Need help with design 36" patio RF

[imattatx]

I'm new to the smoker world and need some help. I'm having a pit built for me but I want to make sure my design is right. Here is what I want, hoping y'all can help.

36" long smoking chamber using 20" diameter oil field pipe, the ends will be flat

12" firebox using the same 20" pipe < Should I go bigger?

The main things I can't figure out is:

How do I figure out the half moon cutout? Feldon calculator says 30 square in.

Should the reverse flow plate slant down and when should I stop it?

How much space between flow plate and grill grates?

Where should vents go for firebox?

This is the design I like just with a cylinder pipe vent: http://www.katbbqsmokers.com/reverse_flow_smoker/

 

[daveomak]

Evening and :welcome1: Please stop into roll call for a proper introduction and welcome from our members..... Dave


Click on pictures for an enlarged view......

http://www.1728.org/circsect.htm

Shane.jpg

• daveomak
• Jun 17, 2014

One option for the RV plate end that works well....

Barlowds 2.jpg

• daveomak
• Jun 17, 2014

Calculator and drawing.jpg

• daveomak
• Jun 17, 2014

smokehouse-firebox-5.gif

• daveomak
• Jun 17, 2014

 

[imattatx]

Can you help with figuring out the half moon shape for 30 square in? 

Also the recommended firebox is 12 in for a 36 in chamber, that seems kinda small to me. Would it be okay to do an 18 inch?

 

[daveomak]

Please stop into "roll call" for a welcome from out members and put your location in your profile so we can better answer questions in the future...

Did you look at the calculators in post 2 and try to figure out you smoker sizes ???

 

[doodle2]

Fire box is better being bigger.. 12x20 is 100% but I would put it up to 125% which would be 15x20.. As for the half moon to fire box it should b 9.80 inches so call it 10 inches so draw a line 10 inches long and half circle below that for your half moon. I have 5" between my rack and ref plate with no issues. And for the drain of slanting for easy cleaning Thats just a pain I did that and didn't like it so now I just lay foil down to catch the grease and use two cookie sheets as mywater pans but tThats just my 2¢ hope that helps

 

[imattatx]

Thanks doodle, that's what I was having a hard time figuring out. So if I use 10" just do a perfect half circle or is there a certain length from the middle of the line I should go down?

Also how low should the rf plate sit and how much of a gap should I leave at other end?

 

[doodle2]

10" up from bottom straight line across that mark.... so measure up 10" from the.bottom in the center of your pipe ur using as the cook chamber and draw a straight line across to the sides Thata the half moon as for the ends of your rf plate it should be roughly the same as your half moon opening so 10" there as well