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Cyclone Separator for Ground Coffee
As a small lot home roaster, using a Gene Cafe roaster, I'm currently building a small cyclone separator in order to remove the specs of chaff remaining after grinding (pics to follow in a few days). Anyway, I've read where chaff negatively affects coffee taste and although most of the chaff is removed by the roaster, there remains enough, after grinding, to tantalize one about its removal.

The system I'm building uses a small 1" port dust separator (Amazon), 1" hoses for sleep apnea machines, a small 12 vdc centrifugal blower, speed variable, and a small port venturi:

Hopefully I'm simply going to use trial/error (once system is built) to find the blower speed that will just separate the coffee from the chaff.

So, what do you think? Will there be a recognizable taste difference if this chaff is removed? Will this be a beneficial endeavor, or not worth the effort?
Edited by renatoa on 05/03/2022 12:22 PM
Some people is so worried even about chaff inside the bean crack, that is released at grinding time, so they designed a grinder who blows that chaff at grind time Grin https://en.coffee...om/airmill

For brew grounds, where silver skin is visible, you can simply remove it by blowing, with your breath.
Having the grounds in a container with lid, preferably transparent, you shake gently, to bring chaff at surface of grounds, then blow, shake again, blow... will be surprised how effective it is.
For espresso this method is not working because chaff is too small, same size as the coffee grounds, and can't be separate.

The really bad taste chaff is the burnt chaff inside the roaster, much worse than the chaff remaining after cooling.
Actually, it seems that chaff in the grounds has no taste, if it were to believe some people that tried to do a tea style drink just from chaff Grin
What should worry us about chaff inside the grounds is the channeling it creates, thus altering the extraction.
Edited by renatoa on 05/06/2022 10:44 AM
renatoa: that AIRMILL grinder would solve the situation but its initial price of $ 295. far exceeds the amount I spent to build this cyclone separator, as described. Note this separator IS for the removal of the bits of chaff that remain in the coffee after grinding, and not for the roast process, itself. My Gene Cafe seems to do a good job at that.
After my experience with breath blowing chaff, I think could be easy to reproduce the principle used by Airmill for an existing manual grinder, just create a 3d printed intermediate piece between the burrs exit and collector canister, and blow air from lateral slow enough to remove the skin and fines, but not affect the grounds free fall.
I don't see the need of a cyclone for such design... the critical point is to find the right airflow, not the separation.
And a small enough pump to not make the whole setup bigger than the grinder Grin
For an electric grinder though, the bigger grinding speed complicates the airflow tuning even more, imo.
Keep in touch with the progress of your build !
Will try to make a movie with me blowing the chaff my way Grin
Koffee Kosmo
Just use variable speed and variable heat - hair dryer

I used this method a decade ago and it may apply for your situation

I home roast and I like it. Designer of the KKTO
Roaster Build information

Blog - http://koffeekosm...gspot.com/

Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex,
(KKTO) Turbo Oven Home Roaster.
For anyone not familiar with the goal of this thread, below you have some grounds before and after... blowing chaff using breathing.
renatoa attached the following image:

Edited by renatoa on 06/30/2022 7:01 AM
Beam me up... Acaia Grin


Forget RDT, static is not evil, just need to learn how to remove chaff and fines smartly, not by mixing them into the grounds.
Well chaff from my small FB roaster was never an issue for me but testing my prototype TO roaster it is more of a concern. Need to work on that.

Has anyone put ground coffee in a clean ultrasonic cleaner, let the chaff rise and blow it off?
Beware, this thread is about the chaff after roasting, inside the bean crack.
It is released during grinding.
This video tell more:

...but beware, it is about influence of chaff in espresso roasts...
for brew chaff removal is even more important, chaff flakes creates in the coffee bed the equivalent of channeling in espresso puck
If I was to setup a workflow to do this at home I would try this.

1. Course grind (Pre-Break) with a conical grinder.
2. Remove chaff with my home made tool.
2. Grind for brew type using a flat burr grinder.

If you like silky gelatin like mouth feel for espresso you might want to try this double grind technique anyway.
For me both can be done better with a single ghost teeth grinder.
This type of burrs is the sleeper of brew grinders world, imo... hope to change with the launch of Sculptor grinder, which also includes a static chaff catcher.
Do you own a Sulptor, people have reviewed them but no one that I could see claim it can make Espresso using the combo ghost teeth burr (Turbo). The S versions have no ghost teeth on the burrs?
Not yet, I am on the KS bidders list, but I own other chinese ghost burrs grinder.

Considering the machining of ghost burrs, either pure version, as mine, either "hybrid" versions, as Timemore, is hard to believe is possible to cut so good matching teeth for espresso requirements.
The S versions burrs actually have no ghost teeth, just flat blades, more or less sophisticated, as you can see in the attached image, from KS project page

The 78 model has two rows of ghost teeth, one more than the 064 model.
renatoa attached the following image:


HarryDog wrote:

2. Remove chaff with my home made tool.

Dare to ask sharing hints about this tool ?
I have been testing using a low profile plastic dish (2 inch) I do the first grind into it then touch it to a running reciprocating saw. This causes a vibrating rotating wave in the container and I blow off the chaff as it works it's way to the top.

Thinking of ways to automate or I won't use this much past the testing phase.
Will see if I can find some very fine sieves and try pushing the air through it in a small tube chamber.
Sieving adds more grounds fragmentation if not done very gently.
Definitely not shaking, as we see in Kruve demos.
The cyclone idea of this thread seems the best and closest to AirMill idea.
Too bad the OP didn't updated us with the progress of his build.

An interesting device that I contemplated to mod for chaff separation is nasal baby aspirator.
Some models only suits this purpose, there are a lot of designs of this baby accessory, most of them not useful.
Need to figure a 3D printed piece to place between grinder output and collector canister, serving as aspirator coupling, and possible cyclone.
Just another idea in an endless list, that needs my attention Grin
Was thinking a simple column of air with the screen at the bottom, dump the grinds in, chaff is blown out, the sieve or screen just keeps the grinds suspended so air can move around the grinds.

Removing the chaff during the grinding would be far more elegant.

So far I say the cups are cleaner with more flavor clarity but how much is the loss of fines contributing to this? Double grind affects particle size as I need to grind slightly larger to maintain same flow rate.
Quickly patent the device name... Shock Fluid Bed Dechaff ! Grin
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