Final project modeling
Throughout this semester, I plan to explore a theme of Space Exploration and DIY space hacking technologies. My final project idea for How To Make Almost Anything is also a research project I am pursuing for cubesat deployment. The Solidworks assembly shown below is a proof of concept, self-assembling buckyball. This set of magnet-jointed tiles serves as the payload for a cubesat launch, testing a passive self-assembly in zeroG design for future space habitats (likely paired with an inflatable BEAM habitat for the ISS or other space-bound applications). In subsequent weeks, I look forward to 3D printing test assembly parts, embedding neodymium magnets, and exploring pcb design for circuitry on the surface of the tiles. When assembled, the final structure should enable an emergent functionality as all surface ciruits are connected.
I began by sketching the individual tiles, and the bonding faces where the pentagons and hexagons would meet. I based the tile edge slope angle on the published dihedral angles for buckyballs, 138.189 degrees for hex-hex bonding and 142.62 degrees for pent-hex bonding. For example, the Hex-Hex edge slope should be: [360 - (138.189 + 180)]/2 + 90 = 110.90 degrees. Similarly, the Pent-Hex edge slope should be: [360 - (142.62 + 180)]/2 + 90 = 108.68 degrees. See sketches below for calculation details and geometries. I also used sketching to plan the magnetic joints (both the logic of distinguishing between hex-hex and hex-pent bonds, and how to recess magnets in the tile edge).
Tile slope angle (based on dihedral angle)
- Pentagon to Hexagon bond: 108.69 degrees
- Hexagon to Hexagon bond: 110.90 degrees
Next, I started modeling the individual pentagon and hexagon tiles. After several attempts at other ways of defining the geometry and edge slope angles, I settled on plane-mediated surface cutting (thanks to advice from several solidworks gurus). Below you can see the approach of defining reference geometries at set angles, and the remaining shapes after the straight-sided edges were cut away.
Then, I sketched squares on the surface of the tile edges and used extrude-cut to make the magnet recesses. In the parametric design, I made affordances for the apoxy I plan to glue the magnets in with, so the recessed holes are .012 in larger than the explict dimension of the magnets. I designed the magnets to be paired in the center of each tile edge, to avoid unnecessary interference from rogue bonding (e.g. if I had placed the magents near the edge vertices, other magnets not intended for that joint might be attracted to it). Finally, I modeled the tiles to be thick enough to accomdate the sloped, recessed magnet holes and include sufficient material on the top and bottom to dissipate any magnet force outside of the mating faces.
With the base tiles now ready, I transitioned to an assembly file and mated the hexagon and pentagon tiles, generally using face mates and edge mates. You can see two intermediate stages of the assembly below: