May be an elementary question, and I hope not to re-open any cans that have been open for too long here. I'm learning my RK and have found some improvement by adjusting my profile a little toward a faster ramp in the thermal load.

I'm wondering if this is *generally* better than a slow ramp (e.g., 10 degrees F per minute). I prefer a sweet-ish cup, and less on the malty.

I'm only going on air temp.

Any help here appreciated.

P.S. Generally, for a ~23 minute roast I'm at about:

7 mins drying
10-11 mins ramp to 1C
4-5 beginning of 1C to end of roast

That sounds like a baked flat coffee to me. 15min makes for a pretty darn malty roast. If you want sweet with low malt, you'll have to get to first between 7-10min and finish between 10-14.

I had a hunch.

Is this so even for a 7-pound roast?

So my drying would only go perhaps 3-4 mins, then--I suppose rapid ramp high heat to really charge the bean mass in order to hit first in that 10 - 14 window? I think I've been waaaaay slow in the early stages. I've hit first between 20-22 mins in some roasts.

Batch sizes shouldn't affect ideal profiles. That's too slow to 1C.

I wouldn't worry about splits right away. First find a heat level that gets you to 1c by 10min without any input.
After that, you might choose to worry about how balancing the time spent <310, 310-390, >390 affects the cup.

I have an RK drum also - it seems to me you are trying to use some advice you've read about other roasting devices and apply them to the RK.. I suspect that doesn't work. When I've tried to allow specifically for drying time, it slows the roast too much. I just crank it up and let drying take care of itself. I note that Shane Lewis recommends an air temp of 550-600 for a 4 pound roast with an expected 1st crack at 18 minutes. I don't know what to think about that time except that it seems too long. As a result, in my 4 pound RK drum I limit my roasts to 2 pounds, roast at 500-525 till 1st crack, which I typically get between 10 and 11 minutes - then I back off on my gas a lot to a temp of around 450 on my top thermometer to get 3 minutes or a little longer between onset of 1st and onset of 2nd crack. This gets me a nice roast. My hunch is that there are folks with bbq drums doing pretty big roasts - after all 20 pound capacity drums are being sold. But I haven't seen anybody's account of a nice roast, full of flavor that took say 25 to 30 minutes for say 8 pounds. I'd love to hear about them.

It sounds like your batch size may be beyond the heat transfer abilities of your roaster while maintaining a safe MET to avoid scorching. RK/BBQ roasters don't have air flow to add convection which aids in heat transfer. Similar to old style drum roasters. Many commercial drum roasters are found to be rated for a larger batch size than what is found by cupping to be the real sweet spot. Further, adjustments of batch size and MET must be considered with softer and harder beans. Also what your trying to bring out of a specific bean in terms of acidity will factor into the necessary speed during different phases of the roast. I find I can increase batch size and times when roasting what I call comfort coffee for the general public where extremes might not be so desired. I'll use med. quality beans with good base notes that can do ok with longer roast times.

Do you preheat the drum?

I can run the same grill settings (1lb batch, green) on a cold and hot drum, the time to first crack will shrink by 5-minutes on the hot drum.

For a cold drum I'll run the grill at 460F and hit first around 12-minutes and finish the roast no more than 5 minutes after that.

On a hot drum running at 460F, FC will hit at 8-minutes, again stopping no longer than 5-minutes after that.

Take into account that with a cold drum, the first couple to several minutes the drum is taking on the heat before it gets to the coffee.

I've learned that with the RK-Drum huge loads aren't the best route, trim down your batches, and follow your tastes. I've had stunning coffee from a cold-drum with first crack at 13-14 minutes and roast stopped at 17-18 minutes.

For me, the coffee seems to develop better in the slower, cold drum roasts. YMMV

Thanks, all, for your detailed answers. I think this will help set me on a better trajectory.

If I understand the recommendation above ("Batch sizes shouldn't affect ideal profiles"), then does that mean I could have a FC roast of two pounds, four pounds, six pounds, that all reach 1C and end of roast at roughly the same time? And this is achieved simply by cranking up or down the heat?

Tim, yes, I preheat the drum. Yours is a surprising recommendation. Do you go back and forth between preheat and no preheat depending on your specific goal? I'll try without for a few rounds and see what I come up with.

A little more info: I'm using the eight-pound RK. I've roasted as few as two pounds and as many as seven. Usually two to six. I always get "good" results, sometimes, as you said, stunning. I've had batches in the RK brewed in my siphon that have boggled the mind (mouthfeel, flavor, etc.). But more often it is just "good" in my demanding estimation.

No, I try to always start with a cold drum. Luckily I am usually only doing one batch at a time.

Judging from my experiences with my RK Drum what I read with most people using the drum is they a) overload it horribly or b) roast way too long.

I'll take one pound of green to First Crack at 12-13 minutes (no sooner) and end the roast (City) at 14-15 minutes (hopefully not any slower than that) and Full City at 16-17 minutes (at the latest). I cringe when I hear people taking 18-minutes (or even worse 7-8 minutes) to First Crack in the RK Drum. I've not in my experience had any coffee properly develop per my tastes with those time frames. Something else I"ve learned is that it doesn't take a huge thermal charge to get there. My roasts rarely top 475F-480F at any point, most average around 460F. The coffee looks so much better and the aroma compounds stay intact.