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RoasterRob Air Roaster Designs
allenb
Top  #54 Print Post
Posted on 11/20/2012 10:24 AM
In my impatience I broke out the abacus and slide rule and here's what I've come up with for Rob's neat asymmetrical round RC for a 1 lb fluidbed:

- RC diameter = 4"
- RC bottom is sloped at a 45 degree angle down to the point where it meets the perf plate which is flat.
- perf plate area is 25% of a 4" circle or 3.142 square inches.
- perf holes diameter = .125" or 3.175 mm
- holes center to center approximately .318" or 8 mm. (diamond pattern).
- perf open area % = around 14%
- total combined open area = around .4418 square inches.

For calculating perforated metal % open area (for 60 degree staggered center) you can use this formula: (hole diameter squared x 90.69) ? (hole center to center distance squared).

Allen
Edited by allenb on 11/20/2012 12:54 PM
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
RoasterRob
Top  #55 Print Post
Posted on 02/06/2013 3:14 AM

Quote

allenb wrote:

In my impatience I broke out the abacus and slide rule and here's what I've come up with for Rob's neat asymmetrical round RC for a 1 lb fluidbed:

- RC diameter = 4"
- RC bottom is sloped at a 45 degree angle down to the point where it meets the perf plate which is flat.
- perf plate area is 25% of a 4" circle or 3.142 square inches.
- perf holes diameter = .125" or 3.175 mm
- holes center to center approximately .318" or 8 mm. (diamond pattern).
- perf open area % = around 14%
- total combined open area = around .4418 square inches.

For calculating perforated metal % open area (for 60 degree staggered center) you can use this formula: (hole diameter squared x 90.69) ? (hole center to center distance squared).

Allen


Hi Allen

Sorry missed your posts in November I would have replied if I had seen them at the time. Feel free to PM thru HR. I have a template somewhere in an Autosketch file. Most of what you worked out looks about right.

Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
 
ciscobob
Top  #56 Print Post
Posted on 10/14/2013 10:23 PM

Quote

seedlings wrote:

Quote

ryanjelena wrote:
So gravity is enough? Is there no air leakage between the RC and furnace? Does anyone see a problem with the furnace section being 8" as opposed to 6"?

Chad,

Do you have any pics of your roaster posted I would be curious to see different ideas. I am just about to start building a roaster. Basically plan to copy Rob's ideas, but would love to see any variations that might be easier or better.

Thanks,

Ryan


Very slight leakage on my roaster. Rob has his down to a science with much better fabrication, so I'm sure it's negligible as well. 8" instead of 6"... there has been some discussion about reducing the airspace between the heat element and the roast chamber- theory being that more air acts like a bigger spring cushion, causing bouncing of the bean mass and reducing flow efficiency... but it's mostly theory, and you may not notice any trouble whatsoever.

My roaster is NOT easier or better:
http://forum.home...post_20940

Another build thread:
http://forum.home...ad_id=1905

Please feel free to start your own thread specific to your roaster!

CHAD


I also used Robs design, to seal the RC to the bottom I used a band of insulating tape around the bottom and then a 2" wide thin aluminum as a clamping band. When I put the RC on top I just tighten 2 6" hose clamps to keep the RC from moving around to much.

I actually need some air leaks since my VC is too powerful for smaller roast, even with the dimmer on its lowest setting an a screen over the inlet.
4kg home built Fluid Bed roaster AKA the Steam Whistle. 3 chickens, 2 boys, 1 wife
 
tamarian
Top  #57 Print Post
Posted on 12/16/2013 8:26 AM

Quote

RoasterRob wrote:

The new RC is 200x200 square at the bottom then 200 X 320 at the top.
forum.homeroasters.org/forum/attachments/7kgrc.jpg
Rob


I'm curious how did this roast chamber work out? Did it work well for 5-7 kg? How high is it? 1 meter? Did it require more than the 2941 burner?
Wa'il. 1 Kg PID'ed gas-fired fluid bed roaster, GS/3MPS, K10F
 
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