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Need advice on small RF build dimensions (finished pictures added)

austinb

Newbie
11
10
Joined Jun 22, 2012
----update---- pictures of the finished smoker at the bottom

Hey everyone,

I'm new to the site, found it while looking around to find some ideas for a build I'm planning.  Lots of great info on here and I'm hoping I can pick some of your brains about my build.

I have this nice tank that is 24" in diameter and I plan on trimming it down to be around 36" wide in total. I don't want the thing to be too huge and I feel like this size would be big enough but not too big.  Unless there is some reason to go bigger that I am unaware of.



Here is a rough drawing of what I'd like to do:



So first off what do you guys think of having the firebox detached like this?  My thinking is the cooking chamber would get alot less direct heat this way than with the attached style.  I would add some bracing not pictured.

I have two options on the picture for the smoke stack.  Is the exit on the end better than one on the top for any reason?  Then how far from the top of the cooking chamber should the exit be (dimension D in picture)?

Then how high from the bottom of the smoker should the drip pan be (dimension A) and how far from the end should the smoke opening be (dimension C)? 

Finally how high should the cooking grid be off of the drip pan (dimension B)?  I plan on having a removable tray that I could put in on top of the drip pan for charcoal and use the cooker as a grill when I want to, so I imagine I may want the cooking grid to be higher off the drip pan if it it wont hurt smoking performance.

Any feedback is greatly appreciated! 
 
Last edited:

darbinco

Fire Starter
39
10
Joined May 31, 2012
This link should help you with all your required diamentions, firebox size, opening from FB to cooking chamber, FB vent sizes, stack size and length.

http://www.feldoncentral.com/bbqcalculator.html

I wouldn't hesitate to make it bigger. My tank is 20"x60" long and after cutting the door in it, I wouldn't want it much smaller. It will allow me to smoke a brisket some chickens and ribs all at the same time. With 36" a good sized brisket going to eat up that space in a hurry and not leave enough left for anything else. Good luck and keep us posted on your progress!
 

daveomak

SMF Hall of Fame Pitmaster
OTBS Member
SMF Premier Member
26,458
3,837
Joined Nov 12, 2010
Austin, evening and welcome to the forum..... please fill in where you are from, on your profile, so we can better help you when the need arises...
Hey everyone,

I'm new to the site, found it while looking around to find some ideas for a build I'm planning.  Lots of great info on here and I'm hoping I can pick some of your brains about my build.

I have this nice tank that is 24" in diameter and I plan on trimming it down to be around 36" wide in total. I don't want the thing to be too huge and I feel like this size would be big enough but not too big.  Unless there is some reason to go bigger that I am unaware of. My smoker screen is 24x48" and a times it is just too small... I like to smoke foods and freeze for later... I have cooked chicken for 30 people and it was adequate.... it is nice to have the extra space... doesn't cost much... uses the same amount of wood... and it will make it heavier so it won't get stolen (maybe)....I would make the smoker full width of the tank... as is.... I'm so sure of it I will guarantee you won't be sorry.... 



Here is a rough drawing of what I'd like to do:



So first off what do you guys think of having the firebox detached like this?  My thinking is the cooking chamber would get alot less direct heat this way than with the attached style.  I would add some bracing not pictured...Moving the firebox into the smoker will improve heat transfer to the smoking chamber and reduce fuel consumption..

I have two options on the picture for the smoke stack.  Is the exit on the end better than one on the top for any reason?  Then how far from the top of the cooking chamber should the exit be (dimension D in picture)... bottom of the stack opening should be 2-4 inches above the lower cooking rack....?

Then how high from the bottom of the smoker should the drip pan be (dimension A)..1.5-2 times the firebox opening... and how far from the end should the smoke opening be (dimension C) ... 1.5-2 times the firebox opening...

Finally how high should the cooking grid be off of the drip pan (dimension B)... 3" should be sufficient....?  I plan on having a removable tray that I could put in on top of the drip pan for charcoal and use the cooker as a grill when I want to, so I imagine I may want the cooking grid to be higher off the drip pan if it it wont hurt smoking performance... I would but a cheap grill to do "fast" food on... you are going to have a great reverse flow smoker... why try to make it a "one size fits all?"...

Any feedback is greatly appreciated! 

Below is a calculator and an excellent explanation of building smokers..... I'm sure you will have more questions after reading and using these tools.... If you need help with the calculator, PM me or post your questions and someone will jump right in... Our members are here to help you make the best smoker possible so you can make the best q in the neighborhood... Dave

http://www.feldoncentral.com/bbqcalculator.html

http://www.smokingmeatforums.com/t/54542/building-an-italian-offset-smoker/20
edited changes
 
Last edited:

austinb

Newbie
11
10
Joined Jun 22, 2012
Thanks for the reply Dave!

I've been playing around with the calculator and think I've got most of the dimensions figured out.  A couple questions about your reply:

Is having the increased heat from the firebox being attached to the smoke chamber a benefit?  I know too much direct heat can be a bad thing.

Do you have any input on the two smoke outlet options?  Is exiting out the top better/worse than exiting out the end?

When you say '1.5 to 2 times the size of the firebox opening', is that the total cubic inchs of the opening?

Thanks!
 

daveomak

SMF Hall of Fame Pitmaster
OTBS Member
SMF Premier Member
26,458
3,837
Joined Nov 12, 2010
Austin, morning....  The recommendation from the calculator are pretty much time proven for building a smoker that works very well... Of course they can be adjusted for personal design differences... Most folks build to the proven design characteristics.....  Dave
Thanks for the reply Dave!

I've been playing around with the calculator and think I've got most of the dimensions figured out.  A couple questions about your reply:

Is having the increased heat from the firebox being attached to the smoke chamber a benefit?  I know too much direct heat can be a bad thing. Attaching to the fire box will save heat, save on wood and it will be below or part of the RF plate anyway.. 

Do you have any input on the two smoke outlet options?  Is exiting out the top better/worse than exiting out the end?

Out the end, just above the cooking grate is the preferred exit point for the smoke and heat... If you look at the mods folks have made on various SFB smokers, they extend the exhaust stack down to the grate level for improved design ...

When you say '1.5 to 2 times the size of the firebox opening', is that the total cubic inchs of the opening? 1.5-2 times the square inches of the firebox to cook chamber opening... If the firebox opening is 60 square inches, I would recommend 90-120 square inches under the reverse flow plate (or more depending on the smoker design) so the air flow and smoke flow won't be restricted and choke off the smoker.... 

Thanks!
 
Last edited:

daveomak

SMF Hall of Fame Pitmaster
OTBS Member
SMF Premier Member
26,458
3,837
Joined Nov 12, 2010


Squib found it necessary to install a "deflector plate" in his smoker to reduce the heat on the top of the firebox and "get the heat and smoke moving" in the right direction....    Dave
 

austinb

Newbie
11
10
Joined Jun 22, 2012
So its been awhile but I've been working on my firebox a bit in my spare time and have it about finished up, thought I would post up some pictures to share. 

The main body was made out of a 16" pipe (1/4" wall) that was 20" long.  I cut the pipe in half and welded in two pieces of steel (3/8") that were 8x20" to get my firebox volume up to 1/3rd the area of my cooking chamber.  The front and rear plates are both 3/8" so the whole thing is quite a tank, weighing in at just over 200 pounds haha.  I purchased the hinge from a local welding shop and fabbed up a simple latch.  I've very happy with how the door seal came out, I made it from some 1/8x1" flat strap and a bigger plate I cut to fit the curve along the bottom. 

The vents ended up being a bit larger than I planned but I may go back and make the openings in the outside plate a bit smaller.  Currently with the outer plate covering up as much of the inner one as possible there is still some open space air could get in, not sure if this would be a problem when cooking or not.

Anyway hopefully I'll get started on the cooking chamber soon.  Going to cut the hole in the firebox once its attached.






 

austinb

Newbie
11
10
Joined Jun 22, 2012
Finally finished up this beast, figured I would post some pictures of the build and finished product. Have cooked ribs, pulled pork and a turkey on it, seems to work great.











 

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