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YOU CAN 3D PRINT THIS ROBOT DOG THAT WALKS LIKE THE 75,000 DOLLARS BOSTON DYNAMICS ONE

A 3D-printed robot dog with custom cycloidal gearboxes that walks like the Boston Dynamics one, for the cost of the motors.

by James Bruton

FULL CAD BOM FIRMWARE DOCS

RoboticsOpen-hardware

difficulty
●●●●●
time
weeks
license
MIT
repo
repo ACTIVE478 stars

WHAT YOU’LL NEED

  • 3D printer + filament — printable parts — files are in the repo
  • Electronic parts — full list with part numbers in the repo BOM
  • Dev board / microcontroller — runs the project firmware
  • Soldering kit + basic tools — one-time buy, serves every future build

Partner

Reach your Pi from anywhere — Remote desktop to the machine running this build — no port forwarding, works right from the browser.Try Getscreen.me
Videos
1

COMPAREE VERDICT

openDog V3 is James Bruton's third iteration of a DIY quadruped robot. The mechanical design is the real achievement here: custom 3D-printed cycloidal gearboxes that reduce backlash and give it that smooth Boston Dynamics gait. Apart from motors, bearings, and fasteners, the entire frame prints on an ordinary FDM printer. The firmware runs on Arduino and talks to ODrive motor controllers, which handle the closed-loop control. The hardest part is not the printing — it is tuning twelve motors to walk without tearing themselves apart. The ODrive controllers alone cost 400–500 dollars for a set, the motors another 200–300 dollars, and you will need a bench power supply that can deliver 24V at serious current. If one leg behaves differently from the others, you are in for hours of PID tuning and mechanical adjustment. The documentation is thorough for a hobby project, but this is not a weekend kit — expect weeks of assembly, wiring, and debugging before it walks. If you have built multi-motor robots before and have the tools and patience for iterative tuning, this is one of the best open quadruped designs available. If you have not, the gap between 'it printed' and 'it walks' will eat your month.

NOT IN THE REPO

  • —MIT license — commercial use allowed.
  • —STL files and Fusion 360 source files for all printed parts, including the cycloidal gearboxes.
  • —Arduino code and wiring diagrams for the ODrive motor controllers.
  • —Assembly guide with photos and part numbers for motors, bearings, and hardware.
  • —No PCB files — this is motors, controllers, and mechanical parts.
  • —BOM lists specific motors (5010 brushless outrunners) and ODrive S1 controllers, but those exact models may be hard to source or expensive.

Can I build this?

PrintFull frame, leg assemblies, and twelve cycloidal gearbox sets — multi-kilogram print job, plan for a week of printer time.
BuyTwelve 5010 brushless outrunners, ODrive S1 controllers (or equivalent), bearings, M3/M4 hardware, 24V power supply (10A+), Arduino.
ToolsFDM printer (Prusa/Ender size or larger), hex keys, soldering iron, bench PSU, basic motor tuning knowledge.
SkillsAdvanced — you need to wire and tune twelve motors, understand PID loops, and debug mechanical binding. Not a first robotics project.
TimeWeeks — printing is a week, assembly is another week, and tuning it to walk without self-destructing is open-ended.
Cost$$$ — motors and ODrive controllers alone are $600–800, bearings and hardware another $100–200, plus filament and power supply.
SafetyLithium battery if you go mobile (fire risk, charge outside the house). Powerful motors can pinch or crush fingers during testing. No mains voltage, but high-current DC (24V, 10A+) can arc and burn.

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

A desktop 3D printer that prints in full colorPartner · Kickstarter
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HeyGears G1: 10M+ colors and transparent parts in one print, plus UV printing on flat objects. Figures, parts and labels — no painting.

See how it prints

Videos

openDog Dog Robot #1 | Planning & Explanation | James Bruton

No official build video in the repo. Community walkthroughs exist but are not linked.

Gallery

https://opengraph.githubassets.com/ffa941d099b104d9c0cc9f61e985437d6ab043a3c712c7022e8bb0940b0d82f5/XRobots/openDogV3
https://img.youtube.com/vi/0BoPoWF_FwY/maxresdefault.jpg
https://img.youtube.com/vi/yXA_KeuYpCY/maxresdefault.jpg
https://img.youtube.com/vi/bp9HsysRu-M/maxresdefault.jpg

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 full assembly guide and BOM in the repo (Check motor and controller availability before printing — the exact models may be hard to source.)
  2. 2.Print one leg assembly as a test(Validate fit and gearbox tolerances before committing to the full frame.)
  3. 3.Order motors, ODrive controllers, and bearings(Budget $600–800 for electronics, and verify ODrive firmware compatibility.)
  4. 4.Print the frame and remaining parts(Full print job is multi-kilogram — plan for a week of continuous printing.)
  5. 5.Assemble and wire, then tune one leg at a time(Do not power all twelve motors until each leg has been tested individually.)

Resources

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

Meet Beni, Your First All-Terrain Camera Robot!Partner · Kickstarter
Meet Beni, Your First All-Terrain Camera Robot!
See how it works

KNOWN ISSUES

  • The ODrive S1 controllers cost $400–500 for a set of three, and older ODrive versions may not run the latest firmware — check compatibility before buying.
  • The 5010 motors listed in the BOM are not always in stock, and substituting a different motor means re-tuning the entire gearbox and control loop.
  • Cycloidal gearboxes are print-in-place and sensitive to tolerances — if your printer is not well-calibrated, they will bind or have excessive backlash.
  • Tuning twelve motors to walk without oscillating or binding takes days, not hours — budget time for PID tweaking and mechanical adjustment.
  • The power supply needs to handle 24V at 10A+ under load, and cheap PSUs will brownout or shut down when all motors spin up.
  • If you skip the leg-by-leg testing and power everything at once, a wiring mistake or short can destroy an ODrive board (they are $120 each).

Can I use cheaper motor controllers instead of ODrive?

You need closed-loop control with position feedback, which most cheap ESCs do not provide. ODrive is expensive but purpose-built for this. Alternatives like VESC or custom STM32 boards exist but require firmware porting.

How long does the full print take?

A week of continuous printing for the frame, legs, and gearboxes, assuming a single Prusa-sized printer. Faster if you have multiple printers or print overnight.

Will it walk on carpet or outdoors?

It walks on hard floors and low-pile carpet. Outdoors depends on terrain — loose gravel or mud will stall the motors, and the printed parts are not weatherproof.

What is the hardest part of the build?

Tuning the gait. The mechanical assembly is straightforward if you follow the guide, but getting twelve motors to coordinate without oscillating or binding is iterative and requires understanding PID loops.

Community builds

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

Discussion1

FROM THE COMPAREE TEAM

Twelve motors, twelve gearboxes, and a week of PID tuning before it walks — what would you use it for once it is running?

CompareeTEAM27d agoedited

Practical notes from our verification: the repo contains STLs, Fusion 360 source files, Arduino code, and a detailed assembly guide with photos. The BOM lists specific motors (5010 brushless) and ODrive S1 controllers, but availability varies and substitutions require re-tuning. The cycloidal gearboxes are the standout feature — they print in place and reduce backlash significantly, but they are sensitive to print tolerances. If your printer is not well-calibrated, they will bind. No official build video is linked in the repo, though James Bruton's YouTube channel has progress updates. The single biggest time sink is not assembly — it is tuning twelve motors to walk without oscillating, which is iterative and requires understanding PID loops. This is not a weekend project, and the electronics cost alone is $600–800 before filament, hardware, or power supply.

James Bruton

James Bruton is a maker and YouTuber known for building large-scale 3D-printed robots, including combat robots for Robot Wars. openDog started as an experiment in DIY quadruped locomotion and is now on its third iteration, with custom gearboxes and full inverse kinematics.

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