# Another new guy with fire box questions

#### xprmntl1

##### Newbie
Original poster
Ok, here's what i've got, a 250 gallon propane tank that someone already cut into. I'm needing to figure my firebox size but am having trouble with the calculators on here. My smoker main body is 30in diameter x 66in. long. I was planning on building my firebox 30w x 24h x 24 long. Also how big does my box to smoker opening need to be and how long should my exhaust be? Thanks!

#### mballi3011

##### Gone but not forgotten. RIP
OTBS Member
SMF Premier Member

Well thats all sounds good to me but I bought my smoker. Can you stop into Roll Call and introduce yourself and your equipment. But then you can wait and someone will come around and give you all the info that you'll need.

##### Master of the Pit
OTBS Member
Looks like a big project!!  Can't wait to see pix of the progress.  I've never built a SFB unit, but stick around and someone will be along to help with the calcs.  Welcome to SMF!

#### xprmntl1

##### Newbie
Original poster
Well, went ahead and got started on the firebox yesterday at weld class, dimensions are 30w x 24 1/8 x 24 1/8. Guys at class are questioning its size, but I told them I researched the net and what I came up with is firebox should be 1/3 the size of the smoker. This thing is heavy and huge, it took 3 guys just to get it on the trailer and i'm not done with it yet! Made out of 3/8 AR plate.

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#### jonnyrod

##### Fire Starter
Your firebox is plenty big, better than too small. According to the calculator you need;

17" x 8" rectangle firebox to main cook chamber opening

4, 4" rectangle firebox air inlets

A 69" stack at 4" i.d.

These #s change if you go from rectangular to circular as well as stack length depending on what size pipe you use.

You can also use square tubing as long as you have 864 cu inches of volume.

#### sqwib

##### Smoking Guru
OTBS Member
Off to a good start.

Looking forward to the build photos

In my signature is a pit calculator

#### xprmntl1

##### Newbie
Original poster

Actually I am almost finished now, just need to cut the hole for my temp. gauge and finish the other side of the trailer for my wood storage. Been pretty busy working on it on my days off. Thing cooks great, holds a good even temp even in cold temperatures!

Look's Cool!

#### smokermark

##### Meat Mopper
Hey hey that rig of  yours there looks mighty NiCE. I like the way you positioned your firebox in there into the cooking chamber. Inside pics please, inquiring minds want to know!

#### cheese meister

##### Newbie
Sweet setup! Just one request: More Pics

#### realtorterry

##### Master of the Pit
OTBS Member
SMF Premier Member
very nice. great job!

#### xprmntl1

##### Newbie
Original poster

Here's the firebox to smoker damper, I made several settings to shut down heat if needed. I need to make changes to my fire grate, my cast iron ones have got too hot and bent.

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#### turn4fun

##### Fire Starter
For your firebox grate, how about using some of the same size angle iron you used for the riser.  Cut several pieces that will set down in your framework like this:

^^^^^^^^

Lay them in with enough of a gap between each one for adequate airflow and for ash to fall through, and just tack them in place.  Should never warp enough to matter.

#### SmokinAl

##### SMF Hall of Fame Pitmaster
Staff member
Moderator
OTBS Member
That's sweet xp! Great job, can't wait for some Qview!

#### anstissk

##### Smoke Blower
Looks really good.  Whats a final price on the build?

#### deepinthewoods

##### Newbie
NICE JOB.... VERY IMPRESSED

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