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renatoa
11/24/2022 8:17 AM
Trick or... crack... er... Grin

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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 1:30 PM
 
David
That sounds really exciting, Dan.
Please keep us posted and take lots of pictures along the way!
ThumbsUp
 
JETROASTER
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 3:03 PM
 
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
 
JETROASTER
Dan,
Another elegant design! Is the drawing done on the 'Old School' drafting table, or is it a program?
Thanks, - Scott
 
Unta

Quote

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.
 
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

Quote

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
 
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 12:31 PM
 
Koffee Kosmo
Interesting
I have seen commercial roasters with the same concept
They are however at least 100 years old

KK
I home roast and I like it. Designer of the KKTO
Roaster Build information
https://homeroast...ad_id=1142

https://docs.goog...lide=id.i0
Blog - http://koffeekosm...gspot.com/

Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex,
(KKTO) Turbo Oven Home Roaster.
 
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 6:41 AM
 
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.
 
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.
 
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.
 
coffeeroastersclub

Quote

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 6:19 PM
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
 
Dan
Len, Making the gas line concentric with the rear shaft is a great idea, especially for version 2.0 I wouldn't be surprised if the old commercial units used that idea. I used that same technique on a parts washer recently. The washer's main drum shaft has two concentric fluid lines. One for the high pressure washer line and the other for the heated forced air drying ducting.

Puttng the torch fuel line into handle shaft adds more complexity, and build time, than this proof of concept prototype needs right now. After all, no one knows if it will roast better tasting coffee yet, and that's why I'm making this. I think it is a good idea and something to consider for the future, especially with larger roasters. One potential problem with it is that it limits the flame to being on the center line, which might not be the optimal position for roasting. I intentionally didn't show the torch holder in my sketch because I have no idea where the torch needs to be located and at what angle. The torch makes a 3-6" long flame.

Of course with your idea you could add elbows to move the torch around inside the drum, but then the fuel line would have to be fixed, which then means the durm couldn't be removable for dumping unless the entire roaster tilted and dumped. That's how I unload the parts washer, by tilting the washing chamber.
 
Coffee makes the world goround
What if , instead of making the gas line concentric with the rear shaft

then make the rear shaft THE gas line :)
make it hollow , and attach the burner head at the end , inside the drum

the non rotating nozzle could be pointed into the hollow shaft, and at the end the shower head for at soft flame
 
Dan
That would work well, too. Lots of great ideas coming out. Using a non-rotating hollow shaft with the drum having a bearing so it can spin is exactly how my parts washer works Of course you'd have to deal with a gas hose attached to the whole durned thing while removing the drum for dumping (or tilting it). I had company this weekend and needed to hang a new light over the range, so I didn't get very much done on the roaster. Pix soon.

Here's a page describing the parts washer I've been talking about. A picture being worth a thousand words. It's inspiration was a coffee sample roaster.

http://claycritte...washer.htm

claycritters.com/washer/pw7_small.jpg
Edited by Dan on 03/14/2011 8:03 AM
 
Beaner
I have questions about this direct flame concept. Is the intention that the flame will be touching the beans during the entire roast and will the tempature be ramped up as other roasting methods?

I am by far no guru on roasting but it seems to me that if the tempature control is by changing the intensity of the flame, and if the intent is for the flame to be in contact with the beans the entire roast, that the beans would be charred by the time the temperature is at the 1st crack point.

Or, will the flame be at a constant level (I would think low) and temperature control be some other means like venting?

It also seems to me that you would want a burner the length of the chamber containing the beans for even contact or am I missing something here.

Just my feeble thoughts.
 
Dan
Beaner, Those are all valid concerns. One of the reasons I'm building this is to answer them along with the $64,000 question: "Does this produce the superior tasting coffee they claim it does?"

From what I can tell and have learned so far, the idea is for the beans to pass through the flame occasionally. The drum lifts the beans and then drops them. On their way down they pass through the flame. Other than that, the flame isn't touching any beans. In essence, a rotisserie type of roasting: on-the-heat, off-the-heat.

The torch has a very good control valve. Full blast is 26,000 watts, it can probably be throttled down to 2600 watts. I think I'll buy some cheap Brazilian beans to test with!

If I happen to have the right torch, and I'm building the right size of drum for it, then who knows? Maybe home roasters will have another method to roast with, and perhaps another flavor profile to enjoy.
 
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