Cocoa Cooler (3D Printed Planetary Gears to Cool Hot Drinks Quickly)

Hi Everybody,

I decided to make the Cocoa Cooler because I thought it would be a fun way to learn about planetary gears, while also serving the purpose of keeping you warm. You may be confused how a fan/cooler keeps you warm, so let me explain. When you are cold, a great way to warm up is by drinking a nice hot cup of coffee or hot cocoa. However, you typically have to wait for them to cool down and be safe to drink. The purpose of what I built is to speed up the cooling process in a fun way. I know this isn’t the most practical project, but I wanted to make something that requires very little parts and can be easily replicated. All of the parts for the cooler are 3D printed, and not a single piece of hardware or glue is required. I used PLA because that is all I have, but if you are going to build your own, I would recommend using PETG as it is more heat resistant.

Incase you are unfamiliar with planetary gears, here is a little about them. Planetary gears also known as an epicyclic gear train is a gear reduction assembly. The ring is a large internal gear that houses the other gears. For the Cocoa Cooler, the ring will have to be held in place or in other words it will be fixed. In the middle, there is a sun gear which in my case is connected to the fan as the output. Lastly, there are planet gears which connect the sun gear with the ring gear and are my inputs. The amount of planet gears can vary, but in my case, I used three. Planetary gears can be varied in all sorts of ways to make many different reductions for many different purposes.

1. 3D Printer
2. Computer (For Slicing)
3. Filament (I used PLA, but a filament like PETG is more heat resistant and is safer with foods)

I designed the planetary gears layout in Gear Generator 2. On this website, you are able to change teeth amounts, pitches of teeth, and number of planet gears. This was really helpful to play through before making the final design because it showed which combination would work. After doing some calculations, I found this setup will lead to a 6:1 gear ratio which means the sun gear/fan will spin 6 times faster than the planet gears you spin. I decided to go with this setup because a 6:1 gear ratio is a good speed for a fan.

I used the information about my planetary gears setup that I gathered on Gear Generator to design my Cocoa Cooler. For this project I am using TinkerCad which has a really useful gear generation tool. I started by generating all of my gears by entering the teeth amounts and teeth pitches into the generating tool. The ring gear in planetary gears, is an internal gear. This means it is basically a negative cutout of a gear. By knowing this, I could just generate a normal gear, and then use it to cut a circle. For this project, I also designed a clipping axle system which became very helpful for repetitive connections. I added some cutouts into the body to act as ventilation holes, to help with the cooling process. The holes above the fan are intakes and the holes going out the sides is the exhaust for the steam of the drink. Lastly, I modeled some simple fan blades by modeling a single blade and duplicating it every 45 degrees.

Now, if you are going to make your own Cocoa Cooler, here is where you have to start paying attention. Like I said before, I used PLA because that is all I have. If you are going to build your own, I would recommend using PETG as it is more heat resistant. The only part that needs supports is the body in the cavity where the fan goes. The ventilation holes do not need supports. Once you print all of the parts, clear the supports and clean off and imperfections.

Insert the three planet gears into the carrier. Then secure each of them with a clip. Each gear should be able to spin pretty freely. I did not need to, but you may need to sand a little bit to open up some tolerances.

Push the sun gear down through the hole. Then from the underside carefully push on the propeller. Make sure there is a gap between the body and the propellers, so there is no added friction.

Lastly, push the carrier assembly onto the body. You may have to slightly adjust the gears, so the teeth line up.

There you have it! A new tool to cool down your hot drinks faster. Once you turn the gears for a bit, they work themselves in and it starts to become smoother. I did realize the carrier assembly tries to pop out as you turn it, so I may eventually add a cover on top to hold it down. I did not not originally do this because I wanted to showcase the planetary gears. This problem can also be solved by just turning the carrier rather than using the crank. Something cool to try is spinning the fan instead of the crank. By doing this, you are reversing the 6:1 ratio, so it takes six spins of the fan to spin the crank once. You can't see in the video, but the Cocoa Cooler actually does cool down drinks pretty quickly. I hope you enjoyed this project and learned something about planetary gears. Please let me know if you have any questions.

Thank You!