gehacktes /// noniq.at

0024Matrix Grand Prix (Part 2)

Continuing the journey of building a hardware car racing game.

3D Printing Electronics Hardware Projects Microcontrollers

In part 1 I had experimented with a stepper motor that includes a gearbox. This time I’ll try one without:

The SP20181 is a very small stepper motor with only 20 steps (18° per step) and no gearbox. It can rotate very fast, but has very little torque.

Because the motor’s shaft protrudes a few millimeters at the back side I couldn’t fasten it directly to the chipboard. So I built a quick contraption, using even more chipboard scraps. And then I realised that drilling a small hole below the motor would have been way easier, but hey …

I changed two more things in this second prototype:

SP2018 stepper motor on an unnecessarily complex mounting contraption.Adjustable idler pulley.

I could reuse the Arduino program for controlling the motor, only the parameters setting the number of steps and the motor speed needed to be adjusted.

How did it turn out? Well … double-edged. The motor’s torque is really low, so I had to use it at a slow speed. Otherwise it would instantly skip steps or not move the string at all. However, it still moved considerably faster than the motor I tried last time.

What I hadn’t thought of in advance, though: And having only 20 steps the motor turns a whopping 18° at each step, making the movement rather junky:

Next Steps

Okay, this motor is fast, has low torque, and no gearbox. Why not … add a simple gearbox? I suppose it would still be fast enough while at the same time noticeably improving the torque. Stay tuned for part 3!


  1. Available for example from Pollin

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0023Matrix Grand Prix (Part 1)Lego Police Car0025