Assembly

A project log for Five Finger Robot Hand

I have been working on robot grippers for a humanoid and this is an Arduino powered, servo motor controlled, 3d printed hand.

Mike Rigsby • 04/16/2025 at 23:42•0 Comments

Setup the Servo Motors:

Use 3D printed parts and six serial servo motors.
Refer to the three-finger hand for the humanoid robot project on Hackaday for information on setting up the servo motors.

Connecting the Take-Up Reel:

Use 3 M3 by 16mm screws to connect the take-up reel to the servo horn.
Use one M3 by 12mm screw to connect the wire that runs the finger.
Use the set finger Arduino program to place the reel at the 9:00 position when the servo motor is at the 3700 position.
Fasten the horn screw on the servo.

Preparing the Cable Wire:

Cut two 275mm pieces of thin cable wire.
Thread the lower wire through the end of the finger and crimp.
Thread the upper wire through the end of the finger and crimp.
Thread the lower wire through the middle finger and the upper wire through the middle finger.

Using the Setup Jig:

Use a special 3D printed jig with 12mm and 30mm screws to hold the setup for the finger.
Drill out a hole with a 1/8 inch bit--not designed into the setup jig.
Install the knuckle on the setup jig.

Connecting the Finger:

Use an M3 by 20mm screw to connect the end of the finger to the middle of the finger, serving as a bearing for the finger.
Thread the upper wire through the knuckle.
Install an M3 by 25mm screw through the knuckle as the bearing point.

Securing the Servo Motor:

Secure the servo and the servo motor mount using the four tiny screws included with the servo motor.
Install the servo motor to the rear of the test jig using 2 M3 by 20mm screws.
Fasten the extension spring (8.7mm diameter by 46.8mm long) to the top of the servo mounting housing.
Use an M3 by 12mm screw through the 3D printed washer to hold the spring.

Tightening the Cable:

Tighten the cable so that the finger is fully in the up position and crimp the cable.
For the lower cable, press the special crimp onto the cable, thread the cable through the lower pulley, tighten, and crimp the cable.
Remove the setup jig.

Final Assembly:

Use 2 M3 by 10mm screws on the front of the wrist and two M3 by 30mm screws on the rear of the wrist.
Fasten the finger and the servo motors.
Repeat this process three times.
Fasten the thumb as shown in the photos.

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