Auto-assembled, not yet reviewed

Yale OpenHand Project

Family of 3D-printed underactuated adaptive robot hands from Yale GRAB Lab.

Reproducibility65/100Partial source coverage, unverifiedCADBOMWIREFWBUILDLICREPHow it is computed
Yale OpenHand Project source parts laid out side by side, 3D render from a1_part1.STL (not the assembled robot)
Parts preview: not the assembled robot · a1_part1.STL

About Yale OpenHand Project

The Yale OpenHand Project is an open-source initiative from the Yale GRAB Lab (Raymond Ma, Lael Odhner, Aaron Dollar) to advance rapid-prototyped, underactuated robot hands. This repository holds the mechanical CAD (SolidWorks SLDPRT plus STL meshes) for a family of designs: the single-actuator four-finger Model T, the two-actuator Model T42, the modular Model M2, the variable-friction Model VF, the four-actuator anthropomorphic Model O, the finger-gaiting Model Q, the Stewart hand, and others. The hands use Dynamixel servos and tendon-driven flexure joints made with hybrid deposition manufacturing and Smooth-On urethane. The Model F3 assembly guide includes a BOM for that model, without prices, listing XM430 actuators, Spectra tendon, Smooth-On urethanes, McMaster fasteners/bearings/pins, a C920x webcam, and printed STL parts. Assembly instructions and ROS control code live on the project website; the CAD here is released under a non-commercial CC BY-NC 3.0 license.

Licenses

Hardware
CC-BY-NC-3.0NC
Software
Not published
Docs
CC-BY-NC-3.0NC

Degrees of freedom

4 DoF

No per-group breakdown has been sourced yet.

Underactuated handsource

How to build Yale OpenHand Project

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. Pick a hand model

    Choose a design from the repo (Model T, T42, M2, O, Q, VF, Stewart, etc.) based on the number of actuators and grasp behavior you need.

    Upstream stepgithub.com/grablab/openhand-hardware/blob/b10197dcd79e7bcfa9...

  2. Print the structural parts

    3D-print the finger, palm, and pulley parts from the provided STL meshes; SolidWorks SLDPRT sources are included for editing.

    Motari summarygithub.com/grablab/openhand-hardware/blob/master/model%20f3%...

  3. Cast the flexure joints

    Make the compliant flexure joints with Smooth-On urethane using the hybrid deposition manufacturing approach described on the project site.

    Upstream stepgithub.com/grablab/openhand-hardware/blob/b10197dcd79e7bcfa9...

  4. Source hardware and assemble

    Source the hardware listed in the chosen model's assembly guide (the Model F3 guide lists Dynamixel XM430 actuators, tendon line, Smooth-On urethanes, pins, bearings and fasteners), then assemble and route the tendons per that guide.

    Motari summarygithub.com/grablab/openhand-hardware/blob/master/model%20f3%...

  5. Wire and control

    Connect the Dynamixel servos (the Model F3 guide daisy-chains its two XM430s) and use the control code and ROS node in grablab/openhand_node, which covers Model T, T42 and O.

    Motari summarygithub.com/grablab/openhand-hardware/blob/master/model%20f3%...
Print timenot published
Assembly timenot published

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

Yale OpenHand Project bill of materials

22 rows

Cost to build

The sources do not publish a cost total. The rows below are what they list, without a sum.

Yale OpenHand Project parts, as the source lists them. Prices are the source's, not checked against vendors.

Yale OpenHand Project bill of materials
PartQtySpecSourceConfidence
Power Pro Spectra tendon lineModel F3 BOM lists one tendon item.
1Tendon line; unit length/spool size not specified
Amazon link from the projectprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
PMC-780 urethaneModel F3 BOM lists one PMC-780 urethane item.
1Finger joint urethane; amount not specified
Smooth-Onprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
Dragon Skin 10 siliconeModel F3 BOM lists one Dragon Skin 10 item.
1Finger pad urethane/silicone; amount not specified
Smooth-Onprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
1/4 in diameter, 1-1/2 in long 8-32 female standoffModel F3 BOM lists four support standoffs.
4Zinc-plated support standoff
McMaster 93330A482price not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
3 mm x 32 mm dowel pinModel F3 BOM lists eight joint pins.
8Joint pin
McMaster 91595A138price not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
3 mm shaft shielded stainless steel ball bearingModel F3 BOM lists eight joint ball bearings.
8Joint ball bearing for reducing tendon friction
McMaster 7804K126price not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
8-32 x 3/4 in countersunk boltModel F3 BOM lists eight support bolts.
8Support bolt
McMaster 92210A197price not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
M2.5 x 8 mm boltModel F3 BOM lists two center bolts.
2Center bolt for Dynamixel; guide notes included with Dynamixel
McMaster 91292A012 / included with Dynamixelprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
M2 x 5 mm boltModel F3 BOM lists four mounting bolts.
4Dynamixel mounting bolt
McMaster 91290A012price not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
4-40 x 0.135 in heat-set insertModel F3 BOM lists four heat-set inserts.
4Bolt-anchor insert
McMaster 93365A120price not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
4-40 x 1/4 in countersunk screwModel F3 BOM lists four tendon/spring anchor screws.
4Tendon/spring anchor screw
McMaster 91253A106price not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
Dynamixel XM430 actuatorModel F3 BOM lists two Dynamixel XM430 actuators.
2Servo actuator; exact XM430 variant not specified in the F3 table
Robotis / various vendorsprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
Logitech C920x HD Pro WebcamModel F3 BOM lists one Logitech C920x HD Pro Webcam.
1RGB camera for Model F3 force-estimation setup
Amazon link from the projectprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
F3 finger thin-wall moldPrinted Parts List gives two F3 finger thin-wall mold parts.
2Printable mold/finger item from F3_finger_mold.STL
make yourself from the project's STL meshprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
a1 part 1Printed Parts List gives one a1 part 1.
1Finger base with camera mount, a1_part1.STL
make yourself from the project's STL meshprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
a1 part 2Printed Parts List gives one a1 part 2.
1Extended camera mount, a1_part2.STL
make yourself from the project's STL meshprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
a2 motor fixture topPrinted Parts List gives one a2.
1Motor fixture top, a2.STL
make yourself from the project's STL meshprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
a3 motor fixture bottomPrinted Parts List gives one a3.
1Motor fixture bottom, a3.STL
make yourself from the project's STL meshprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
a4 robot-arm mountPrinted Parts List gives one a4.
1Mount to robot arm, a4.STL
make yourself from the project's STL meshprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
b1 motor tendon-routing partPrinted Parts List gives two b1 parts.
2Tendon routing for motors, b1_xm_f3.STL
make yourself from the project's STL meshprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
d1 casePrinted Parts List gives two d1 parts.
2Case part, d1.STL
make yourself from the project's STL meshprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high
Bearing sleevePrinted Parts List gives eight bearing sleeves.
8Sleeve for ball bearings to prevent tendon slipping, bearing_sleeve.STL
make yourself from the project's STL meshprice not listedModel F3 Assembly Guide 1.0.pdf, Bill of Materials / Printed Parts List
high

Rows from the source's own parts list 3

README.md@b10197dmarkdown

Source rowQtyPrice and vendorLine
OpenHand hardware source structure and flexure-material context
Yale OpenHand hardware READMEno price listed
L6

model f3 (forces-for-free hand)/Model F3 Assembly Guide 1.0.pdf@b10197dpdf

Source rowQtyPrice and vendorLine
Model F3 itemized unpriced bill of materials
Source PDF quantities: 1 tendon, 1 PMC-780, 1 Dragon Skin 10, 4 standoffs, 8 dowel pins, 8 bearings, 8 support bolts, 2 M2.5 bolts, 4 M2 bolts, 4 inserts, 4 4-40 screws, 2 XM430 actuators, 1 C920x webcam
Model F3 Assembly Guide 1.0.pdfno price listed
L20
Model F3 printed STL parts list
F3_finger_mold x2, a1_part1 x1, a1_part2 x1, a2 x1, a3 x1, a4 x1, b1_xm_f3 x2, d1 x2, bearing_sleeve x8
Model F3 Assembly Guide 1.0.pdfno price listed
L149

Yale OpenHand Project source files

9 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.

Yale OpenHand Project 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 model f3 (forces-for-free hand)/stl/a1_part1.STL at b10197d, with the parts laid out side by side because the source has no assembly.

Builds of Yale OpenHand Project

0 reviewed

No reviewed builds of Yale OpenHand Project 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 grablab/openhand-hardware: 2025-03-25 (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-reviewed 2026-06-08.

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 Yale OpenHand Project? Show its reproducibility score in the project's README. The badge links back to this page and updates with the score.

Badge: reproducibility 65/100

Markdown
[![Motari reproducibility score for Yale OpenHand Project](https://motari.io/api/v1/badge/yale-openhand)](https://motari.io/r/yale-openhand)
HTML
<a href="https://motari.io/r/yale-openhand"><img src="https://motari.io/api/v1/badge/yale-openhand" alt="Motari reproducibility score for Yale OpenHand Project" height="20"></a>

Not fully met yet: wiring diagram, oshw-compatible license. 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