A Raspberry Pi with an Adafruit MAX31855 thermocouple interface board and a solid-state relay is used to control the temperature profile in an oven for reflow surface-mount soldering. The software running on the Raspberry Pi is here: https://github.com/apollo-ng/picoReflow. The instructions in the README.md file in the picoReflow project are good, with one modification needed: to auto-start on power-up, the reflow script in lib/init needs “#! /bin/sh” on the first line of the file, not line 12 as given.
I set my Raspberry Pi with a static IP address of 192.168.0.222, so the address to browse to see the oven interface is 192.168.0.222:8081.
The oven used is an Argos Cookworks 20L 1380W model with top and bottom heaters. The heaters are connected in parallel. Extra insulation is added around the top and sides of the oven chassis and in the door. The seams are sealed with high-temperature putty. Some cross-bars in the rack are removed to reduce thermal mass.
The unmodified oven:
Rear label:
Dismantled:
Resistance of top elements (two in series):
Resistance of bottom elements:
Sealing the joints:
Door insulation:
Internal wiring:
Complete: gold reflective tape covers seams and glass surface of door
