Some time ago I began roasting raw coffee beans in a popcorn popper. It didn’t take long for the limitations of this method to become apparent, and so I’ve progressed to an improved method using a tripod-mounted heat gun, which I hereby reveal.

I blogged about my popcorn popper roasting setup (see Confessions Of A Coffee Snob), which gave reasonable results in cool weather. However, in warmer weather the roasting process happens too quickly to allow the full flavour of the beans to develop, and the popper’s heat can’t easily be adjusted. Another method was needed, which would allow slower roasts during the long hot Perth summer.

A lot of great information on home coffee roasting is available on the CoffeeSnobs website, and Sweet Maria’s has an inspiring illustrated collection of home-made roasting devices. With ideas from these, I built the tripod-mounted heat gun and bowl roaster shown in the photo.

It’s basically just a heat gun - normally used for drying or stripping paint - pointing into a stainless steel bowl, with the beans stirred by hand with a wooden spoon. A motorised stirrer could be added … but that’s another project. The tripod mount allows the heat gun to be positioned in just the right spot, which is how the temperature in the bowl is controlled (as measured using a multimeter). Also the setup is easily moved around, and dismantled for storage.

This is a manual, hands-on and low-tech method of roasting coffee beans, but the degree of control means much more of the bean’s potential can be realised. By adjusting the height of the gun to slow the rate of temperature increase, a roast can be extended to 15-18 minutes instead of the 5 or 6 minutes it would take in a popcorn popper on a warm day. The slower roasting leads to better flavour in the cup, not to mention the satisfaction (and money savings) of doing it yourself.

It makes me wonder what else can be achieved at low cost by tinkering with household bits and pieces.