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CharcoalRoaster
11/04/2019 1:58 AM
+1 snwcmpr

snwcmpr
11/03/2019 2:16 AM
Can we make the shoutbox UNAVAILABLE until a member has a certain number of posts?

allenb
11/01/2019 2:20 AM
Funopt, please post in the gas and electric heat sources forum

Funopt
10/30/2019 5:17 AM
Can someone help me for using forced propane burner as my heating element. I rather want to use lpg than electric. Do you think it would work

snwcmpr
10/22/2019 5:31 AM
Thanks to you all....... I was not sleeping ... I stayed awake worried about it all. :)

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CoffeeAir II Roaster Build
seedlings
Scott or Rob, what's a perforation ratio that works well? This square tube is 3.75" x 3.75" inside. The airflow area is 0.75" x 3.75", or right at 20% of the area; of course not all of that is wide open.

I better not mount the glass yet, if the bottom has to be cut and re-welded for a different perf pattern. I'll try a dry run first to see airflow.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
JETROASTER
That's flattering, but I have no idea. Rob or Marshall might have that one. -Scott
 
seedlings
Circulation isn't quite right - seems to circulate more from the middle than from the bottom. What do you think? Cut a wider opening for perforations? Change the angle?



CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
endlesscycles
Looks good to me! Really cool to have that window there, to see how much it actually circulates.

edit: however, it confirms my concern that beans at the top of the ramp sit a long time waiting to recirculate, while those that fall at the edge just spill back into the stream. I'm sure it all evens out, but for how long are those corner beans loosing heat?
Edited by endlesscycles on 05/11/2010 2:50 PM
-Marshall Hance
Asheville, NC
 
RoasterRob
per row 9 mm apart, rows 5mm apart, offset 4.5mm. means that the spacing between holes is 6.7mm from memory. Sort of a diamond pattern formed by any 4 holes. with any side being 6.7mm hole centre to hole centre. just the way I did it.
wouldn't worry too much about how the beans flow on your roaster , see how even the roast is and how often a couple of coloured beans get blown around.

Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
 
JETROASTER
That's a fantastic first run! You'll figure out the minor adjustments in no time.
...Then on to the heat thing....Good luck -Scott
 
seedlings
Would a larger opening and lower density of perforations push a larger chunk of beans up and over?

CHAD
seedlings attached the following image:
13largeropening.jpg

Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
JETROASTER
Perhaps controlling bean movement with a wing may work as well
..similar to the pipe that Rob used -Scott
JETROASTER attached the following image:
13largeropening_1.jpg
 
Unta
Might need to be wider at the bottom. One of things that I took into account during my contemplation of the roaster is from sivetz. His roasters are spouting cones untill you get over 12lbs. I dont know why, but i respected this design concept.It was also easier for me to get parts to create a spouting cone with manufacturing.. I know Rob doesn't do this, it was just something that I considered.I really like robs mulit collerd bean approach and his reccomendation of turning on the heat. Nothing more telling thenm even/unevenly roasted beans.I think the wing will cause you more problems. my half a farthing. sean
Sean Harrington
educate.
 
http://www.untacoffee.com
jerstew
Perhaps tipping the RC might do the trick. I would tip it backwards first, toward the perforated side. That increases the angle of the angled floor "bean slide", giving the beans more gravitational help back into the airflow. Tipping the other way towards the seam weld on the square tubing I think would exacerbate the stagnant bean problem.
If this works, is it possible for you to change the angle on the fly with the blower on and beans flowing? If so, it would be nice to see another video of how the angle affects circulation.
Also you may be seeing poor bean circulation near the sight glass, but perhaps they are flowing well the near the center.
Very nice job so far. Its great to have welder friends.
Jeremy
 
RoasterRob
Only if you have enough air flow and pressure from the blower and thru the perf plate.

Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
 
seedlings
Just occurred to me that there is a 1/8" offset where the glass meets. So the beans nearest the glass hit a ledge on the way down.

Maybe I should do nothing right now.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
endlesscycles
I'm not sure about wider, but I really like the wing!!!
I was wondering how to implement Rob's genius pipe idea; thank you for solving that!
-Marshall Hance
Asheville, NC
 
John Despres
seedlings wrote:
I learn something new everyday. Tempered glass can't be cut (unless it's un-tempered first), so my plan to salvage the glass from halogen lamps has been foiled, Marshall. It's first cut to shape, then tempered.

I called around and found a local glass place with a scrap of 1/4" pyrex large enough to cut to the size I needed for $21.

The sight glass should be installed tonight.

CHAD


Yeah, and ordering a custom piece is EXPENSIVE!:@

John
Respect the bean.
John Despres
Fresh Roast 8, Gene Cafe, JYTT 1k, Quest M3, Mazzer Mini, Technivorm, various size presses and many more brewers.
 
www.sceneitallproductions.com
seedlings
John, I found a place online that would've made my 3.25x12.5" piece for $30.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
allenb
seedlings wrote:
Would a larger opening and lower density of perforations push a larger chunk of beans up and over?

CHAD


Bean flow unfortunately looks very similar to some of my attempts at a roast chamber that required modifications.

Symptoms on mine were:
-Thinner than normal plume density (probably subjective)
-Bean lift a little high for that density of plume.
-Slow bean migration back into plume.

The last item for yours may not be as bad as it looks. Maybe just the layer against the glass due to the ledge you mentioned.

As far as what to do to fix it? I don't know if widening the perf area would be as beneficial as moving the perf area a little toward the center.

Unfortunately, this would require cutting and welding to create a second sloped plate which is easy to recommend but a pain to do.

I would give it a good try before cutting and welding. There's a chance it could roast great coffee.

One thing that will be hard to overcome without modifying is if it's taking too many cfm to achieve the movement your getting now.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
nufsaid
one thing you need to do is more DD on insulation. Cement board is heat resistant but not primarily insulation. I spent 36 years in the ceramic industry and I tell you when firing 200 foot kilns you wrap them like a baby to prevent heat lose. Do you have any idea what firing 6 kilns that big 24/7 365 forever costs. And the temps were about 2900F. Look under refractory insulation and furniture. Gerry
 
RoasterRob
Hey Chad, 20% is fine, from memory my 4" RC was 25%, my 6" RC was closer to 20%. The perf area makes a big difference.
You shouldn't need a wing.
Belong is a pic of the inside of my 4" RC. It hasn't been used for a long time hence the rust on the perf plate which is not SS. Holes are 1/8".
After making a few RCs with this perf, I used a piece of off the shelf perf that had smaller holes but a much greater total percentage of hole relative to the perf plate area. The bean flow was very random with some beans jumping out the top. I cut it off and went back to hand drilling.

Rob
RoasterRob attached the following image:
100mmrcperf.jpg

VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
 
seedlings
gerry wrote:
one thing you need to do is more DD on insulation. Cement board is heat resistant but not primarily insulation. I spent 36 years in the ceramic industry and I tell you when firing 200 foot kilns you wrap them like a baby to prevent heat lose. Do you have any idea what firing 6 kilns that big 24/7 365 forever costs. And the temps were about 2900F. Look under refractory insulation and furniture. Gerry

Gerry, I have a metric ton of 1.5" rigid fiberglass insulation. The only part that might benefit from insulation is the heat tube, which is about 5" x 2.5" x 3", a small volume to insulate, which is good. Insulating the roast chamber would be almost pointless since 99% of the heat goes up and out.

Rob, if I understand what you're saying, your picture illustrates what does not work well, and your previous post says what does work:
RoasterRob wrote:
per row 9 mm apart, rows 5mm apart, offset 4.5mm. means that the spacing between holes is 6.7mm from memory. Sort of a diamond pattern formed by any 4 holes. with any side being 6.7mm hole centre to hole centre...


I'll probably cut this plate off, re-weld and re-drill. My buddy will be so excited...

CHAD
Edited by seedlings on 05/13/2010 2:31 AM
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
endlesscycles
seedlings wrote:
... Insulating the roast chamber would be almost pointless since 99% of the heat goes up and out....

CHAD


There are conductive losses through the roaster walls as the beans slide down to reenter the flow. I believe this is detrimental to quality, as a decrease in bean temp results in a flatter and less sweet cup.

Rob,
That perf plate shows very sparse drilling. You say that results in smoother bean flow with less jumping out of the top? I would love to keep my convection high without beans jumping ship.
-Marshall Hance
Asheville, NC
 
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