Offset fabrication question

mnbadger · Oct 2, 2015

I'm looking into building an offset smoker in the coming year. So far, I have had a really hard time finding the size tank I want (80-120 gallons). Has anyone here ever had a metal fabricator roll plate steel for them to make a tank?

We have a big fabricator here in town that I'm going to check in to see how much it would cost to roll a 4x8 plate for me. Based on a quick internet calculation that would result in a 3' diameter tube 48" long. Which would be pretty huge... I'm thinking 24" in diameter is probably more what I would want.

What I was wondering is if you guys could let me know what roll diameter between 2 and 3' I should ask them about. Also, what thickness of metal would be best. I know guys look for 1/4 or 5/16 steel. If you guys could pick any thickness for the steel what do you think I should get a quote for?

Thanks!

columbia1 · Oct 2, 2015

Yep, that is how I built my pit, it cost $450 for a 24" by 72", and they welded the seam together. 1/4" is fine for most apps.

landarc · Oct 2, 2015

1/4" steel is the way to go for the cook chamber.

In terms of diameter and length, that's a question of style of cooker and desired capacity. I would want a minimum of 26" and 5 feet in length.

mnbadger · Oct 2, 2015

Thanks for the comments. The other cookers I have looked at are predominantly the Jambo and Shirley models. They both look really solidly made and I could see modeling my smoker after one of them.

I originally thought 4 feet would be big enough... But I'm thinking I should go for a 5' cook chamber since every thread I read here is to get/make a bigger smoker than you think you need.

I'm leaning towards the Jambo style of cooker vs the reverse flow model. I also plan on making an insulated firebox.

Do people think going for one big door or two smaller ones is the way to go? I know people like the ability to do a whole hog with the bigger single door. I'm just wondering if the double doors ends up giving you a more efficient cooker with not losing as much heat when you open it up.

landarc · Oct 2, 2015

Again, this gets back to needs and expectations, do you really plan on doing whole hog cooks, on an offset? If so, you have to had a door large enough to accommodate a whole hog. Remember though, that door will be heavy, and with a single large door, every time you open it, the impact of the cook chamber will be larger than with two small doors.

In terms of chamber length, I am a believer that a smooth, even flow of air through the cooker makes a difference, a longer cooker allows for a smoother air flow and more options of where to place meat. Especially important in a traditional offset.

For me personally, because of limitations of not being able to easily lift things above shoulder height, the only offset that has a door configuration that would work for me is Shirley cabinet style doors.

Smokin J's PIts · Oct 2, 2015

For a 24” diameter you need the plate to be 75-3/8” for a but to but, subtract about ¼” for welding to get full pen. For a 20” diameter you need the plate to be 62-13/16” for a but to but, subtract about ¼” for welding to get full pen. I did the same thing but out of 10Gauge for the pit, and I made a square fire box. I really wish I would have gone with the 24” instead of 20”, not so much so I could put more in, but it would allow more spacing and better air flow. Check with the shop,
I found that here locally it was cheaper for me to purchase the steel and have them shear and roll it, vs them using their steel.
I shopped around and got the sheet for 100 bucks, and the shop only charged me 80 to shear and roll it, if I went completely thru them they wanted 325 bucks for it. I also only had them tack it so it could be rolled and I did the finish seam weld.

mnbadger · Oct 2, 2015

I think the two smaller doors are the way to go. I would probably go with a "full" grate from the firebox to the smokestack (like a jambo or Gator pit) and then have two smaller pullout upper shelves for each door.

Porcine Aviator · Oct 2, 2015

If you roll the 8' length, I get 30" diameter-- is that too large? Cut it to length.

If you have an electric utility near you, you could find some reel tubes that are 4' long and 24"-30" in diameter. These are usually 3/16-1/4" thick. They usually discard these when they are empty.

Large electrical transmission wires are spooled on these hubs, and you will see them on linemen trucks and spool carriers.

Smoke & Bark Barbecue · Oct 2, 2015

It doesn't take much more wood, if any, to run a 250 gallon tank vs the 100-120 gallon you first mentioned. We use a 250 gallon offset RF and within a month after we got it, I wished we had got a 1000 gallon. Some may argue with this, but as stated above, the bigger the cooker and more air flow the better it will cook. 20"-24" is just a tad on the small side to me. To each their own.

mnbadger · Oct 3, 2015

Thanks for all the great information everyone. It's really appreciated.

The main reason on settling around the 60" or 120 gallon length is just space to store it and moving it around. We only have a vehicle with a 1500# towing capacity as well...

My plan is to make more of a "backyard" model on big wheels since almost all the use is going to be at home and it will take up much less space than a trailer. Then if we want to take it to competitions or over to someone's place to cook for them I'll grab my inlaws Dodge Ram and utility trailer.

Diesel Dave · Oct 3, 2015

There are ways to shorten a trailer, like Paul does and make a removable tongue.
You mentioned moving it possibly, that's going to be a lot of weight to push on/off a utility trailer. And as to the towing weight, that's hitch weight. A well balanced trailer will be fine to tow with a smaller vehicle

DouG M · Oct 3, 2015

mnbadger said:
Thanks for all the great information everyone. It's really appreciated.

The main reason on settling around the 60" or 120 gallon length is just space to store it and moving it around. We only have a vehicle with a 1500# towing capacity as well...

My plan is to make more of a "backyard" model on big wheels since almost all the use is going to be at home and it will take up much less space than a trailer. Then if we want to take it to competitions or over to someone's place to cook for them I'll grab my inlaws Dodge Ram and utility trailer.

Why not make a patio flate back,top and sides model more room to cook on and then you only need to roll the bottom of it or put some what of a V on the bottom so greese etc. runs to your drain pipe.Would cost less to get a simple bend as to a round one. Yes with the golf cart wheels on it. Could use electric winch to help roll up onto trailer, If by your self wieght not so much a facter now. Smaller than trailer model for storage. IMO Show us pic. when you get it done. Good Luck

Offset fabrication question

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