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TWO MIT STUDENTS BUILT A MACHINE THAT SOLVES A RUBIK'S CUBE IN 0.38 SECONDS

Six motors, two cameras, and a solve faster than you can blink — this held the world record.

by Ben Katz and Jared Di Carlo

FULL CAD BOM FIRMWARE DOCS

RoboticsOpen-hardware

difficulty
●●●●●
time
a month
license
MIT
repo
repo ACTIVE171 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

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1

COMPAREE VERDICT

This is the most thoroughly documented ultra-fast cube solver in the open-source world, and it is not close. Ben Katz and Jared Di Carlo published everything: the SolidWorks models for the aluminium frame and 3D-printed grippers, the custom motor driver schematics, the Beaglebone firmware, the PlayStation Eye camera setup, and the min2phase solving algorithm. The 0.38-second solve held the world record when it shipped in 2018. Newer closed-source machines have gone faster, but nothing else this fast has files you can actually build from. That said, this is a five-out-of-five difficulty for a reason. You are machining aluminium on a mill, winding custom three-phase motor drivers, synchronising two cameras at 300+ fps, and tuning a control loop that runs at 32 kHz. The motors alone cost over 400 dollars. If one timing parameter is wrong, the cube explodes. This is not a weekend project — it is a capstone. If you have access to a machine shop, experience with brushless motor control, and a month to spend, this is the build. If you do not, start with a slower solver and work up.

NOT IN THE REPO

  • —CAD for all mechanical parts (SolidWorks assemblies and STLs) is in the repo.
  • —Complete BOM with part numbers for the six brushless motors, two PlayStation Eye cameras, custom motor drivers, and machined aluminium structure.
  • —Firmware for the Beaglebone Black controller and min2phase solving algorithm included.
  • —Detailed build documentation across README, blog posts, and video — but no step-by-step assembly guide.
  • —Licence is MIT — fully open for commercial use.
  • —This is a 2018 record holder; newer machines have gone faster, but this remains the most documented open-source speed solver.

Can I build this?

Print3D-printed cube grippers and camera mounts (STLs provided)
BuySix brushless motors (~$70 each), two PlayStation Eye cameras, Beaglebone Black, custom PCBs for motor drivers, machined aluminium frame stock, power supply, and a Rubik's cube
ToolsCNC mill or machine shop access, 3D printer, soldering station, oscilloscope for motor tuning, and a Linux machine for cross-compiling the Beaglebone firmware
SkillsAdvanced — requires machining, PCB assembly, brushless motor control, real-time embedded programming, and computer vision setup. This is not a first robotics project.
TimeA month if you have all the tools and skills; longer if you are learning motor control or machining as you go
Cost$$$ — motors dominate at ~$420, then the Beaglebone, cameras, aluminium stock, and custom PCBs push the total past $700
SafetyBrushless motors spin cube faces at extreme speed — a mistimed move can shatter the cube and send pieces flying. Safety glasses required during tuning. The motor drivers handle significant current; standard electronics safety applies.

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

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Gallery

upload://cmrvt9p2h0ghnri1z0usto04a/upload-375a2a65.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 README and Ben Katz's blog post (The blog post (linked in the README) explains the control theory and motor tuning — read it before ordering parts.)
  2. 2.Check the BOM and source the motors(The six brushless motors are the single biggest cost and lead time — confirm availability before committing to the build.)
  3. 3.Machine or order the aluminium frame(SolidWorks files are provided — you will need CNC mill access or a machine shop to cut the frame.)
  4. 4.Build and test the motor drivers(Custom three-phase drivers — test each one individually before integrating into the full system.)

KNOWN ISSUES

  • The six brushless motors cost ~$70 each and have lead times — if you order the wrong model or they go out of stock, you are stuck. Verify part numbers in the BOM before buying.
  • The motor control loop runs at 32 kHz and requires careful tuning — if the timing is off, the cube will jam or explode. An oscilloscope is not optional.
  • The PlayStation Eye cameras must run at 300+ fps and be synchronised — the setup is not plug-and-play on Linux, and the repo assumes you know how to configure v4l2 drivers.
  • The aluminium frame requires CNC machining — if you do not have mill access, this becomes a custom fabrication job and the cost doubles.
  • The min2phase solving algorithm is CPU-intensive — the Beaglebone Black is specified, but if you substitute a slower board, the solve time will increase and the system may not keep up.
  • This is a 2018 design — some parts (especially the custom PCBs) reference suppliers that may have changed. Expect to adapt the electronics BOM.

Is 0.38 seconds still the world record?

No — newer closed-source machines have gone faster (sub-0.3 seconds), but this remains the fastest open-source solver with full documentation. The record moved, but the files did not.

Can I use different motors?

Possibly, but the control loop is tuned for the specific motors in the BOM (their torque, inertia, and back-EMF constants). Swapping motors means retuning the entire control system, which is non-trivial.

Do I need to machine the aluminium frame, or can I 3D print it?

Aluminium is specified for stiffness — the motors generate significant torque and a flexing frame will throw off the timing. 3D-printed ABS or PETG will likely flex too much for a sub-0.5-second solve.

What is the single most likely failure mode?

Motor timing. If the control loop is not perfectly tuned, one motor will lag, the cube will bind mid-turn, and the whole thing jams or breaks. This is where most of the month goes.

Community builds

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Discussion1

FROM THE COMPAREE TEAM

Six motors, two cameras, and a month in the shop — and the 0.38-second solve is still the fastest open-source one documented. Would you tune the control loop to go faster, or is this already past the point of diminishing returns?

CompareeTEAM1mo agoedited

Practical notes from our verification: This is the most complete fast-solver documentation we have seen, and it is not close. The SolidWorks assemblies, motor driver schematics, and Beaglebone firmware are all in the repo, and Ben Katz's blog post (linked in the README) walks through the control theory. The repo has not moved since 2018 and there is no official video — the 0.38s solve footage exists in news coverage, but not as a walkthrough. The single biggest surprise is the cost: the six motors alone are over $400, and that is before the Beaglebone, cameras, aluminium stock, and custom PCBs. If you do not have CNC mill access, add another few hundred for machine shop time. This is a capstone-level build, not a weekend one.

Ben Katz and Jared Di Carlo

Ben Katz and Jared Di Carlo built this solver as MIT students, combining Ben's motor control expertise and Jared's mechanical design skills. They held the world record for fastest Rubik's cube solve in 2018 and published the entire design — CAD, firmware, electronics, and control theory — as open source.

GitHub

Star the project on GitHub

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