How to build Aero Hand Open
7-DoF dexterous robot hand · Beginner
Build Chestnut Robotics' Aero Hand Open: 7 Feetech servos drive 16 joints through tendons, ESP32-S3 firmware, Python SDK, ROS 2 and MuJoCo, about $316.
Mostly printed parts and plug-in servos. Good first build.
Our estimate, part-time
$316.48 BOM total (project BOM.csv), excluding power supply and optional PCB
CC-BY-NC-SA-4.0 · non-commercial
What is Aero Hand Open?
Aero Hand Open is a five-finger, tendon-driven hand from Chestnut Robotics (formerly TetherIA). Seven motors pull Kevlar or Vectran tendons that move 16 joints, which keeps the hand under 400 g while still giving the thumb three active degrees of freedom for opposition and pinch.
The project says each fingertip pulls about 10 N, enough to squeeze a drill trigger, and shows the hand hanging on to a full 5-gallon water jug. Tendon routing and low gearing also make it fully backdrivable, so it's safer to work around than a stiff geared hand.
Hardware files are CC BY-NC-SA 4.0 (non-commercial) and the SDK is Apache 2.0. A kit is also sold for builders who'd rather not source parts.
Aero Hand Open specifications
- Actuated DoF
- 7 (3 on the thumb)
- Joints
- 16
- Mass
- ≈389 g
- Servos
- 7× Feetech HLS3606M serial-bus
- Controller
- Seeed XIAO ESP32-S3
- Fingertip force
- ≈10 N
Figures as published by the project. See Sources below.
Bill of materials
| Part | Qty | Notes |
|---|---|---|
| Feetech HLS3606M servo | 7 | ≈$29.83 each in the BOM |
| Seeed XIAO ESP32-S3 | 1 | |
| Feetech TTLinker Mini | 1 | UART to servo bus |
| MR52ZZ miniature bearings | 23 | |
| Kevlar/Vectran tendon line, springs, pins and inserts | — | |
| PLA printed parts and silicone finger pads | — | Pads cast from printed molds |
| 6 V 10 A power supply | — | Not in the BOM total |
Where's the full bill of materials?
The full BOM, with exact quantities and vendors, lives in the project's own files. Prices change often, so treat $316 as a ballpark from the project. Start at the project repository.
Tools you'll need
- Bambu-class FDM printer (0.4 mm nozzle)
- Silicone casting supplies
- Torx and hex drivers
- Soldering iron
Step-by-step build overview
Electronics & wiring overview
The seven servos share one serial bus. The ESP32-S3 drives that bus through the TTLinker, and a 6 V high-current supply powers the servos. The optional PCB tidies those connections into one board.
Software
There's a standalone Python SDK, ROS 2 packages for teleoperation, a MuJoCo model for simulation and reinforcement-learning examples. The hand supports position control, torque control and inline tendon-force sensing.
Tips from the bench
- ☕ Re-tension tendons after the first few hours of use, as the line beds in.
- ☕ Don't skip the silicone pads; they do much of the work on small objects like M5 screws.
- ☕ Size the supply for stall current on all seven servos at once.
Aero Hand Open FAQ
How much does Aero Hand Open cost?
The project's BOM totals about $316, and Chestnut Robotics quotes a complete kit at around $314.
How many degrees of freedom does it have?
Seven actuated DoF driving 16 joints, with three of the seven on the thumb.
Can I sell hands built from the design?
No. The hardware is CC BY-NC-SA 4.0, which rules out commercial use without permission.
Does it work with ROS 2 and MuJoCo?
Yes, the repo includes ROS 2 packages, a MuJoCo model and RL examples.
Sources
Written by Bots n' Beans from the project's own documentation. Check the sources for the latest revision before you buy parts.
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