Is a stepper motor the right choice for my project?

Im starting a new project and im completely unsure of how to accomplish it.

I am working on a model b17. I want to direct drive the props at a really slow rotation. like maybe sub 20rpm. Im working in really tight spaces. the cavity has roughly 20mm in length and room for about 10-15mm for the body diameter.

So far I have been looking at PWM drivers or Gear drive motors. Ive been told that PWM might not be such a great idea to use with the quadcopter motors i have. Gear drive could possibly be a bit noisy. while thinking about it i looked at my 3d printer and though, what about steppers?

Can i reduce the rpm of a stepper that low? My thought would be to use an attiny and maybe an extra Pololu stepper driver i have. I would just have it turning constantly.

So far this is an early thought I had and this is my first stop in research. Any thoughts or suggestions?

DC motors would require a little load to spin so slow with just PWM control.
There are tiny stepper motors from old DVD-drives. Their diameter is 16mm and 12mm long, with an ~80mm long shaft, they can be placed wherever it suits you.
They can run very slow too.
If the space is too tight, maybe one motor in the fuselage and some rubberband belts/pulleys can drive all propellers?

Interesting you suggest old DVD drives. I had no idea those were steppers.

Since i will not really be worrying about position in relation to the steps, Could I use a single stepper driver to run 4 motors wired in parallel? I dont know if i just need to worry about current or if there might be complication in doing this from two way communication.

Any preferred control suggestions for turning those tiny steppers nice and slow?

Given your size restriction I think gear motors make a lot more sense. I'm not convinced you can find a stepper that size with sufficient torque.

For example something like this is highly unlikely to swing a prop at 20rpm: [www.aliexpress.com]

A stepper with an integrated gear box should have no problem, but is larger: [www.aliexpress.com]

Should you find apropriate steppers, controlling them will be no problem. You can connect four small ones in series/parallel to save costs, feed a square wave into the step pin to control speed (either a 555 or arduino).


Apropriate gearmotors are extremely easy to find. Speed regulation really isn't a problem if the gear motor is already near your desired speed. Get something rated like 30RPM and run it at lower voltage to cut down on noise. [www.pololu.com]

thank you very much for your input on this. This forum has always been a great help to me. I think i might have enough information now to feel comfortable enough to spend the money on some trials. Thanks a bunch everyone