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• Assembly

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

  1. 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.

  1. 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.

  1. 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.

  1. 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.

  1. 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.

  1. 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.

  1. 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.

  1. 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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