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snwcmpr
10/18/2019 2:37 PM
Eth Nat Yirg Idido roasted yesterday. I dropped some off at a friends coffee shop. In a few days he will brew it and tell me what he thinks. We believe my roasts are better than what we buy.

snwcmpr
10/16/2019 2:52 PM
Thank you for all you guys do.

JackH
10/15/2019 2:02 AM
They seem to be after the shoutbox. They have been removed. I don't see anything in the forums.

snwcmpr
10/14/2019 3:27 PM
We have been hacked. A whole lot of posts that have filled up the whole forum.

snwcmpr
10/10/2019 4:49 AM
Honduras Royal Reserve today.

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CoffeeAir I - Roaster Build Log
seedlings
This thread will loosely document the unprofessional planning theory and practical construction of a homemade coffee roaster from scratch. The roaster is un-built, and, in fact, only a very few parts are already at hand; some nichrome heat coils salvaged from a space heater, two router speed controls, and a Coleman glass globe that may or may not incorporate into the roaster.

Primary Goals:
1) All-in-one roaster/cooler/de-chaffer that will run off a normal 20amp electric circuit.
2) Variable load size from 0.5 pound to 2 pounds and everywhere in between.
3) Able to reach first crack in 10 minutes at full load, 15 min to second crack.
4) Smokeless for indoor use.
5) Uncomplicated to load and unload into bags or jars.
6) Built-in chaff collection.
7) Less than $100 in new and used parts.
Secondary desired goals:
8) High WAF (wife acceptance factor) looks.
9) Simple to duplicate or recreate.
10) Easy to access interior for repairs/upgrades.

i206.photobucket.com/albums/bb54/seedlings/coffeeairroasteri.jpg

Theory:
The roast chamber will be removable for loading and dumping. It will be at least partially glass (Coleman lantern globe) for viewing the beans. The beans will be agitated by forced air via a fireplace heater blower. (At the time of writing a blower has not been purchased, but a used model is available at a local repair shop for $30.) The air will blow upwards, across the nichrome heat coils, into the roasting chamber, into a rear chamber of the roaster. In the rear chamber of the roaster, the hot air and chaff will blow across aluminum screen which will contain the bulk of the chaff. The filtered hot air will then return to the fireplace blower inlet and repeat the process. Once the beans are roasted, the heat coils will be turned off and ambient air allowed to enter and blow across the beans to cool them. The chaff will be collected for easy disposal.

Problems:
First and foremost, the ability of the blower to loft a given quantity of beans is unknown. Second, this roaster must be airtight to avoid smoke. Sealing the majority of seams will be easy, but those areas around the removable hopper will pose significant problems. The hopper will have to be an exact fit, or use some sort of gasket to keep the heat in and fresh oxygen out. Keeping the cost under $100 will also be difficult. The entire roaster will be hot inside, so there must be insulation between the interior and exterior, otherwise it will burn anything that comes close by.

And now to start collecting parts...

CHAD
Edited by seedlings on 07/25/2008 8:31 AM
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
seedlings
Here's the blower:

Fasco B47120 (used but working)
1/22 HP
115VAC
1500rpm, 180cfm (top speed of 3 speeds)
i206.photobucket.com/albums/bb54/seedlings/FascoBlower.jpg



Purchased today for $30 cash from local supplier Ragdon Corp.
i206.photobucket.com/albums/bb54/seedlings/Ragdon.jpg



i206.photobucket.com/albums/bb54/seedlings/Scrap.jpg
I also stopped by Missouri Iron and Scrap to get a price on some Aluminum for the structure of the roaster. They will sell a 4'x10' piece of 19ga aluminum sheet for $35.90 (which is about the same price of a 24"x24" piece at the hardware store). It's about the thickness of duct work sheet metal. I don't need 4'x10', so I may buy a smaller piece, but thicker... but first thing is to find out how much coffee this blower will circulate.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
seedlings
Tried a couple of setup options for this blower, and the results are (as you and I probably suspected) less than desired. This blower can violently circulate about .75 pounds of beans in an area the size of the blower outlet, and about 3 inches deep. Any more beans and the blower can't begin circulation. Looks like if it is possible to do 2 pounds, the container will have to be large enough in diameter so that the bed of beans is only 2.5 to 3 inches deep.

I covered the blower outlet with aluminum screen then bent aluminum flashing to fit over the outlet and the screen and with a bean depth of about 3 inches the beans circulate, but this is less than half the desired amount... now to find out how to make it work anyway...

i206.photobucket.com/albums/bb54/seedlings/Blower8.jpg

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
georgel
You could add a venturi to accelerate the the air flow at the blower outlet. Start with a standard square to round HAVAC adapter. Install a restriction in the center ala jet engines. A heavy glass xmas tree ball is one thought.
georgelc:3
 
Yergeshef
seedlings
georgel wrote:
You could add a venturi to accelerate the the air flow at the blower outlet. Start with a standard square to round HAVAC adapter. Install a restriction in the center ala jet engines. A heavy glass xmas tree ball is one thought.
georgelc:3


Venturi? Hmmm. In a brief 2 minute search of the 'net, it appears that a venturi is used to create lower pressure for measurement purposes..? Perhaps I should simply lower my expectations instead of increase the flow ;) .

(And, Dan, I know you've probably had your fingers on the keys already but hesitated to respond. You've already told me in a previous thread that this blower wasn't likely to work well. I'm just cheap and stubborn. I've already scolded myself for probably wasting $30 when I was supposed to be saving $80.)

One more battle in this war... the motor on the blower says the max ambient temp is 40C. How could this ever have been used to blow air from a fireplace? Burning wood produces a lot more than 40C air.
:@

CHAD
Edited by seedlings on 07/27/2008 6:59 AM
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
Dan
Chad, It's not that that blower won't work, just that it isn't the best. Georgl is on the right track. If you install a restrictor it will increase pressure (will loft a taller height of beans) and use less cfm (use less BTU, too). If you neck down that outlet to about half the area it is now, that should be pretty close. It will probably be about 2" diameter. Then use that 2" in the bottom of a 6-8" diameter roasting chamber. That should be pretty close.

Oh, that blower would have blown room temperature air into a fireplace unit. Not suck hot air out of one. That's how it would survive the heat, by avoiding it in the first place.
 
http://www.intactamerica.org
dBndbit
Chad, since I'm sitting comfortably in my rec room, I have consulted with the fireplace on my right. He claims to be an expert on fans, but I have my doubts. My fireplace claims that many fireplace fans don't handle any hot fireplace air. They just draw in room air from the front of the fireplace and blow it back out the front of the fireplace. The heating takes place only in the output-side of the air pipe which passes near the hot fireplace walls, possibly with the help of some metal heat collectors. The fan doesn't ever need to feel any heated air.

Take this opinion for what it may be worth. I know my fireplace doesn't get out much, he never reads, and I didn't give him a connection to the internet.

I do know that if you're asking a blower to lift beans it's going to have to have a reasonable static pressure, which is the pressure difference between the input/output with one of them blocked up. So if you see a blower that has a visible open gap around the blower cage that allows air to pass directly back from the output to the input... that fan is not going to be able to generate any significant pressure. Low-pressure air flow (CFM) maybe, but not pressure (PSI).

Maybe this is the time to consider reducing the diameter of the air tube going in to the roast chamber. That way you might increase the air speed you need to loft the beans and prevent the pressure that is available from spreading out over too big an area, at least until after it hits the beans.
Edited by dBndbit on 07/27/2008 1:51 PM
Jim
11 years old... forever!
ReeferDoor.com
>home-built roasters and fair trade
 
http://www.ReeferDoor.com
seedlings
dBndbit wrote:
So if you see a blower that has a visible open gap around the blower cage that allows air to pass directly back from the output to the input... that fan is not going to be able to generate any significant pressure. Low-pressure air flow (CFM) maybe, but not pressure (PSI).


Dang! (Admittedly, though, I knew that...)
i206.photobucket.com/albums/bb54/seedlings/Blowergap.jpg


Here's my ghetto reducer and ghetto roast chamber prototypes (immediately to be scrapped). I tried to make a "bubble" out of screen so that there would be a shallower bean mass just above the inlet. It circulates, but not very well.:

i206.photobucket.com/albums/bb54/seedlings/blowerghetto.jpg


And here it is in motion. Well, a little motion. This is about 2 cups of beans or about 3/4 pound. The beans circulate, but not well...

i206.photobucket.com/albums/bb54/seedlings/blowerghettomotion.jpg


To sum up: either I'm going to make more with less or less with less. Hmph. Always tinkering, though! What about a giant popcor popper? Who knows. I will say now that SOME roaster will result from these efforts.

CHAD
Edited by seedlings on 07/27/2008 3:43 PM
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
dBndbit
Yep, that's the gap. It makes them very easy to manufacturer. What would be interesting with your setup is to see if there is an easy way to close that gap with a metal flashing or collar that would get much closer to the fan cage. Probably the best effect would come from a flat surface of metal that would come very close to the flat side of the fan cage and cover the entire side so you couldn't see the fan blades looking straight on.
Jim
11 years old... forever!
ReeferDoor.com
>home-built roasters and fair trade
 
http://www.ReeferDoor.com
seedlings
Jim, there's also a 1/4 inch gap on the flat back side of the cage. I wondered about prying the cover off the back and making the entire housing narrower. The depth could be adjusted via the mounting on the front side.

I also would like to know if there is a radial blower wheel available. Anyone know where I can order something like this pictured below?

CHAD
seedlings attached the following image:
radial blower wheel[1035].jpg

Edited by seedlings on 07/28/2008 2:31 AM
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
georgel
The point of the venturi is to accelerate the air. Jim is right back pressure will reduce the affect but probably won't obviate it. a flat plate over the intake with a hole in the center obout or slightly smaller than the inside of the " squirrel cage" impeller... One classic venturi would be a funnel . I didn't see any provission for hot air recirculation in your set up. If nthat is the case the fan is not seeing hot air. If you are reciculateing then you would duct the air exiting the roast chamber into the inlet of the cage. but not across the motor. Other than bearings the " fan" won't care about the temp. The motor does care. Olive oil for bearing lube??
georgel c:3
I see from a second look at the pics, that you would need to change the configuration of the Blower. which is what we have been talking about. Mounting the motor on the back side on the housing would simplify the the mods.
Edited by georgel on 07/28/2008 6:08 AM
 
Yergeshef
seedlings
Does the angle of reduction matter in a venturi? I mean, covering half of the outlet is not the same as reducing the outlet by half via a venturi, right? You suggested a funnel. Is there a way to guess the appropriate angle of reduction and the area of reduction?

CHAD
seedlings attached the following image:
Venturi[1036].jpg

Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
dBndbit
Chad, I have run across fan blades like that in various internet searches, but they were always very expensive. I just looked for some of the links but I couldn't find any in my bookmarks. After seeing the prices I decided to build my own high-pressure blower out of aluminum stock. I haven't tried it yet so I can't say how easy it will be to make anything useful like that.

I do recall on one major manufacturers website they recommended no less than a 60-degree angle on adapters. But I think in their case they were measuring the inside angle. So that would be a 30-degree angle on your drawing. Mathematically I don't think there is any "correct" or "minimum" angle. Any angle is bad, so the longer the transition, the better.

The air speed will increase (inverse-proportion) with the reduction of cross-section area. Half the area means roughly twice the speed. Venturi's discovery was that the pressure of the fluid in the smaller area was lower than in the larger area before it. Not that it was moving faster, which I guess was just assumed.

Also, fluids like round better than square shapes. But square may be easier to build. So what the heck.

I don't think the gap on the flat backside is a problem. Unless there are holes in the back plate of the squirrel cage there should be nowhere for the air to go.
Edited by dBndbit on 07/28/2008 1:04 PM
Jim
11 years old... forever!
ReeferDoor.com
>home-built roasters and fair trade
 
http://www.ReeferDoor.com
seedlings
Jim, how did you make the hub of the wheel where the shaft attaches? And, I'm guessing you probably welded the parts together. I don't have a welder. I sent an email yesterday to Electric Trading Company (www.blowerwheel.com) to get a price quote.

I'll mock up a rectangular-to-round Venturi and investigate it's new potential (or it's new kinetic, depending on how you look at it).

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
Mike
Chad,

Another thing that you may take into account while you are still in the design stage is that that the actual height of the bean column that the fan has to move may be used to your advantage. You are undoubtedly aware of the old trick used by popper roasters of tilting the roaster 15 or 20 degrees. It does two things .... 1st is to lighten the load on the fan by allowing it to blow against a shorter head (lower pressure needed) which increases the air flow etc.etc. .... 2nd is to establish a circulation pattern within the roast chamber.

In the attached drawing the air flows in at the bottom (seems like that is how your setting this up). You can easily see how the 'head' (the pressure the fan has to develop) in the tilted chamber 'Y' is considerably less than the head in the level chamber 'X'. The other advantage of the tilted chamber is that it sets up a gravity assisted circulation in a clockwise direction.

And your idea of a smoother transition in the air ducting is definately worth following thru with. It is amazing how little disturbance in a ventilation system of any type can reduce the flow substantially.

Mike
B)
Mike attached the following image:
Roast Height[1037].jpg
 
seedlings
Thanks Mike! I've employed this technique with poppers. However, in your diagram, do you think the beans in the lower area of the hopper will stagnate? In a popper there is still air flow at the bottom, but in my setup there may not be.

Had a 16 hour work day yesterday, so no progress.

CHAD
seedlings attached the following image:
Roast[1039].jpg

Edited by seedlings on 07/30/2008 2:41 AM
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
dBndbit
From a previous question, here's a possible link for all kinds of blower cages (wheels) and fan blades: Electric Trading Blowerwheel.com. But the prices seem too high for my budget.

I don't have a welder either. Sure wish I did. Maybe next year?

For assembling my home-built blowers and centrifugal roaster I'm using various forms of the industry standard quick-disconnect (QD) bearings and flanges. I have the parts in hand but haven't built it yet. To connect the drive shaft to the back plate I'm using a flange for a 3/4" keyed shaft. In QD bearings this is normally the inside which fits into a bigger diameter flange. I can use the just the shaft adapter or also use the outer flange for a more solid connection to the plate. If you're new to these modular bearings, they're very modular and inexpensive, and they come in many styles and sizes. Just make sure to stay within the same family (SD, SH, SK) so inside and outside parts will fit. There are lots of sources. Here's some links:

PNWB - very good prices, but many errors on the website. I think this may be one guy working out of his car.

Direct Industrial

Huston Bearing - they rep many manufacturers. See the Huston catalog for a huge amount of good reference material at the end. And here's a gif of their QD product dimensions from my website: Martin QD dimensions

McMasters-Carr - search for quick-disconnect hubs
dBndbit attached the following image:
QD-flange1a[1040].jpg

Jim
11 years old... forever!
ReeferDoor.com
>home-built roasters and fair trade
 
http://www.ReeferDoor.com
dBndbit
Mike definitely makes a good point. Take a look at the tilted roaster from the godfather of coffee engineering, Mike Sivetz. Look down the page at his 1/2-bag gas fired roaster. It uses a triangular roasting chamber tilted to the right. Some of his other machines also use the same concept but it can be hard to see. It's like a funnel cut in half vertically, but all the beans still flow down to a small port where the air blows in.

Am I speaking out of place, Mike?
Edited by dBndbit on 07/30/2008 4:13 AM
Jim
11 years old... forever!
ReeferDoor.com
>home-built roasters and fair trade
 
http://www.ReeferDoor.com
georgel
Round is better than rectangle for a venturi. I don't agree that a long transition is always bettor. standard venturis look like ) ^ ( or > ^ < . [ up arrow indicates air flow ]The reduction of turbulence is a double edged sword. It eats power but on the out flow would increase agitation. As Jim says buying Impellers could be pricey. the squirrel cage would work with modification. I like Jims Idea for a bearing on the back plate.
georgel
 
Yergeshef
Mike
Jim - This is not a place where there is an "out of place" from which to speak. I would like to think that I came up with my 'Circulation' idea before seeing what Sivitz does in his roasters .... but I'm not entirely sure that I'm being factual about it.

Physics dictates that the air will flow in the easiest direction with the least required pressure drop - pretty straight forward.

Chad - from my experience (making up models to fit with the somewhat limited information that I witness) .... the lower, Red, portion of your drawing would be the fluid bed area ... with a popper you can see the level of the beans raise and lower a bit when the fan is on / off , fast / slow.

Again - the caveat that I'm building mental models here. The bean circulation thru that area is determined (in the tilted model) by the beans being 'spit up' on the left (low pressure) side of the chamber and going back 'down' into the roast chamber on the right hand (higher pressure) side. The circulation seems to be entirely driven by the displacement of the left over space on the left hand side, caused by the beans that are lofted up, out and back on top and then down and in on the right hand side (gravity assisted). This model meets my mental needs and when watching the circulation in a popper (easy to watch with a glass chimney), seems like a workable explanation.

Mike
B)
Edited by Mike on 07/31/2008 12:01 PM
 
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