Galileo Hand V 2.0 - 3D Printed Prosthetic Hand

GalileoHand is a project developed at Galileo University of Guatemala. It was born from the idea of creating a low-cost prosthesis made with 3D printers; with files available for free download. Personal 3D printing and global collaboration over the Internet have enabled the creation of inexpensive prosthetic arms. There are few truly inspiring open projects collaborating globally to create and improve mechanical prostheses with 3D printing.

In order to improve the functionality of 3D hand prostheses, the GalileoHand was designed to be fitted to conventional mechanical prostheses replacing the terminal device, usually consisting of hooks or clamps. Traditional action mechanism that allows the extension and flexion of the fingers through shoulder movements is maintained. A major improvement in this design is the Thumb Blocking Mechanism which allows the thumb to rotate obtaining three different types of grips: digital grip, tridigital grip and lateral pinch. This instructable contains the steps to print and assemble the GalileoHand.

Step 1: Prototyping Galileo Hand Parts and Other Materials

A total of 16 ABS 3D printed parts are needed to build the GalileoHand.

01.Palm.STL
02.Palm_Cap.STL
03.Thumb_Palm_Mechanism.STL
04.Joint.STL
05.Adjust.STL
06.Slider_Thumb.STL
07.Thumb_Prox.STL
08.Thumb_Top.STL
09.Index_Prox.STL
10.Index_Top.STL
11.Middle_Prox.STL
12.Middle_Top.STL
13.Ring_Prox.STL
14.Ring_Top.STL
15.Pinq_Prox.STL
16.Pinq_Top.STL

The .STL files can be downloaded at http://www.thingiverse.com/thing:655432 along with the instructions for prototyping each piece.

OTHER MATERIALS

Pen spring
Rivet 3 x 30 mm (is necessary to size and cut part of it)
4 screws 1/8" x 1/2"
Elastic Cord 1mm
Non-Elastic Cord 1mm Nylon
Filament (PLA or ABS)

TOOLS

Lighter
Scissors
Screwdriver
Cutter

OPTIONAL

Cable and cover for gear change or bicycle brake
Adjusting Barrel or Cable Clamp to hold the bicycle brake cable
An 8 mm wide screw
Miniature round file
Sandpaper
Super Glue
Long nose pliers
Wide eye needle

NOTE

The video attached "3D printed Galileo Hand assembly instructable V 2.0" shows how to assemble the Galileo Hand V 2.0 step by step.

Step 2: Fingers Assembly

RECOMMENDED

Before assembling the fingers, remove any support or residue from printing, verify that the finishing of the mobile parts works, otherwise it could require some work with the lime or sandpaper to smooth the imperfections or widen the holes.
If you need sanding a part and it gets opaque compared to the rest of the piece, it can be fixed by rubbing it with a cloth moistened with solvent.

PROCESS

To start you need to join the distal phalanx of all the fingers with their matching proximal phalanx (i.e. the part 07.Thumb_Prox.STL matches the part 08.Thumb_Top.STL; the part 09.Index_Prox.STL matches the part 10.Index_Top.STL; and so on to complete the five fingers).
Take a piece of filament approx. 6 mm longer than the width of the finger you’ll work with. Insert the filament in the holes of both pieces to connect the joint.
With the lighter, heat the metal blade of the cutter, put it next to the filament to melt and widen the filaments ending. Repeat on the other side. Verify that the joint moves loosely.
Cut elastic cord pieces and nylon cord pieces approx. 10-15 cms longer than the fingers (5 of each, 10 in total). Make a knot in one side of the nylon cord. Introduce the nylon cord from the fingertip all the way through the distal phalanx following the inferior holes.
Make a knot in one side of the elastic cord. Introduce the elastic cord from the tip of the finger all the way through the distal phalanx following the superior holes (you can use a wide eye needle to make it easier).
Repeat the whole process with the other 4 fingers: place the filament that connects the joint melting it's edges and introduce the nylon and elastic cord on the corresponding holes.

If you get stuck at any step check the video uploaded on Step 1"3D printed Galileo Hand assembly instructable V 2.0".

Step 3: Fingers to Palm Assembly

The piece 01.Palm.STL has 2 holes for each finger that correspond the two cords. The hole for the elastic cord is above and the hole to for the nylon cord is below. Start introducing the elastic and nylon cord of the fingers “Ring” and “Middle”.
Cut a piece of filament wider than the distance of both fingers (“Ring” and “Middle”). Introduce the filament by the side of the “Ring finger” all the way through both fingers to connect them to the palm joint.
Melt one of the endings of the filament in one side.
Then melt the filament in the middle of both fingers to completely secure the finger you’re working with. Repeat the filament process to secure the joint of the other finger. Repeat the whole procedure with the pinky and index finger: introduce the elastic and nylon cord on the 01.Palm.STLs corresponding holes and place the filament that connects the joint melting the edges).
You must be able to see the elastic cord at the top of the fingers endings and the nylon cord while seeing the hand from the bottom at the fingers endings. Tense the elastic cord and pull the nylon cord to test if it works correctly (the non elastic cord allows the movement and the elastic cord brings the finger back to it’s original place). Adjust the fingers tension and make knots on the elastic cords. Cut the excess of the elastic cords. DON’T cut the non-elastic cords yet.

If you get stuck at any step check the video uploaded on Step 1 "3D printed Galileo Hand assembly instructable V 2.0".

Step 4: Thumb Assembly

Introduce the elastic cord in the hole from the part that connects the proximal phalanx through the 03.Thumb_Palm_Mechanism.STL (the elastic cord must go out from the hole at the left of the slider). Introduce the nylon cord in the other hole (the nylon cord must go out at the right of the slider).
Introduce filament to secure the joint and melt the endings as done previously.
Insert the nylon cord that comes from the 03.Tumb_Palm_Mechanism.STL in the corresponding hole of the 01.Palm.STL (the upper hole).
When 03.Tumb_Palm_Mechanism.STL and 01.Palm.STL are aligned push the piece 04.Joint.STL through the axis. (The side with tips of 04.Joint.STL must be inside) you must hear a “click” which means that the piece is fixed in place.
Fix the tension of the thumb by pulling the elastic and nylon cord. When you have the right tension make a knot on the elastic cord. Cut the excess of the elastic cord.

If you get stuck at any step check the video uploaded on Step 1 "3D printed Galileo Hand assembly instructable V 2.0".

Step 5: Slider Assembly

Insert the pen spring inside the 03.Thumb_Palm_Mechanism.STL shaft.
Then insert the rivet (previously measured and cut to fit) with the head towards the spring.
Once in place, the rivet must be able to lock the 4 different types of grasping.
Insert the 06.Slider_Thumb.STL in a way that it “pushes” the rivet against the spring.

If you get stuck at any step check the video uploaded on Step 1"3D printed Galileo Hand assembly instructable V 2.0".

Step 6: Flexion Mechanism

Tense the nylon cord and make a knot in the corresponding holes (from left to right: 1. Thumb, 2. Index, 3. Middle, 4. Ring, 5. Pinky). Make sure that the knots won’t get loose and take care of the tensions of each finger. (Test the fingers tension before making the knot).
Make sure that the hole of the piece 16.Adjust.STL and the adapter for the wire brake are aligned so you’ll be able to screw the cable later. Apply super glue to fix the pieces.
Introduce the bicycle wire first through the hole of the 02.Palm_Cap.STL and then screw it in the adapter for wire brake.
Secure the 02.Palm_Cap.STL with screws to the 01.Palm.STL. Pull the bicycle wire brake and the fingers will make a fist. If all the fingers have the same grip you’re done!

If you get stuck at any step check the video uploaded on Step 1"3D printed Galileo Hand assembly instructable V 2.0".
For a better grasp cut the fingers of a latex glove, and put them on the fingertips of the hand.

After building the Galileo Hand prosthesis, it needs to be assembled to a socket. There’s a hole where you have to attach the prosthesis with an 8mm width screw. This process can be adjusted or modified. Patient Test: Finally the prosthesis was attached to a low elbow conventional prosthesis socket fitting perfectly as a substitute of a hook. The patient performed some tests with the Galileo Hand, such as holding a bottle and reading a newspaper. The device is lightweight and is easily operated.

FUTURE WORK

Improve the tension adjustment, so it can be easily calibrated.