For the final year Electromechanics module, I worked in a team of four to bring my automated aeropress concept to life. This project brought together the skills learned in the Electronics and Mechanics modules: systems design, circuit building, 3D printing, metal machining and more.
The design is based around a central carousel, which is accurately rotated with a stepper motor and spur/ring gear train. This allows the program to select the correct mechanism for each stage of the brewing process.
After being pumped up from the storage tank, cold water is fed down a copper tube, which is wrapped concentrically around a cylindrical aluminium block. This houses six cartridge heaters, which heat the water as it travels down the tube.
The aeropress plunger is connected to a linear actuator using a 3D-printed insert. When positioned and engaged, the plunger works as it would in an ordinary aeropress, and forces the hot water through the coffee grounds as it lowers.
A high-torque 3D-printed burr grinder turns the beans stored in the acrylic tube into grounds, which drop into the aeropress chamber below.
The user is guided through a selection process, where they can determine their desired coffee strength. The machine then determines the correct speed for the linac, and modulates using PWM. They can also decide whether they want milk and syrup, which are dispensed using solenoid valves.
An embedded system was developed using a PIC microcontroller, programmed using C on MPLab. Separate sub-systems were built individually on a breadboard, before transferring to stripboard for more robust circuitry.
3D printing was used as the primary method of manufacture for all of the housing parts and many of the mechanical components. Water-jet cut steel plates separated by lengths of M8 threaded rod formed the structural core of the machine.