Chaff collector observations

Like many people here, I have been opening the little chute and vacuuming out the chaff in between roasts. I’ve had the feeling for quite a while that the vacuum isn’t doing a very good job. I bought an extra Chaff collector assembly from Sweet Marias and I can now change out the entire assembly in just a few seconds in between roasts even when the Bullet is hot.

For the last roasting session that I did, I roasted two batches of Ethiopian Dry Process (400g) beans. I didn’t use the vacuum and shut off the Bullet and let it cool to room temperature.

I put and endoscope camera in the vacuum port and looked at the Chaff basket. It was completly covered with chaff.

Without powering up the Bullet and with the fan off, I used my shop vac and vacuumed from the chaff port with a crevice tool on the vac and recorded the amount of chaff that was removed. The vacuum did not remove much of the chaff. This really wasn’t a very accurate test because normally the exhaust fan would be on in between roasts and holding the chaff against the screen of the chaff basket. I also opened up the bean loading silicone plug to see if more air flow would help dislodge the chaff, but it did not.

i took the cover off of the chaff collector assembly and mounted in on the bullet so that I could better visualize the setup.

(A lot of the chaff got knocked off when I took off the cover.)

I have noticed that If I am doing back to back roasts with chaffy beans, the second and third roasts have a lot more “noise” in the profile. (not smooth curves)

I am just sharing my findings.

You should be able to verify what I have noticed by holding open the chute port and using a small mirror and looking at the chaff basket.


Another observation that I have had is:

The first time I did a deep clean of the chaff collector and removed the stainless steel sheet metal barrier, I did not re-assemble it correctly and had problems getting the chaff collecter to ‘lock’ in when trying to re-install it on the Bullet.

What I found was:
you need to be careful to make sure that the locating button pins are fully seated in the bore of the sheet metal.

Not like this:

If you see a gap between the button pin and the sheet metal, you will need to wiggle the button pin until the shoulder of the pin aligns and then allows you to screw the pin all the way down.

If you look at the holes with the pin removed, you might see this:


The holes have to be aligned the same. (Concentric)


I usually roast a max of 5 batches, 454g each, before pulling off the chaff collector and cleaning.

My process is:

  1. Remove chaff collector box.
  2. Use shop vac to get most of chaff out.
  3. Remove metal chaff filter basket.
  4. Use toothbrush to clean metal chaff basket.
  5. Re-assemble chaff collector and remount.
  6. Clean other areas using shop vac.

I was suprised how much chaff you get from just one pound, especially Ethiopian Naturals.

Billc, excellent writeup and pics. Thanks for pointing out that potential issue.

Hi Shane,
I just watched a question and answer video from Roast Rebels with Steffen Lav from Aillio and he made the comment that depending on the beans being roasted that using a brush on the fileter basket isn’t enough, If you hold the basket up to the light, you can see that there is some buildup that he esitmates reduces airflow through the screen by 20% to 30%. I have noticed this also. (not the percentage of reduction, just that the screen is getting clogged)
One of the first things that I did was to buy an extra chaff basket and in between darker roasts with chaffy beans, I would pull the basket out, Vaccum the chaff collector and then put in the clean basket. Then I woud take the dirty basket and put it in a bowl of Cafiza for a few minutes and then rinse it and dry it with a towel and it would be ready to go.

I now have a complete extra chaff collector assembly that I can swap out in just a few seconds so as not to slow down my back to back roasting and have to wait for the heat in the drum to stabilize again.

I believe that I paid around $110.00 USD for the complete assembly.

This may be unnecessary for most people. If you have come up with a process and are getting good back to back roasts, then you don’t need to worry about this.

I am a bit OCD and can’t let it go… :sunglasses:

Another thing that Steffen points out: If the chaff basket does get clogged up and reduces the air flow, then your recipe (manual or automatic) will no longer be accurate because if the chaff basket is clogged, then F2 might be the equivalent of F1, and F3 might be the equivalent of F2. The bullet has no way of knowing that the air flow has been compromised.

My prejudice says he/you are right on the money. And no amount of testing says what a particular bean is going to do. As you say above it’s more of an issue for those that roast dark. I think yours is a good approach though it consumes time between/during roasts.

Also I have found a wire brush (something used to prep copper for soldering) works well for cleaning the tarry glue that sticks to the screen. Clearly Cafiza is a better answer, especially mid-session. The wire brush makes the screen material of the filter shiny but it does a poor job clearing the material from the tiny openings in the screen mesh- and that’s what blocks air flow.


Bruce: As you know all too well the eingineering mindset:

The elimination of variables leads to better consistency.

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I do see some residual “stuff” on the screen when cleaning mid-session, but that has been my solution so far. I am ordering another screen so that I can swap out for clean during roasting sessions and clean one while continuing the roast session.

I don’t know if this forum has stickies, but this is definitely a candidate.

Excellent info for anyone in their first year of Bullet roasting. I just found out I had been roasting for weeks with the pins loosened and was not getting proper connection, my airflow was horrible. “The invisible killer” because at a glance everything looks good, and you have to have the gumption and time to just do a rebuild.

I’ll also add that the bolt shafts can come out a little and that creates an air gap between the metal plate and the plastic casing. And once that happens, you get heat build up in the chaff box, and once that happens you get plastic warping, and once that happens, you get permanent airflow woes.

nice visual. Depending on coffee I roast I can do 3 roasts (usually 800g +) to 4 maybe before I have clean out the collector.

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