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YOU CAN 3D PRINT YOUR OWN 6-AXIS ROBOTIC ARM AT HOME

A desktop robot arm with six degrees of freedom, 3D printed and driven by stepper motors through printed gears and belts.

by Ángel LM

FULL CAD BOM FIRMWARE DOCS

RoboticsWorkshop

Built withArduino3D printing

difficulty
●●●●○
time
several weekends
license
CC-BY-SA-4.0
repo
repo ACTIVE1,605 stars

WHAT YOU’LL NEED

1
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COMPAREE VERDICT

Thor is a genuine six-axis arm with the yaw-roll-roll-yaw-roll-yaw layout of an industrial robot, scaled down to a desktop footprint. It is driven by stepper motors through 3D-printed gears, GT2 pulleys and belts, and it moves on G-code just like a 3D printer — the firmware is GRBL or RepRapFirmware depending on your board, the Asgard app gives you a simple control interface, and there is a separate ROS2/MoveIt2 package if you want real motion planning. The structure prints on a normal printer, and the bill of materials, wiring guide, firmware setup and assembly videos all live on the project's documentation site. The assembly is not trivial — you are building a kinematic chain with six geared joints, and each one must move freely without binding. The documentation is thorough, but if you have never assembled a multi-axis mechanism before, expect to pause and reason through the order of operations. The README rates it at 750 g payload including the end effector and a hardware cost below 350 euros. If your goal is to understand robot kinematics and you are comfortable iterating on mechanical assemblies, this is worth the time; it also has an active forum and Discord when you get stuck. If you need industrial repeatability, you are building the wrong arm.

GOOD TO KNOW

  • —STL files for all printed parts are in the repository, along with STEP files for remixing.
  • —Full bill of materials (motors, bearings, belts, fasteners, electronics) is on the project's documentation site.
  • —Runs GRBL or RepRapFirmware and is driven by G-code; the Asgard app controls the motors and Thor-ROS adds ROS2/MoveIt2.
  • —Documentation is on thor.angel-lm.com: printing, assembly videos with interactive instructions, wiring, firmware and control software.
  • —All source files are CC BY-SA 4.0, which permits commercial use with attribution and share-alike.
  • —Repository updated in 2025, with official forums and a Discord server for builders.

Parts to buy

6 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

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Can I build this?

PrintAll structural parts — base, articulations, wrist and gripper — using 3-4 kg of PLA or PETG plus about 0.5 kg of ABS for the parts near the motors, at 0.3 mm layers as the printing guide recommends; expect many days of printing.
BuyStepper motors and drivers, GT2 belts and pulleys, bearings, M3 hardware, a control board (the ThorControlPCB shield on an Arduino Mega or a commercial board), power supply — full list on the BOM page
Tools3D printer (split versions of the largest parts exist for smaller beds), soldering iron, hex keys, screwdrivers, calipers for checking fit
Skillsintermediate 3D printing, flashing and configuring GRBL or RepRapFirmware, mechanical assembly experience — the assembly videos help, but you must understand how bearings, gears and belts fit together
TimeWeeks rather than a weekend: printing several kilograms of parts takes many days on one printer, then a day or two assembling and wiring, and another session configuring firmware and testing each axis
Cost$$$ — the creator puts hardware at under 350 euros, dominated by the stepper motors, drivers and control board; assumes you already own a 3D printer
SafetyLow-voltage DC only, no mains voltage exposed; geared steppers have real torque and can pinch fingers — keep clear of the arm while it moves

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

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Gallery

Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Read the README and the documentation at thor.angel-lm.com (The documentation site has assembly videos and interactive instructions for each joint; the README explains the overall structure)
  2. 2.Print all STL files from the STL folder — parts are organized by subassembly(follow the printing guide on the documentation site for orientation and settings; check the mods folder for improved part versions)
  3. 3.Source the BOM from the repository's Components list (Follow the motor list on the BOM page exactly — the printed housings are sized for those steppers)
  4. 4.Configure and flash GRBL or RepRapFirmware for your control board(the firmware page explains the settings for the DIY ThorControlPCB shield or commercial boards)
  5. 5.Install Asgard and jog each axis(Asgard gives a simple interface for the motors; switch to Thor-ROS later if you want ROS2 and MoveIt2)

Resources

Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.

KNOWN ISSUES

  • Substituting cheaper or smaller stepper motors than the BOM specifies — the arm will skip steps under its own weight; buy exactly what the BOM lists.
  • Ignoring the printing guide — it recommends 0.3 mm layers, 3-4 walls and 20% infill, printing the large Articulation 2 parts in one piece if they fit (split versions are in the Mods folder), and ABS rather than PLA for the small parts that touch the motors, which get warm.
  • Assembling joints without checking for free rotation first — if a bearing seat is too tight or a servo horn binds, the entire kinematic chain locks up; test each joint individually before stacking the next.
  • Skipping the firmware configuration for your board — wrong steps-per-degree or axis directions will send joints the wrong way and the arm may hit itself; check each axis slowly first.
  • Expecting more than the rated 750 g including the gripper — the printed gears and belts are the limit; this arm is for light pick-and-place, not lifting tools.
  • Not securing the base — fix the base to a stable surface before running fast moves, so the arm's own motion does not shift it.

What is the reach and payload?

Stretched height is 625 mm without the end effector, and the creator rates payload at 750 g maximum including the gripper — the FAQ says it still lifts that load stretched horizontally, the worst case. Test with light loads first while you tune your build.

Can I use different motors?

Stick to the motors in the official bill of materials — the printed housings, gears and pulleys are sized around them. Swapping motor sizes means editing the FreeCAD sources, which are in the repository.

Does it support ROS or other robot frameworks?

Yes. The creator maintains Thor-ROS, a ROS2 and MoveIt2 package that runs in Docker. Day-to-day control is G-code over GRBL or RepRapFirmware, with the Asgard app as a simple interface.

How accurate is the positioning?

The project does not publish a positioning accuracy figure. Thor uses stepper motors through printed gears and belts, so backlash and belt tension set the limit — it is a learning platform, not precision robotics. Home the arm carefully and measure your own build.

Is the project still maintained?

It is not abandoned — the repository was updated in 2025 and the creator runs the Thor forums and a Discord server. All files are CC BY-SA 4.0, so you can fork and keep building regardless.

Community builds

No community builds yet — be the first, we feature the best ones.

Discussion1

FROM THE COMPAREE TEAM

Thor drives six joints with stepper motors through printed gears and belts, and it is rated to lift 750 g including the gripper. What motors and drivers did you use, and how did the arm hold up near that limit?

CompareeTEAM2mo agoedited

Practical notes from our verification: the repository is complete and still maintained — the last push was in May 2025, and there is an active forum and Discord. The best guide is the documentation site at thor.angel-lm.com, which covers printing, a full bill of materials, assembly videos with interactive instructions, wiring, firmware and control. Thor is driven by stepper motors through 3D-printed gears and GT2 belts, not hobby servos, and it runs G-code via GRBL or RepRapFirmware; the creator's own ThorControlPCB is an Arduino Mega shield, or you can use a commercial board. Control comes from the Asgard software, with an optional ROS2 and MoveIt2 setup in the Thor-ROS repo. The arm stands 625 mm tall and lifts up to 750 g including the end effector, and the creator puts the hardware under 350 euros. All source files are CC BY-SA 4.0. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.

Ángel LM

Ángel LM designed Thor as a desktop-scale robot arm with the joint layout of an industrial one at a hobbyist's budget. He has been developing it in the open since 2015, and makers, schools and universities have built it as a kinematics learning platform.

GitHub

Star the project on GitHub

DISCLAIMER

  • Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
  • Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
  • Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
GitHub repo