Chaff not going in the chaff collector

Hi everyone,

I’m a new Aillio roaster, I’ve roasted 10 times so far and absolutely loving the experience. What a beautiful machine.

My question is about the chaff collector(s). It looks like there are 2 places where chaff gets collected: in the black plastic chaff collector at the back, and in the metal chaff collector inside it. Some chaff falls out the front during roasting, but that doesn’t bother me.

All of my chaff is ending up in the black plastic collector, and literally no chaff is getting into the metal one. Is this a problem?

When I look more closely at the machine, the chaff comes in the top from the exhaust and drops down into the plastic chaff collector. I can’t imagine how the chaff should be getting into the metal collector.

Could someone please clarify for me where the chaff is supposed to be ending up?

Thank you!

I think you’re fine. I can’t explain why but I find some types of coffee seem to produce more chaff that get trapped by the mesh filter. I just did a Kenyan yesterday and there was almost nothing in the filter.

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The black plastic collector is where the chaff will collect. The metal one is a filter for the exhaust fan and traps fine dust during roasting.

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The screen cup is the filter which is used in a counter-intuitive way: the chaff collects on the outside of the filter. When you remove the filter from the rubber seal, that seal scrapes the chaff off the outside of the filter. After a roast you should be able to easily vacuum the collected chaff through the hole where the filter mounts or thru the little rubber door (flap? whatever it’s called) at the lowest end of the collector.

Chaff also dribbles out the front of the roaster below the door. It’s just a gravity exit… no air pushing it. There’s a tiny gap between the front plate and the outer housing of the roaster. The interior of the drum actually has a very slight low pressure (compared to the room) which draws air in the rear of the roaster thru the central part of the drum and then out thru the air duct at the upper right of the roaster and into the chaff collector. The air then passes thru the chaff filter and into the inlet of the exhaust fan where it then exits the roaster.



Thanks for the clarification KK, Cash and Bruce! Great to know where things were meant to end up – and using a vacuum to clear the chaff collector is a great idea! I appreciate your comments :slight_smile:

How much chaff are you all getting in your beans at drop? I have a lot and wondering if its affecting my roasts.

The amount of chaff is dependant upon the beans and the process. Decafs have almost no chaff. Dry or natural process beans typically have the most chaff.

Chaff in the cooling bowl when you drop isn’t much of a concern for single batch roasts if you clean the chaff collector and screen after each roasting session. If you are doing back to back roasts, then it can make a difference.

The amount of chaff that will end up in the cooling tray is determined by several factors.

At higher Fan speeds, (the F value) more chaff will get moved to the chaff collector.

At higher drop temperatures there will be less chaff as it can burn off. BUT letting it burn off in the drum can lead to smoky flavors on the finished beans.

If the chaff collector screen gets clogged after a roast, then the heat in the drum will be different from the provious roast. The fan won’t be able to cool the drum the same as it did in the previous roast.

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“Use more fan to get the chaff out as it can lead to smoky flavors”-thx

I never had this issue with my gas drum as even at low fan speeds all the chaff was sucked out.

Hey Brian, I came here looking for a similar explanation. I “vacuumed” my chaff collector after my most recent roast and I swear there was next to nothing in it…now the cooling bowl was another story! I had to remove the hot beans/bowl just so I can vacuum the chaff clogging the fan so I can I cool it in time. Final fan speed was F4. Perhaps I’ll punch it up just before dropping, I just don’t want to suck out those last precious bits of momentum leading up to my finish. Have you played around more with this since?

I get virtually no chaff at the rear collecting area where the rubber dump plug is, the ratio from dump/cooling tray to the rear area is something like 80/20. It all staying in the beans.

I tried running higher fan earlier (F4 before yellow) on one of my last roasts but same issue. I’ll run it higher next time.

I also think I’ll try a roast without the collector cup and see what happens.

Thanks for the airflow path clarification Bruce.

From my experience with my Bullet that Seems odd. Just to confirm-

  • are you roasting with the bean chute plug in place? If that’s left off or if the funnel is left in the bean chute, that will cause the exhaust fan to pull air from the bean chute instead of the drum.
  • there’s a small seal between the (sort of) rectangular transfer tube to the chaff collector- you should be able to see it when you remove the chaff collector. It serves to keep the exhaust fan from getting air from anywhere but the transfer tube (again- sort of; it’s not a perfect pressure seal). If that seal is missing or damaged the air flow from the drum will be affected.


Edit- as a comparison I am getting enough chaff in the collector that I must vacuum the collector every other roast or the air flow will be affected to the point the Recipe-driven profile doesn’t track properly.

Which makes me think- have you run the Calibration on the exhaust fan? or for that matter confirmed the air flow exiting the rear of the Bullet? It would be pretty extreme but I wonder of there’s a exhaust fan motor issue… ??

Hey Bruce-

Thanks for your assistance.

I have the chute plug in place for most of the roast. I do gently lift a corner a bit to listen to 1C but the impact due to duration and amount of lift can’t be much.

I’ll check out the seal between the rear transfer tube and rear chaff collector.

I do vacuum the tube out between roasts (shop vac, bean chute plug off, hand briefly over rear transfer tube exit) to clear. There is usually not much in there or the rear chaff box but a ton in the cooling tray.

I’ve not calibrated the exhaust fan. Will read up on that.

I do lose a bit of chaff out the lower part of the front door during roasting but no beans. I think the door is shut pretty well but know it can leak sometimes. I did review SM’s noisy drum returned unit video. My drum is pretty hard to turn when off and makes a bit of noise but the spindle is only out the front by 1 mil+/-. I’ve not mic’d it.

I do the same- haven’t seen a noticeable effect.

I mentioned vacuuming the chaff collector to give you a sense of how much more chaff I’m seeing than the 20/80 ratio you mentioned. Just confirming for you that there seems to be a hardware problem. I only rarely see anything in the transfer tube, so if you’re finding something there to vacuum then exhaust air movement is probably lower than what I see.

You should see chaff dribbling out the front of the Bullet below the door- that’s an intentional part of the design. The fan located at the rear of the Bullet guarantees some air movement to carry that little bit of chaff out the front. It’s as it should be.

The drum shaft protrusion doesn’t sound in any way remarkable- probably just fine. The real criteria is the spacing between the front of the drum and the face plate. If you aren’t hearing any scraping and you aren’t getting beans trapped in front of the drum then it’s likely ok.

As a point of reference I roast at F2 till near the end of the roast when I up the fan to F3. I’m not using a huge amount of fan which of course would affect the movement of chaff. The only time the exhaust fan gets higher speeds is during the Cool mode when I’m shutting down.