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Dan's Direct-Flame Roaster
Dan
I started assembly on V2.0. It goes much faster the second time around! I'll post pictures as I go. That's the cool thing about this forum, lots of pictures.

Here is the drum and drum drive ass'y. I'm using 4 spokes this time only because I've decided to use 4 vanes inside the drum, and that makes layout easier. The spokes attach to that 3/4" x 3" diameter hub. The hub slides over the gearmotor shaft. You can see the large drum-drive gearmotor on the upper-left and the little gearmotor I'll use for the cooling tray dasher.

claycritters.com/coffee/bollinger_flame_roaster/bfr-v2-1.jpg
Before welding, I located the center of each bowl and drilled a 1/2" hole. I put that temporary 1/2" rod through those holes to align the hub perfectly on center. That should eliminate drum wobble. Once the spokes are bolted on I'll remove the rod and cut out the bottoms of both bowls.
Edited by Dan on 11/30/2011 12:40 PM
 
JETROASTER
Very nice!!! What method did u use for locating center?
(I found the right angle method tricky on the bottom of bowls and such)
-Scott
 
Dan
Yeh, regular center finders are almost useless. I know, I tried. On the first version I found center using the swirl marks from polishing, they were pretty darn close. On the second version I traced the bowl rim on a board, find the circle's center, then positioned an indicator directly above. Then I slid the bowl back over the circle and marked the center directly below the indicator. It was only 1/16" off center from the swirl marks, so who knows where the true center is. If my lathe could swing 15" I would have found the center dynamically.
 
mk1
Dan,
Very excited to see the latest. Also glad to hear the swirl marks were that close because that is what I used. One bowl is drilled on my project so I'm thinking 20012 for the other. That looks like a pretty healthy gearmotor.

Mark
 
Dan
It is the Dayton gearmotor 4Z063A, 28 rpm, 50 pound shaft load, plenty of torque. I'm building this one with longevity in mind, whereas the first one was just a sacrificial prototype. I'm sure you could find a suitable motor at Surplus Center. One reason I got this motor was because it was enclosed.
 
seedlings
Love to watch your work Dan.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
mk1
Dan,
I'm making some progress on mine, holes all drilled, mounts somewhat prototyped, etc. I have my bowls latched at 180 so I can unlatch, pull a lever, one half slides back about 2" and the beans dump to a cooling tray directly below.
On closer examination of the Whitmee roaster video it appears the flames exit from a large diameter tube (3-4") almost straight down. What I'm wrestling with is the heat arrangement in my setup. Straight down flame seems to simplify the whole vane size, placement and to a lesser degree rpm variables. Burner design is last in my assembly schedule as I can run a pipe in straight or go 90 degrees inside the drum. I'd be interested to know if you can shed any light on the whole heating flame thing. How hot do the bowls get? Is there much distortion with heat?
Maybe I'm over-thinking the process about BTU's, flame spread and placement, but I'd sure like to bring my target a little closer in range. Any observations you might share would be appreciated.

Roast Strong!
Mark
 
Dan
Mark, The concept is new to all of us, so it is natural that we imagine the worse. The bowls get hot, but not so hot that they discolor. My bowls haven't warped or sounded like they were going to, and mine have the bottoms cut out, which weakens them a great deal. Long story short, don't worry about the heat.

There are two types of burners used in these roasters, venturi torch, and pipe burner. The pipe burners have a deflector across the top. I think that's so that the beans can't fall across the orifices and snuff the flames. In the Whitmee video I think you are seeing the flame coming out from the deflector. I would play around with the pipe burner position. For a CW turning drum, I'd begin with the pipe burner on center or right of center. Position the flame horizontally pointing towards the bean mass and so that the falling beans pass through the flame. Add a deflector strip over the top of the burner if you have problems with flame integrity.

On my second version the drum will tilt downward, dumping beans into a waiting cooling tray with fan and dasher.
 
mk1
Dan,
Thanks for your insight. I think you might be right about the deflector. I sure would love to see a Whitmee up close in action. With tilt added to your drum do you have to use "cement mixer" vane positions and shapes? Also glad to hear the heat isn't much of a problem as I have some low temp stuff for bearing support out near the ends of the shaft. We'll see...

Roast Strong!

Mark
Edited by mk1 on 01/01/2012 9:19 AM
 
Dan
No, not concrete mixer vanes. I'll tilt the drum 90? to dump. My vanes are parallel to the shaft with the ends tilted upward slightly to keep beans from falling out the large openings on the end. I also added angled then leading edges of the vanes upward to lilft the beans higher and get a good cascading action. That way the beans fall through the flame.
 
Dan
After a two-month work-related hiatus, I'm back on the BFR. I added a beauty ring to the front opening. It looks good, but is practical. The most important reason was to dampen vibration; the front bowl wants to ring like a bell. The other reason is to cover the sharp edge; this will make roasting safer.

claycritters.com/coffee/bollinger_flame_roaster/bfr11.jpg

I bent 3/8" aluminum rod into a circle (took two tries to get the diameter right because of spring back). After joining the ends with a tension pin I turned an angled surface to match the bowl's edge. It is held in place from the inside by eight #4 screws.
Edited by Dan on 01/16/2012 9:13 AM
 
seedlings
You never cease to amaze Dan! Super-nice touch. How the heck did you tap for #4 screws??? I'm dumfounded.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
Dan
VERY CAREFULLY! I use Tap Magic, a very good tapping fluid, which helps a great deal. Drill blind holes, begin the thread with a plug tap, and complete with a bottoming tap (just grind the tip off a regular plug tap). I just happened to have some #4 - 1/8" long round head aircraft screws. I tapped these holes by hand, but for #8 through 1/4" I use a cordless drill, saves bunches of time. There's no torque on the part, so these little screws should perform just fine.
Edited by Dan on 01/16/2012 11:11 AM
 
JETROASTER
Nice finish work...as always.:Clap: -Scott
 
Dan
Thanks. It's the business end, so I thought it deserved a little attention.
 
mk1
Dan,
I don't see any screws. Are you sure? Very nice,

Roast Strong!
Mark
 
Dan
They are blind screws, installed from inside the drum.
 
Dan
I hope to get back on this project soon. First I need to finish a 5-gallon color blending mixer for work. Now that the weather has turned I'm looking forward to roasting some larger batches outside again.
 
JETROASTER
Any pics of the whole assy? -Scott
 
Dan
No, I'm not that far yet. I have some sub-assemblies done and most of the parts assembled, though.
 
JETROASTER
Upfront I have to say...I've never roasted an ounce with a drum. I'm accustomed to the immediacy of air roasting.
As I skim thru some of the drum threads...there seems to be alot of lead and lag to be dealt with in terms of heat. Whether it's ET or thermal mass, there seems to be alot of anticipating involved.
It seems to me...(the one that knows nothing) that this design would negate alot of that.
True? False? or simply unknown yet? -Scott
 
Dan
Quite true, I believe. The thermal mass in most drum roasters, as you and a lot of people have noticed, is very high. That is, they take a long time to cool off, making adjustments difficult. Because the drum on my flame roaster is open on both ends and the drum itself is thin stainless, there is very little thermal mass.

Another consideration is that heaters have a response time that can add to this problem. Here are tests I made many years ago. Note that gas drops VERY fast at first but does not go to zero because you have to keep it lit. Bare nichrome, which is what most hot-air roasters use, drops nearly as fast, but cools off even further, and this is without the added cooling benefit of a blower.

claycritters.com/coffee/heater%20response%20time.jpg
 
JackH
Dan,
How do the larger commercial drum roasters deal with these lags? I am assuming they run on gas mostly. Just a case of knowing the reaction time and tuning off/on at the right time?

Sorry to stray a bit from your original subject, but your chart had me thinking.
 
Dan
Jack, They must know when to adjust the heat up or down based on evidence, either data-logging or observation by a master roaster, or both. You don't burn very many expensive roasts before you figure out how to do it right each time.
 
Dan
I had a chance to work on the roaster recently. I have the 8 vanes installed inside the drum. I had to make a cardboard template first so I could get the curves and angled ends just right. I went with 8 so that there would be a more constant flow of beans over the flame.

The next step is to install a hurricane shield on the rear opening. I want excess heat and chaff to exit out the rear, but I don't want a breeze coming in because it can snuff out the flame. If I'm lucky, I'll find a large colander. If not, then I'll have to fabricate something from perforated metal.
 
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