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Transparent Fluid Bed Design
Hello fellow coffee roasters. Like many of you, I started roasting using modified hot air poppers. That was about 4 years ago, but I found the quality, quantity and controls quite limiting. It also took many batches and a long time to roast a kilo... an upgrade was needed.

This fully manual 350g roaster was first designed using 3D CAD software. When the design felt right, I sourced for parts, 3D printed custom pieces, and hand crafted the current edition. Overall R&D took about a year, with multiple motors, iterations and materials being used and discarded.

The specs for the build are;
3 x 4000w SCR controllers
2 x 1400w heat elements (taken from 2 hot air poppers)
1 x 240w stick vac blower

I'll try to keep with the thread and any updates, for example when I have a new version running an Arduino with TC4. A video is coming too, but I'm still learning the video editing software...
CK attached the following image:

Edited by CK on 01/09/2019 12:57 PM
Hey, it looks quite interesting! Looking forward to the video.
The cyclones mounting position seems strange for me, the airflow seems reversed, how will they work ? Where goes the chaff in this scenario ?
:need confused/puzzled emoticon: Grin
There is only one active cyclone on the left side. The other one was cut (right side) in half and you only see the top cap of the unit, there is no bottom. This was done so I could use the same high temperature 3D printed mounts for both sides... a little more cost, but keeps it looking symmetrical.
Still... how is the air path, and where goes the chaff is a mystery for me...
I guess you want to implement some kind of air recirculation, but not get it... the big picture.

For those interested into air recirculation without any headaches, filtering and smoke /catalytic burner, I might have a brilliant idea... :)
I'm at work now, but later I will provide detailed build images, and a video that shows the machine function throughout the roast cycle. This unit doesn't have air recirculation. It can roast a 350g batch to city+, while spending about 425 watts of power from the utility company.
That's really impressive, eager to see this achievement, almost unobtainium, until now I thought I am the least power hungry, with 900 W for 500 grams, in a TO setup.

Or, maybe you mean 425 Watt-hour, which is more realistic, but has a different sense, assuming 10 minutes roast time it equates to 425 * 60 / 10 = 2550 W power consumption.
Your 2nd paragraph is correct... about 6 batches an hour using around 2550 watts.
Edited by CK on 12/12/2018 6:58 AM
A video of the transparent roaster during its first 300g test.

Edited by CK on 12/25/2018 5:06 PM
Nicely done, cool design.
ECM Synchronika
Ceado E6X
Bread Machine Heat gun formerly, here to find a better mouse trap.
D'oooohhh... dumb me... I thought you roast in both sides, that why I was puzzled about air/chaff circulation... Grin
This was the source of confusion: "2 x 1400w heat elements"

Does the RC cover, taken from a second cyclone, requires a cut job, or you succeeded to dismount the cyclone in the two component parts ?
Impressive. It looks like a very well thought out design!


Does the RC cover, taken from a second cyclone, requires a cut job, or you succeeded to dismount the cyclone in the two component parts ?

The aluminum cyclone is one piece and needed cutting. Here's an image of the underside of the RC and CC lid with the solution that worked in this setup.
CK attached the following image:

Edited by CK on 12/15/2018 3:53 PM
Here's a view of the connection point for the RC and CC top.
CK attached the following image:

Edited by CK on 12/15/2018 3:54 PM
Very nice indeed! I really like the spouting action. It stays very fluid throughout the roast with a large % of the bean mass being lifted which is hard to accomplish with many builds.

Let us know how the roasts turn out.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
Thank you allenb. The roasts turn out really good compared to my old hot air popper roasts. (No comparison really) This machine allows me to draw out the profile in a proper way... slowly, albeit manually at present. I have to say there is a lot to learn about roasting, and what is best for my bean varieties from Peru. Any suggestions?

The spouting action was made better by using SS mesh from a MAF (mass air flow) from a spare car part. Very fine wire and strong. This allowed me to narrow the inlet with minimal resistance, upping the air velocity, and imparting more kinetic energy to a focused point in the center of the bean mass.

The limits of the food grade high temperature silicone in green is supposed to be stable to 450F, but I called the company and a technician/engineer said it should be fine with fluctuations to just about 500F. The inlet area part may be re-cast using a lead-free pewter that is good to a higher temp to allow more versatility in future roasts.
Wiz Kalita
Very nice! Looks both beautiful and user friendly.
Honeycomb MAF mesh is looking cool Grin

Nice job.

6 batches an hour? 10 minute roast, including unload/load?
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".


6 batches an hour? 10 minute roast, including unload/load?

Not really. That was one example of roast time to show power consumption. It really depends on the profile that is desired... long roast or short roast. This is controlled manually with the POT's for desired heat level.

There is also a few minutes (2-3) to cool in the RC, and say a couple minutes for unloading/loading and assembling the RC. So with that profile, 4 complete batches per hour would be reasonable. Thanks.


Hey, it looks quite interesting! Looking forward to the video.

The video has been updated. Here's a picture of what internals are inside the body.
CK attached the following image:

Edited by CK on 12/20/2018 2:50 PM
Here's a view of the air passage holes with duct work removed.
CK attached the following image:
This is the top side taken apart to insulate the heater. Without ceramic insulation the regular PLA plastic covers melt/deform easily. I did experiment with high temp 3DK TOP PLA filament. It is food grade, and can withstand temps to 230C, however, when annealed, it shrinks about 3-4% which makes it a challenge to design to specification.
CK attached the following image:

Edited by CK on 01/09/2019 2:43 PM
Here's a video showing the custom HEPA filter on the intake side.

Edited by CK on 03/17/2019 1:45 PM
Great info!

Can you tell us more about the logging setup you are using? It looks like a thermocouple connected to a tablet?

And what are the three displays for?
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