Thor 6-DOF Arm

1,450 stars on GitHub.

Thor is an open-source 6-DOF 3D-printed robotic arm designed by Ángel Larrañaga Muro, published under CC-BY-SA 4.0. Standing 625 mm tall with a 750 g payload capacity, Thor uses a yaw–roll–roll–yaw–roll–yaw kinematic configuration typical of industrial manipulators, making it a natural teaching platform for industrial-style kinematics, trajectory planning, and inverse kinematics without the industrial price tag.

Source: https://github.com/AngelLM/Thor

Every structural part is FDM-printable, and the arm uses NEMA 17 stepper motors with reduction stages (belt-driven for joints 1–3, harmonic-style printed reducers for joints 4–6). Motion is controlled by a standard Arduino Mega + RAMPS/CNC-shield stack running a Marlin-derived firmware, with optical endstops on each axis for reliable homing. This makes Thor approachable to anyone who has built a RepRap-class 3D printer — the electronics and firmware pipeline is nearly identical.

The project has a very active global community: a public forum, live user map, Discord, wiki, and dozens of community-contributed mods (new tools, parallel grippers, suction cup end-effectors, modified articulations with higher torque or better cable management). Over the years Thor has been built by students, universities, and makers in more than 60 countries as a platform for robotics and automation coursework.

This program exposes cloud-side action endpoints (home, per-joint move, coordinated multi-joint target, gripper open/close, e-stop) that relay to the onboard Arduino controller over WebSocket. A Raspberry Pi acts as the WebSocket-to-serial bridge and handles the high-level path planning.

Credit to Ángel Larrañaga Muro (angel-lm.com) — upstream repository at https://github.com/AngelLM/Thor under Creative Commons Attribution-ShareAlike 4.0. Share-alike requires that any derivative works be published under the same license.