Coffree - The open-source coffee grounds dryer

Coffree - Open-source DIY coffee grounds dryer

This project is an open-source coffee grounds dryer. The goal of this project is to have a simple device to dry coffee grounds in order to re-use them for many practical uses(Skin care, plant fertilizer, grow mushrooms,…), build things, or make beer. I want to build a accessible device to provide a solution for people to help reduce waste from coffee.

This model is to create the “Heating Chamber”. The cement resistor will heat to ~50°C (can't exceed 55°C) and the fan will push the hot air on the coffee grounds to dry them.

Printing settings

For those who don't use Bambulab product, here are the settings you can use with PLA :

• 2 walls
• 3 top and 3 bottom layers
• 15 or 20% cubic infill

Electronics

Here is the BoM :

• Ceramic cement power resistor (10W4ΩJ or 10W5ΩJ)
• 1N5819 diode
• Prototype board 2cm x 8cm
• 80mm PWM PC fan (I use an Arctic F8 PWM)
• 4 * M2.5x12 screws
• Micro-USB breakout
• Terminals
• Wires
• USB power switch (optional)

The schematics are really simple. You only need some basic soldering skills. Just follow the schematics, look the photos and everything will be okay!

I choose the Micro-USB breakout for one reason : I can use any 5V power generator with that (USB, Solar panel, Wind turbine, …).

Coffee box

Now, just use any box. Add a 70mm hole for the heating chamber and another hole for the air outlet. Just put a tray with well-spread coffee grounds into the box and… VOILA! Your Coffree is now successfully completed!

After tests, 15g of coffee can be dried in 4/5h. You can use them for many things, just type “Coffee grounds use” on Google, and enjoy!

You can store your dried coffee grounds in an air-tight jar for future uses.