thick for an instrument of this size. A thinner soundboard with cross bracing would likely give more volume but I wanted it to be sturdy enough to survive being packed in a backpack without much padding so I went with a thicker soundboard and no bracing. I inlaid a single ring of black-maple-black purfling around the soundhole and a double ring around the joint between the soundboard and the maple frame. The bridge is rosewood with a bone saddle, and the finish is about 6 coats of Tru-Oil. The strap is a hiking boot lace, naturally.
Here are two views of the back, showing the spring-loaded latch that I made and the leather gasket I glued around the edge, which keeps the pot from buzzing against the soundboard:
Below are close-ups of the fretboard and headstock. I made the fretboard from bloodwood with inlaid paua abalone marker dots, and it has a 13-inch scale length which is typical (a bit on the short side) for a soprano uke. The tuners are upside-down compared to how they would normally be installed, i.e. the knobs point toward the front of the instrument. This looks a little odd and it is not as easy to adjust because you have to reach around to the front to turn them but it keeps the overall profile flatter this way since they stick up on the same side as the bridge, and this should make it easier to pack in a backpack. Planetary tuners would have been even better (flatter), sticking straight out to the sides, but the standard tuners don't add much height since they're about as high as the bridge. I also considered mounting them in a solid headstock with the knobs out to the side but then I'd have to angle it back to make the strings break properly over the nut, so I think that would have been a less packable shape. To make the FRETBOIL text I used the CNC router to V-carve the letters and then filled them with a mixture of epoxy and bloodwood sawdust, and sanded it flush.
Here is a sound clip, recorded with an AKG C3000 microphone into a Fostex MR8 mkII 8 Track Multitrack Recorder in a small room using no reverb or other effects, just the natural reverberation of the instrument. It's strung with Aquila Nylgut strings with a low wound G string, which are my favorite. My uke playing is a bit rusty and may not win any contests but I think the instrument has a nice sweet voice. This is with the cooking pot's urethane jacket and plastic bottom cover in place as shown in the photo near the top, which doesn't seem to have much effect on the volume and I think it improves the sound by damping out some of the tinny quality of the aluminum pot.