Help with High Torque Motors

Hello arduino community! I'm relatively new, just venturing off into non-tutorial projects, and need a bit of help.

My project involves turning a physical key in a door with the assistance of a motor. I need help figuring out a good motor and motor driver based on these specs.


  • The motor needs to turn at least 360 degrees, so I imagine we need a DC continuous motor (or maybe a stepper?)
  • Because we're probably going with a DC motor, we also want an encoder so we can be sure how much it is turning and use this in our code
  • We've recorded the torque necessary as 12 to 16 kg-cm (ideally a bit above this to cover sturdier locks)
  • Speed is not an issue (slow is fine)

If anyone has recommendations for a motor that will work well with this, I'm open to solutions, even if you have an idea that I haven't thought of. I have an H-bridge IC that I've used with the Arduino before, could this be used as the driver?

tl;dr please give me motor and driver suggestions for the specs bolded above, open to all ideas! :slight_smile:

Using a geared stepper you would need a lower power driver and power supply. The stepper would allow to do away with the encoder (count steps). Pololu has a variety of stepper drivers. Pick the motor with enough torque then the driver.