In custom space frame structures, design and construction of joints present a significant challenge. The objective of this project is to provide a tool which generates joints for multiple edge connection scenarios. It provides controlled user interaction on material choice, cross section size, as well as shape of joints. Loads at connections from self-weight of the structure are factored in determining the topology of each joint. For this project, we take a classic computer graphics algorithm, the Marching Cubes, and turn it into a fabrication solution.
We developed the project as a C# plugin for Grasshopper. The code first analyzes a set of wireframe bars and places it into a graph data structure, taking into account the radius of each bar according to user input. Then we calculate the angle of the incoming bars and assign a custom length to each joint. The next step is to implement the marching cubes algorithm at each node to generate an equipotential surface according to the grid density. The 3D grid of density values is then augmented or subtracted according to the structural results that structural simulation software Millipede outputs and a refined surface is produced.
One potential use of the tool could be to turn any mesh model from Google’s 3D Warehouse into a human-scale deployment with PVC pipes as a low cost linear elements and 3D printed joints as the custom solution for n-number of bars meeting a joint.
The custom spaceframes joinery project was done in collaboration with Alpha and Hunmin.