Recreating My Childhood Memories: a Magnetic Powered Lego Compatible Music Box

Among my most treasured childhood memories are visits to the Lego store in the mall, the clock tower and enjoyed sweet treats from the ice cream car parked nearby. The ice cream truck would also play a music-box style melody to attract kids (see here). Therefore, I recreate this scene through a music box that combines my childhood memories, motion, and engineering.

What makes this music box unique is its LEGO-compatible design. The LEGO platform on the music box allows users to personalize their creation by adding their own LEGO-built decorations. If you'd like to recreate this project, the LEGO decorations can easily be replaced with your own LEGO design.

Materials

1. Music Box Mechanism (Dollarama, $5 CAD)
2. 3D Printing Filament (Variety of colors to suit design aesthetics)
3. Small Lego – Several (Depends on the decorations you intend to add)

Hardware Required

1. Roland BN-20 (or any sticker printer)
2. Prusa MK4S 3D Printer

Software Required

1. Autodesk Fusion 360 (for precision 3D modeling and simulation)
2. Studio 2.0 (for LEGO design)
3. Blender (for file conversions)
4. Adobe Illustrator (for sticker designs)
5. Prusa Slicer (for 3D print settings)

Buy a music box from Dollarama.

Measure the dimensions of the music box mechanism, including the screw holes and any other critical features. These measurements are important for designing the components in CAD software.

Create detailed models of the following components in Autodesk Fusion 360:

1.Music Box Body

A housing that accommodates the music box mechanism with a flat surface for decorations/ movement of ice cream car. Screw holes are added according to the measurement above.

The hole support is created with shallow angle (15 DEGREE) to avoid overhangs in 3D Printing.

2.Music Box Base

3.Rotating Support

Includes three magnet slots per side, ensuring balanced and smooth rotation movement of the ice cream truck.

4.Decorative Elements

A clock tower, pool, and palm trees modeled in Studio 2.0.

LEGO-compatible designs were converted to STL format in Blender. (See tutorials here)

5.LEGO Platform

A LEGO platform downloaded (here) and scaled and cut in fusion 360 as a circle for this project.

6.Ice Cream Car

Given the limitation of 3D printing, I simplified the shape of the car for 3D printing with fine details added as custom-designed stickers printed on the Roland BN-20.

I created the flatten pattern of the car by the drawing tab in fusion 360, the scale must keep as 1:1 so that the image dimension would be exactly fit the model. Also, eliminate all the dash line.

Engineering Considerations for the above components:

1.Manufacturing Considerations:

Given that the majority of the components are fabricated using 3D printing, the design should be optimized to minimize overhangs and complex geometries that could complicate the printing process or compromise the structural integrity of the parts.

2.Magnetic-Powered Car:

It is essential to ensure the stability of the rotating components to prevent any unintended movement or imbalance during operation. The magnetic system must be designed to maintain a consistent and stable force, ensuring it is sufficiently strong to propel the vehicle while maintaining control.

Use Fusion 360’s motion study tools to test component alignment and fit and simulate movements to detect potential interferences or collisions.

Settings: Set a layer height of 0.15 mm for smooth finishes.

Fit testing for the Lego base:

The Lego base must have a tight fit with the block above. Since different machines have different tolerance and setting, therefore print test pieces for the LEGO base is necessary at varying scales to ensure compatibility.

Assemble Components: Bring together the music box mechanism and 3D-printed parts.

The magnetic should be either installed in North-South-North pole or South-North-South pole, or they will repel each other.

Enjoy!