Auto-assembled, not yet reviewed

Moss v1 Robot Arms

Affordable 6-DoF leader/follower teleoperation arms, superseded by SO-100.

Deprecated. Upstream points builders at a newer design.

Successor: SO-ARM100 / SO-ARM101 (Standard Open Arm) (source)Lifecycle source

Reproducibility57/100Early source coverage, unverifiedCADBOMWIREFWBUILDLICREPHow it is computed
Moss v1 Robot Arms source parts laid out side by side, 3D render from Print_Follower_SO_ARM100_08k_Gripper.STL (not the assembled robot)
Parts preview: not the assembled robot · Print_Follower_SO_ARM100_08k_Gripper.STL

About Moss v1 Robot Arms

Moss v1 is an affordable, easy-to-assemble robot arm design for teleoperation. Built around Feetech STS3215 bus servos in a 6-DoF leader and follower configuration, it predates and has largely been superseded by the SO-100 arm, and LeRobot removed Moss support in June 2025 (PR #777); the README says Moss v1 will be deprecated. The only 3D files in the repository are SO-100 gripper parts, so no full Moss arm model is shown.

Licenses

Hardware
Apache-2.0
Software
Not published
Docs
Not published

Degrees of freedom

6 DoF arm 5gripper 1

Breakdown source

Serial armLeader-follower pairsource

How to build Moss v1 Robot Arms

5 steps

Steps marked Motari summary condense the linked source; follow the source for exact instructions. Upstream step marks a step taken from the linked guide.

  1. Print the gripper parts

    Print the two gripper STLs in so_100_gripper_parts in PLA at 13% infill with supports. The rest of the arm uses metal STS3215 brackets.

    Motari summarygithub.com/jess-moss/moss-robot-arms

  2. ID the servos

    Assign each Feetech STS3215 bus servo a unique ID using the Waveshare adapter board.

    Motari summarygithub.com/jess-moss/moss-robot-arms

  3. Assemble the arms

    Follow the assembly video tutorial to build the leader and follower arms.

    Upstream stepgithub.com/jess-moss/moss-robot-arms/blob/da15b56f01e94e62ca...

  4. Wire power and data

    Power each arm from its 5 V supply (12 V if you bought the 12 V STS3215 servos) and connect each arm to the computer with a USB-C cable.

    Motari summarygithub.com/jess-moss/moss-robot-arms

  5. Calibrate and teleoperate

    Configure with LeRobot, then drive the follower from the leader arm.

    Motari summarygithub.com/jess-moss/moss-robot-arms
Print timenot published
Assembly time2 h

Wiring, power and firmware are safety-relevant and shown for reference only. Check them against the source before building.

Moss v1 Robot Arms bill of materials

12 rows

Cost to build

$288USDsource total
  • two-arm leader and follower set, README US prices, excludes printing$288source total
  • one arm, README US prices$159source total

In the source currency, as read on 2026-09-30. Not converted, and not checked against current vendor prices: none of these is a Motari-verified checkout total.

Moss v1 Robot Arms parts, as the source lists them. Prices are the source's, not checked against vendors.

Moss v1 Robot Arms bill of materials
PartQtySpecSourceConfidence
STS3215 ServoREADME single-arm BOM line 44
6Feetech STS3215 serial bus servo
Alibaba / Taobao$14 (US price)README.md line 44 at commit da15b56; source table also lists EU/CN alternatives where available
high
Motor Control BoardREADME single-arm BOM line 45
1Waveshare Bus Servo Adapter A / compatible board
Waveshare / Amazon / Taobao$5 (US price)README.md line 45 at commit da15b56; source table also lists EU/CN alternatives where available
high
Bracket SetREADME single-arm BOM line 46
10STS3215 metal bracket set
Alibaba / Taobao$3 (US price)README.md line 46 at commit da15b56; source table also lists EU/CN alternatives where available
high
U BracketREADME single-arm BOM line 47
10STS3215 U bracket
Taobao/TmallUS price not listedREADME.md line 47 at commit da15b56; source table also lists EU/CN alternatives where available
med
Bottom BracketREADME single-arm BOM line 48
3STS3215 bottom bracket
Taobao/TmallUS price not listedREADME.md line 48 at commit da15b56; source table also lists EU/CN alternatives where available
med
Side BracketREADME single-arm BOM line 49
3STS3215 side bracket
Taobao/TmallUS price not listedREADME.md line 49 at commit da15b56; source table also lists EU/CN alternatives where available
med
USB-C Cable 2 pcsREADME single-arm BOM line 50
1USB-C cable, source table lists two pieces
Amazon / Taobao$7 (US price)README.md line 50 at commit da15b56; source table also lists EU/CN alternatives where available
high
Power SupplyREADME single-arm BOM line 51
15 V barrel-jack power supply per source footnote
Amazon / Taobao$10 (US price)README.md line 51 at commit da15b56; source table also lists EU/CN alternatives where available
high
Table Clamp 2pcsREADME single-arm BOM line 52
1two-piece table clamp set
Amazon / Taobao$5 (US price)README.md line 52 at commit da15b56; source table also lists EU/CN alternatives where available
high
Lowstrength ThreadlockerREADME single-arm BOM line 53
1low-strength threadlocker
Amazon / Taobao$9 (US price)README.md line 53 at commit da15b56; source table also lists EU/CN alternatives where available
high
Screwdriver Set (includes Phillips #000, #00, #0, #1)README single-arm BOM line 54
1precision Phillips set #000/#00/#0/#1
Amazon / Taobao$6 (US price)README.md line 54 at commit da15b56; source table also lists EU/CN alternatives where available
high
WrenchREADME single-arm BOM line 55
15.5 mm wrench
Amazon / Taobao$5 (US price)README.md line 55 at commit da15b56; source table also lists EU/CN alternatives where available
high

Rows from the source's own parts list 24

README.md@da15b56markdown

Source rowQtyPrice and vendorLine
STS3215 Servo
12
AlibabaTaoBao$14
L26
Motor Control Board
2
WaveshareAmazon$5
L27
Bracket Set
20
Alibabaalibaba.com$3
L28
U Bracket
20
TaoBaoitem.taobao.com---
L29
Bottom Bracket
6
TaoBaoitem.taobao.com---
L30
Side Bracket
6
TaoBaoitem.taobao.com---
L31
USB-C Cable 2 pcs
1
AmazonTaoBao$7
L32
Power Supply
2
AmazonTaoBao$10
L33

16 more rows in README.md

Moss v1 Robot Arms source files

3 files

Files stay in the upstream repository under their own licenses; these links open them there. The 3D model on this page is Motari's conversion of the file named under Simulation.

Moss v1 Robot Arms in simulation

Robot description files a simulator or CAD tool can load, linked at the commit they were found.

No URDF, MJCF, SDF, USD or Onshape model has been found in the sources.

The 3D specimen on this page is converted from so_100_gripper_parts/Print_Follower_SO_ARM100_08k_Gripper.STL at da15b56, with the parts laid out side by side because the source has no assembly.

Builds of Moss v1 Robot Arms

0 reviewed

No reviewed builds of Moss v1 Robot Arms yet.

A build log records the evidence (photos, a video, your repository), what the build cost, how long it took and what you changed. Each one is checked by Motari (until a maintainer claims this page) before it shows here, and reviewed builds count toward the reproducibility score.

Sources and provenance

Sources

Last push to jess-moss/moss-robot-arms: 2025-02-12 (checked 2026-10-01)

Related links

How this page was made

Assembled from public sources on 2026-06-04, not yet reviewed by the maintainer. Each figure links to where it is stated; a value the sources do not state reads "not published". Last source review: source README BOM da15b56f.

Original files stay intact and separately licensed; Motari adds only the summary on this page. Maintainer? Request a correction or removal.

Badge for the README

Maintain Moss v1 Robot Arms? Show its reproducibility score in the project's README. The badge links back to this page and updates with the score.

Badge: reproducibility 57/100

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Not fully met yet: cad / mesh present (partial), wiring diagram, build instructions (partial). The score is read from the project's own sources, so publishing what is missing is what raises it. A score of 90 or more needs a reviewed build. How the score is computed