Lego Coin Sorter

About
I did this project almost two years ago and it's still one of my favorites. I'm always surprised about the reaction people have to seeing it because they usually don't realize how dang simple the mechanism actually is. Common theories about how this thing works include the machine weighing the coins or an electronic device such as a Mindstorms guts. 

Here's the secret though: the coins are sorted based on diameter size. The mechanism that makes this work is composed of sloped Technic beams and different sized gates for the coins to fall through. The coin is inserted standing up and gravity pulls it along the sloped Technic track until it reaches a gate big enough to fall through. 


The Design
I wasn't too thrilled about how the case came out but I was happy with the mechanism part. Many of the LEGO coin sorters I've seen require the whole unit to be tilted which I think looks weird so I wanted to make my coin sorter with a sloped ramp so the rest could be level. 

I wanted to enclose the mechanism to create a bit of mystery and get people thinking about how the machine might work. I also liked the idea of being able to see the coins drop so I added a few extra layers of bricks to make the machine taller. 

This machine is made to work with US pennies, nickels, dimes, and quarters but could expanded to include less common coins such as half dollars. It could also be easily modified to work with other coins from around the world as long as the sizes aren't too similar to each other.   


Making One
The end of the video shows how to make the mechanism. As demonstrated, the mechanism can work as a standalone piece or can be taken a step further and include an enclosure. It would be fun to see creative enclosures such as a pig or a transparent design.