So, Sundays batch helped me develop some consistent findings as far as how my roaster operates under normal conditions.

I'm keeping all my batches at 150g for now, and having it wired up with two thermocouples plus the analogue thermometer that came with the unit, serving as an ET probe, helped guide my decisions.

I keep finding consistently, I can't get my BT up to 220 for a drop in, with the fan off and the amperage set only at 5. It sits at 198-202. But this only applies to the first batch. Once the mass of beans helps retain additional heat in the drum, it's easy to keep it at 220 at 5 amps after cooling a batch down with rear cooler, even with the fan back to off, it will stabilize at 220 easily.

The basics of this roast found 1C hitting right at 195, on all 3 batches, quite loud and vigorously. My times to 165 are still quite delayed, a great deal of my time in the roast is spent getting to and just past the drying stage. On this roast, wanting to stay at only C+, I wasn't able to time a period between 1C and 2C, but I didn't want to drop the roast the second 1C ended, the beans didn't have the appearance of a C+ yet, so I let them go a bit longer after 1C, usually around 20 seconds after the end of 1C.

My long post ( I apologize if these bother some) but it's the only way I can learn and share; leaves me with two difficult questions; 1) If MET shouldn't exceed 250 ideally ( and it never got close on my analogue ET thermometer) what should I do about seeing my ET thermocouple that sits right outside the drum that registers a much higher temp? ( 296C- 323C) at times during the roast. This is installed in the upper M4 Allen head bolt that holds the drop shute in place, according to the instructions.

I think I'm left with two options to get my roasts thru the dry down phase quicker without such a precipitous temp drop, One, is to start the warm up at 7 Amps, and let the fan trickle at about 3, which seems to get my BT up to 220 in a reasonable time. I use the warm up period to get everything else prepared, but really, I don't need 30+ minutes to try to establish a drop in temp.

Or my second of two options I'm toying with is to do what I did on my third batch. I dropped in at 220 from a stable 5Amp/0 Fan setting, but had to quickly ramp up to 7 Amps and a bit of fan, to help me push up to a BT of 165 to get thru the dry down phase as quick as possible.

All of this also leads me to strongly consider insulating my M3. I think I'll be able to retain those higher initial BT readings, with less fluctuations, and less drop in temp when starting, if the whole mass of the drum is greater.

Every time I roast in my kitchen, the ambient temp is 71 degrees. My humidity levels don't seem to change, being so close to the ocean, and my storage seems to be stable, so I think I have a nice stable baseline to start from.

1st 150g batch finished at 11:15 -213BT


2nd 150g batch finished much faster due to a initial BT of 220 and my faster race thru the dry down. it was done at 9:30 -215BT


3rd 150g batch seemed dialed in the way I wanted, both tweaking the drop in temp, yet moderating the ROR to finish where I wanted at 11:35 - 215BT


I look forward to trying all of these, starting with the 3rd batch.

I'm open to input from anyone with experience with the outside the drum MET measurements. There's just no way I can see myself getting to a 220BT without having an elevated MET on that thermocouple beyond what others are saying is unsafe. But the inside of the drum is never getting close to that. I don't think I exceeded 235C on any ET on the inside of the drum.

This morning, batch 3 had some very bright fruit notes. Predominantly peach and tons of jasmine tea. It was like Don Pachi Lite.

I don't think there's much convective heat when the drop in door is open. It just allows you to smell the vapors. As heated beans are giving off moisture, it's going to vent thru that lid easily. If you had the lid closed and no fan, I'd imagine you'd have some difficulty with stalling at only 5 amps from the drop in. Even a mild fan speed will allow for convection to occur, drawing air out of the unit. Since the drum isn't air tight, the fan will pull that moister air out and dryer air will be entrained.

Hot dry air "cooks" things a heck of a lot slower that hot moist air.

The geisha was good, but quickly fading after day 5. I finished the last of it yesterday afternoon.