This Instructable is for you to build a 3D-printed programmable musical instrument. I was inspired by the beautiful sound from a real music box so I designed, printed and assembled a 1:1 model.
This is an interesting project for us to apply mechanical engineering ideas to create a music box. I designed the model by CAD Solidworks and printed the components by UP BOX and Form 2. The mechanical motion of the device is realized by the worm-and-gear system.
In reality, I do not own a 3D Metal Printer so the "reeds" of the musical instrument do not sound very graceful. However, the project shares useful experiences about how to 3D design and fabricate a delicate musical artwork.
To build the musical instrument, the following tools and materials need to be prepared.
1. 3D Printers: UP BOX, Formlabs Form II
2. 3D Printing Materials: PLA Filament, Tough Resin, Alcohol
3. Tools: Pliers, Tweezers
In this Instructable, both the Solidworks Part Documents and the STL Files are attached.
Step 1: Mechanical Structure of the Music Box
The music box is made up of a base, a holder, reeds, a notes cylinder, the gear-and-worm system and bolts. You turn the worm driver like a rocker to actuate the motion of the gear underneath it, through which the notes wheel rotates with it. There are a series of holes on the notes wheel where you can insert rods. When the notes wheel rotates, the rods come into contact with the reeds and then vibrations of the reeds generate the sound.
Step 2: Design the Model
Firstly, we design the base and the main holder. The design can be simply achieved by extrusion and cut in Solidworks.
Secondly, we design the acoustical generator, the reeds. We create twelve pieces in the model with evenly decreasing lengths to generate tones from pitch C to pitch B. Each pair of adjacent reeds create equal temperaments. The stronger and more elastic the reeds are, the more clear and melodious the sound they usually produce. If you have a Metal 3D Printer, you will fabricate the reeds with higher quality. After printing the reeds, we should also calibrate the tones with tuner, which means we may need to modify the lengths of each reed until they sound correct.
Thirdly, we design the notes sheet. We cut a hole in a sheet and pattern this feature in Solidworks. In this step, we should make the holes perfectly match with the positions of the reeds. And then we fold the sheet and mate it with a cylinder. This function is realized by Metal-Sheet in Solidworks.
Finally, we design a pair of worm-and-gear system. We can download the parts in the Solidworks Tools Library and modify the components to the required shape and size.
Step 3: CAD Visualization of the Assembly
The base, holder and the reeds are connected by the screw joints (M2.5*0.45). When turning the worm, it drives the revolution of the gear whose motion plane is perpendicular to that of the worm. The revolution of the gear further drives the rotation of the notes cylinder by the rack joints. So eventually, with rods inserted in the corresponding holes in the notes cylinder, the reeds can generate desired sound when turning the hand shank.
Step 4: 3D Printing of the Parts
In this Instructable, the reeds are printed by UP BOX with PLA resin. It is actually not strong enough for the reeds to produce clear sound. If you can do 3D Metal Printing, then you will create and re-program a real music box by yourself!
The other parts, including the base, holder, worm, gear, notes cylinder and bolts are printed by Form 2. The base and holder are printed by castable resin. The notes cylinder is printed by tough resin so it can hold the rods firmly. The worm, gear and bolts are fabricated with clear resin and you can observe their motion more clearly.
Step 5: Final Work
Finally, we have our assembly here. It is a challenge to make such a delicate workpiece.
You can also modify the materials and size of the model to create your own music box. Enjoy the artwork.