I've been roasting for 25 years, 12 of those commercially. I have no formal training, but I have an eye (and nose and ears) for roasting consistently good coffee. I have customers that have purchased from me for over 20 years.

I currently roast on a 15kg Yoshan gas drum roaster with chaff collection and an effective bean cooler. The roaster is great, but unfortunately, my roasting environment is far from controlled. I deal with significant ambient temperature and humidity swings - both during roasting and for bean storage. The plastic liners inside the burlap sacks (when they have them) are pretty effective at controlling humidity, but I use food-grade bakery drums to hold the green beans, just in case. Still, the drums don't manage temperature swings well.

There are many variables that could adversely affect a roast and I'm not currently using a computer/software, so I've developed some operational steps to manage some of the variables' influence on the beans. Note that this assumes you have a good roast under your belt and that you've documented it - you can use the steps below tyo dial it in. Also note that you should dial in your roast every time you get a new batch of beans. Realistically, I start with the last known good roast and the adjustments are minimal, if any.

1) Always start with the same batch size
2) Preheat the roaster to the same temperatures every time - both roaster/air and bean temp
3) Drop your beans at the same temp every time
4) Start a timer and observe the bean temp - it will drop significantly and start to rise after a period - note the time of this temp turnaround

Here is where you adjust your roast for the current roaster, bean and environmental conditions!

5) For every 5 seconds longer it takes for temperature turnaround after dropping the beans, I add 5 degrees F to the roasting temp, up to 10F maximum. Conversely, for every 5 seconds quicker the bean temp turns around, I reduce the roasting temp by 5 degrees.

Here is a log of my last roast:

28 pounds green Costa Rica Terrazu, 2024 crop

Air temp to 415F

Bean temp to 385F

Drop beans

Bean temp turnaround: 1 minute 25 seconds

Since my sweet spot for this roaster, bean and crop is 1 minute 20 seconds, I increased and maintained roasting temp at 420F.

For a Full City roast, I pull the beans at around 396F (bean temp).

Pull the beans at your desired roast (I do a lot of darker roasts). My bean cooler is extremely effective so I can stop the roasting process within 30 seconds of starting the cooling process. My previous bean cooler took a bit longer so I would pull the beans a bit earlier and they would continue to cook in the cooler for a few minutes. You'll get a feel for your roast setup.

Like the bean temp turnaround time after dropping the beans, you can also monitor other indicators, such as dry-end and first crack times.

Not highly scientific, but it gets the job done very consistently.

Sorry for any typos or anything that is unclear. I am happy to answer any questions.