Stringman
Based on published sources · Not tested by us ·
License: Apache-2.0, CC-BY-SA-4.0 · no license identified for electronics · Details by part
Overview
Room-scale four-line cable robot (Arpeggio hardware) with two corner anchors and a hanging camera gripper, driven by a host-run Python motion controller; a public prototype. [S005] [S010]
Stringman, from Nathaniel Nifong's Neufangled Robotics, is a cable-driven robot that hangs from the corners of a room. In the current "Arpeggio" hardware, two anchors in opposite corners each reel two lines, ceramic eyelets sit in the other two corners, and a gripper hangs from the four lines. Cameras on the anchors and gripper watch printed markers so a host program can estimate positions. The documentation calls it a public prototype that is "not yet reliable enough" for a home appliance. Nothing was built, installed or run for this entry. [S001] [S004] [S005] [S010]
Specifications
| Detail | Description |
|---|---|
| Type | Cable-driven parallel robot: two corner anchors with motorized spools, two eyelets, and a gripper hanging from four lines. Reported by source [S005] · Checked 2026-10-05 |
| Intended users | Builders with a suitable rectangular room, a capable host computer and experience assembling 3D-printed mechanisms and Raspberry Pi systems Editorial assessment [S005] [S010] · Checked 2026-10-05 |
| Assembly | Separate Arpeggio anchor and gripper build guides; kit assembly about 4 to 8 hours. Reported by source [S010] · Checked 2026-10-05 |
| Calibration | Full calibration from the maintenance menu locates anchors and eyelets in each new room. Reported by source [S001] · Checked 2026-10-05 |
| Operating system | Linux; macOS; Windows Reported by source [S001] · Checked 2026-10-05 |
| Computer needed | At least 8 cores and 8 GB RAM; PyTorch acceleration needed for local inference Reported by source [S001] · Checked 2026-10-05 |
3D preview
Preview not available yet. Design-source links are available. A configuration-matched assembly and its file-level reuse scope have not yet been reviewed for a hosted preview.
Model sources
Design-source links are available. A configuration-matched assembly and its file-level reuse scope have not yet been reviewed for a hosted preview.
Assembly and use
Who it suits
It suits people with a roughly rectangular room, a wall stud in each anchor corner, outlets near two opposite corners, an ordinary shared Wi-Fi network and a capable host computer. The kit page calls the build multi-day and "fairly difficult", estimating 4 to 8 hours of assembly; the Arpeggio print guide estimates about 80 hours of printing. [S005] [S010] [S011]
Configuration and requirements
The Arpeggio BOM lists four Damiao DM-H6215 hub motors, two Raspberry Pi 3A+ boards with Camera Module 3, custom anchor HATs, a slip ring, braided fishing line and FEP power cable for the anchors. The gripper uses a Raspberry Pi Zero 2W, a wide camera, two STS3215 servos, a laser rangefinder and a force-sensing resistor. The system-architecture page instead says all three components run on a Pi Zero 2W, so the anchor board needs confirming. The kit page claims a 2 kg payload anywhere in a room up to 7 m from ceiling corner to opposite floor corner. [S007] [S008] [S010] [S012]
The motion controller, stringman-headless, runs on a host computer from the nf_robot Python package (version 7.0.2 at this commit, Python 3.12 or newer), and the README notes PyTorch and CUDA dependencies of about 5.5 GB. It asks for at least 8 cores and 8 GB of RAM, plus acceleration for local AI inference. A web UI runs locally, and binding the robot to a neufangled.com account for remote relay is optional. LeRobot policies connect through a telemetry websocket. [S001] [S004]
Cost scope
The Arpeggio BOM sheet totals US$673.69: US$187.69 for the gripper and US$486.01 for the anchors. Its unit prices are derived from the maintainer's batch purchases, so it is not a one-off delivered quote; printed parts, shipping and tax do not appear in the sheet. The store lists the hardware kit at US$655 and the assembled robot at US$965. The kit page showed "Sold out" at retrieval, and the kit excludes printed parts other than a PCTG gear; the assembled robot's stock state was not established. Neither price includes the host computer. These are dated figures, not re-quoted. [S007] [S008] [S009] [S010]
Sources and licenses
The cranebot3-firmware repository holds the code for both the host and the robot components under an Apache-2.0 LICENSE. Hardware design files live elsewhere: Onshape CAD, STL archives and a Google Sheets BOM linked from the documentation, and KiCad projects in a separate stringman-pcbs repository. The Onshape documents and STL archives were not preserved. The downloads page releases the CAD, STLs, print guide and BOM under CERN-OHL-W 2.0, with a user-responsibility addendum, while the documentation home page says the design is published under Apache 2.0, a conflict to resolve with the maintainer. No license file was identified in stringman-pcbs. The documentation is stated to be CC BY-SA 4.0. [S001] [S003] [S005] [S006] [S013]
The software repository has no published release; this entry covers commit 8e72ee4 of October 5, 2026, which had 103 GitHub stars at retrieval, a dated popularity signal only. The documentation itself warns that the gripper sometimes crashes into things when moving fast, that "some of them have broken during operation" and that AI policies can act unpredictably, and it tells users to keep the kill switch at hand. Payload and calibration robustness remain unverified. [S002] [S005]
Cost
| Version | Price |
|---|---|
| Stringman Arpeggio, one system (gripper + two anchors), BOM sheet | USD 673.69 [S007] [S008] Parts estimate |
Upstream USD (US suppliers) · Checked 2026-10-05
| Included | Motors, servos, Raspberry Pis, cameras, sensors; Custom PCBs and wiring harnesses; Line, power cable, slip ring, bearings, fasteners; Two power supplies |
|---|---|
| Not included | Printed parts and filament; Host computer; Shipping, taxes and assembly labor |
| Stock | Supplier stock not rechecked. |
| Delivery and tax | Not established. |
Price details
BOM sheet grand total (gripper US$187.69 + anchors US$486.01) from per-unit prices at the maintainer's batch sizes; printed parts not listed; not re-quoted.
Upstream USD (US suppliers) · Checked 2026-10-05 · Quantity 1
Printed parts and a host computer.
US store; ships to listed countries · Checked 2026-10-05
| Included | Pis, cameras, motors, wires, screws and PCBs from the BOM; PCTG finger drive gear |
|---|---|
| Not included | Other printed parts; Host computer |
| Stock | Sold out at retrieval. |
| Delivery and tax | Shipping shown at checkout; Canada tariff noted on kit page. |
Price details
Store list price; page showed Sold out at retrieval. Kit page says price is based on about US$630 landed parts cost plus margin.
US store; ships to listed countries · Checked 2026-10-05 · Quantity 1
Print STLs; host computer.
| Version | Price |
|---|---|
| Stringman, fully assembled | USD 965.00 [S009] Vendor price |
US store · Checked 2026-10-05
| Included | Assembled system ready for installation and calibration |
|---|---|
| Not included | Host computer; Shipping and taxes |
| Stock | Not established. |
| Delivery and tax | Not established. |
Price details
Store list price for the fully assembled system; stock state not established from the static page.
US store · Checked 2026-10-05 · Quantity 1
Host computer; wall mounting.
Source files and licenses
Software, PCB projects and documentation are available; mechanical CAD is external and unpreserved, and hardware licensing statements conflict.
| Layer | Availability / license |
|---|---|
| mechanical design | available · License not fully assessed Onshape CAD and STL archives linked from the downloads page; not preserved or inspected. License statements conflict: downloads page says CERN-OHL-W 2.0 with a liability addendum; documentation home says Apache 2.0. License left unset pending clarification. [S005] [S006] |
| electronics | available · No license identified KiCad anchor and gripper HAT projects and Gerbers in stringman-pcbs; no license file identified in that repository, and the downloads-page license names CAD, STLs, print guide and BOM but not PCBs. [S006] [S013] |
| firmware | available · Apache-2.0 Component-side code (Raspberry Pi services) is in the same nf_robot repository; motor and servo firmware are vendor-supplied. [S001] [S003] |
| software | available · Apache-2.0 Host motion controller and UI; PyTorch and model downloads carry their own terms. [S001] [S003] [S004] |
| model weights | not found · License not fully assessed README says production targeting and grasping models are downloaded from Hugging Face; their location and license were not inspected. [S001] |
| documentation | available · CC-BY-SA-4.0 Documentation site states CC BY-SA 4.0. [S005] |
No dataset is distributed in the inspected sources.
References
Links identify the documentation and revisions used in this profile. Access dates record when each source was retrieved.
- S001 · Nathaniel Nifong / Neufangled Robotics
cranebot3-firmware README (nf_robot)
Accessed 2026-10-05 · README.md at 8e72ee45f2397117ba6611a676d75a9bf73513a2Source notes
Controller installation, headless motion controller, optional cloud binding, minimum system specs, telemetry, LeRobot policy connection, component images.
- S002 · Nathaniel Nifong / Neufangled Robotics
Repository revision and acquisition metadata
Accessed 2026-10-05 · 8e72ee45f2397117ba6611a676d75a9bf73513a2; commit date 2026-10-05T13:35:46Z; manifest retrieved 2026-10-05Source notes
No published release; default-branch commit snapshot archived; dated repository popularity.
- S003 · Nathaniel Nifong / Neufangled Robotics
cranebot3-firmware license
Accessed 2026-10-05 · LICENSE (Apache License 2.0 text)Source notes
Software repository license file.
- S004 · Nathaniel Nifong / Neufangled Robotics
nf_robot package metadata
Accessed 2026-10-05 · pyproject.toml at 8e72ee45f2397117ba6611a676d75a9bf73513a2Source notes
Package name, version 7.0.2, author, Python requirement, dependencies.
- S005 · Nathaniel Nifong / Neufangled Robotics
Stringman documentation home
Accessed 2026-10-05 · Page snapshot sha256 94a24898a384… retrieved 2026-10-05Source notes
Room requirements, architecture summary, prototype status, safety and license statements.
- S006 · Nathaniel Nifong / Neufangled Robotics
Stringman downloads page
Accessed 2026-10-05 · Page snapshot sha256 60726ff019ac… retrieved 2026-10-05Source notes
Links to software, Arpeggio and Pilot STLs, Onshape CAD, BOM sheets, KiCad PCBs; hardware license statement.
- S007 · Nathaniel Nifong / Neufangled Robotics
Stringman Arpeggio BOM — gripper sheet
Accessed 2026-10-05 · CSV export of the Gripper tab (gid 204754068); snapshot sha256 48f84ee1ea57…Source notes
Gripper parts, batch and unit prices, gripper subtotal.
- S008 · Nathaniel Nifong / Neufangled Robotics
Stringman Arpeggio BOM — anchors sheet
Accessed 2026-10-05 · CSV export of the "2 Anchors" tab (gid 1686100532); snapshot sha256 746062ef0fdc…Source notes
Anchor parts, anchor total and grand total.
- S009 · Nathaniel Nifong / Neufangled Robotics
Neufangled Robotics store
Accessed 2026-10-05 · Page snapshot sha256 fa1a853923d3… retrieved 2026-10-05Source notes
Assembled robot and hardware kit list prices.
- S010 · Nathaniel Nifong / Neufangled Robotics
Stringman Hardware Kit page
Accessed 2026-10-05 · Page snapshot sha256 9b44e4bb7dc0… retrieved 2026-10-05Source notes
Kit price, sold-out state, contents, payload claim, difficulty and pricing basis.
- S011 · Nathaniel Nifong / Neufangled Robotics
Stringman Arpeggio print guide
Accessed 2026-10-05 · Page snapshot sha256 938360bce80f… retrieved 2026-10-05Source notes
Hardware version, total print time and default print settings.
- S012 · Nathaniel Nifong / Neufangled Robotics
Stringman system architecture
Accessed 2026-10-05 · Page snapshot sha256 f577fd1e5b17… retrieved 2026-10-05Source notes
Component computers, motion controller role and telemetry websocket.
- S013 · Nathaniel Nifong / Neufangled Robotics
stringman-pcbs repository
Accessed 2026-10-05 · Filename inventory of e56d90bd411c3b297b48d3b9ac0d1aaf037eeb07 archive (commit snapshot, sha256 ac8c6faa9561…)Source notes
KiCad anchor and gripper HAT projects and Gerber packages; no license file identified.
Correction guidance · Discussion is not enabled · Profile format 0.7.0-draft.5
Change history
2026-10-05 — Created from Growbotics-listing lead; all claims checked against preserved upstream sources. No physical build or test.