The Project

To build a simple cheap method of testing small electric motor output torque.

Design Goals

  1. Cheap - I should be able to use the things I have lying around to make this
  2. Support many motor profiles - It should be able to test n20s, 16mm, 22mm, servos and more
  3. Easy to use - I don't want to have to assemble and disassemble a lot of things when changing motors during testing.

Things needed

  1. A Scale - the faster the scale the better. It turns out that if there is a delay in the reading registering you could burn out your motor or get an invalid result.
  2. A 3d printer - to make the the parts
  3. A few nuts and screws.
  4. A camera (smart phone will do) for capturing data since it can happen really fast.
  5. A current meter for measuring No Load and Stall current
  6. A visual tachometer for measuring No Load RPM.
  7. A spreadsheet for tracking results

The Story

I designed and printed up a PETG testing rig. It has different adapters for different motors sizes and a 100mm long arm (from pivot to contact point) that presses down on the scale. It works reasonably well, but the motor mount solution is dumb, takes a long time to print, and doesn't hold the motors as securly as I'd like.


Next Steps

  • Design and print a motor mount that is fast to print and easily secures the motor.
  • Design a built-in rack to hold all of the motor adapters.
  • Share the cad files

The Results

I've managed to measure the torque of a quite a few of my motors lying around (I have a bucket of un labeled mystery n20s)