The concept for this machine came about during a brainstorming session where ideas were tossed about to determine what kind of a machine was to be made. The group came up with some desirable (and amusing,) properties, in addition to the required properties, for whatever we decided on.
In the end there were several rounds of voting that whittled the choice down to a vending machine. This seemed like a reasonable scope for a group project. Then we needed to decide what kind of objects we wanted to “vend”. The Lab has a Nespresso machine and a display of the capsules created by one of the student workers.
We decided to create a cylindrical machine that would rotate to dispense a coffee capsule, requested by the user by flavor. The lab currently has 10 flavors of coffee, so this dictated the size of our machine.
One large issue: nespresso capsules do NOT stack!
Our first solution was the creation of the rings which hold the coffee capsules so they could stack in an organized way. These became known, affectionately, as “napkin rings.” We created the napkin rings in Fusion 360 and then 3D printed them in colors that coordinated with the color of the capsules. The napkin rings will be reused when the carousel is reloaded.
The main components of the project were divided up among team members, displayed in the following list:
- Kobe Collison
- User Interface & Selection Panel
- Rachelle DeCoste
- Motor Programming & Cup Adapters
- Justin Foong
- Cup Collection Chute
- Garner Holdsworth
- Dispensing Mechanism & Carousel Baseplate
- Sarah McGrail
- Machine Case & Structure
- Justin Vielleux
- Carousel Construction
The input includes an LCD screen, 3 buttons and neopixels. The user can use 2 of the buttons to scroll through the list of options (forward and backwards) and the third to select their coffee. To complete this part of the project, Kobe milled and soldered the buttons to a board.
The code takes in the user input, sends the first stepper motor commands to rotate the carousel to the appropriate position and then sends a signal to the second stepper motor to “kick” out the coffee capsule, along with its napkin ring. The carousel is sent back to its original position after each coffee selection so there is never confusion about where it sits and how much to rotate. Rachelle and Kobe coordinated to ensure that the program seamlessly passed information and moved the motors at the appropriate times.
The design of the coffee carousel, jointly by Garner and Justin V, has several parts. The base of the carousel and the capsule towers had to be designed with several characteristics in mind. The base is a circle of laser cut acrylic. The slits in this base coordinate exactly with the slits in the bottom of the towers. These slits are integral to the functioning of the machine, as they allow the coffee capsules to be pushed out . The towers were 3d printed, but necessarily too tall to print in the Prusas we have in one piece. So they were designed in 2 parts, with a peg and hole design to keep them joined once attached.
The towers were attached to the base and then placed on the rotation stepper motor. Note how the colors of the towers so beautifully match the napkin rings.
The outer box, designed by Sarah, was cut on the CNC. The bottom inside of the box was designed with pockets to securely fit the 2 stepper motors. It also hosts the 2 arduinos, which are connected in series. The box also has holes for the cords for the motors and arduino to connect to power, for the buttons outside to connect to the arduino inside and for the coffee to exit the carousel to the outside of the box.
The coffee exits into a “catcher” designed by Justin F.
^^ Video of the machine "working" ^^