The New Roaster

December 26th, 2022, 2:33 pm

I finally made a short video of the Roaster908 in action. Driving this machine with power-based profiles took a while to learn, but based on batch sizes of about 2 pounds it works pretty well now. The machine is nimble, with low thermal inertia and can turn its environment temperature quickly, following most profiles one desires... almost like a fluid bed roaster. Processing a batch takes about 11-14 minutes, plus about 3-5 minutes for bean cooling. I've put around 100 kilograms of beans through it in the past 18 months.

#2: Post by **Chert** » December 26th, 2022, 3:27 pm

Nice video!

I like what I see, but I would draw the air through the cooling beans mass and exhaust it out of the roasting room.

#3: Post by **lagoon** » December 26th, 2022, 4:35 pm

What is the maximum payload of this one? 1kg?

December 26th, 2022, 6:24 pm

Chert wrote:I would draw the air through the cooling beans mass and exhaust it out of the roasting room.

Thanks, and I agree. That would have been preferred, but the compact footprint didn't allow for a high-temperature exhaust fan to be installed. Maybe a future mod... This build uses the same inlet air blowers for heating as it uses for cooling.

December 26th, 2022, 6:29 pm

lagoon wrote:What is the maximum payload of this one? 1kg?

Yes, it was designed as a 1kg machine. I generally roast about 900 grams at a time... this size batch works well for 3 valve bags of 250 grams yield.

#6: Post by **smite** » December 26th, 2022, 7:22 pm

Interesting design. Would be nice to see some roast profiles vs drum and also a look at the exhaust and cyclones.

#7: Post by **Almico** » December 27th, 2022, 9:09 am

From my experience with fluid bed roasters, making lots of minute power changes to steer a roast to a particular profile does the coffee no favors. Also, it is rarely desirable to increase heat at any point throughout a roast. Best results are achieved by energizing the beans as much as possible in the beginning, without scorching or tipping, and gradually decreasing heat as moisture evaporates.

December 27th, 2022, 1:57 pm

Almico wrote:Best results are achieved by energizing the beans as much as possible in the beginning, without scorching to tipping, and gradually decreasing heat as moisture evaporates.

Much thanks for your professional experience and advice. I have experimented with a lot of profile shapes while learning how this machine reacts. There have been both, wonderful results and some not-so-great results... trial and error. Much of those results seem related to the original greens.

December 27th, 2022, 2:01 pm

smite wrote:Would be nice to see some roast profiles

Here's one recent profile.

December 31st, 2022, 7:19 pm

Here's another profile I tried today using Almico's experience of steady high heat being the best, and then tapering off the heat at the end. The machine ran at 84% heating power. This roaster is basically a fluid bed machine that uses an agitator (electric hot air roaster) for improved bean movement. It was my first time roasting this particular bean type... looking forward to sampling this in a few days.