SO-101 robot arm · build guide

Build the SO-101, one checked step at a time.

A build companion for the SO-101 open-source robot arm. Every step says which parts, which servo and gear ratio, which screws and tool, how the cable runs, and what to check before moving on. Every fact links to its public source. What no source confirms is flagged, never invented.

Start the follower arm → Build the leader arm 26 steps each · 3D view per step

Before you start

Print settings

From the upstream README.

SO-100 or SO-101?

Tell them apart if you are not sure which arm you have.

Reference

Servos by joint

IDs, gear ratios, voltages and supply per joint

Bill of materials

26 parts with upstream file, licence and vendor names

Troubleshooting

3 assembly issues, searchable by error string

Kits and vendor part numbers

10 vendors, cross-referenced to upstream part names

Data compiled 2026-09-08 from SO-ARM100 and LeRobot at pinned commits; build 84d9343.