Frostomatic | DIY Milkshake Maker

The situation: As college student tired from a long day full of classes and machining, I get back campus and open up my fridge for a cool treat. And.... it's empty :(

The solution: Instead of simply walking down to the supermarket, the clear solution is to spend way too much time over-engineering a contraption to make a frozen treat, utilizing both an Arduino and 3D printing. While I am fortunate to have the resources of my school's Maker-space, the basic design and concept are definitely open to being more DIY-ed with common tools and materials.

While this project was put together in a short timeframe, there is a lot of potential to it, as well as applications for other ingredient combinations. Additionally, there is room to reduce the footprint of the machine and create a better form factor. I am excited to continue to iterate on this project and improve its functionality and design, which will be documented on Instructables!

Electronics:

1. Arduino
2. L298 Motor Controller
3. DC Motor
4. 9V Battery
5. 2S Lipo
6. XT30 Connector
7. Wires (16 AWG for power, 22-24 AWG for control signals)

Hardware:

1. 3mm Screws
2. 3mm Heat Set Insert

Misc:

1. 3D Printer Filament
2. 7-Up 2L Soda Bottle (Or Similar)
3. Trader Joe's Peanut Butter Jar (Or similar)

Tools:

1. Soldering Iron
2. 3D Printer
3. Lasercutter
4. X-Acto Knife

This project started as a doodle in the cafeteria, inspired by industrial ice cream makers that slowly churn cream, chilling it to the texture of ice cream we all know and love. Using budget materials such as a peanut butter jar and soda bottle in addition to spare electronics lying around, the design would be center around 3D printability for ease of mounting and ability for rapid prototyping.

My design philosophy was for a sleek, easy to use, and easily disassemble-able gadget that could be made within the constraints of my school's Makerspace equipment. To do this, I started with a 2D layout view to block out space for the essential parts (motor/battery/bottle). Following this, I blocked out the same for those essential parts in 3D before modeling the casing and additional parts, carefully thinking through hardware mounting between parts. This included factoring in rough tolerances between fits between parts.

Fusion 360 was my CAD software of choice, with easy export options for STL and DXF files for manufacturing!

Follow this wiring diagram using a soldering iron with properly gauged wires (22-24 for control signals, 16 for power).

1. Power Connections:
2. Connect the 3S LiPo battery's positive lead to one terminal of the switch
3. Connect the other terminal of the switch to the XT30 connector's positive lead
4. Connect the negative lead of the LiPo directly to the GND of the L298.
5. Connect the XT30 output positive to the Vcc (12V) input of the L298 motor driver.
6. L298 to Motor Wiring:
7. The two motor terminals are connected to L298's motor output pins (Out1 and Out2)
8. L298 to Arduino Wiring (Control Pins):
9. L298 IN1 → Arduino Pin 4 (Reverse Direction - Blue Wire)
10. L298 IN2 → Arduino Pin 5 (Forward Direction - Yellow Wire)
11. L298 ENA (Enable A - Motor Speed) → Arduino Pin 9 (PWM Speed Control - Purple Wire)
12. Powering the Arduino:
13. Connect the positive terminal of the 9V battery to the Vin pin of the Arduino.
14. Connect the negative terminal of the 9V battery to the GND of the Arduino.
15. Connecting L298 and Arduino GNDs:
16. Connect the GND of the L298 to the GND of the Arduino using 22-24 AWG wire. This is crucial for proper communication between the Arduino and motor driver.

After soldering the electronics, use the Arduino IDE to run the following code:

You can find the CAD & all files needed here: https://a360.co/3FNsWsv

1. 3D Printing: Because structural integrity is not crucial, infill isn't that crucial. Make sure to use supports for the threads!
2. Heat-Set Insert: Anywhere a screw goes into a 3D printed part, use a soldering iron to press in a heat set insert!
3. Laser-Cutting: Laser cut parts for centering the peanut bottle and blades
4. Trim Soda Bottle: Use an Xacto knife to trim down the soda bottle to size by placing it into the outer case then trimming.

1. Top - Electronics Mounting
2. Start by running the switch through the top before screwing into the L298
3. Mount the electronics casing to the motor plate
4. Attach the bottom portion of the casing, before screwing on the cover. Make sure that the lipo charging end pokes out of the hole for ease of charging
5. Bottom - Ingredients Jar
6. Use a soldering iron to make a small hole for a screw on the bottom of the soda bottle. Screw in the bottom block and bottom plate from the this hole, then seal it up using glue
7. Press fit the soda bottle into the outer case, then the centering rings for the peanut bottle. Firmly press the peanut bottle jar to fit into the bottle

The milkshake recipe is based on this recipe: https://www.loveandlemons.com/homemade-ice-cream-recipe/

To set up the machine, fill up to the top of the peanut butter jar with water and salt (to reduce freezing point), then freeze in the freezer

Into the peanut butter bottle goes:

1. 0.25 cups heavy cream
2. 0.25 cups whole milk
3. 1.5 tbsp cane sugar
4. 1/3 teaspoons vanilla extract
5. a sprinkle of sea salt

Return the assembly to the fridge (ideally - if on the go place in insulated area) and turn on the top switch. Wait for around 45 minutes, or until motor whir starts to slow down (indicating greater resistence forces from the viscosity of the milkshake). Enjoy!

Because of the short timeline of this project and my lack of experience in product design, it is nowhere near perfect. While it works, there's still so much space for improvement! Below are a few ideas to iterate on the current design and to design in more desirable functions:

1. Adding a buzzer that acts as a self-timer to indicate when the 45 minutes is up!
2. Using metal (aluminum/stainless steel) for the blade instead of lasercut wood
3. Reduce form factor with more efficient packaging of electronics
4. Decrease the insulating effect of the peanut butter jar using using metal alternatives