20 Batches in a Row on the Aillio Bullet R1 Coffee Roaster …here’s what to expect

Roasting on a Bullet coffee roaster requires some awareness of maintenance and cleaning.

The reason we tout the Aillio Bullet R1 Coffee Roaster as a potential shop roaster is because it can manage 2 lb roast batches with relative ease and roasts while cooling coffee simultaneously, making it an ideal candidate for roasting back-to-back. But we hadn’t really tested how consistent the roaster is from one batch to the next. So when the opportunity to provide 30 bags of coffee for charity came up, I knew it was time to see how well-suited the Bullet R1 is for a big job like this.

OK, exactly how much coffee is 20 batches? That all depends on how much coffee you roast and how dark your roast level is. Darker roasts lose more weight than light roasts and will require more green coffee to reach your desired output weight.

For my project, I needed 30 x 325 gram bags of roasted coffee, or roughly 22 lbs. I tend to gravitate toward lighter roasts, and for the Colombia I chose to roast for this, I was shooting for something like 15% moisture loss green-to-roasted coffee. Some quick napkin numbers helped me deduce that I needed at least 26 lbs green, which led me to settle on 20 x 600 gram batches of coffees to hit my mark.

Cold air is sucked in the front of the Bullet and warmed as it passes beneath the drum, meeting the cool air intake at back and circulating across the drum and up through the top tube, exiting at the rear.

I know the Bullet can handle 800 grams+. But running any roaster at max capacity tends to slow down roast progression. I prefer the complex acidity that comes with hitting 1st Crack (“1C”) around 8 minutes in the Bullet, and in my experience with my particular R1 that is still running the old PCB, 800 gram roasts stretch 1C well beyond that mark.

The roasting is done and so I’ll get right into performance and a few observations. All in all, I was very pleased with how consistent the Bullet performed across all 20 roasts. Save the warm-up batch and any “operator errors”, replicating my initial roast parameters was easy, the roast legs close, as long as I remembered to make my changes in heat and airflow at the same times.

Roast Time graph from roast #6 of 20 – green line is drum temp, purple line IBTS sensor temp and pink line rate of rise 

I kept my profile simple so there weren’t too many twists and turns to remember (or forget!) making replication easy.

The gist: I started with heat high, slowly tapering off before 1C. Drum and airflow are low to begin with, ramping up toward the end as to slow down the rate of rise and pull chaff off the roast.

The specifics: I started with settings P9 (power), F1 (fan), D3 (drum speed). At 4 minutes in, I increased fan and drum speed to F2 and D4. Once I was 20F degrees from 1C (350F – 1C happens around 370F on my roaster), I decreased power to P8 in order to start slowing roast progression. At 1C, I increased fan and drum speed to F3 and D5, and 1 minute later increased fan speed to F4 and decreased power to P7.

I replicated this roast as best I could across all 20 batches. You can “replay” a roast on the Bullet, but that’s not what I did for this test.

I should also note that I’m roasting back to back without letting the roaster cool down to the pre-heat temperature that I have set to 400F. This meant that after dumping a roast in the cooling tray, closing the roaster door, starting the charge sequence and weighing out my next roast batch, the roaster temperature dropped to about 440F. If I were roasting a softer, less dense bean, I would likely let it cool down much closer to the pre-heat temp to keep from scorching the coffee. But the Colombia is very dense and has a slightly higher moisture content than most, absorbing a lot of that extra energy after entering the roast chamber.

So how consistent were my roasts? Very consistent. Below is an overlay of three roasts at different intervals to illustrate, roasts #6, #12 and #20.

Overlay of Roast Time graphs for roasts #6, #12 and #20

What stands out to me in this graph overlay are the fact that the drum (green) and IBTS/bean (purple) temps are nearly identical across all three roasts. Though rate of rise (“ROR” in pink) is somewhat erratic, that’s to be expected. I have ROR set to update every few seconds and the temperature is bound to vary slightly depending on where in the bean mass the IBTS sensor is reading. It’s also worth noting that 1C time for all of the roasts was right around 7:45.

Key takeaways from the experience and recommendations for roasting multiple batches back-to-back:

  • Start with a clean roaster. Don’t set off on a lengthy roast session like this with a dirty roaster as you’re likely to damage the machine and can even start a fire.
  • A warm-up batch is HIGHLY recommended as they tend to run  longer than the successive batches and will taste different.
  • I vacuumed the chaff from the access hole on the bottom of the chaff collector every 5 roasts. I would recommend more frequent cleaning if roasting a natural or honey process coffee since they produce more chaff than washed. Failing to do this will likely cause a fire.
  • Check the cooling tray filter and vacuum between each roast. See the photo of mine below after roasting 20 batches. I was able to clean it up enough to continue using, but it’s good to have a few of these on hand to make sure air is flowing freely.
  • Don’t try to fit too much in a single day. 20 roasts took about 3.5 hours. While this isn’t a terribly long time, I worry that too much coffee through the roaster without a deep cleaning in between is dangerous.
  • Perform a deep cleaning after the roaster has cooled.
Check the cooling tray filter often. If it’s too gunked up for air to pass through it, replace it!

All in all, this was a very informative exercise. We know the Bullet R1 is a capable and consistent 2 lb. roaster, but the test helped put into perspective just how well it performs across a marathon of roasts. As with any roaster, the Bullet should be cleaned regularly between roasts, and in the case of roasting several batches in a row like this, you should vacuum the chaff drawer every few roasts to avoid a potential fire. None of this is unique to the Bullet and just part and parcel with roasting large volumes of coffee, which the Bullet R1 is certainly capable of.

Other Aillio Bullet Coffee Roaster Information

Our Aillio Bullet R1 Resource Page

Our Bullet basic cleaning guide

Aillio Bullet Sample Roasting Video

Our Video of the .pdf in action

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