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Restored Homebuilt Drum Roaster
allenb
Top  #1 Print Post
Posted on 10/27/2023 5:11 PM
I thought I'd post a few videos showing my old 1995 home built 1/4 lb electric drum roaster that I recently restored back to original heater and drive train. I had made all sorts of mods that never worked out well and decided to go back to the original layout. Glad I did as it's again roasting some good coffee.

1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Top  #2 Print Post
Posted on 10/27/2023 5:20 PM
Another video during a roast. The 600F + ET seen on the Arduino readout is the temp below the drum. By the time the air enters through the drum perforations, it's much lower. You'll see some chaff blowing out of the funnel but the majority of it ends up leaving the rear of the drum and down into the collection area. This design has forced very hot air coming up from below the drum, in through the perforations, across the coffee going back towards the rear perfed drum plate and out through the rectangular exhaust stack with screen to catch stray chaff particles.

1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
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Posted on 10/27/2023 5:22 PM
Another
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Top  #4 Print Post
Posted on 10/27/2023 5:24 PM
One more

1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
HarryDog
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Posted on 10/27/2023 5:36 PM
Well I think it's cute!
Did you model it after the Bullet?
 
renatoa
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Posted on 10/28/2023 1:53 AM
Does Bullet exists in 1995 ?
Aillio.com creation date is 2013-04-14.
 
HarryDog
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Posted on 10/28/2023 4:56 AM
Oh well I never paid much attention to the date as I was looking at the roaster, very nice!

Looks like Youtube just implemented a new round of anti Ad blocker blocking.
No longer see anything using a blocker.
Edited by HarryDog on 10/28/2023 5:07 AM
 
renatoa
Top  #8 Print Post
Posted on 10/28/2023 6:08 AM
Here works, on Opera with embedded blocker.
 
nickr
Top  #9 Print Post
Posted on 10/28/2023 8:48 AM
Very nice!
 
allenb
Top  #10 Print Post
Posted on 10/28/2023 10:56 AM
Thanks! This was a real fun project. On emulating the bullet? I think those guys were probably still in high school when I built this one.
I luckily had a very capable sheet metal shop to fabricate/weld the aluminum body for me as well as another shop to form my drum and weld the vanes in.

I've been doing a lot of experimentation with this roaster on roast development and as with a recent post where renatoa mentioned in the 1lb FB hopper roaster thread, a shorter development time, 8 min FC and 1:30 final phase, I'm finding great results with a 7:15 FC and 1:30 development. Longer roasts and or longer development kills much of the floral and spice notes. I've come to a point where my philosophy is to roast no longer than absolutely necessary to achieve full flavor notes and as light as a coffee is willing to allow.

I've also come to the conclusion that the only reason to take a coffee beyond that is to mask green coffee defects. This is only related to brewed coffee, not espresso obviously.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
renatoa
Top  #11 Print Post
Posted on 10/28/2023 12:42 PM
Could be a kitchen pot suitable for the body, if finding the right size ?
I means the stainless steel 0.8mm thick, as they are usually using to build pots of such size.
For example a 16x28cm 6 litres pot, as attached image.
renatoa attached the following image:
image_2023-10-28_204243278.png
 
nickr
Top  #12 Print Post
Posted on 10/28/2023 2:23 PM
What are you using as a drive motor? I think a drum built is next for me. I’m thinking of using quartz heaters but can’t decide on perforated or solid drum.

Also in addition to pots, stainless steel Bain Marie make good options for smaller diameters that have some length to them
 
CK
Top  #13 Print Post
Posted on 10/28/2023 2:37 PM
What a beautifully made machine Allen. It's amazing what some elbow grease, creativity, and quality-made parts can do. You've built a machine that has lasted for decades. Bravo!
 
allenb
Top  #14 Print Post
Posted on 10/29/2023 9:05 AM

Quote

What are you using as a drive motor?

A shaded pole (C-Frame) fractional hp gear motor with around 105 rpm output. I used a synchronous belt and pulleys to get rpm down to 90.

Quote

I’m thinking of using quartz heaters but can’t decide on perforated or solid drum.

Perforated or solid depends entirely on how you will accomplish air movement in and out of the roaster. And, if perforations are solely for allowing hot air to convect up through the drum wall onto the coffee or if perforations are for radiant heat which in that case the perforations would need to be a very large open area % and radiant heat source mounted out of the path of falling chaff/debris.
Edited by allenb on 10/29/2023 9:11 AM
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
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Posted on 10/29/2023 9:12 AM

Quote

What a beautifully made machine Allen

Thanks CK! I appreciate that. All I had to go by in those roaster building days was looking at a British racing green Probat L-12 that was used for all roasting at a place called the Brewing Market in Boulder Colorado. The head roaster let me lift the hood many times and was a great resource for all things roasting. I obviously didn't follow the heating plant and air flow design but did what I had the ability and resources to do.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
HarryDog
Top  #16 Print Post
Posted on 10/29/2023 5:14 PM
Hello Allenb, I would like to ask a couple of questions about your current roast approach.

What is the time to your Dry End?
Do you know the bean temp at drop?

I know this will change per bean/moisture content but will give me a couple of targets to shoot for. My first 4 intentional light roasts are resting now but I'm starting longer to see how the flavor changes for me as I drop the FC times. Not sure what bean temps I should be targeting? Once I get to the FC range I want to try a few bean temp changes to see how much a difference it makes as well.
 
renatoa
Top  #17 Print Post
Posted on 10/30/2023 3:34 AM
Roast time ranges are a matter of heat transfer method, i.e. machine build.
The higher the convection, the lower you can go with roast time.
"you can" having the meaning as "you are allowed"
The other way to reduce roast time, without increasing convection, is by increasing temperature, with the risk of roasting defects, or unbalanced roast of beans core versus surface.
Increasing convection could be done either by airflow, either by agitation.

The above are valid for majoritary convection roasting, i.e. hot air machines, either fluid bed, either mechanical agitation.
When you have also a quota of IR in the mix, good recipe for headaches... Shock
 
HarryDog
Top  #18 Print Post
Posted on 10/30/2023 8:59 AM
So far all looks ok, taste test in two days. FC was at 8:50
The Ethiopian Abyssinia Aroma is very Blueberry.
Hope I still have what I call Bakers spice, ginger, nutmeg and a touch of cinnamon?
 
allenb
Top  #19 Print Post
Posted on 10/30/2023 10:37 AM

Quote

HarryDog wrote:

Hello Allenb, I would like to ask a couple of questions about your current roast approach.

What is the time to your Dry End?
Do you know the bean temp at drop?

I know this will change per bean/moisture content but will give me a couple of targets to shoot for. My first 4 intentional light roasts are resting now but I'm starting longer to see how the flavor changes for me as I drop the FC times. Not sure what bean temps I should be targeting? Once I get to the FC range I want to try a few bean temp changes to see how much a difference it makes as well.


Time to yellow (dry end) is around 3+ minutes, bean temp at drop has been around 415F with first crack occurring at 400F.
I want to emphasize the importance of maintaining sufficient rate of rise during the development phase. Be sure to go in with sufficient heat to allow rate of rise to never stay more than a couple of seconds at a rate less than 8/min and should be closer to 10/min.
For testing purposes, scale everthing I mentioned on temperatures to your particular temp when first crack begins.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Top  #20 Print Post
Posted on 10/30/2023 3:23 PM
I want to point out that my batch size being 113 grams or 1/4 lb allows me to easily do an 8 min roast without any negative issues but with my 1 lb drum, 8 min roasts do not develop all of the possible attributes of a given green coffee. Your 1 lb fluidbed may fluidize the batch sufficiently to allow a short roast and cup nicely but when I was doing 1 lb fluidbed roasts, I needed at least 10 min to produce the best a coffee could do.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
HarryDog
Top  #21 Print Post
Posted on 10/30/2023 5:29 PM
I have been testing 1/2 pound only on the light roasts, I don't think 1 pound would be very even? We were down to -26C already, Roasted at -5C on Saturday.

My plan is to add a little heat after TP then more when it recovers to charge temp, continue about the same over the middle stage and drop a bit after FC and only add back half of what I drop? The current ROR was 11.9F/min.

I might need to add a bit of air before FC, will need to see how it responds to the changes.
 
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