55/20gal RF with dual purpose fire box build..tips please

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gonzogrill

Newbie
Original poster
Jul 5, 2016
3
10
So I am planning my first build. What i am thinking is a 55 gal drum smoke chamber with 2 slide racks and a 20 gal grease drum that will be used as a grill and fire box. I plan on using a full length RF plate with a fabricated external tunnel to bring the smoke to the top of the chamber. The idea i have for the fire box is pretty simple...put the door on the front/top similar to what will be on the smoke chamber with pressure latches and angle iron welded length wise inside to place a removable grilling grate and side door for placing wood in the fire box when not using it as a grill. I plan on putting the exhaust on the same side as the fire box just above the RF plate.i have tried to include as much detail as possible. I would like any input or design tips to help with this build. Thanks...
 
Will it work? Does it seem like a decent design? How far off the bottom of the 55g drum should i put the RF plate? Does anyone actually read these posts? or is this simply a waste of time, maybe i should just start building and post pictures you can tell me what im doing wrong. looks like only posts with photos get replies..should i weight the lid? thought of maybe painting with rhino liner? better to bolt or weld firebox to cooking chamber? propane burner in fire box to use as starter? or dont they make electric fire starters? could they run on batteries? make grates out of rebar or expanded steel? so far all i have seen is my post fall down the page with no replies.. not too impressed! i was really hopin get some good info from this site BEFORE starting my first build. 
 
You have had 47 folks look at your post....   I'm confused about what you are attempting.... maybe they are also...   

Make a drawing of what you are thinking to do...    Seems pretty much multi tasking unit...  
 
 
If the RF plate is full length, shorten it to leave about  4-5" from the end of the drum, for this size smoker....

A couple drawings to shoe the "theoretical" operating parameter of a RF smoker.. and the Fire Box.....


Dave,

Maybe I should start new thread? Not sure about forum etiquette, but I saw that you suggested the the RF be approx. 4 to 5 inches from end of drum. What about on a 250 gallon tank, do you suggest the same gap? Also, what thickness should I use for the RF plate? I found a few 3/16 sheets and wanted to see if that could be used? Am I correct that the main purpose of the RF plate is to direct the smoke up and around for a more even flow? I guess if the RF is too thin, the residual heat will effect lower cooking zone. I am planning to have RF about 4 to 5 inches below bottom cooking grate so maybe the 1/4 inch RF plate wont be a bad idea after all. Just trying to save money where I can but don't want to  make mistakes that I will regret. Thanks, and by the way, I have gone through just about all of your threads and have learned so much. Thanks, Steve
 
Why would you start a new thread ??  All RF smokers dimensions should be based on the size of the Cook Chamber....   Gallons is not a criteria for dimensions....   Diameter and Length determine dimensions...   Gallons / Cubic Inches are used to express those numbers...  

Soooooooo, Diameter and length.....    run your numbers using the tutorial below.....

http://www.smokingmeatforums.com/a/reverse-flow-smoker-how-to-calculate-build-tutorial
 
Great. I have went through and ready to go.

I just want to make sure of one thing in order to best calculate the volume. I hope I don't sound too stupid, but for a tapered (rounded ends) propane tank should I determine the length (A) as the length from factory weld to factory weld, and (B) from end to end, then split the difference? And, should I account for the portion of the tank that will be cut off for the fire box?

Thanks, Steve
 
 
Why would you start a new thread ??  All RF smokers dimensions should be based on the size of the Cook Chamber....   Gallons is not a criteria for dimensions....   Diameter and Length determine dimensions...   Gallons / Cubic Inches are used to express those numbers...  

Soooooooo, Diameter and length.....    run your numbers using the tutorial below.....

http://www.smokingmeatforums.com/a/reverse-flow-smoker-how-to-calculate-build-tutorial
I don't understand what is meant by - Area under the RF plate in square inches?

If it was cubic inches I would understand for I would need a specific volume under the RF plate, but I dont know what is exactly meant by square inches. To quote Forrest Gump, "I may not be a smart man, but I know what smoking is" Thanks, Steve
 
If you go through the tutorial and figure each number as you get to it, it will walk you through each step and the numbers will be there....  The height of the RF plate from the bottom of the CC will be in square inches....   The circle calculator will do that for you....
 
 
Great. I have went through and ready to go.

I just want to make sure of one thing in order to best calculate the volume. I hope I don't sound too stupid, but for a tapered (rounded ends) propane tank should I determine the length (A) as the length from factory weld to factory weld, and (B) from end to end, then split the difference? And, should I account for the portion of the tank that will be cut off for the fire box?

Thanks, Steve
Pick a distance half way between the welds and the round end and use that for the length...    Close is good enough...
 
Ok, the RF plate is the same height as the top of FB, so once you calculate you FB/CC opening by the circle calculator, your good to go.
 
Ok, the RF plate is the same height as the top of FB, so once you calculate you FB/CC opening by the circle calculator, your good to go.
 
Why would you start a new thread ??  All RF smokers dimensions should be based on the size of the Cook Chamber....   Gallons is not a criteria for dimensions....   Diameter and Length determine dimensions...   Gallons / Cubic Inches are used to express those numbers...  

Soooooooo, Diameter and length.....    run your numbers using the tutorial below.....

http://www.smokingmeatforums.com/a/reverse-flow-smoker-how-to-calculate-build-tutorial
Dave,

Want to make sure I am correct in my logic of the circle calculator:

So I entered my inside radius: 13.75 inches

And I adjusted my Segment height (ED) until the segment area matched my calculated FB/CC opening area of 216.7 (based on 28 diameter & 88 length CC)

The Segment Height of 10.8 got me pretty close = 216.48

My understanding is the segment height is all I need to know and as long as my FB/CC opening has a height of 10.8 inches then I'm good to go. 
 
You got it......  The green area is now the FB/CC opening.....    The area under the RF plate.... Be sure to take into account the thickness of the top of the FB when cutting out the opening....  and the thickness of the CC metal...    AND the number you get AB is the width of the RF plate....

 



I won't say not to build your smoker the way you planned, but it is ambitious and thus will be harder to make work 100% chances are you'll end up with a smoker that works just ok and a grill that is alright.

If I am getting your idea right you want your heat/smoke channel to be OUTSIDE your cook chamber, running along the bottom, to heat it up, then take your external bypass back into the chamber to cross over.

How would you fab this on the bottom of a round drum? I fab a lot and it seams like a lot of work to me, if you idea is space saving, the bottom of the drum is sorta wasted anyways, and makes a perfect area for smoke as is, just cut and drop in a plate the correct size and it will rest on the edge of the drum, then just weld or seal it in place. Just leaving enough space at the end like dave said.

If you really want to make the grill/firebox work, I'd make sure you have the right size vent from FB/cc and then make a gate/door to block it during grilling, and make sure your door will seal 100% for smoking.

But don't let me tell you not to try, give her a go and see how it goes!
 
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