Resources to learn about smoker design

[DogFaced PonySoldier]

So where do I look?

Ahumadora has offered to help me with the design and layout of the new offset, but I want to read up, learn about pros and cons of various designs, etc. I know the basics of a reverse flow vs a classic single flow, but I don't really know much else.

Like, is it better to have a round or square firebox? Is there a difference at all?

End load firebox or top load firebox? Or is there a downside to doing both side and top load on the same firebox, besides complexity and leaks, etc. Those can be mitigated with proper design. But an end load box can be a PITA to clean out, even to load wood if it's very low as you get older.

How low on the main chamber should a firebox be attached? Should it undercut the tank as well, or just hang off the side?

Are internal dampers or baffles something to consider with a very looooong cookchamber?

How do you determine diameter of exhaust stack? And length? Is a collection chamber useful (from what I've seen in my limited research this seems minimally effective, if at all).

How and where would be the best way to implement a square box chamber for additional smoking capacity and/or cold smoking? The end? Above the firebox on a reverse flow?

Would doing a reverse flow with sliding or removable baffles be useful? What about 2 racks, the main cooking rack and a set of sliding racks above (aka 'rib racks') get differing heat levels due to the lower racks being close to the reverse flow baffles on the bottom?

Has anyone ever tried a built-in water chamber/pan? I thought of a 'trough' along the length of the smoker, with a drain exiting, and maybe even a fill spout. Maybe along the upper back wall...

What is the best material for racks? Expanded metal? Stainless? Different choice for sliding racks or simple removable racks? These are more questions for later, obviously... but my mind is working on things.


I mean, I've search YouTube, but I don't find a lot of in-depth discussions of the pluses and minuses of the various design elements. I'm sure there are people out there who have had experience with lots of different types, but it seems like I don't know how to find what I'm looking for other than an explanation of reverse flow designs. I'm pretty familiar with that by now, and I understand the pros. Cons, I'm not sure.


So our tank is 9 feet long, 30" in diameter. I am actually thinking of doing 3 doors, 30" each, but a lot of the very large smokers, even 500 gallon ones, still have 2 doors. I'm not sure it matters too much. But even with 30" doors, I could easily have 4" between doors and 5" on either side, or thereabouts. Make them 28" doors and I can move them in a little more. That might be better. Triple 28" doors.

A lot of questions, and I know the more research I do, the more questions I will have. I don't want to bother anyone too much all the time, as I'm a total n00b to offsets, but the pros and cons of the various design elements kind of fascinate me. I actually thought of doors on each side, which would be killer, but how would one manage counterweights for the doors so they don't interfere? I guess you could just make it to where you don't open both sides at once... I dunno.

Maybe I'm reaching for the sky. I'm probably overthinking things and planning way more than I can really bring into implementation. But that's ok, I'm excited. We've got our tank in our possession, which is a several thousand dollar start and savings to begin with.

Here's some pics of us moving it yesterday:







I kind of think if we keep the entire length of a 9 foot cook chamber, a reverse flow is almost going to be a requirement... or so it would seem. However, even guys with yuuuuuge 1000 gallon tanks run plain old single flow/direct flow and just learn their pit, so they can judge how things are at different areas.

What do you think?

[DogFaced PonySoldier]

Oh yes, door flanges. Better inside, better outside?



What about paint? I've seen 'em where they're just natural, that's fine. What about high temp 'grill paint' like you can buy in a spray can? I'd like something that is essentially maintenance free, so this doesn't need a cover but it is still super durable. Even considered ceramic powdercoating or Cerakote. The cook chamber I've learned really doesn't transmit a lot of heat in these big beasts, even running 400ºF, the surface is still under 200ºF, even under 150ºF in some areas. That's awesome, but this thing is going to be in the weather, not under a carport or anything. I like the look of some of the linseed oiled ones like Ahumadora posted (that red one is BEAUTIFUL), but I don't want to have to keep coating it all the time, either.

Really really considering a high temp ceramic powdercoat at least on the firebox. I dunno. Jeremy Yoder just sprays his firebox down with cooking oil spray when it is hot, which seems easy enough, lol.

[Andrrr]

Sorry to be that guy but I can't help you AT ALL. But I love the ambition behind the build and I'm hoping to do the same someday so I'm following along vicariously.

[RiverJeff]

Wish I was closer would love to help looks like a great build! Just bear in mind Do Not RUSH!!

[DogFaced PonySoldier]

Long as we don't cut off things we are going to miss... we should be fine. lol

The biggest expense is going to be trying to find a trailer for it. We need to get to work on that....

[RiverJeff]

Check into looking at old mobile homes the frame under them are usually built with the main frame and a sub frame that holds the axle assemblies Hell for stout!

[Murdy]

Or old agricultural equipment. I had a friend who bolted his ice fishing shack on top of an old hay bailer frame and made his own RV.

[DogFaced PonySoldier]

Interesting thoughts...thanks!

[lumbrjk]

Following!

[Bob's BBQ]

When building mine I looked at a lot of pictures on-line and read several articles. At the end of the day, I chose features that I wanted and dove in. All cookers "work" - you just need to learn how fuel and operate your unit after it's done. Yes - basic airflow and dampers are important, but beyond that don't overthink it. Just design in features that you like. At the end of day, it's just time an temp. I've had great BBQ off some really weird looking smokers (even converted refrigerators and garbage cans).

[Henrik]

Given the length I would not do a reverse flow. To me reverse flow is better for smaller smokers where it evens out temp. In this smoker the air has quite a few feet of travel, so you’ll be alright. I’d rather keep it simple, be able to have better shelf spacing and good draught.

[DogFaced PonySoldier]

Excellent to know! I was thinking longer meant more variable temps, but honestly the 250-gallon I've borrowed lately has surprised me at the temps. End to end is pretty stable, about 15-30ºF lower in the middle.

[DogFaced PonySoldier]

Henrik having hand-built a number of smokers yourself, do you have any advice on the firebox? Square vs round, mount middle, mount low, undercut or hang off the end, etc.?

[Jerod Broussard]

Don't fret on temperatures being even all the way across. If you load that thing down with briskets I doubt every brisket is going to be the same size. It's also an almost known fact that no one has ever died rotating meat.

[Ahumadora]

Exactly. Most of the time you are cooking a variety of cuts and meats that need different temps.

[jfmorris]

Yeah, my advice is to embrace the fact it WILL be hotter right next to the firebox - that becomes your "searing station" as it were, where you can crisp stuff up if you need to.

My much much smaller offset it was hot where the firebox opens into the main cooking chamber at one end, and I made a baffle by putting a 9x13 pan tipped up over that opening, below the cooking grate, to force the hot air to the left and right and down, versus coming straight up and out of the firebox. That simple trick made my end to end temps a lot more consistent. I don't bother unless I need to put meat all the way at that end of the cooking grate, like loaded up with butts end to end.

[DogFaced PonySoldier]

Yes, the one I am borrowing has the firebox mounted seemingly quite high to me. And we use a thick 3/8" plate angled over it to obscure a portion of that and direct flow downward - this helps quite a bit.

[jfmorris]

DogFaced PonySoldier if I were building a new one, I would take a tip from Ahumadora and put the firebox LOW, with the opening well below the cooking grate. If you get a good seal, no reason you can't do a top loading firebox. Mine is top loading, and doesn't seal all that well, but when I close the top, the majority of the heat is going into the cooking chamber.

[DogFaced PonySoldier]

Yeah, I am thinking of ease of tossing on another log, rearranging the fire, etc. A side door for cleaning and such is fine, too, just I don't like really reaching in deep from the end to rearrange logs and such.

[Henrik]

Square or round firebox doesn’t matter much. It comes down to which design you prefer, as well as cost of material and manufacturing. Round is more common because it’s less fabrication, and it’s easier to find scrap tubes lying around.

I prefer having a regular fire box door (on the end as opposed to top loaded), simply because it’s less risk of burning hands, arms and eye brows when you want to add another split. Heat rises up, fast 🔥.

I would hang the fire box low, with a 4 inch overlap (meaning it “protrudes” into the food chamber a bit. That gives you the hot air entry hole for free so to speak, plus it’s easy to weld fire box and food chamber together that way. It will be structurally strong for free so to speak.

[smokin fool]

Ratz I was at my brother's last night, his son had his latest offset build right there in the garage and I never thought to take pics of his work.
Just randomly looking at it he had some unique features.

[DogFaced PonySoldier]

Ask him to send you some pics and share some secrets smokin fool!

[Ahumadora]

Ok. Here's what I would do.
I converted the measurements to metric so it is a bit easier to calculate and also to confuse the folks here
Pipe is about 2800mm long, so cut it at 660mm mark. Before cutting you need to decide if you want a left or right hand firebox as you have the tanks ends welded on already and the weld seam will go on the back side of the pit. (The drawings are for a firebox mounted on the left).
So you are going to cut the pipe, then rotate the firebox arond so 1 of the tank ends becomes the back of the firebox and is already done.
Use white correction pens to mark the tank where to cut.


You want about 5 - 6" in between the doors (120-150mm) to stop the tank distorting.






Wrap a tape around the diameter of the tank then divide into 4 to get the 12 /3 /6/ 9 o'clock points. As it has feet already place on level ground and use a level to find and verify the 12 and 3 o'clock points.

Measure 10 x and cut once. Don't rush this part Run a tape from the 12 o'clock down about 150-180mm and this will be the position of your top door cut. Again run tape down about 50-75mm from the 3 o 'clock position to mark the lower door cut.

I would cut the top 1/3 out of the firebox and get a 3/16" hotplate bent up to fit. The 1/3 section left over can be used inside the firebox to make it double wall. This also allows you to raise the firebox on the pit and not have ground clearance issues for a trailer pit.

I posted some pics of how I have done it.

[Stuey1515]

Ok mate, my little project was nothing compared to the proportions of your pit, but I see myself and my experience in all the questions you have here. Take the invaluable advice on the design that you have been given here, trust it and just get on and do it!! Stop all the hand wringing about ceramic coating and heat transmission b$llshit. I took two years to finish mine and only because I stopped procrastinating about making it perfect and just made the bloody thing. As soon as you set fire to it the first time, all thoughts about door flange flange seals on the inside or the outside waffle become totally irrelevant. Seal the chamber as best you can with what you've got handy, I wasted a lot of valuable cooking time by way over thinking it, my advise is JUST DO IT!!
This is intended as encouragement in my own special way, not a criticism.

[Ahumadora]

This build needs more Whiskey, I say!