Designing a Sand Extruder
This project aimed to contribute to the search for sustainable materials in the construction sector, and to create a standardised method for the robotic manufacturing of these materials.
Viewing desert sand as an untapped resource yet to be utilised for any practical application, we began experimenting with different recipes in order to find the most durable, sturdy mixture. In parallel, the appropriate hardware that would facilitate it's smooth extrusion was developed after a rigorous, re-iterative process of testing.
Material Testing
A variety of combinations were tested during the development of the sand recipe. It was important to ensure that the material held it's form upon being extruded, but at the same time, did not dry too fast or too slow. The former would result in difficulty during cleaning, and waste of material due to jamming inside the extruder, whereas the latter would result in collapsing structures, unsuitable for 3D printing.
Hardware Design
Extruders & Plungers
This phase involved designing the hardware through which the material was to be printed. This included designing a system that accommodates a gearbox and the motor that propels it, the plunger which would push the material downwards, and the extruder through which it would output.
Initial Tests for the Top Cap. This threaded component was made to accommodate the gearbox and the rod, while also serving as a lid for the plunger. In order to make sure the rod fit perfectly within the gearbox, we also needed to create adapters. (Bottom right)
The plunger was required to be a very specific dimension, having to accommodate two rubber bands and fit perfectly within the tube without leaving any tolerance, which would cause it to get stuck within the tube. Therefore, it required several iterations until we achieved a satisfactory outcome.
Our bottom cap was a component that evolved over time. Initial iterations catered to a system where the plunger connected to a tube, which then connected to the extruder. Later, however, we began to modify this to a system through which the pipe would be eliminated, connecting the plunger and extruder directly. In order to ensure that they aligned perfectly so that the extruder was perpendicular to the print bed, we needed to test the thread several times. (Bottom)
