How to Build the InMoov 3D Printed Robotic Finger

NOTE: I originally wrote this tutorial in 2013, but forgot to publish it. Oops! Better late than never!

This Instructable is a guide for building the InMoov 3D Printed Robotic Finger.

InMoov is a project by French sculptor Gael Langevin that aims to create an open-source 3D printed robot that can be created by anyone with access to a 3D printer.

If you're interested in creating a 3D printed robot, this is a great way to get started by building a small module that will leave you with something you can be proud of.

Get started by downloading the files from Thingiverse, and jump ahead to the instructions when you're ready to get started!

Supplies

This project requires:

Arduino Uno
3D Printer
Hitec HS311 Servo motor
Fishing line
2.8mm and 3.2mm drill bits
Dremel tool
3mm nuts and bolts
Rubber pads
Computer for programming Arduino

Step 1: Printing the Components and the Base

The first step is printing out the parts for this project.

I printed out the base and the finger joints at a .25mm layer height and the gear that attaches to the servo at a .1mm layer height. This allows the gear to slip onto the teeth of the servo gear a little easier. The parts have already been laid out for printing, so printing is fairly straightforward.

Step 2: Assemble and Add Non-Printed Components

Attach the Arduino and the servo motor to the base.

Drill out the finger joints first with the 2.8mm bit, then switch to the 3.2mm bit to prevent the plastic from cracking or separating.

I used a Dremel tool to shave down some of the material on the inside of the finger joints; this allows them to move with less resistance. The finger should move freely before adding the fishing line and should not have any catches or burrs in the joints preventing it from moving smoothly.

Step 3: Add Fasteners

Now that the parts have been assembled, run the bolts through the joints and add nuts to fasten them in place.

Add the rubber pads to the bottom of the base to give it a bit more grip when in use.

Step 4: Wiring

Run the fishing line through the holes in the finger and tie the ends off on the servo mount. Moving the servo back and forth should cause the finger to move; this is a good point to go back and address any areas that are not moving freely. Once tied off on both ends, attach the end of the finger to the model.

I chose to cut the plastic terminal off of the servo wiring, and wired it directly to the Arduino. The servo is powered from the 5V/Ground pins, and control is sent via Pin8. Power to the Arduino can be supplied either through USB or the onboard 9V connector.

Step 5: Programming and Testing

Now for the fun part! Using the Arduino IDE, the servo can be programmed to move the finger back and forth. I used the “Servo Sweep” code from the Arduino tutorial database, and modified it to work for this specific application.

The speed and range of the servo can be controlled using this code, and can be tailored to your particular application. There's no right or wrong way to do this, just experiment until you are happy with the results. I wanted to test the full range of the servo, so my code rotates the servo motor the full 180 degrees.

Once programmed, you're finished! Congratulations!

You can make additional modifications as you see fit; have some fun with it!