5-6 rpm dc low voltage motor?

Using Arduino Motors, Mechanics, Power and CNC
1

Project: Make a small model (very small) slowly turn at a maximum of 5 to 6 rpm.

Restrictions:

  • Can't be wider than 35mm to 40mm
  • Keeping it under 20mm-30mm tall
  • Motor needs to run at or under 3v to 4.5v

Unrestricted: I don't need to worry about torque - this is what I plan on having rotate slowly, a very small model: http://4.bp.blogspot.com/-g5uhEK4giJU/UMUbM2CtTZI/AAAAAAAAFK0/Vpqeui5YjNc/s1600/Egregore.JPG

I have tried a normal 6v motor with a POT and a POTrimmer and both work in slowing it down, but once I turn it down to a certain level the motor simply stops which means I'm under the minimum at that point.

I thought about trying a stepper motor and i found a small driver that will handle it, but I think I need a controller? Is it possible to just run the thing at a set speed so I can get the 5-6rpm I want?

I can't seem to find a solution which will get me down to the 5-6 rpm I need in the size constraints I have.

I found these stepper motors and would like nothing bigger, smaller if possible...

Stepper Motor URL: http://www.aliexpress.com/item/NEW-3V-DC-4-wire-2-phase-DC-Micro-stepper-motor-step-angle-18-Degree-with/32674067716.html?spm=2114.01010208.3.162.IGLFTS&ws_ab_test=searchweb201556_7,searchweb201602_2_10057_10056_10055_10049_10059_10058_10017_405_404_10060_10061_10062_412,searchweb201603_2&btsid=13c92120-3730-4fe4-9fe4-1e6ca03dc056

And this is a small controller which can handle 2.5v+ for a stepper motor...

Stepper Motor Controller URL: Pololu DRV8834 Low-Voltage Stepper Motor Controller

Any ideas on how I can accomplish this?

I plan on including an article and a step by step on how to do this once I have it figured out and would happily reference any help!

Thank You!

2

You're going to need a gear reduction (gearmotor) to get that slow, look at this link:

3

I've always thought worm gears were nifty. Might give you the large reduction ratios you seek without needing too much space.

4

Did you look on eBay for 5rpm motors?

I found this without much effort:

5

What about a stepper motor? You can get it to move in precise increments by controlling the stepping sequence. If you just want continuous rotation you don't need a microcontroller, you could work it entirely in discrete logic with a 74HC194 Shift Register clocked off a 555 timer. With a few NAND gates you should be able to add on/off and reverse functionality to it. Then you only need to control the clock frequency of the 555 timer to change the rotation speed.