I spent last summer (2016) working on making a variety of instruments for use with students to learn about music and the physics of sound. I made a few other instruments which I have already posted, but I have been working on perfecting a laser cut box ukulele since it will be fairly simple to build and not use too much material. My design for this is based off a ukulele shown on Thingiverse (http://www.thingiverse.com/thing:30986) made by Ben. My svg files have been modified from the original Thingiverse files. I have changed the design to use 1/8" inch plywood, a hardwood bridge, and a thicker neck. A sloped neck with frets have been added to cut down on the strings hitting the neck or frets without having too much "action".
The SVG file doesn't seem to download well in Safari so you may need to try out different browsers. BoxUkulele2 is the one used for the ukulele shown with frets. BoxUkulele is the one without the frets and the treble clef hole. You should cut the red lines completely through and etch the other colors (blue or green). Also cut out the blue on BoxUkulele.
I have also been working on a scaled up version of this that is guitar size (picture included) which I hope to post soon. I thought I took a lot more pictures while making it so I will need to make a second one to get more details to post. It is basically the same design but with a little more support.
Step 1: Parts
The parts for this were laser cut out of two sheets of 1/8" baltic birch plywood (12" x 18") (actually 11.6" by 17.7"). The bridge is made from a short piece of oak dowel (1/2" or 3/8" will work). I have used a few different styles of tuning pegs depending on what is cheapest on Amazon. I also purchased the cheapest strings (I have tested fishing line out which sort of works, but I need to play around with this more). The ukulele shown in this Instructable was also stained with a polyurethane/stain mix. The artwork on this one was added for my niece who is a robot and Star Wars fan.
2 sheets 12" x 18" baltic birch plywood
~3" length of 3/8" dowel
wood glue (or white glue)
2 zip ties
4 tuning pegs (2 left and 2 right)
set of strings
Dremel rotary sander
Cut out the parts shown from the plywood. The red lines should be cut through fully. The blue (or green) lines should be etched in partly. The fretboard etching of the blue lines will require a little testing depending on the power of your cutter to get the depth right.
Step 2: Bridge
To make the bridge:
1) Flatten one side of the dowel so it will sit flat on the ukulele.
2) Cut the dowel to length to match the length of the line on the ukulele front.
3) Use the marks on the ukulele front to mark the 4 spots for the strings to run through.
4) Use a drill (7/64" bit was used for this) to drill out the 4 holes parallel to the flat side.
5) Drill 4 holes offset slightly from the first set of holes. Be careful not to put these too close to the original holes or the strings will rip out the wood when they are tuned.
6) Glue and zip tie the bridge in place on the front panel of the ukulele. Make sure the holes are lined up with the marks and the bridge is centered on the line. The zip ties should come up from the bottom of the front panel so the connection part will be inside.
7) Tighten the zip ties and trim off the excess.
Step 3: Make Box
Glue together the body of the ukulele. Make sure you line up any art work to face the way you want it to before you glue the pieces. The top panel (left picture) has the holes where the neck will attach. I used painter's tape to hold the pieces together tightly while the glue was drying.
Step 4: Fret Wire
Once the grooves are cut you should be able to fit the fret wire across the fret board. I cut the wire pieces and then glued them using white glue. I am sure other glue choices might work better, but it is what I had at the time, and I can always reglue them if they fall out. I sanded the edges of the wire using the rotary sander bit on the Dremel once the fret board was in place. You want to make sure they aren't any sharp edges that catch your hand while playing.
Step 5: Headstock
There are 4 pieces to the headstock. The front piece doesn't have screw holes. The screw hole positions and dimensions may need to be adjusted in the svg file depending on tuning pegs you buy. The pieces are not completely symmetrical so you will need to line them up for the tuning pegs to fit through. I should fix this in theory, but it works okay so I haven't gone back and redone this part. You should glue these 4 pieces together. I put the tuning pegs and screws in at this point to make sure everything is lined up before the glue dries.
Step 6: Tuning Pegs
Put the tuning pegs in. You will need to drill new holes if your tuning pegs screw holes don't line up, and you didn't fix it earlier. You will need two left and two right tuning pegs.
Step 7: Neck
This part requires the most gluing effort. You should dry fit these parts first to make sure you know how they line up. Once you start gluing you want to get all of the pieces together before the glue dries. Make sure the part that attaches to the body is tight against the body and the place where the "nut" goes in is lined up.
The order of the pieces is:
In center: longest piece - put "teeth" through center holes on top of body of ukulele.
next on both sides: long piece without teeth
next on both sides: long piece with teeth
next on both sides: long piece without teeth
next on both sides: short piece without teeth
last on both sides: long piece with teeth
Make sure the neck is as flat as possible.
Attach the nut in groove at the top. I used clamps here to hold the neck together as it dried. Tape would also work.
Spread glue on the top of the neck and attach the little "ramp" pieces so that the neck slopes down from the body to the neck. You should line these pieces up with the longer neck pieces.
Once the glue has dried, use a palm sander to smooth out the "ramp" from the nut down to the ukulele body. You want to make this smooth for the fret board to sit on.
I also sanded the head stock end at an angle to fit snuggly up against the "nut". The palm sander worked for this, but a sanding belt would have worked better to keep it even. There is more about this in the next step.
Step 8: Sand Neck Etc.
Finish smoothing out the neck and then glue on the fret board and head stock. It is important for the fret board to be tight the whole way down. You can tape it on instead of gluing it on at this point and test it out with the strings, but then gluing it on later around the strings is a little more difficult.
Step 9: Finish Ukulele
I sanded the ukulele down and put on a couple of coats of stain/urethane according to the instructions on the can. I think the ukulele sounds better after being stained and urethaned but it may just seem that way.
Step 10: String Ukulele
Put the strings on the ukulele. I used "standard" stringing for this, but there seem to be a variety of options. The strings run over the bridge and through the hole on the dowel. Then you pass the string back through the second hole without pulling it tight yet. Then pass the string back over the bridge through the loop formed by the string passing back through the hole. You will probably need to tie a little knot at this point to keep the strings from slipping when you tune the ukulele.
Run the string up along the neck through hole in the appropriate tuning peg. You should wrap the string around the peg and pass it through the hole again. You may even want to tie a knot for the thinner strings. Once you are happy with the string position, you can cut off the extra.
You will need to tune over and over in order to get the strings to stretch out enough to stay in tune. I recommend buying a ukulele tuner unless you have a great ear. The tuning apps I tried didn't work as well for me.
Step 11: Done
Tune and play. Overall I think this sounds pretty good. It may not be as good as some of the curved body ukuleles, but it is definitely a project I can have my students do fairly quickly. Please let me know if you make this and if there are any ideas you have for improving the design. Again I would like to thank Ben for his original design at http://www.thingiverse.com/thing:30986 . You can make this without the frets, but playing chords is harder.