Moss v1 parts list
Metal-bracket STS3215 leader and follower arms for LeRobot; still supported but deprecated in favor of SO-100/SO-101.
Robot armsbeginner by Jess Moss
Exploded view
Tap any part to see where to buy it. Diagram is schematic, not to scale.
Every part you need
| Part | Qty | Spec | Where to buy |
|---|---|---|---|
| Feetech STS3215 7.4V (C001, 1/345) leader and follower servos | 12 | 7.4V, 19.5 kg.cm; 6 per arm; official BOM lists $14/unit Same servo as SO-100, so Moss motors can be reused in an SO-100 later. | Seeed Studio: $20.00 OpenELAB: EUR 23.57 Akizuki Denshi: JPY 3,200.00 RobotShop: $34.32 Alibaba: check price (unverified) single; BOM link |
| Waveshare Bus Servo Adapter (A) servo bus controller | 2 | Official BOM lists $5/unit at Waveshare USB link and power entry for each arm's servo chain. | Waveshare: $4.99 Amazon: check price Akizuki Denshi: JPY 1,280.00 |
| STS3215 metal bracket set metal brackets | 20 | Official two-arm qty 20 from the Alibaba link; China list splits into 20 U brackets, 6 bottom and 6 side brackets; M3x4 screws come with the brackets Moss is a bracket-and-servo frame, not a fully printed arm. | Alibaba: check price (unverified) single; BOM link Taobao: check price (unverified) single; BOM link, U bracket |
| USB-C cable 2-pack USB cables | 1 | Data cable Board to computer. | Amazon: check price |
| 5V power supply servo power | 2 | 5V barrel supply; 12V 5A+ only if you buy 12V servos Powers each arm. | Amazon: check price Amazon: check price |
| Table clamp 4-pack mounting | 1 | Holds both bases down. | Amazon: check price |
| Low-strength threadlocker assembly | 1 | Loctite 222 class Stops M3 nuts backing out. | Amazon: check price |
| Screwdriver set with Phillips #000 to #1 tools | 1 | Small screws throughout. | Amazon: check price |
| 5.5 mm (or 7/32 in) wrench tools | 1 | Holds M3 nuts while tightening. | Amazon: check price |
Quantities follow the official Moss v1 docs: https://github.com/jess-moss/moss-robot-arms. "Unverified" prices come from search listings or older BOMs that we could not confirm on the seller's product page.
3D printed parts
Needed. Only two gripper files are printed (leader and follower), PLA, 13% infill. Files: https://github.com/jess-moss/moss-robot-arms/tree/main/so_100_gripper_parts
Mistakes builders make
- The authors now recommend SO-100/SO-101 for new builds; Moss motors can be reused in an SO-100.
- The Alibaba bracket listing went unavailable for a while; check stock before ordering servos.
- The M3x4 screws come with the brackets, so you do not need to buy them separately.
- A dot of low-strength threadlocker on every M3 screw into a nut keeps the arm from loosening.
FAQ
How much does it cost to build the Moss v1?
About $288 to $360 in parts at current prices, Two arms per the official BOM total ($288); high end uses US retail servos. Only the grippers are printed. Excludes computer, cameras, shipping..
Do I need a 3D printer for the Moss v1?
Yes. Only two gripper files are printed (leader and follower), PLA, 13% infill.
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Last checked 2026-10-25. Sources: github.com · github.com · github.com · www.seeedstudio.com · www.waveshare.com