I have a toaster oven that started to burn things, because the timer would sometimes fail to turn off the oven. When searched how to repair it, I found solder reflow oven conversions. I'm into hobby electronics, but had not tried reflow soldering at this point. Converting the oven replaces the built in heat controls with an electronic controller that controls the temperature to match the the requirements of the solder paste used. I found the picoReflow project which provided schematics and software to control the oven. I designed a Raspberry Pi Hat that would control the oven and work with a touchscreen too. This setup let me run the oven on my workbench without needing another computer to access the picoReflow web interface.

Supplies

Raspberry Pi

K-Type Thermocouple

DIY or Adafruit MAX31855KASA+T Board

Solid State Relay

(optional) Touch screen

(optional) Touch screen stand

Check my Tindie Store, I may have some items for sale.

Step 1: Temperature Control Hardware

First you will need to decide how you want to build this. One can use off the self modules or make everything from individual components.

This will need a relay module that will turn the AC powered heating coils on and off to control the temperature.

Soild state is recommended over mechanical relays because of the many off and off cycles and the amount of clicking would be annoying. You can use off the shelf SSR Module. I chose to build the open source Toast-R-Relow Power Board

K-Type Thermocouple and a MAX31855 controller is supported by picoReflow software.

You can use the Adafruit breakout board or build my touchscreen compatible HAT

Raspberry PI talks to the MAX31855 over SPI and by default it controls the relay with GPIO 23