Mock Toaster Machine

This project aims to provide high school students with basic engineering design concepts through the creation of a mock toaster. This mock toaster simulates the functionality of a real toaster through electronic circuit components such as a limit switch, button, timer, and LEDs. Incorporating both the physical and electronic components of this design will provide students a better understanding of real product design.

Frame

• Plastic (Polypropylene): $23.68
• Alternatives: Cardboard, wood

Breadboard

• BB400 Solderless Breadboard: $6.75

Sheet Metal

• Hillman 6x18 Solid Sheet Metal: $10.48

Solder Wire

• TOWOT 63-37 High Purity Solder Wire: $7.99

Microcontroller

• Arduino atmega2560: $20.99
• Alternatives: LM555 Timer IC

Slide Release Mechanism

• Adafruit 2.5kg Holding Force Electromagnet: $7.50
• Alternatives: Micro SG90 Servo, Stepper 42MM NEMA-17

Slide Down Sensor

• Adafruit Limit Switch PN#819: $1.95
• Alternatives: HC-SR04 Ultrasonic Distance Sensor, PN#1766 Motion Sensor

Button

• Omron B3F: $0.30
• Alternatives: Panasonic EVPBV, Adafruit Mini On/Off Button Switch

Timer

• Built in timer on the Arduino atmega2560.

Spring

• Everbilt Spring Assortment Kit (84-pack): $5.38

Lights

• WP7113SRD/D: $0.35
• Alternatives: MV5754A, APA102-202 Super LED

MOSFET

• IRLB8721 $2.25

Total Budget: $87.62

The first step of constructing the toaster is to cut out the plastic frame for the design. The toaster's dimensions for our design is 9''x5.8"x6", and there are 6 sides that need to be marked and cut out from the plastic. Feel free to create your own toaster with a design you thought of.

Front and Back: 2x 5.8"x6.0" sheets

Top and Bottom: 2x 9.0"x6.0" sheets

Sides: 2x 9.0"x5.8" sheets

After cutting out these sheets, the top and front sides of the toaster will require additional cuts to open up space for the slide down mechanism and the toaster LEDs. The front side will need a centered cut with dimensions 1.6"x4.0". The top side will require two cuts. The cuts will be evenly spaced from the sides going in 1" from each side with dimensions 1.5"x6.0".

Drill two holes in the front panel near the bottom left corner with diameter 0.5". These will be for the button and the potentiometer.

Solder the wires coming from the electromagnet to your own wires that can fit inside a breadboard. For the limit switch, solder your own wires to the three metal prongs. Solder wires to each end of each LED. Solder wires to each metal pin of the potentiometer and the button.

Step 3 Code Link

Purdue ECET Mega Arduino Uploader

The ATmega2560 controls the electromagnet, timer, LEDs, and button input. Download the test program provided here (LINK). Build the circuit displayed on the breadboard. While running the program, when you hold down the limit switch the electromagnet should activate and provide a magnetic force until the limit switch is released, where the electromagnet should once again deactivate.

To use the program you will need to install Microchip studio, which is free online. Afterwards you will need to open the program and open the included uploader. In the uploader with your Arduino plugged in via USB you will then need to select the port from the drop down menu. Afterward you must find the hex file for the project by clicking file browse then finding the place you downloaded the project, then going into the folder labeled project name, again going into the folder labeled project name, going into the folder labeled debug, and finally double clicking on the .hex file. Last you must press the upload button when you do so you should see the orange lights flashing on the Arduino.

The Slide Down Mechanism consists of the spring glued to a 0.5"x0.5" plastic square cutout, and the pull down mechanism that is made of a 1.5"x2.0" metal cutout glued to a plastic handle. The plastic handle is made of two rectangular pieces that are 0.5"x1.5". The handle should be able to fit through the front cutout. During the glue process, ensure that there is a gap between the metal and the plastic. After building these two pieces, glue the spring to the plastic on top of the metal cutout with the handle and glue the top of the spring with the plastic square to the inside of the toaster at the top of the front cutout..

Grab the plastic sheet specified for the electromagnet, and then glue the electromagnet to one side of the plastic. Afterward, glue the sheet to the inside of the front panel where the top of the magnet is approximately 2" below the top of the front panel cutout.

Connect one side of the electromagnet to the ground on the Arduino and one side to the 5V pin of the Arduino. Move down the handle to a level where the electromagnet is able to hold the metal plate with tension on the spring. Press the limit switch into the metal until it clicks, and then glue it to the front panel so that the metal is still pressing the switch. Remove the power from the electromagnet.

Glue the Arduino and the breadboard to the bottom plastic of the toaster centered towards the middle of the toaster.

Glue 4 LEDs to each of the specified LED plastic plates. Place each of these plates on the top openings and connect them to the top panel with hot glue.

Glue the potentiometer and the button to the two holes in the front panel, and feed the wires through the hole.

Glue all of the frame pieces except for the bottom panel with the Arduino together based on specification.

Step 11 Code Link

Connect the Arduino to all of the components in the circuit following the above diagram (See Step 3 for instructions on getting the code into your Arduino). Carefully place the rest of the toaster on top of the bottom panel.

Run the Arduino program provided, and verify that the program is operational.

1. When you push down the lever mechanism, the electromagnet operates and holds the plate down.
2. After a predetermined time, the electromagnet should automatically turn off and release the lever.
3. The push button should immediately release the lever when pressed.
4. The potentiometer should change the predetermined time in Step 2.
5. While the lever is down, the LEDs should be on.