Oil drum smoker help needed

[Smokey_MattUK]

Hey all.
UK bbq here.
Now I’ve got myself an oil drum bbq that I used as a smoker over the weekend. Did a cracking ribs recipe which was a winner using “madscientistbbq” YouTube. But I struggled burning a clean fire as there’s not a huge amount of air getting in even though I’ve got a vent there.
now I fancy converting this drum into an offset smoker but I’m struggling to find a replacement firebox here in the uk.
The drum is 21” diameter and 33” length
Volume is 11424 cubic inch and feldon says the firebox volume needs to be 3808 cubic inch
But my question is how do I get this in dimensions?
I’ve done some rough calculations and I’m coming out with 16” diameter and 18.71”
Does that sound right? As I’ve got the drum horizontal I’d use a have moon opening between the FB and the CC

So in terms of the photos. I’ve got the adjustable vent inlet on the lower left hand side, below the cooking grate and the chimney on the right hand side above the cooking grate.
i did manage to get clean smoke over the weekend, but had to use wood coals and couldn’t burn wood inside as I couldn’t get enough oxygen into the fire without opening the lid and then I lose heat.
Appreciate all your help in this. If anyone has any firebox plans that I can give to a fabricator that would be amazing!

the link below
Link to BBQ Pit Calculator

 

[DRKsmoking]

But my question is how do I get this in dimensions?

Hi welcome from Nova Scotia, Sorry i can not help with this but there are quite a few people here that should chime in to help you with this. As there are some builders on the Forum that have made some fantastic smokers
David

 

[radioguy]

Matt welcome to SMF. You are on the right track. You just have to assume a width based on your drum and solve for the other dimensions. Do a seach for "Char-Griller E1515 Patio" . Not sure if you can get one in the UK. But its about the right size for your drum. I like to go 10 to 20% larger on the firebox. You can always use a smaller fire in the larger box. Look up Dave Omak here he has a better calculator.

RG

 

[Smokey_MattUK]

Matt welcome to SMF. You are on the right track. You just have to assume a width based on your drum and solve for the other dimensions. Do a seach for "Char-Griller E1515 Patio" . Not sure if you can get one in the UK. But its about the right size for your drum. I like to go 10 to 20% larger on the firebox. You can always use a smaller fire in the larger box. Look up Dave Omak here he has a better calculator.

RG

Thanks for this. I’ll take a look at that and the calculator. Time difference and all I’m working now. So will check tonight.
now the hard part is finding a fabricator as the ones I’ve seen only do railings and stairs. I’m sure if I plan this well I could get a welder to do most of the work if I get the materials

 

[Smokey_MattUK]

daveomak
Need your help here please.
I’m struggling with the circle calculator. Can’t seem to get my head around it.
Ive found a fabricator, but they need drawings and I’m writing a brief for them.
What I need help with is the FB/CC opening dimensions. I’ve put the link to the pit calculator in my original post.
But for clarity the CC is 21” diameter by 33” length
Firebox would be 16” diameter by 19” length
Calculations show that FB/CC opening needs to 8.81 diameter but I’m struggling with getting something written down to pass to the fabricators.
Appreciate your help with this.