Modifying a servo for continuous rotation opens up a number of possibilities for new Arduino projects, the modified servos essentially function as a PWM variable speed and direction motor which can easily be controlled by an Arduino or similar micro controller. This is a fairly simple modification to do and the process will be similar for many different servo models and sizes.

Do you have an old servo with stripped gears? Here’s a guide to repairing your stripped servo gears for under a dollar.

What You Need To Modify A Servo For Continuous Rotation

  • Analogue Servo – Turnigy TG9e Used Here
  • Precision Screwdriver Set – Buy Here
  • Side Cutters – Buy Here
  • Small Drill Bit Set – Buy Here
  • Electric Drill – Buy Here
  • Needle Nose Pliers – Buy Here
  • Electrical Insulation Tape – Buy Here

How To Modify The Servo For Continuous Rotation

The video below takes you through the step by step process to modify your servo for continuous rotation. A list of steps has also been provided after the video.

Steps To Modify Your Servo

  1. Remove the servo arm.
  2. Use a philips screwdriver to remove the four screws at the bottom of the servo.
  3. Remove the top gear cover.
  4. Remove the first, largest gear. The one which on which the servo arm is mounted.
  5. If you turn this gear over, you’ll see a stopper which mechanically limits the rotation of this gear. This stopper runs into the  adjacent gear when the arm reaches its travel limit. Use the side cutter to remove this stopper as close as possible to the gear.
  6. Next you’ll need to drill the hole in this gear slightly larger so that the gear turns freely on the potentiometer arm/shaft without being too loose. Some gears, like the one in this video, actually have a flat landing which locates the gear on the potentiometer arm for position control. This needs to be removed by drilling right through the gear.
  7. Replace the large gear onto the potentiometer shaft.
  8. Replace the top gear cover.
  9. Remove the stickers on the side of the servo which also hold the bottom cover in place.
  10. Remove the bottom cover and then move the small circuit board out of the housing and away from the potentiometer.
  11. Use a screwdriver to remove the small plastic cover which protects the potentiometer terminals.
  12. Now use your needle nose pliers to remove the three wires from the potentiometer terminals.
  13. Stripe the insulation off of the three wires and twist them together to make a secure connection.
  14. Cover the joint with insulation tape to prevent a short circuit on the circuit board.
  15. Flatten the potentiometer terminals to make place for the insulated joint.
  16. Push the plastic cover back into place.
  17. Replace the circuit board.
  18. Replace the bottom cover.
  19. Replace the four screws and tighten them to secure the top and bottom covers.
  20. Your servo has now been modified for continuous rotation. Your servo will now run continuously in each direction and will be speed controllable around the mid point of the PWM signal.

Have you got a good idea for a servo based Arduino project? Try building your own servo controlling xduino board.

Have you modified one of your servos for continuous rotation? Let us know in the comments section below.

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