101 build sheet Star on GitHub

Open-source robot arm · LeRobot ready

Build your own SO‑101.

Everything you need to buy, print and assemble on one page. Pick your country and each part links to a local supplier first, then to stores that ship worldwide.

12STS3215 servos
for two arms
6DOF per arm
incl. gripper
~$245parts for both arms,
before printing
See the parts list → Download STLs
SO-101 follower arm: a white 3D-printed 6-axis arm with a gripper
Follower does the work
SO-101 leader arm with a handle and trigger for teleoperation
Leader you move it by hand
What are you building?
Reference cost
$0official US BOM, excl. printing
01

Bill of materials

Quantities change with your build. Tick off items as you order them; your list is saved in this browser. Local or regional store Ships worldwide Search results (commodity part)

Before you buy servos

  • Follower arm: six C018 servos (12 V, 30 kg·cm) powered by a 12 V supply.
  • Leader arm: one C001, two C044 and three C046 (all 7.4 V) powered by a 5 V supply. See the motor map.
  • All STS3215 servos look the same, so check the code on the listing or the label before you pay. Never connect the 12 V supply to the leader.
  • Each servo ships with its horn and M2×6 / M3×6 screws, so you don't need to buy screws separately.
Optional upgrades and bundles
02

Motor map

The follower uses the 12 V C018 on every joint. The leader mixes three 7.4 V gear ratios so it holds its own weight but stays light to move by hand. If you mix these up, the leader will feel stiff or sag.

Diagram of the SO-101 arm with joints numbered 1 to 6 from base to gripper 1 2 3 4 5 6
#JointLeaderFollower
03

Or skip the sourcing: buy a kit

Kits for your region are listed first, followed by sellers that ship worldwide. Listed in the official repo marks sellers named in TheRobotStudio's README.

04

3D-printed parts

Official STL files from TheRobotStudio/SO-ARM100 (Apache-2.0), mirrored here unchanged. Click any part to view it in 3D.

Print settings

Material
PLA+
Nozzle / layer
0.4 mm @ 0.2 mm
or 0.6 mm @ 0.4 mm
Infill
15%
Supports
Everywhere, but skip slopes steeper than 45°. No supports in horizontal screw holes.
Bed
Clean and level, plus a thin layer of glue stick if your printer recommends it

Print a gauge first. Check the fit against an STS3215 servo or a 4×2 LEGO brick before you commit to printing the full plates.

Full plates all parts for one arm, pre-oriented

↓ Full assembly reference model (38 MB) A model of the complete arm for reference only. Don't print it.

Individual parts Download all (.zip)

    Base_SO101.stl Download

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    No printer? Order printed parts

    05

    Assemble & bring it to life

    Once the parts arrive, the official guides take it from here.

    1. Set up the motors

      Install LeRobot with the Feetech SDK (pip install -e ".[feetech]"), then run lerobot-setup-motors. It gives each servo its ID one at a time, so do this before assembly.

    2. Assemble joint by joint

      Each joint has a short video. Use M2×6 screws for motors and M3×6 screws for horns and frames.

    3. Calibrate both arms

      Run lerobot-calibrate so the leader and follower report matching positions.

    4. Teleoperate, record and train

      Move the leader and the follower copies it. Record demonstrations and train a policy.

    Assembly guideHugging Face · LeRobot docs Hardware repoTheRobotStudio / SO-ARM100 LeRobothuggingface / lerobot CommunityLeRobot Discord