Grasp Bionic Hand

Grasp is a robotic hand designed to to be assembled by a non experienced user and can be useful for different applications.

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Grasp is a 6 DOF bionic hand based on the Arduino Nano micro-controller. The main design motivation behind this project is to achieve an affordable prosthetic hand able to do the most important types of grasps for the activities of daily living and could be improved for the DIY community but, can be used for different purposes: robotics, research, education, hobby. The features achieved are close to the best prosthetic hands: 350g, 6.8 N of fingertip force and 72 º/s of finger flexion-extension speed.

This is the last iteration of the project with 6 DOF.

Printed parts on PLA:

1x Palm 

1x Bottom cover 

1x Top cover 

1x Thumb core 

1x Thumb distal phalanx 

4x Joint 

4x Distal Phalanx

 4x Proximal Phalanx

The Covers of the fingers can be made with silicone ore rubber using the molds. At least you will need:

1 x Finger mold1 

1 x Finger mold2 

1 x Thumb mold1 

1 x Thumb mold2

1 x Arduino Nano 

5 x Actuonix PQ12R 

1x Micro servo MG90S 

6V Power supply 

10 x M3 allen screws 10 mm long 

12 x M3 allen screw 16 mm long 

1 x M3 allen screw 20 mm long 

4 x M2 blade screw 8 mm long  

2 x M4 star screw 

1 x M10 allens screw 30 mm long 

1 x MG90S servo screw

Grasp Design and Preliminary Testing of an Open-Source, 3D Printable Bionic Hand .pdf

Article also available on engrXiv:

Adobe Portable Document Format - 1003.42 kB - 08/20/2020 at 17:36



STEP Files of all parts and the assembly

x-zip-compressed - 2.12 MB - 08/20/2020 at 17:35



Basic control of the hand.

ino - 3.06 kB - 04/26/2019 at 23:15


Standard Tesselated Geometry - 487.58 kB - 04/14/2019 at 19:27


Standard Tesselated Geometry - 386.70 kB - 04/14/2019 at 19:27


View all 16 files

View all 4 project logs

  • 1

    Assembly steps

    • Printing and removing support material
    • Fingers assembly
    • Thumb assembly
    • Inserting the motors on the palm
    • Inserting the motor on the thumb
    • Fingers and palm assembly
    • Casting silicone in the molds
    • Gluing the silicone “skin” in the fingers
    • Mounting the electronics and electrical components in the palm
    • Electric conections
    • Assembling the covers
    • Upload the firmware
    • Start exploring!


    • Micro USB cable
    • M3 allen key
    • Little flat blade screwdriver
    • Phillips (star) screwdriver
    • M3 drill bit with driller
    • Lime
    • Super glue

    Bill of materials

    • 5 x Micro linear servos motor Actuonix PQ12R
    • 1 x Rotary servo motor Tower pro MG90S
    • 1 x Arduino/Genuino Nano
    • 2 x DFRobot OYMotion SKU:SEN0240 EMG analog sensor or Mioware EMG analog sensor
    • 1 x Pololu DV2425F6 Voltage regulator
    • 1 x Pololu Switch ON/OFF
    • 1 x Grasp PCB board (optional)
    • 1 x Tournigy Nano-tech 6000 mAh or other Li-po 7.4 V power supply
    • 1 x Li-po battery charger
    • 1 x DFRobot 0029-B Pushbutton module
    • 10 x M3 allen screws 10 mm long
    • 12 x M3 allen screw 16 mm long
    • 1 x M3 allen screw 20 mm long
    • 4 x M2 blade screw 8 mm long
    • 2 x M4 star screw
    • 1 x M10 allens screw 30 mm long
    • 1 x MG90S servo screw

    3D printed parts

    • 4 x Finger distal phalanx
    • 4 x Finger proximal phalanx
    • 4 x Joint
    • 1 x Palm
    • 1 x Thumb core
    • 1 x Thumb distal phalanx
    • 1 x Top cover
    • 1 x Bottom cover
    • 1 x Finger grip mold
    • 1 x Thumb grip mold
  • 2
    • Printing and removing support material

    Once you have the downloaded files you can use any SLS or FDM printer to print the parts in PLA, ABS or resin, a tough resin is recommended for their mechanical propierties.

    As an example the hand can be printed in a FDM printer (BQ Hepsteros 2) using the following settings:

    • Material: PLA 3D850.
    • Wall thickness: 1.2 mm.
    • Filling percentage : 20 %.
    • Filling pattern: Lines.
    • Printing temperature: 230 ºC
    • Printing speed: 60 mm/s
  • 3
    Fingers assembly

View all 13 instructions

Enjoy this project?



Xavi Cano wrote 11/07/2019 at 17:27 point

Thank you very much! What a nice time in Bucharest! Amazing competition!

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Gabriel Chira wrote 11/06/2019 at 17:26 point

Awesome documentation and Instructions, this project rocks! \m/ 

Best of luck with the project, i was the red-haired dude from Saturday in Bucharest!

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