In the world of FDM 3D printing, dominated by classic Cartesian systems, some innovations are overturning established codes. Such is the case with the 4-axis core-RΘ 3D printer designed by Joshua Bird. This audacious maker has pushed back the boundaries of traditional FDM design by developing a machine based on a polar kinematic system.
Unlike conventional FDM 3D printers, which operate on a Cartesian system with three axes (X, Y and Z), Joshua Bird’s core-RΘ printer turns to a polar system. In simple terms, the polar system distinguishes itself by using a rotating circular build plate combined with angular and radial movements, instead of linear displacements in horizontal planes. This choice makes it possible to create radial slices rather than flat layers.
The core-RΘ 3D printer uses a round build plate that rotates.
This approach offers a major advantage: better overhang management, since the printer is able to print with a 90° orientation to the build plate without any particular difficulty. In his video presentation, Joshua Bird illustrates this capability using the core-RΘ 3D printer with a tree-shaped part, where the horizontal and inclined branches are printed without supports, thanks to the print head mounted on a rotating axis that extrudes the material inwards, directly onto the existing sections.
How the Core-RΘ System Works
To make this possible, Bird has developed a new kinematic system called “core-RΘ”. This combines :
- A circular, rotating build plate (c-axis) ;
- A vertical screw for z-movement;
- A horizontal rail with belt for the x-axis;
- A rotating print head (b-axis), capable of tilting in the XZ plane.
Its system uses two motors linked to a pulley that controls both x-movement and printhead rotation, all mounted on a z-axis. This design allows the printhead to move and tilt to reach any point above the platen, making radial printing possible.
The system named “core-RΘ” by Joshua Bird uses a pulley to control both printhead rotation and x-axis movement.
An Innovative, Open-Source Project
The challenge of this machine doesn’t stop at the mechanics. Standard firmware and slicers are not compatible with this type of kinematics. To get around this obstacle, Joshua Bird configured the Reprap firmware used by Duet3D boards and developed his own cutting software, the Radial Non-Planar Slicer, specially designed to generate G-code adapted to this unique printer.
In the spirit of sharing and community innovation, Joshua Bird has made his creations, both the printer and the slicer, available as open-source on GitHub. This allows anyone to reproduce or improve the project, in the spirit of the reprap project. According to Bird, the cost of manufacturing this printer is estimated at between $300 and $400, a relatively low barrier for such an interesting technology.
To learn more about this project and perhaps even replicate it, check out the GitHub projects: HERE for the printer, and HERE for the slicer.
With this polar 4-axis 3D printer, Joshua Bird offers a solution for applications requiring support-free printing, while opening up new perspectives for complex shapes. His project, detailed in a YouTube video, is already attracting interest from users on YouTube:
“I feel like this guy is a time traveler. I mean, he’s single-handedly building a completely insane next-generation 3D printer for under $400 and offering it to the community for further development. Amazing! Just incredible!!!”
“This man is single-handedly moving the 3D printing community forward. (…) And on top of that, he’s sharing everything open source, what a legend.”
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*All Photo Credits: Screenshots from Joshua Bird’s YouTube Video