Press Fit Assembly Butterfly

MAT 111PF: Press Fit Assembly Project

For this project, we were requested to design, model, and make a 3D press fit structure, using plywood and a laser cutter. I chose to make a butterfly, because they are so pretty, relatively simple in shape, and just generally my favorite insect.

1. 1/8th inch plywood
2. Something to sketch on
3. Fusion 360
4. Laser cutter
5. A sense of whimsy (optional, but highly recommended)

Start with a vague sketch of the final design, then figure out the shape of the pieces necessary to create said design. I also noted where each slot would connect.

CAD all the pieces according to the concept sketch.

Assemble the pieces in CAD to make sure it looks good, and export the face contour of each part as a .dwf file, adding kerfs according to the type of laser on the laser cutter (in this case, ~0.25mm).

Organize the shapes in software so they fit on the plywood & laser cut!!

Assemble the pieces according to the predetermined slots, and the project is complete!

This week’s reading “Build from the Bottom Up” from Skylar Tibbits’ book Things Fall Together really made me think about forms and assembly geometry. In one of the sections in this chapter, Tibbits talks about the merits of bottom-up construction in a complex system with many parts. In such an assembly, Tibbits claims that utilizing bottom-up construction and thinking not about the physical form of each piece of the puzzle, but instead in the purpose of the overall assembly and how each piece would need to connect to each other, would do well in simplifying the assembly design process. I have followed this train of thought in this project. I’ve never worked on anything like this before, and I wasn’t entirely sure how to approach designing an assembly that slots into itself like that. Using the bottom-up method, I started by thinking about the most critical joints, in the butterfly’s body, and was able to successfully figure out the rest of the assembly from there.

Overall, this project went pretty smoothly! The joints were fun to figure out and build in CAD, and seeing it all come together after being laser cut is genuinely a really cool process. I did, however, run into a minor problem whilst converting the CAD model to a tool path for the laser cutter. A few of the smaller specks i had added to the edges of the wings in CAD were lost during the export phase because they were too small. The final result still looked great, so I didn't see cause to change it, but I could have spent some more time messing around with the sizing of things to get them not to vanish.