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Weird and Unconventional musings
oldgrumpus
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Posted on 03/25/2024 4:42 PM
Rhetorical question (no answer needed): The difference between a fluid bed roaster and a drum roaster is what?

This question led me to thinking. Hot air flowing over beans floating in air is the fluid bed. Why can't a drum roaster do that? Maybe it can. My thinking says that If I don't preheat my drum, the profile (the actual graph) will resemble a fluid bed profile. I put it to the test today.

That said, my drum is a whopping 27 lbs (12.5 kg). It takes a lot of heat to get it hot. My profile looks OK, but took longer than I was hoping because with 100% burner input (31,500 btu), my roast took 17 minutes with not enough time in development. But, even so, it tastes pretty good (despite not letting it rest!) Go figure!
oldgrumpus attached the following image:
3-25-2024_sonofresco_ethiopia_sidamo_no_preheat.jpg
Clever Coffee Dripper
Grinder: Macap M4
Roaster: Completed drum roaster project photos shown here:
Photos https://goo.gl/ph...Da6K4wfqw5
Videos https://www.youtu...Bd1NrdpSUH
Build thread https://homeroast...post_38189
 
Mike_Mathis
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Posted on 03/25/2024 9:39 PM
I have 3 roasters. 2 are fluid bed and the other is an infra-red carbon fiber filament lamp. I can't figure any of these out, but they are fun to play with. Now I've just about talked myself into biting the bullet. But even it marches to a different tune of the drum. I figure it will be my end-game, so I guess I will never experience the gas energy solid metal drum thing...................... unless I change my mind and get the BC-2 roaster. I'm confused at every turn. Absolutely zero constructive input to the gist of this thread. I suspect you may get the normal conductive heat -vs- convective heat, which has merit.

Thank goodness the bean succumbs to all of them.
*Kaffelogic Nano 7
*Skywalker V1
*2023 BC-2
 
Ben N
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Posted on 03/26/2024 9:54 AM
I wonder how much the fresh air exchange effects the profiles. I love drum roasted coffee, but I have a fluid bed... and its easier to click buttons on artisan than build a drum.
 
btreichel
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Posted on 03/27/2024 11:37 PM
A new thought (to me at least) is that while convection heating dominates in an air roaster, it is also more interactive with more beans more of the time than the time that a beans spends in contact with a drum. Also, while convection takes place in a drum roaster, its is much more 'gentle' than a fluid bed / bean bubbler type of roaster.
 
oldgrumpus
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Posted on 03/28/2024 11:08 PM
Drum roaster bean contact with the drum varies with how fast the drum is turning. This video shows the maximum speed a drum can turn without the centrifugal force actually pinning the beans to the drum. So a drum might mimic a FB roaster to some degree.

https://youtu.be/...dQFPuFyL63
Edited by oldgrumpus on 03/28/2024 11:13 PM
Clever Coffee Dripper
Grinder: Macap M4
Roaster: Completed drum roaster project photos shown here:
Photos https://goo.gl/ph...Da6K4wfqw5
Videos https://www.youtu...Bd1NrdpSUH
Build thread https://homeroast...post_38189
 
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