Here’s a bit of info on my previous coffee roasting rig from a few years ago. It started life as a steel popcorn popping pot, which is just like a stovetop cooking pot, but has a hinged lid and handle mounted hand crank mechanism to turn a paddle at the bottom of the pot and agitate the beans.
I drilled a small hole in the lid and fed in a thermocouple probe from my multimeter to measure temperature. I used the gas side burner on my outdoor grill for roasting — there is simply too much smoke to roast this way indoors.
This worked well, but I wanted to make the 15-20 minute process less physically taxing! So, I took apart the hand crank mechanism and I grafted a power drill directly onto the shaft of the pot’s paddle. By wiring down the trigger at a slow speed, I could sit back and enjoy watching the coffee roast itself.
Ultimately, this method still produces quite a bit of unevenness in the roast, so I eventually abandoned it for a purpose-built home roasting machine, the Behmor 1600. But, it was a fun period in the evolution of my coffee roasting process that I wanted to share.