How to build SO-ARM100 / SO-ARM101 (Standard Open Arm)
6-DoF desktop robot arm · Beginner
The SO-100 Standard Open Arm: the original Robot Studio and Hugging Face design that made LeRobot arms cheap, how it differs from the SO-101, and how to build one.
Mostly printed parts and plug-in servos. Good first build.
Our estimate, part-time
Project's own total, source currency
Apache-2.0
What is SO-ARM100 / SO-ARM101 (Standard Open Arm)?
The SO-ARM100, usually just called SO-100, is the original Standard Open Arm from The Robot Studio and Hugging Face. It brought a leader-follower arm pair down to roughly the cost of its twelve Feetech servos.
It's now superseded by the SO-101, and its docs are marked deprecated, but LeRobot still supports it. The main differences: building the leader meant opening its servos and removing gears, and the wiring was more exposed at the joints.
Versions and forks
- SO-101
- Moss v1
- PingTi
SO-ARM100 / SO-ARM101 (Standard Open Arm) specifications
- DoF
- 6
- Servos
- Feetech STS3215
- Leader prep
- Gears removed
- Status
- Deprecated for SO-101
Figures as published by the project. See Sources below.
Bill of materials
| Part | Qty | Notes |
|---|---|---|
| STS3215 | 12 (pair) | |
| Adapter board | 2 | |
| Power supplies | 2 | |
| Clamps and printed parts | — |
Where's the full bill of materials?
The full BOM, with exact quantities and vendors, lives in the project's own files. Prices change often, so treat $123 as a ballpark from the project. Start at the project repository.
Tools you'll need
- 3D printer
- Small screwdrivers
- Tweezers
Step-by-step build overview
Electronics & wiring overview
Each arm has one servo chain to its adapter board and supply.
Software
LeRobot.
Tips from the bench
- ☕ Reprint the parts to upgrade to the SO-101, keeping most of the motors.
SO-ARM100 / SO-ARM101 (Standard Open Arm) FAQ
Is the SO-100 still supported?
LeRobot still supports it, but new builders are pointed to the SO-101.
Why remove the leader's gears?
So its joints move freely by hand.
Sources
Written by Bots n' Beans from the project's own documentation. Check the sources for the latest revision before you buy parts.
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