Some information please.

[Clive]

Totally new to smoking, I have just got an old stainless steel beer barrel, it is 14.5 inch diameter x 18 inches long. I would like to make an offset smoker with a square firebox. Would this be feasible and work?w

 

[fivetricks]

That would be so small. Haha. Sure it'll work in theory. Prob only need 1 or 2 coals to get to temp!

The calculator says you will need a firebox with a minimum volume of 991 cubic inches

 

[Clive]

Thanks, there is only my wife and I so we wouldn’t need a lot which is why I liked the idea of a small machine, I have seen vertical ones about the same size so figured there was a chance it could work. I haven’t come accross it yet but is there a calculator on this site?

 

[fivetricks]

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

 

[Clive]

Thanks for that.

 

[fivetricks]

Not sure of your welding a fabrication skills, but I'm assuming the beer keg is made of aluminum correct?

So it will take special welding techniques to join a steel firebox to an aluminum barrel.

 

[Clive]

No it is stainless steel, I have a dual trade, General machinist/ Heavy duty fabricator welder( boilermaker) apart from stainless’ tendency to move when beingwelded, lots of tacks and 309 weld wire, that is not a problem. My problem is knowing nothing about smokers and smoking.

 

[Clive]

Using the calculator the size of the firebox works out at 10x10x10 which is dead easy.

 

[daveomak]

Feldon's calculator has issues... Using it, increase the opening of the FB to the CC by 50%.. same with the exhaust stack.. If the stack says you need 2", make it three"....

 

[Clive]

Thanks, I am not starting anything immediately for reasons like this, I want to get it right first time. If the smokestack needs to be say 12 square inches area then am I right in assuming the inlet air should be the same?

 

[daveomak]

Air inlets work well at 0.004 X the volume of the Cook Chamber....
The upper and lower inlets work well at 20% for the upper and 80% for the lower....

 

[Clive]

Thanks, I’m not rushing into this, I have a few cash jobs half finished in my workshop and need to get them finish welded first, we have just had a total fire ban but it appears to have been lifted today so hopefully I can get them underway and then start on my smoker.

 

[Clive]

Daveomak, the calculator recommended a firebox 10”x10x10, I have a strip of 12 inch wide cut off a shhet, can I make the box 12x12x12 as it will be easier with less cutting?

 

[daveomak]

Yes.... When calculating for a smoker build, the CC determines the critical dimensions... The FB can be as big as you like... As long as it is properly positioned for good air flow and has positioned air inlets, you are good to go... If you have 16" firewood available, I'd make it 18" long... or get a cut off saw and cut down the 16" wood to fit the 12" FB...

 

[daveomak]

Due to the smaller size of the CC, I would exaggerate the opening to the CC, and enlarge the exhaust... There is a point of diminishing returns on smaller smokers.. surface area vs. volume .... You get more friction loss on a smaller smoker... that translates to reduced air flow from friction...

 

[Clive]

Thanks
Daveomak, the strip I got is 8 foot long so I can make it 18 inches easily. I would have never thought of friction playing a part in a smoker, there is a lot more to these than I originally thought.

 

[daveomak]

In a gravity flow smoker, friction is a BIG deal... So, it pays to enlarge areas so the effective volume is increased compared to the friction causing surfaces... Don't know how to calculate it but, our members proved it true with their many builds...

 

[Clive]

I was always thought it was on the principal of heat rises, I will start next week, I try not to grind and wallop steel on the weekends, my neighbours are pretty good but I try not to push it, I’ll try to video it as I go, it will most likely be a protracted affair, it’s the middle of summer so when it gets too hot I stop for the day. Thanks for your help and advice.

 

[daveomak]

You are welcome...... Dave

 

[Clive]

I am at the stage of fitting the firebox to the cooker, the calculator gives a round hole of 4.88 inches. It is easier to cut a circle in the barrel and have a short tube connecting the two. It is a lot less work and welding. Is it a good idea or am I better off inletting the barrel and inserting the burner in the hole?