Your roast technique is pretty similar to mine, but I'm even more aggressive to get the Behmor to roast hotter when needed, which is most of the time since my preferred coffees are high grown Central American coffees. I'll quote and edit so you can see what we do differently.
DavidZ wrote:1. Load the drum with beans. Insert the chaff tray but keep the drum out. Preheat to 325 degrees by pressing 1, Start, P5. It usually takes about 6 minutes. Quickly remove the chaff tray, insert the loaded drum, and replace the chaff tray.
2. For 155 grams of beans, press 1/2, Start, P5. This places the machine at 100% power in manual mode.
3. When the machine recovers back up to 325, lower to P4 to avoid the Err7 code, at which point the Behmor thinks it's too hot and turns itself off.
4. At 7:00 on the countdown timer (5:00 into the roast), press P5 (this offsets the affect of the afterburner, which comes on at 5:00 with these settings)
5. At 5:50 on the countdown timer (after 70 seconds), press P4
6. When first crack beings to accelerate, usually at or before 7 minutes, or 5 minutes on the countdown timer, press P3
7. Depending on the roast trajectory I'm looking for, I may continue reducing the heat to allow longer development time while monitoring A temperature to make sure the roast doesn't stall. Anything Full City or above I leave on P3, but for lighter roasts I usually reduce to P2 midway through first crack.
8. At 12:00 * 0.25 = 3, press Start to prevent the Behmor from helpfully shutting off and ruining your beans! My roasts are usually done at this point, though.
9. Press Stop when the roast is at the desired point. Wearing gloves, quickly remove the chaff tray, remove the drum, and press Cool to start the cooling cycle. Immediately begin the cooling procedure. Cool beans in as close to 4 minutes as possible.
A lot of the differences between our techniques is likely just because of my bigger charge of 155g vs your 113-ish grams, and it looks like most of the heat and time management follows similar principles. I do
handle things differently with dry processed coffees (P4 instead of P5 during the drying phase) but otherwise this is what I do every single time. I've been really happy with it, and it's neat to see someone else figuring out something so similar that works for them too.
One quirk I have noticed, though, is that you only have about 2 minutes of useful temperature readings on the Behmor. B temperature is basically useless for me since it should always be high due to the preheat. And A temp, which is supposed to be the best correlation to bean temperature, only turns on with the fans at the 5 minute mark, and I don't trust it for at least the first minute (see below. There's no WAY my RoR is changing that much). I also don't trust it after first crack ends. On the rare event I take my beans into second crack, the A temperature actually drops, which would be expected of the environmental temperature in a drum roaster. So I'm really not sure where the "A temp correlates to bean temp" idea came from.
Anyway, here's a manually drawn graph of a typical roast on my Behmor.
The Blue line represents A temperature, and is graphed with the black numbers on the left.
The gray line is what I believe the bean temperature likely is, based on the average temperature that these stages happen (drying ending, first crack beginning and ending, second crack, etc). I drew it so that it lined up well with the blue once I began to trust what "A" told me.
I didn't draw the RoR curve, but I wrote the values in purple beneath the curve. This calculation was based on A temperature readings, not the estimated true temperature (gray).
The red lines are where things happened (drying end, first crack, first crack ending), and the green lines are when I made temperature adjustments.
I actually dropped this roast at 8:45, so the blue and gray line continuing from there is just to show what WOULD
happen in a darker roast: the bean temp MUST
be going up or else second crack wouldn't happen, but A temp actually goes down. So I estimated using the top heavy blue lines as being the range that A temperature is actually useful.
SO at the end of the day, this technique works pretty well, but it's all about evaluating the roast and tweaking the next based on the results, instead of using hard-fast data DURING the roast to decide what to do like those with data-logging drum roasters can do. It can be a bit of a hassle, but I don't often have unpleasant results using this method.
"Wait. People drink coffee just for the caffeine??"