Offset 250 Gallon Build

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josheaton

Newbie
Original poster
Sep 27, 2012
27
10
New Orleans, LA
I’ve been wanting to build a large offset smoker for quite a while now.  Been busy and distracted with life for a long time and after getting sober, I’ve finally had the time, patience, and commitment to start a project of this size.

Found a 250 gallon tank for sale from a local shop, and bought an old boat trailer with title for only $300 bucks.  Quite a steal considering I got the tank for $150, so I’m only set back $450 to start.



Started by marking my cuts and then filling it with water and cutting my doors.  The doors are 33 inches wide and 19 1/2 inches tall.  I was going to use a torch but wanted a finer cut so used some steel cutting disks and probably burned through at least 10 before all was said and done.



Took the day off yesterday to finish the doors and mount the hinges.  Used 1/2 inch pipe and rod.  I know there are much more elegant and attractive ways to build hinges, but I’m a novice welder, and for this project will be choosing function over form.  








Also ended up grinding off all the valves and piping that came off the top.  This took hours, but I'm happy with how it looks now.  I'll need to patch these somehow prior to sandblasting and painting, so I'll deal with it later.


I’ve ordered two nickel plated spring handles from Amazon that I will be mounting this weekend over some leftover bent rod as well as finishing up the doors and seals.


I'm still working on concepts for the firebox.  I'm thinking about buying another tank, cutting it in half, and mounting it to the end.  This 250 gallon tank is 30 inches in diameter.  Would a 30 inch cook chamber with a 30 inch firebox be too big?  The reason I’m doing that is to avoid having to completely fabricate a tank, plus the cost that goes along with it.  Also the smoke stack, how high does it need to go?  How big a diameter should I use?  I have lot's of questions...

I’ll keep you all updated as I make more progress and I'd love to hear your feedback and pointers, especially as a first timer building something like this.
 
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Incredible build!  Looking great.  I guess my question is more regarding the firebox and how it looks like you've done yours.

I was thinking of just buying another 250 gallon tank and cutting it in about a third leaving the end cap on.  Then Cut the other end cap off and weld it on to the cut end to create a smaller tank of the same diameter.  Then cutting a whole for the firebox and mounting it to my cook chamber.  What are your thoughts on that? 
My cook chamber is 41" with a 41" fire box, then I boxed that in with a 48" square box. Smoke stack I would guess maybe 8" diameter and 5 feet tall. Can always damper it. I know 500 gallon builds usually do 10" pipe about 6 feet tall. But you don't need THAT much draft. lol

Mine has a 10" pipe 8 feet tall.

http://s10.photobucket.com/user/SxFxZ/media/F4A9BC5E-A7E8-43C9-9329-F410190D2391.jpg.html
 
I honestly thought of doing that. lol But then I wanted to insulate my fire box, which you could still do if you did a sleeve inside, but I wouldn't only use 1/3 of that tank. I would leave your fire box as long as possible. I'd even go as far as finding a smaller propane tank in diameter but longer. You stuff your fire too close to your cook chamber and that area near the firebox is going to almost have direct flame and be too hot. The first 2/3 of my first door is this way. Most of it doesn't even have a grate in it for this reason.

But I got 1/4" plate for the firebox door and 10ga plate for the rest and boxed it in to insulate it. Was cheaper than buying another propane tank. Plus I wanted the fire box to have as much internal volume as possible. Which the firebox internal volume is 250 gallons and the cook chamber is 1,000.

http://s10.photobucket.com/user/SxFxZ/media/5A6E368F-C7FA-4BE7-B7E7-C9B280B50A41.jpg.html
 
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I honestly thought of doing that. lol But then I wanted to insulate my fire box, which you could still do if you did a sleeve inside, but I wouldn't only use 1/3 of that tank. I would leave your fire box as long as possible. I'd even go as far as finding a smaller propane tank in diameter but longer. You stuff your fire too close to your cook chamber and that area near the firebox is going to almost have direct flame and be too hot. The first 2/3 of my first door is this way. Most of it doesn't even have a grate in it for this reason.

But I got 1/4" plate for the firebox door and 10ga plate for the rest and boxed it in to insulate it. Was cheaper than buying another propane tank. Plus I wanted the fire box to have as much internal volume as possible. Which the firebox internal volume is 250 gallons and the cook chamber is 1,000.

http://s10.photobucket.com/user/SxFxZ/media/5A6E368F-C7FA-4BE7-B7E7-C9B280B50A41.jpg.html
 
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It was quite a lengthy process. lol I butted the 2 tanks against each other and keeping a marker parallel to the ground I kept the back of the marker touching one tank and the tip drawing on the other. Made that cut, moved the tank in, and repeated the process until I got it where I wanted. Originally I extended my marker to do the "full circle" which actually ended up being dang close to what I needed. But decided to cut little by little. Better than having to weld chunks back on. lol

As you can see here I had my big red mark I originally drew but then opted to cut it out little by little just to make sure it was right.
http://s10.photobucket.com/user/SxFxZ/media/067DD0A9-41CC-4788-9409-6787313F0C6E.jpg.html
 
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It was quite a lengthy process. lol I butted the 2 tanks against each other and keeping a marker parallel to the ground I kept the back of the marker touching one tank and the tip drawing on the other. Made that cut, moved the tank in, and repeated the process until I got it where I wanted. Originally I extended my marker to do the "full circle" which actually ended up being dang close to what I needed. But decided to cut little by little. Better than having to weld chunks back on. lol

As you can see here I had my big red mark I originally drew but then opted to cut it out little by little just to make sure it was right.
http://s10.photobucket.com/user/SxFxZ/media/067DD0A9-41CC-4788-9409-6787313F0C6E.jpg.html
 
The fire box will only be 35" deep? May want to keep more than that if possible. As I said I'd think the further away from your cook chamber you can keep your fire, the better off you'll be.
 
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