DIY Reflow Oven: ESP32 Touchscreen, PID + Feed-Forward

I turned a mini convection oven into a reflow oven for my own PCBs. An ESP32 board with a touchscreen controls the heaters, using a thermocouple and a solid-state relay, and I wrote the firmware myself. This is a build log: what I built, why, and what it took to make the oven actually follow the reflow curve. ⚠️ This project switches mains voltage and reaches 250 °C. It is a build log, not a step-by-step guide. If you copy any of it, you own the risk – involve a qualified electrician. Firmware, 3D-printed housing, electrical design and run logs: https://github.com /toomuchtinkering/reflow_oven Inspired by "DIY REFLOW OVEN" by Vulcaman on Instructables (STM32 + Nextion display), CC BY-NC-SA: https://www.instructables.com /DIY-REFLOW-OVEN/ Chapters 0:00 Intro 0:40 Why build one? 2:24 Hardware & safety 4:48 Firmware & UI 6:13 PID tuning 7:23 The run 8:36 Outro What's inside • Controller: LCDwiki E32R35T, an ESP32-WROOM-32E with a 3.5" touchscreen on the same boardVideos • Temperature: K-type thermocouple (ungrounded) on a MAX31855 amplifier • Heaters: two 750 W elements, switched by a solid-state relay in a 2-second time-proportioning window • Mains side: IEC inlet with an 8 A fuse, a double-pole switch, and the oven's original 215 °C thermal fuse in the heater circuit • Firmware: ESP-IDF and LVGL; PID with feed-forward; a safety state machine (260 °C hard limit, sensor and task watchdogs, faults you must confirm); a web interface that saves every run; OTA updates with a self-test and automatic rollback • Filament drying: a second mode that holds the oven between 40 and 100 °C for up to 16 hours The profile in the video soaks at 150 °C for 90 s and peaks at 240 °C for 30 s. The run overshoots the peak by about 5 °C and stays above the solder's melting point (217 °C) for about a minute. Narration: a synthetic voice (Google Gemini TTS) reading my own script. Music: synthesised for this video. #reflowoven #esp32 #electronics