Here is the current pit I am building. Going to be a long post... offset 125-gallon backyard model.

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realdocBBQ

Smoke Blower
Original poster
Aug 15, 2014
105
113
Well, I've built a few, and am working on trying 'break into' a slightly higher end market. So this cooker I am hoping is going to come out nice and snazzy and bring a good price at the end of it all from some yuppie suburban dude wanting a nicer backyard offset to complement his higher-end Traeger or something. lol

I've had this tank about 9 or 10 months. Finally decided to get to work on it, but this spring in OK has been exceedingly rainy, which limits the time and ability to work on it. I use my friend's shop and tractor, and don't want to leave ruts in his yard, so I have to lay off for days on end when we get a lot of rain.

Here's the tank:
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As you can see - lots of valves and such that needed to be cut out. Some people leave these, but I like the cleaner look of cutting out and patching the tank.

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Tank is right at 1/4" (.250wt) thick.

So patching the tank is a bit of a challenge. I want to make the patch contour to the tank, so the best way I've come up with is using my band roller to roll a long(ish) piece of plate to the same contour, then cutting it into pieces and welding them alongside each other to form a patch, then trimming, grinding and beveling the patch, tacking it into place and then fully welding it in and grinding my welds (which are undeniably ugly and amateurish) flat to try to make the eventual patch as unobtrusive as possible.

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And a profile view to show the appropriate contour/curvature.

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I don't know how many pics are allowed per post on this forum, so I'll start a followup post to record more progress.

This may not be the best, most appropriate or most efficient way to patch a tank like this, but this is what I came up with, and I'm fairly pleased with the end result.
 
Next is starting in on the firebox. This is going to be an insulated firebox - 24" pipe inside (.250wt), 28x28x28 outside. Because this is a backyard pit, I want to save some weight, so I did overcomplicate things a little bit. I decided to do 1/8" (.125") thickness for the outer plate, but I didn't want the internal pipe (the actual fire chamber) to have those thin ends. So I used my new Primeweld CUT60 plasma and the circle cutter jig to cut out the endplates. Because the endcap is thicker than the wall of the external box, I needed to inset the 1/4" cap by 1/8" or so to try to match up the ends. Various ways I could have done this, but as I said, I sometimes overcomplicate things. lol So the endcap was cut slightly smaller than the diameter of the pipe - so it could 'nest' inside the pipe.

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The other endcap is larger, and will overlap the entire end of the pipe, including the pipe wall - there is a method behind this madness, as you will see later...

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This is the endcap with the throat opening cut into it with my Metabo, then beveled on the edges, again for better welding joinery.

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Time to rotate the plate around to fit into the pipe properly.
Something a lot of people don't realize - this pipe usually isn't truly round. It's 'egged out' some, meaning just sitting there under its own weight, it will sag a bit and widen on the sides and shorten top to bottom. This happens at any of the larger sizes, I think 18" or greater, if it's 1/4" wall thickness or so. I believe (not 100%, but I THINK) that I was told this happens all the way up to 3/8" wall thickness, where it is strong enough to hold its own weight. This is why they love 3/8" so much for oilfield pipe, where it sits around for years sometimes. So, anyways, this presents an issue when you are cutting out a perfect circle (or as perfect as my palsied hands can achieves, lol) and then trying to fit that circular cutout into the slightly oval-ish pipe. Problems.

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Anyways, rolled it around, got it fitted into the right (ish) spot and tacked it in place.

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Here is a closer look at the 'inset':

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Then fully welded into place:

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Ground down my ugly welds so the 1/8" endplate will sit on the edge of the pipe, hopefully just about level with the surface of the 1/4" endcap.

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Then began welding around in a radial pattern, like tightening lugs on a wheel.

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Unfortunately, due to the endplate being so thin, I did get some warping of the material from the heat input, so I will have to deal with those as I move further in the build.

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Had to find TDC (top dead center) on the pipe with the throat opening in a level position, so that I could mark a reference point to be able to properly 'clock' the two endplates to each other in relation to the throat opening.

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TDC marked:

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Then marking the center of the plates, lining them up and shifting around to get them properly fitted on the end of the firebox pipe.

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And the endplate on the throat opening side fully welded in place.

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The other endplate also in place (this is the endplate for the firebox door). Also radially moving around to try to minimize heat input, lots of shifting it, laying on its side, rotating, rolling, etc. Finally got it done.

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In general, it is coming together.

Now, insulation. 2 layers of 1" thick 2400ºF ceramic fiber mat from Amazon.

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Next post - putting on the sides....
 
My fitup and joinery is certainly not perfect, even though I tried to take as much time and measure as carefully as possible when cutting out my plates, trimming, cleaning up the edges, etc.

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I had to use pipe clamps at times to pull the edges into place well enough to get them tacked in.

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Eventually got all the sides in place, but haven't completely welded up all the seams yet. Probably about 80% done, but they are all in place and welded out enough to hold there so I could call it a day (this was on Wednesday, two days ago).

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Today is Friday, and I worked until noon, now about to change clothes and go back out to the shop to finish welding this, and start on the door...

The door is going to be a double layer 'bank vault' style door, with insulation inside. Similar to this one I did on my first smoker, which resides in my backyard.

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This is the reason for the larger plate that will fit/overlap the pipe, so it will seal with the door closed. It will be 1/4" plate inside, then insulation, then 1/8" plate outside. I will also be putting in a butterfly damper through the door, so I will have to line up the two door plates perfectly before welding them all up. Should be a little bit of work, a little tricky, but I think I should be up to it. I hope. lol

On the one in my backyard, I just use the door itself as the air inlet, but - as I mentioned before - often people are looking for a 'feature' that is neat and looks cool, even though it may offer no real functional benefit. So I'll put a butterfly damper in, so people can keep the door closed while still allowing them to adjust airflow.

We'll see how it turns out in the long run.
 
Oh yeah, forgot about the wheelios - this is a big part of the higher end cooker market. Expensive, but that will get added into the final price. Details make the difference in a higher end build, I think. Or I hope, anyways. lol

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Beautiful start Danny! That thing oughta hold heat like a charm as well as you're insulating it. I'm in for the finish of this one!

Red
 
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Watching till the 1st fire 🍿

Well, I guess I'm done here!

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hahaha!

Seriously, I didn't get out to work on it Friday, life got in the way, so it got rained on - and with the seams not completely welded, that means water inside, on the insulation. lol. So, I pulled it out away from the shop and loaded it up with wood and burned the hell out of it for a few hours to heat it up and hopefully evaporate any moisture inside.

Then I let it cool off and brought it back inside and welded up all the seams. Now the firebox is truly done!

While I was waiting, I went ahead and measured my wheel offset.

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Ok, ok, I'll be honest. I had my wife measure the wheel offset, because I forgot to do it before I left home to go to the shop. After a few minutes of frustratingly trying to convey what I wanted her to check - including sending a picture of a Jeep wheel I measured to demonstrate - she still sent me measurements from the wrong side. <sigh> But eventually I got the right ones, which allowed me to calculate my axle length, given the spacing I want between the wheel and the firebox, and then I cut my axles and drilled 32 holes in them on the drill press (ruining one step bit in the process) and went to work hammering in my hubs and spindles, then plug welded them in place. They are NEVER coming out of those things!

So now my axles are done, just need to grind the plug welds flush, which I'll do later, since I'm going to have to clean them all up before painting anyways.

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I'm still not sure how I'm going to do the frame and front axle and steering, etc. I've done it with a full hub and spindle for previous 250-gallon pits, but I am leaning more toward just a big bolt through this time, or maybe even doing something with a pillow block bearing or a tapered roller bearing or something. Gotta sit down and give that some serious thought.

<edit> Sorry, thrust needle roller bearings was what I was thinking of...
 
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Been a while since I've updated this, so I'll add some things I've done lately. Been a crappy spring for working in the shop - lots of wet stuff falling from the sky, keeping the ground soft and squishy, which inhibits my ability to work, as I don't want to leave ruts in the ground from the tractor, as it's not my shop or yard.

Decided to try to get the door completed. This is going to be a bank vault style door, insulated WITH pass-through air inlets, so that makes it a bit more complicated.

Rolling a hoop out of 1/8" flatbar (1.25" wide, I think) on my band roller.

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Had a buddy cut some holes in my door plates with his plasma table so they would be perfectly lined up:

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Going around in small sections and taking a LOT of time in between, to try to prevent warping. The inner door face (inside the firebox) is 1/4", the outer is 1/8" - trying to save some weight.

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Once the hoop is welded and the inlets are welded on the inside of the inner doorpanel, fit up the outer panel.

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Now to figure out how I'm going to drill holes for the air inlet dampers. Hmmmm... maybe I should have drilled those first. But, that would have had its own challenges, as well.

Decided to level the door as best I can front to back and side to side, then used my laser level moving all around and adjusting height to be the same around all sides. This should work, I think...

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Then move the laser to the sides from WAY above and mark the vertical lines - so it is even on both sides as well. Theoretically, all of these are in line and should be good to run a control rod through...

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One I drill the holes. Ok... outside holes, not too much of a problem. Drilling holes in the inside edges... a bit more of an issue.

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Obviously my drill bits won't reach from one side to the next. And cannot fit from inside the pipe. Decided to use my plasma cutter and burn a hole in each - ugly, rough and not perfectly lined up, but... they were holes.

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After cleaning up with my right angle pneumatic grinder and a carbide burr bit, I managed to get them lined up enough for the control rod to pass through.

Now I began to worry... this door is getting HEAVY. And the outer doorskin is planned to be 1/8" plate. I worried attaching it via 2 hinge points, each about 3" long, was going to lead to sagging - either of the hinges, or the door skin itself might warp. So I decided to go with 3 hinges, each made of 1/4". That made me feel better, but still... 1/8" door skin. Maybe I should rethink that. But I didn't want to do 1/4" for the outer door plate, that's just way too much weight. Not to mention, I build the box for the door plate to inset into the face of the box and to swap that to 1/4" would mean the door face would stick out from the face of the box. Not my ideal aesthetic.

Then I had the bright idea to weld a backing plate to the inside of the outer door skin so the hinges would have a stronger attachment point. So back to my plasma guy I go and he cuts me out a cool backing plate I can weld into the inside of the door, on the backside of the outer door skin. Not just weld the edges, but also plug weld the plate to the door. Boom.

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Took me a good 3-4 hours to weld this up - remember, both of these are 1/8, so I was taking a LOT of time in between doing 2-3 spots to let it cool so it wouldn't warp - warpage of this door panel would be disastrous!

But finally got it done.
 

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So now to finish the door.

First - insulation.

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Drill a hole in the outer plate and weld a nut on the backside (which will end up inside the door and never able to access again) for the door handle to bolt into:

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Attach the front plate on, weld in place - also skipping around and allowing for lots of cooling time in between welds. Sheesh, this takes forever.

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Finally done several hours later and time to go to work on the air inlet dampers:

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Lot of finagling, grinding and shaping to get these right, then get them tacked in place.

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And the door sitting in the face of the firebox^^^^.

This door is a BEAST. I bet it weighs 40-50 lbs. Sheisse.

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Going to go out today when I leave the office and try to spend a couple of hours out there at the shop and get the door actually attached with the hinges I've had cut out. 3 hinges out of 1/4" steel, each hinge with 2 attachment blocks on the firebox, 1/4" also.

I sure hope those hold this thing up well, or I'll end up having to build a hinge 'mechanism' out of 1¼" square tubing or something, which also isn't the aesthetic I'm looking for out of this thing.

So we'll see how it all works out.

Wish me luck! lol
 
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