I’m currently working on a project to reduce a 1 rpm gear electric motor to 0.0004386 rpm which would translate into 1 revolution per 38 hours if I’ve done my math correctly. I believe that I’d need a setup with a gear ratio of 2,280:1 to achieve such a small rotation.
Since I’m essentially brand new to building such a contraption, I’m a bit lost on the best way to build something like this. I’ve got eyes on a few different motors but don’t know what type of structure would best suit this project. The shaft on the motor is 6mm so I’ve found a gear on robotshop.com that would fit, but not sure what kind of structure I could use to go from there. Any and all help would be much appreciated!
Edit to add: This is what I’ve created in a simulator to give a better idea for what I’m going for. bit.ly/2KgyhGu
You might want to opt for a different gear technology - spur gears are not the most efficient and have backlash. Take a look at worm gears - you can get a very large ratio in a single stage. You might need one more spur stage before or after this.
You can also vary the rpm of a DC motor using a motor controller, so your 1rpm geared motor can be reduced even more. If you need exactly a certain rpm, you might use encoders on both th rear shaft of the motor, and the final output shaft of the gear train.
I’ve purchased some Tamiya gear boxes and will experiment with different ways to reduce the rpm. My plan is to link the gear boxes up from one to another and configure the gears in such a way to achieve the desired rpm. If nothing else, I’ll learn more about how gears work. 
When you say backlash, do you mean the amount of “play” between the gears?
I thought about using a micro-controller but I have no idea how to set that all up. Of course, I’m sure the more I look into this subject the more I’ll learn about it.
Yes - more spur gears = more play.
You don’t actually need a microcontroller if you select a DC motor controller which accepts analog (ex. potentiometer / knob) input:
robotshop.com/en/analog-mot … llers.html
