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The Sample Roaster Project
qajariaq
Top  #1 Print Post
Posted on 11/24/2008 4:22 PM
Just making some noise... B)

Preliminary drawing of my sample roaster build below.

The two main goals are to be able to roast about 1 lb. at a time and be able to roast a 1 lb batch in a reasonable time in cold temps. The constraints are that it has to be low cost and require minimal/basic metal working equipment.

I have a propane grill/outdoor kitchen burner and housing to use as a base. The burner should produce plenty of heat (its larger than the largest burner on the gas stove in the kitchen). I can always throttle it down during warm weather...

The drum will likely be made from found objects and perforated sheetmetal since I am not able to fabricate much of anything from metal due to having mostly woodworking equipment on hand. A canning funnel is about the right size and shape required for the front section, but I have to actually get ahold of one before I can be too certain it will work as planned (and I have to find a matching back plate to use). A drum 5.5" diameter and 8" long should handle 1 pound or a little more if I go by the 10 cu-in per oz. drum size rule. Front of drum will likely be supported on ball bearings unless I can find a way to turn some brass to make a solid bearing like Dan's sample roaster.

Housing will likely be sheetmetal, but I don't know how much of it will have to be fabricated yet. I have various boxes and containers that might be repurposed... Gotta get the drum built before I can be sure they will work. I plan to insulate the housing to increase cold weather performance.

Drive motor will be the typical gear drive motor assembly, coupled right to the back of the drum.

farm4.static.flickr.com/3192/3056452407_52e370be77.jpg[b][/b]
Edited by ginny on 01/29/2009 5:20 PM
 
Dan
Top  #2 Print Post
Posted on 11/24/2008 4:44 PM
Looks good! Some things to consider:

Make your drum front a straight walled funnel about 15? or more. That way the beans will fall out quickly.

Put some standoffs between your motor and housing so it will stay cooler.

Cooking with gas gives off a lot of moisture. I suggest you use SS for your drum so it won't rust.

Forget the ball bearing. One that is large enough will be very thick and heavy. A bushing is simple. Just have a home machinist make you that part in exchange for some coffee. I lube mine with one drop of turbine oil each roast session.

I mounted my roaster tilted slightly to the rear so I could do larger roasts.
 
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qajariaq
Top  #3 Print Post
Posted on 11/24/2008 5:09 PM
Thanks for the tips! s:1

I thought I had a drum lined up - a large aluminum bottle - but it turns out that I can't buy just one...

The small grid Behmor drum is tempting. It won't dump beans out the front but I don't know that I could do much better for only $15-$20.

Would you consider brass a reasonable alternative to stainless? It won't rust...
 
seedlings
Top  #4 Print Post
Posted on 11/24/2008 7:43 PM
OH YEAAHH! Great project s:2

qjariaq, I learned on the backside of a project that you don't want to use galvanized sheet metal for a high-temperature project... just to be sure zinc doesn't leach into the roast. My propane torch is made of brass. Should work great.

How will you load and unload this drum?

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
Dan
Top  #5 Print Post
Posted on 11/25/2008 10:43 AM
Sample roasters unload by tilting the drum and housing forward. See the arrow in his dwg. above. To load them you use a funnel with curved tube.
 
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seedlings
Top  #6 Print Post
Posted on 11/25/2008 9:41 PM

Quote

Dan wrote:
Sample roasters unload by tilting the drum and housing forward. See the arrow in his dwg. above. To load them you use a funnel with curved tube.



Ah-ha. I had visions of beans all over the floor if I had tried to load it. This makes sense.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
qajariaq
Top  #7 Print Post
Posted on 11/26/2008 2:17 PM
Here's a few photos of what I've got so far.

The basis of the roaster is a side burner unit with a metal box on top of the cover (area under the additional box will be removed from the burner cover). The drum will be in the metal box more or less, and the funnel end of the drum will be at the back (so that lid can be lifted to dump beans into cooling bin that will be located there). At least that's the plan right now.

Drum will likely be a modified Behmor "small grid" drum since it is relatively cheap and already has stirring vanes. I can't buy the materials to make something similar for what the Behmor drum costs. I'll try to come up with a way to add a funnel to the open end, but I'm not sure what that will consist of just yet.

The drive motor will be on the "controls" end (aka front). I'll likely use the 50 rpm Molon gear motor that is popular.

I'll also be building a cabinet of some sort to hold the burner unit and propane cylinder. This should allow me to build a vacuum-powered cooling/chaff-removal bin into the cabinet (right behind the burner unit) so that the entire process is more or less seamless.

farm4.static.flickr.com/3218/3061246909_8067088a61.jpg

farm4.static.flickr.com/3232/3061246923_69bcf21325.jpg
Edited by qajariaq on 11/26/2008 2:19 PM
 
qajariaq
Top  #8 Print Post
Posted on 11/26/2008 2:18 PM
I don't think too few BTU's will be an issue... Grin

farm4.static.flickr.com/3057/3061246917_3863b7bc07.jpg
 
ginny
Top  #9 Print Post
Posted on 11/26/2008 3:48 PM
Aaron:

WOW...

what a great project. The metal work is beautiful!

I have seen roasters with wood and have wondered about the heat!!

Thank you for posting this roaster!!

ginny
s:1s:1s:1s:8s:8 cuz I need too...
 
seedlings
Top  #10 Print Post
Posted on 11/26/2008 4:22 PM
Absolutely great ideas! Boo-yAAA! It's a thing of beauty! ... so... professional looking...

I canNOT wait to see this one worked up!

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
Dan
Top  #11 Print Post
Posted on 11/27/2008 6:52 AM
That is a great heater base for a roaster! Just the right size. You might want a deflector over that burner, but you'll find out after your first few roasts.

I don't see why you think you need to control from one end and dump from the other. My sample roater, as well as traditional designs, control and dump from the same end. It is much more convenient and space saving.

Regardless, you are going to put us all to shame with that beauty!
Edited by Dan on 11/27/2008 6:53 AM
 
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qajariaq
Top  #12 Print Post
Posted on 12/03/2008 4:50 PM
Progress is s-l-o-w

Main issue right now is getting the drum solidified, as its final dimensions will dictate the housing and how I connect it to the drive motor. I think the Behmor drum is going to work fine, but I'm having trouble finding a funnel to fit the front. I even tried to get some metal spinning companies to quote on a custom funnel, but no one is interested in doing 1 item with no promise of future orders... I also thought about making a form and special tool rest for my wood lathe so that I could spin the part myself, but a piece of thin sheetmetal rotating at 1000 rpm isn't something I want to be in close proximity to.

The metal box I show sitting on top of the burner cover doesn't look like its going to work - there won't be enough clearance inside to add insulation. Maybe insulation won't be a requirement? I'm looking for other aluminum or stainless boxes to use (no leads at the moment, however). I need to go check out the scrap metal yards around here and see what I can come up with, any metal housing that's large enough is way too much money at retail!

I will probably start building the table that will hold the burner and cooling bin, since I don't plan on changing the burner and stainless housing (well, unless something better comes along!). Below is a general idea of what it will look like. B) The burner goes in the large rectangular opening, and a colander goes in the round opening. There will be a "sealed" box under the colander, which will have a port to allow a shop vac to be hooked to it for cooling and chaff removal.

That's the plan for now - seedlings' CoffeeAir 1 roaster has me thinking about scrapping the drum roaster and building a propane-fired fluid bed roaster! ShockGrin

farm4.static.flickr.com/3015/3080276879_4b67bd57a0.jpg
 
seedlings
Top  #13 Print Post
Posted on 12/04/2008 8:12 AM
... because my roaster hasn't given any trouble !?! s:8

I want air-roasted fluid bed because I prefer coffees roasted that way more than traditional drum roasted, but know that I am in the minority! Your design will be drum roasting, and may actually be a "better" roaster..! Don't change designs ... if you have to - just build both!

I love your design, by the way. When you posted that first picture, I thought about jumping ship!

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
qajariaq
Top  #14 Print Post
Posted on 12/04/2008 8:25 AM
Well, the grass always looks greener on the other side... ;)

The problem is that I'm not yet too heavily invested in the drum roaster to feel like I have to make it work.

Hmm... maybe I should buy an expensive component for it so I'll stop looking at other options?

Shock s:8
 
Dan
Top  #15 Print Post
Posted on 12/04/2008 9:07 AM
You can make a funnel yourself without spinning, I did, and I know how to spin metal!

Just cut a circle with a hole in the middle, then cut a sector out of it. Flex the resulting "C" shape until the ends touch. Viola! A funnel. Add tabs for welding or bolting. That's what I did with my sample roaster using 18 ga. To make bending it smooth and easy I put a piece of 1" pipe in the vise and gradually formed the funnel over it with my hands.

A Machinery's Handbook will give you the formula for developing a funnel shape.
 
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Mike
Top  #16 Print Post
Posted on 12/04/2008 1:25 PM
Dan's recommendation is right on. I've produced really nice funnel like construction such as he suggests, several times and have been surprised how easy and nice looking product I produced.

Mike
B)
 
seedlings
Top  #17 Print Post
Posted on 12/04/2008 3:19 PM
Dan (or Mike), You say you put a 1" pipe in the vise and bent the C around that... could you be a little more descriptive?
Why 1" pipe?
Start at an end, or the middle to prevent kinks?
How do you make sure the ends don't curl too much?
And, does it work as well for shallow funnels as deeper ones?

I've only worked with aluminum flashing, and even my wee-little experience with steel suggests there are a few tricks up your sleeve.

Merry Christmas,
CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
qajariaq
Top  #18 Print Post
Posted on 12/04/2008 5:01 PM
I'd be interested in more elaboration on forming a funnel, too! :|

18 ga. stainless would be tough to form by hand. I don't have access to anything capable of cutting stainless that thick anyway... While heavy stainless would be nice, I don't know if it needs to be that thick - 22 to 24 ga. would be a lot easier to work with, even if it won't be as durable. Aluminum would be a different story (especially one of the softer alloys, annealed).

Man, what I'd give to have access to the metal shop in college again!
 
Mike
Top  #19 Print Post
Posted on 12/06/2008 12:22 PM
Actually I believe I used 3" pipe and I was building with 18 gauge brass. I used a tire hammer on the rubber side - -for those of you who haven't had the pleasure - - it is similar to a 5 lb sledge on one side and a fairly hard rubber on the other. It is a very intuitive process - you know what you want it too look like when finished - you hammer long enough, you get there. Magic! the second one will go considerably quicker. If you've never worked any metal, you might want to just play around with a piece of junk sheet metal first.

Mike
B)
 
Dan
Top  #20 Print Post
Posted on 12/06/2008 1:32 PM
24ga. is plenty thick for a drum funnel. Remember, when are bend a material it gets stiffer due to the shape, just as angle is stiffer than flat material of the same dimensions.

Regarding the 1" pipe. You want something small enough to go all the way to the bottom of the funnel. Since most of our funnels will have a hole larger than 1", then a 1" pipe can act like a good mandrel (anvil).

Shallow funnels of thin material don't need to be formed over a pipe mandrel. Just pull the ends together and secure. For stiffer material flew over the mandrel working gradually from beginning to end and back again.

The problem with the ends isn't that they'll curl too much, but not enough. They want to stay flat. You might need to use a rubber mallet to form the ends.

Dan
 
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qajariaq
Top  #21 Print Post
Posted on 12/10/2008 1:16 PM
Dan, thanks for the explanation! s:1 Doesn't sound too difficult now...

I picked up a stainless canning funnel, so I have that as a starting point. Its a little too large for the Behmor drum, but I might use a shorter 'solid' stainless drum instead (aka kitchen utensil canister) so that I can make the entire roaster a little more compact. With a smaller drum, there would be room to have a cooling tray built into the burner cover/housing much like the commercial sample roasters. Only problem with the smaller drum is that it drops the capacity to about 14 oz. Not too far off the 1 lb. goal, though...
 
qajariaq
Top  #22 Print Post
Posted on 01/23/2009 5:43 PM
I'm looking to purchase a gear motor to drive this thing, and what I've settled on for the moment requires a "0.68 mfd (or uF if you wish) run capacitor." Problem is that I cannot find a "run" capacitor less than 1 mfd.

I'm wondering if it must be a "motor run capacitor" or if any 0.68 mfd capacitor with appropriate voltage rating will work? Can anyone with knowledge of such things give advice?

I hope it will work, the motor is cheap, continuous duty, correct voltage, and proper RPM... oh, and its not a shaded pole motor so I can vary the RPM later on... B)
 
seedlings
Top  #23 Print Post
Posted on 01/23/2009 6:24 PM
If you have a non-polarized cap of the right value and voltage, you should be OK. However, with a run-capacitor, how will you vary the RPM later?

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
Dan
Top  #24 Print Post
Posted on 01/23/2009 7:32 PM
I would just use the 1mfd. It is close enough. Run capacitors jump in 2.5 and 5mfd increments, so they can't be that touchy. I think it is more important that you use something made as a run capacitor. Besides capacitance and voltage, they have to be able to deal with a certain amperage, too.

Can't you just cut down the large SS funnel to fit the Behmore drum?
 
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qajariaq
Top  #25 Print Post
Posted on 01/23/2009 7:38 PM
With a motor speed controller! :P lol!

I believe that it is a brushless motor, so it will require a variable frequency drive. Fairly trivial thing to build from RadioShack parts (if I understand it correctly, anyway)
 
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