Koch arm
Based on published sources · Not tested by us ·
Overview
A printable Dynamixel arm with a separate leader design for teleoperation and robot-learning experiments. [S001]
Koch's low-cost arm pairs a printed frame with Dynamixel servos. A second, manually moved leader can control the follower through the repository's teleoperation script. The build combines printing, soldering and individual motor configuration; it is a useful candidate for someone who wants to understand that hardware path into robot learning. [S001]
Specifications
| Detail | Description |
|---|---|
| Type | Desktop robot arm Reported by source [S001] · Checked 2026-09-30 |
| Intended users | Makers comfortable with soldering and servo configuration; Robot-learning researchers Reported by source [S001] · Checked 2026-09-30 |
| Assembly | Print the selected arm variant, configure motors individually, assemble at documented servo positions, wire the driver and adjust the follower voltage reducer. Reported by source [S001] · Checked 2026-09-30 |
| Calibration | Set motor baud rate to 1M and IDs according to selected geometry; install horns at the documented default position. Quantified repeatability is not established. Reported by source [S001] · Checked 2026-09-30 |
| Operating system | Not known |
| Computer needed | Not known |
Assembly and use
Use the detailed tables as the starting point
The README opens with approximate prices of $250 for the follower and $180 for the leader, but its detailed tables list $258 and $183. Those tables imply $441 for the pair before omitted costs. They are upstream US-linked parts estimates checked September 30, 2026, not fresh supplier quotes; current stock, shipping and taxes remain unverified. Printed parts, the host computer, tools, USB-C connections and labor need a separate allowance. A camera or training setup would add another task-specific budget. [S001]
The guide also distinguishes shorter and elbow-to-wrist-extension geometries. That changes the required idler count. Select the geometry and reconcile its files against the parts list before ordering; the headline price does not identify a fully specified build. [S001] [S004]
The follower requires two voltage levels
The listed follower uses two XL430 and four XL330 servos. Its 12V supply feeds a reducer that the guide instructs the builder to adjust to 5V for the XL330 chain. The leader uses six XL330 servos and a 5V supply. Both routes require motor IDs and baud rates to be configured individually. Follow the upstream wiring and assembly instructions for the chosen geometry. [S001]
The guide describes Linux and macOS connections as expected to work, but supplies no validated host requirements matrix. We have not run the control scripts, verified the wiring or measured motion. [S001]
What the local source copy contains
The reviewed commit includes follower and leader STL, STEP and Fusion files, plus Python control and simulation code. Its root license is MIT. That repository license does not establish the design or firmware terms of the separately purchased Dynamixel servos or driver board. [S002] [S004]
No published stable release was found in the checked release listing, so this review pins commit 0602b0c1e6a67d8f6ab96f81d1378639018d98af as a source snapshot. A snapshot makes the reviewed files identifiable; it does not establish a tested build configuration. [S003]
Before selecting this arm for a supported build, we still need a reconciled variant-specific shopping list, current sourcing, a repeatable calibration and motion test, and measured troubleshooting effort. This is a researched candidate; we have not established our ability to build or support it.
Cost
These are the project's published parts estimates, not current shop prices. They do not cover a complete build.
Both prices were checked 2026-09-30. The following applies to both versions.
| Included | Listed servos, driver board, power supply, clamp and listed accessory packs |
|---|---|
| Not included | 3D printed parts/material; Host computer; Tools; USB-C cable; Assembly work; Camera or learning compute |
| Stock | Supplier stock not checked. |
| Delivery and tax | Not established; no landed total. |
Price details
Historical upstream table; not a fresh supplier quote. Discounts are not assumed.
US-linked upstream supplier examples; destination not established · Checked 2026-09-30 · Quantity 1
Printed parts, host, USB-C connection and assembly tools; exact geometry must be selected.
Source files and licenses
Printable CAD and control code are available; this does not establish open designs or firmware for purchased servos and electronics.
| Layer | Availability / license |
|---|---|
| mechanical design | available · MIT Repository root license; external linked material and purchased components require separate checks. [S002] [S004] |
| electronics | not found · License not fully assessed Reviewed arm repository and build guide specify purchased servo/driver components; complete component designs/firmware were not established within that scope. [S001] [S004] |
| firmware | not found · License not fully assessed Reviewed arm repository and build guide specify purchased servo/driver components; complete component designs/firmware were not established within that scope. [S001] [S004] |
| software | available · MIT Repository root license; external linked material and purchased components require separate checks. [S002] [S004] |
| documentation | available · MIT Repository root license; external linked material and purchased components require separate checks. [S001] [S002] |
No specific model or dataset is included in this physical arm configuration.
References
Links identify the documentation and revisions used in this profile. Access dates record when each source was retrieved.
- S001 · Alexander Koch / low_cost_robot contributors
Koch arm build guide and BOM
Accessed 2026-09-30 · README.mdSource notes
BOM tables list $258 follower and $183 leader; opening approximations are $250 and $180. Lists actuators, printing, assembly, voltage setup and example scripts.
- S002 · Alexander Koch / low_cost_robot contributors
Repository MIT license
Accessed 2026-09-30 · LICENSESource notes
MIT repository root license; purchased electronics and external artifacts are not assigned this license.
- S003 · Alexander Koch / low_cost_robot contributors
Repository snapshot
Accessed 2026-09-30 · 0602b0c1e6a67d8f6ab96f81d1378639018d98afSource notes
Pinned default-branch commit; release API returned no published stable release. Repository metadata is not independent adoption evidence.
- S004 · Alexander Koch / low_cost_robot contributors
Mechanical and control source inventory
Accessed 2026-09-30 · hardware/, dynamixel.py and simulation.pySource notes
Follower and leader directories contain STL, STEP and Fusion assemblies; source tree contains Python control and simulation files.
Correction guidance · Discussion is not enabled · Profile format 0.5.0-draft.1
Change history
September 29, 2026 — First research profile published.