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Homeroasters.org » BUILDING A ROASTER » Drum Roasters
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Dan's Direct-Flame Roaster
Dan
I ran across the direct-flame roasting method shortly before the HRO thread, "What's this roaster?" It turned out to be a Whitmee direct-flame roaster. Everything about these roasters is intriguing. They were among the first commercial roasters, and people claim that they produced "case-hardened" glossy beans of superior flavor. In case you missed the discussion, in a direct-flame roaster the flame is INSIDE the drum, and the coffee beans fall through the flame itself.

So, all of this combined to where I wanted to build one. In my experience, the better roasts are ones where the beans alternate between being on-the-heat and off-the-heat. To me, this is true roasting; the rest is just baking.

I made some design sketches and it turns out I have most of what I need, including the expensive part, a propane blowtorch. I'll post my sketches soon, and take pictures as I go. Hopefully, I'll learn about direct-flame roasting, and what the coffee it produces tastes like.

Dan
Edited by Dan on 03/12/2011 12:30
 
http://www.intactamerica.org
David
That sounds really exciting, Dan.
Please keep us posted and take lots of pictures along the way!
ThumbsUp
 
freshbeans
The should be an interesting one. What's the best place to propagate the flame?

Good luck. Looking forward to your progress. -Scott
 
Dan
Here's my current sketch, the design went through many iterations until it all came together. So far, the only thing I've bought are the two SS bowls from Sam's for $10 each. I'm sure there are many ways to do this. The chain is welded to the bowl rims, which is probably the most unique part of the design. The roasting 'ball' is supported on three points, the two sprockets and the handle bearing on the read (not visible in the sketch).
Dan attached the following image:
bollinger_flame_roaster1.jpg

Edited by Dan on 03/12/2011 14:03
 
http://www.intactamerica.org
dja
weed burner and a cement mixer I can see it now. and about 20 LBS beans in it, fire department would be all over me like the strips on a zebra.

interesting consept thou
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
 
freshbeans
Dan,
Another elegant design! Is the drawing done on the 'Old School' drafting table, or is it a program?
Thanks, - Scott
 
Unta
dja wrote:
weed burner and a cement mixer I can see it now. and about 20 LBS beans in it, fire department would be all over me like the strips on a zebra.

interesting consept thou


This I would pay to see...Grin

Dan: would the RC be preheated?

Sean
Sean Harrington
educate.
 
http://www.untacoffee.com
jkoll42
Nice! Love the smell of beans and fire in the morning!
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
coffeeroastersclub
Dan wrote:
Here's my current sketch, the design went through many iterations until it all came together. So far, the only thing I've bought are the two SS bowls from Sam's for $10 each. I'm sure there are many ways to do this. The chain is welded to the bowl rims, which is probably the most unique part of the design. The roasting 'ball' is supported on three points, the two sprockets and the handle bearing on the read (not visible in the sketch).


Looks like it would work fine, Dan. So the handle part just rests on some type of support so you can pick it up and dump when ready? I don't think you would need to have a typical grease packed bearing there, just a piece of metal about 1 inch thick as a support for the handle, with a rounded notch cut out for the handles support. The chain/gear drive you envisioned should supply all necessary support for the drum if you also put another gear on the opposite side of the drum (no motor attached). Then just rest the drum in both gears and the handle in the back rounded notched piece of metal and it should be fine, I'd think. Maybe a bit of grease on the rear rounded notch every now and then to stop any squeaking.

Looks cool. ThumbsUp

Len
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
 
http://www.coffeeroastersclub.com
Coffee makes the world goround
http://www.coffee...%93-part-1

www.coffeebeanintl.com/sites/all/files/u3/Whitmee%20Blog%20Photo%20%234.JPG
Edited by seedlings on 03/16/2011 10:31
 
Koffee Kosmo
Interesting
I have seen commercial roasters with the same concept
They are however at least 100 years old

KK
My web site > koffeekosmo.com.au I home roast and I like it :P
Blog - http://koffeekosm...gspot.com/
Bezzera Strega: BNZ MD74 Grinder: 5 Box hand grinders: Pullman Tamper Convex: (KKTO) Turbo Oven Home Roaster: CONA Glass Rod Syphon: Pyrex Brewer:
 
koffeekosmo.com.au
Dan
FYI: Click on the sketch to see a slightly larger version where the text is readable.

"Weed burner and a cement mixer." I think that's a perfectly reasonable next step!

Ya, just your typical isometric done with a drafting machine. My grandaughter was very impressed with the drawing. :)

"So the handle part just rests on some type of support so you can pick it up and dump when ready?" Right. Just a simple bushing should do the trick.

"Another gear on the opposite side of the drum." That's what I'm doing. It's an idler sprocket, which is the third of the three-point support. The center of gravity is always between those three points, so it should spin OK.

Thanks for the picture, CMTWGR!

Here's the Sievert 294202 burner that's on the torch I have. Its specs: Burner diameter 32mm, Gas consumption, at 4 bar 2000g/h, Effect 26kW, Made of high quality brass.
Dan attached the following image:
sievert_294202.jpg

Edited by Dan on 03/13/2011 04:41
 
http://www.intactamerica.org
Dan
Scott asked, "What's the best place to propagate the flame?"

I have no idea! Note that I don't show some sort holder for the torch in the sketch. I'm going to use some sort of free-standing, adjustable holder for the torch so I can move it all around until I figure out the sweet spot.

The large opening on the drum is to allow exhaust gas to escape. When I tried to do a roast using this torch in my sample roaster, the flame kept snuffing out. But then my sample roaster has a 1.75" opening.
 
http://www.intactamerica.org
dja
stick a piece of flat bar in the front of the roaster and grab one of them cheap Magnetic bases from Horrible Fright for a burner base, use a 1/8 inch pipe nipple in the burner with a needle valve for control.

that will give you front to back and height adjustments will also allow for setting the burner low and pointing it upward to keep the flame away from the mass in the bottom of the bowl.

David
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
 
allenb
Dan, if this turns out as good a coffee as I think it will it would be simple enough to make a great open source project in the drum category. Especially if you can keep most parts obtainable from kitchen and hardware stores.

Something to consider with the burner. The Whitmee looks to have a fairly low temp flame with a lot of orange in it. Is there a burner that can set up like your planning that would not have super high temp?

For those who haven't seen this yet here is one of the vids showing the open flame. You have to fast forward quite a bit to get to the roasting action.

http://www.youtub...I5wX2eIuvc
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Dan
Allen, I'm all for open-source design, especially here at HRO. I'll definitely do what David suggested--take lots of pictures and upload information. I certainly hope that this will work out to be something that people can make using what they have on hand.

For instance, I'm using the chain and sprocket drive simply because I have those parts and I can do light-duty welding. Someone else might want to use a direct-drive gearmotor. I wouldn't be surprised if we don't figure out how to make our own blow torch burners from scratch. There are lots of ways to do this.

I'm using the two 13 qt. mixing bowls because I wanted a size that my torch could handle. I think it'll do 3-5 pounds. I could see someone making a larger roaster using a big blow torch, or even a weedburner, and a SS drum from a washing machine or dryer.

I'm curious about the orange flame color, too. The Whitmees used natural gas. I'm pretty sure that the flame temperature is rather uniform. I figure that the orange flame color comes from burning chaff, and the presence of out gasses. Not positive, but I'll know for sure the first time I fire it up.

There are two types of direct-flame burners. The single-jet blow torch type, like mine, and the multiple jet pipe burners. I'm guessing that the smaller roasters use a blow torch burner and the large ones use a pipe burner.
 
http://www.intactamerica.org
allenb
I've looked over the video some more now and while it's hard to see the flame and where it's coming from it almost looks like it is coming from a single source near the front end of the drum aiming downward.

I think you're right on the reason for the orange color flame. Chaff, dust etc. I don't think it's from outgassing at this stage since it's orange immediately after ignition.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Some design considerations for a direct flame roaster,

You'll see with the Whitmee there is huge agitation. They've got the drum rpm up to a point where any faster would probably cause the beans to lock to the drum wall. I would imagine the beans are arcing across (from left to right to where they're hitting the 90 degree point on the right side of the drum. The high rate of agitation is needed to ensure the direct flame isn't going to tip or scorch.

If you use over-sized agitation vanes with a slight angle to keep the beans migrating forward it would require less rpm to keep them airborne.

BTW, I need to make a disclaimer, this is all educated guesses on my part.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Dan
Allen, I think you are right on all counts. The sprockets and cogged pulleys I happen to have will result in a drum speed of 75 rpm, 25% faster than typical. This should get a decent amount of loft to the beans. If I need more, I can just change the little cogged pulley on the motor. I'm also going to make the vanes removable so I can change their width, shape, and angle. It will take some fine tuning, but I'm not concerned.
 
http://www.intactamerica.org
coffeeroastersclub
Dan wrote:
FYI: Click on the sketch to see a slightly larger version where the text is readable.

"Weed burner and a cement mixer." I think that's a perfectly reasonable next step!

Ya, just your typical isometric done with a drafting machine. My grandaughter was very impressed with the drawing. :)

"So the handle part just rests on some type of support so you can pick it up and dump when ready?" Right. Just a simple bushing should do the trick.

"Another gear on the opposite side of the drum." That's what I'm doing. It's an idler sprocket, which is the third of the three-point support. The center of gravity is always between those three points, so it should spin OK.

Thanks for the picture, CMTWGR!

Here's the Sievert 294202 burner that's on the torch I have. Its specs: Burner diameter 32mm, Gas consumption, at 4 bar 2000g/h, Effect 26kW, Made of high quality brass.


Dan, how long of a flame does that sievert burner put out? I ask because I was wondering if it could be incorporated into your roast chamber on the opposite end from where you currently have it pictured, with the gas line inserted a bit loosely through the "handle" part of the roast chamber. (no solid connection to the end handle to avoid kinking the burner hose as the roast chamber turns.)

The end result being that the burner flame would be "shooting out" of the chamber instead of being directed in. However it would only be good if the flame produced by the burner was a short and not long as you wouldn't want the flame to exit out ot the roast chamber (bad). :(

The benefit of the above idea being that of a design incorporating the burner and roaster chamber as one integrated unit instead of a 2 separate things. ThumbsUp

I took some liberties with the image you provided, just to illustrate my example indicated above:

www.coffeeroastersclub.com/bollinger_flame_roaster1-crcmodified.jpg

Note that the image of the burner is of course inside the roaster drum and not outside the drum as it looks like in the picture. :eye-popping:

Len
Edited by coffeeroastersclub on 03/13/2011 16:19
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
 
http://www.coffeeroastersclub.com
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