An update. In short, I have had some success and some improvement, but I’m still not where I’m comfortable using the R1 for production roasting except for one coffee (and I need to scale that up to 1kg if possible). @pnrenton had posted a recipe on the FB group that he had found to work for a number of different beans. This used a 760g batch size and looked like a reasonable profile to try, so I roasted three different beans, back to back. I blind cupped them the next day and since then have been tasting them as V60 brews using Gagne’s method of 22g coffee, 212 F water to 374 g of water. I grind all V60 brews on a 1zpresso k-plus and note that grind setting.
The profile I copied is here: Roast World - Cup, grade, and analyze your coffee roasts in depth
Visually it looks like this:
The first coffee I roasted was Guatemala La Morena Cabulco (from GO). Altitude: 1600-1800 MASL. This coffee as a V60 is fantastic: no bitterness, very round sweetness and chocolate notes. It tastes similar to the roasts I do on my Artisan 3e fluid bed air roaster (where I never had trouble with scorching). The profile:
The second roast is the Costa Rican Tarrazu Honey that I had trouble with up above. Altitude: 1200-1750 MASL (grinding this it feels like most are lower elevation). On cupping this it had a mild grassy, strawlike flavor, indicative of being underdeveloped. I saw a lot of burnt chaff during the roast, but the beans looked fine. However, I’ve now tasted this at two different grind settings and it is clearly burnt. This is the only one I’ve measure color on. Agtron: 56/79, which is a typical delta for this roast level, though I like to have a delta that is lower.
On cupping the third (Mexican Chiapas) I noticed a mild burnt flavor. Altitude: 1750 MASL. The beans looked fine, but as a V60 it is definitely burnt. This one also shows a crash and flick.
So I really need to get close to a 1kg batch size on these, but I hate to waste so much coffee.
For this latest profile I wonder if starting with F3 would help. I would rather have as much convective heat as possible, rather than conductive heat.
Soak at a lower power, such as P7 until turning point.
Lower preheat temp.
Slowing the roast on the two burnt coffees to a 6 minute yellowing time and 10 minute first crack is probably best. How to get there on the R1 is, in part, why I bought it. On the PID controlled 3e I just draw a curve in Artisan and the roaster follows.