SO-ARM101 Standard Open Arm
B✓ Confirmed fresh May 12, 2026
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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 — ~$100 per arm in printed parts + motors
- Active community — dozens of vendors selling kits worldwide
Specs
| Degrees of Freedom | 6 per arm (leader + follower = 12 total) |
| Motors | Feetech STS3215 servos |
| Reach | ~420mm |
| License | Apache 2.0 (code + hardware) |
| Ecosystem | Hugging Face LeRobot |
Build options
Two paths:
- Buy a kit — dozens of vendors listed in the README (PartaBot US, Seeed Studio, WowRobo, etc.)
- 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.
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
🖨 Print Files (12)
Base_SO101.stl
Base_motor_holder_SO101.stl
Motor_holder_SO101_Base.stl
Motor_holder_SO101_Wrist.stl
Under_arm_SO101.stl
Upper_arm_SO101.stl
Required Hardware
| Item | Qty | Unit Cost | Notes |
|---|---|---|---|
| Feetech STS3215 servo, 7.4V, 1/345 gear (C001) | 7 | $13.89 | Most joints |
| Feetech STS3215 servo, 7.4V, 1/191 gear (C044) | 2 | $13.89 | Specific joint ratio |
| Feetech STS3215 servo, 7.4V, 1/147 gear (C046) | 3 | $13.89 | Specific joint ratio |
| Waveshare Bus Servo Adapter / Motor Control Board | 2 | $10.60 | One per arm |
| 5V power supply (DC barrel) | 2 | $10.00 | One per arm |
| USB-C cable (2-pack) | 1 | $7.00 | Host to control board |
| Table clamp set (4 pcs) | 1 | $9.00 | Mount arms to desk |
| Precision screwdriver set | 1 | $6.00 | Assembly |
| Servo daisy-chain cable assortment | 1 set | $8.00 | STS3215 inter-servo wiring (inferred) |
| M2 / M3 socket-head screw + nut kit | 1 set | $12.00 | Frame fasteners (inferred) |