An intriguing direction for a RasPi 3D printer build using radial arms instead of a more typical tight cartesian arrangement — requiring a more math-intensive approach to positioning, calculated in real-time by the RasPi instead of the sequence of consecutive instructions more typical of microcontroller-driven desktop 3D printers. Given all of the great drawbots, from Hektor, to the RepRap Polar family, and to Polargraph, we are seeing the open source tools out there to help this approach to 3D printing become more than a curiosity in the near future. From 3ders.org:
Standard 3D printers require significant mechanical structure to provide movement on the three axes. But Jon Wise wants to build a machine in a new way. He is working on an alternative design for a 3D printer that uses radial arms with a minimum of mechanical engineering. The calculations is much more complicated than the conventional design, but it can be provided by the Raspberry Pi computer in real-time.
This is a ‘proof of concept’ implementation which I made without any prepared plans. A great thing about it is that you can put the two motors and the third pivot point in a rough triangle to suit the scale of your ideas and then put a suitable platform in the middle with three arms that are long enough to move the platform. Then measure what you have done and transfer the values into the code. The code is a bit messy at the moment but I could let you have a copy if it would help. – Jon Wise