SO-ARM101 Standard Open Arm

SO-ARM101 — Standard Open Arm

A 6-DOF open-source teleoperation arm system designed by The Robot Studio in collaboration with Hugging Face. SO-101 is the next-gen version of the SO-100 with improved wiring, easier assembly, and updated motors.

Built to work seamlessly with the LeRobot library for end-to-end AI robotics research.

What makes it interesting

• Leader + Follower teleoperation pair — move the leader arm, the follower mimics in real time
• LeRobot-native — record demonstrations, train imitation-learning policies, deploy to the arm
• Low cost — $110 per arm ($220 for a leader+follower pair) in printed parts + motors
• Active community — dozens of vendors selling kits worldwide

Specs

Build options

Two paths:

1. Buy a kit — dozens of vendors listed in the README (PartaBot US, Seeed Studio, WowRobo, etc.)
2. Source & print yourself — follow the 3DPRINT.md guide and the Hugging Face Assembly Guide

STL files

This program includes 12 representative SO-101 individual parts (base, motor holders, arm links, wrist roll/pitch, gripper jaw, handle). For the full SO-101 printable set plus the SO-100 legacy parts, Optional accessories (cam mounts, bases, grippers), and Mini variant, browse the STL directory on GitHub.

Note on catalog duplicates

This page covers the standalone SO-ARM101 arm hardware. See also SO-101 Teleop Arm for the paired leader+follower teleop setup framing.

Resources

• SO-101 Assembly Guide (HuggingFace)
• LeRobot library
• Discord community
• Printing guide (3DPRINT.md)
• The Robot Studio

Attribution

Source: TheRobotStudio/SO-ARM100 · License: Apache 2.0 · The Robot Studio / Hugging Face contributors

Build Guide

Official SO-101 / SO-ARM100 assembly guide: huggingface.co/docs/lerobot/so101

Printing

This Print All set is the 12-part SO-101 build. A full SO-101 system is a leader + follower pair, so most structural parts print x2 (one per arm). A few parts are arm-specific:

Leader vs follower (not alternates — print both): the leader arm is the one you move by hand, so it gets the Handle + Wrist_Roll. The follower arm mimics it and does the gripping, so it gets the Moving_Jaw + Wrist_Roll_Follower. A complete teleop pair needs all 12 files.

Single-arm build: if you only want one follower arm (no teleop), print one copy of the 8 shared structural parts plus the follower-specific Wrist_Roll_Follower + Moving_Jaw, and skip the leader Handle + Wrist_Roll.

Servos: 12 Feetech STS3215 total (6 per arm) — mixed gear ratios per the BOM (7× 1/345, 2× 1/191, 3× 1/147). The full upstream TheRobotStudio/SO-ARM100 STL directory also has SO-100 legacy parts, optional camera mounts/bases, and the Mini variant — not included here to keep the Print All set to the standard arm.