After almost a year of using machine-milled metal, our engineers have greatly broadened their skills in working with our computer numerical control (CNC) mill. Through customising our machine to suit the Tumbleweed rover’s specific needs, the team has come a long way in the prototyping process.
Engineering a rover for another planet adds another layer of complexity as compared to working on Earth-based constructions. To make sure the parts survive not only the trip to its eventual destination but also the harsh conditions on the Martian surface, space-grade components are essential. Once on Mars, the wind-driven Tumbleweed rovers will be exposed to unique environments and conditions our engineers must take into account in the design process.
To allow for faster iterations in early phases of prototyping and avoid the high cost of space-grade materials, 3D printing was Tumbleweed engineers’ preferred method for the elaborate mechanical systems. Through our new CNC machine, provided to us by German company CNC-Step, our prototyping approach went through a drastic change, as described in our previous blog posts.
A lack of precision and insufficient strength are two major drawbacks when working with 3D-printed materials. With the CNC machine, parts can be milled from metals, for example out of a strong aluminium alloy, allowing it to withstand very high pressure differences. Tumbleweed engineer Guillaume explains: “If you have more skill and more and more time to spend on it as well, you can make these very intricate, elaborate parts with many cuts and with very high precision that look a lot closer to something that would be considered flight hardware.”
Equipped with many different tips, the tools on the machine can be exchanged to suit the individual needs of each part being milled. “It’s very rarely the case that, when making a part, you only need one tool, so you change the tip because you want different shapes.” When milling objects, the parts heat up significantly, requiring constant cooling. Sabin and his colleagues even developed their own adaptation for milling particularly demanding parts: “We made a nice tray for below the CNC because, especially for tougher materials like spring steel, we flooded it with coolant quite a bit. So we made a tray that would collect all of the coolant, which worked extremely well.”
With varying levels of experience working with CNCs in the team, the process has been a true group effort. While early on it may take more attempts, having our own machine provides a positive learning environment. For Guillaume, mastering the machine offers an excellent complement to theoretical parts of his engineering studies: “You can pick up these skills from your peers and also from experts that are helping us out and this is a skill that you will not learn in the classroom. Our members get to learn things that will be useful for their entire career.” According to Guillaume, being able to make such high-quality, strong parts and for all of the value that this brings to our volunteer members, having such a machine is a true game changer in getting a step closer to a space mission.
Considering the progress made by our engineers in the past year, we look forward to further building our Road to Mars with the help of our CNC machine.
Thank you to CNC-STEP for their support of the team by providing us with the CNC-STEP High Z-S400T. To learn more about their products, visit cnc-step.de.
For further information, please contact office@teamtumbleweed.eu.