55 gallon smoker in the works

[Noseoil]

I said howdy in the newbies forum, but I wanted to do a better job on documenting the build. I'm writing this thread to show what I've been working on. It isn't done yet, we live a small town in northern New Mexico, so I have to mail out for some parts, but it's fun building stuff, so here's what I'm doing. It's going to be a drum smoker with a remote fire box. I was concerned about the thin gauge of steel drums (0.040" is too thin for a fire box, but ok for the oven for cooking), so I'm going to have a remote fire box which goes into the drum on one side, the opposite end will be the chimney.

Using 1" X 1/8" angle to put stuff together, odds & ends & some stuff I have to buy, but there's a little progress every day.

 

[thirdeye]

You did a very nice job on that pit. I especially like the recessed fit of the main cooking grate. Those were popular when I was a little boy in Texas. Almost everyone had one. A couple of options to guard against rust and burnout from hot coals is to pour a thin layer of concrete in the bottom, or build a charcoal grate for the actual coals and let the ash fall to the bottom.

On my buddies rotisserie, which is made from two side-by-side oil drums (and portable ), we set fire brick in the bottom and seal the seams with sand, ash does the final seal. This thing is 30 years old at least and only has a couple of pinholes in the steel. The fire brick really holds the heat, in fact it takes 12 or 15 hours to cool off enough to put the bricks in buckets and move the pit.

Here is a close up

 

[Noseoil]

Thirdeye, thanks for the kind comment. I'm not going to run a fire in this cooker, it will have a "remote" fire box with a pipe to get the heat into the cooking area. Still trying to figure out the box, run, heat & plumbing (I know, keep it simple) needed for slow cooking, but trial & error will get the job done.

It was our motto at work "don't worry, we always get it right eventually..."

 

[HalfSmoked]

Looking good an interesting project. Waiting to see the finish.

Warren

 

[Noseoil]

I'm wondering about the fit on my lid to the base. I've ordered some gasket material (1/5" X 3/4") to attach to the joint, but I don't know if this stuff will compress enough to seal the gaps. I know I need to keep the heat inside the cooker, just not sure how this stuff works. Anyone use the stuff for sealing gaps & will it compress about 1/8"?

 

[Winterrider]

Used this lava lock on my RT because it leaked a lot around the hood. Sealed up nicely.

not sure if there will be enough weight to compress with just your lid ???

 

[Noseoil]

Put the gaskets in place, welded the hinges & attached chains for the lid support. It's getting there. Still a lot of little stuff left, but it's coming together now. Gasket might need a bit of help, as it doesn't compress completely yet, it might settle in after a while, or soot itself shut with a bit of time, but we'll have to see. Waiting for more stuff again, pleased with it so far.

 

[Noseoil]

Worked a little yesterday on a butterfly for the chimney. Had to send out for a length of 2 1/2" stainless steel tubing for the exhaust, the valve will sit just above the "street L" & small nipple, which I cut & ground to take the valve. It should help with heat out of the oven portion. The fire box is on the way now, but not here yet. Small town & shipping parts takes some time, but that's OK with me, I get better ideas while I'm waiting for stuff to arrive & can work on the small stuff. Also did a run of silicone seal to do the seams where the 1" angle meets the drum with a few gaps. Need to keep that heat in place...

 

[Noseoil]

Butterfly is installed now in the SS tube. It's starting to look like a smoker finally. Next week for the fire box, then it's time to start a fire & see how many leaks I have to plug on the edges. I think I have that one figures out now, but we'll have to see what happens when it's lit the first time...

 

[Steve H]

It looks very good. But I'm seeing a danger sticker on the side of the barrel. What was in there previously?

 

[Noseoil]

I have a call into a chemical company about that. It was used to store toluene for an industrial painting operation & I'm getting information about any possible residual product remaining on the surface, after months of sitting empty & open in the sun.

I'll let you know what they say about purging the inside for a cooking vessel. It's sort of like like acetone in many respects & the rate of evaporation, but I need to be sure there's no issue with it once it's been rinsed & smoked a while with nothing inside it. I was happy to find one with just the original tin plating inside, didn't want one with any type of painted interior or storage of strange liquids or sticky chemistry.

 

[Steve H]

I know what that stuff is. Where I used to work. That and MEK was used to make sheets of gasket material. It is pretty nasty stuff.
It is quite poisonous and very flammable. And cause some pretty bad health issues. I do not know if it can, or has, permeated into the metal. I would have continued the search until I found a barrel that is rated food safe.

 

[Noseoil]

"I would have continued the search until I found a barrel that is rated food safe." Steve, in a small town with very limited options, the middle of nowhere in northern New Mexico, it makes choices pretty slim. I've worked with MEK & acetone a fair amount in aircraft work in the 70's & 90's without issues. Gloves, outside air & common sense go a long way here. As far as a fluid penetrating the metal & leaving residual solids behind in the molecular structure, I'm thinking the toluene is so volatile that it has certainly evaporated by now. The only thing actually left behind at this point would be a residual contaminant in the toluene, due to the manufacturing impurities which are left behind on a surface. I'm thinking a good purge & some smoke will take care of things, but...

I'm still waiting to hear back from a chemist on this one. I would gladly hear from a chemist in the forum with experience & knowledge of this type of issue.

 

[Noseoil]

I decided to alter the gasket a bit since the fit isn't good enough to suite me. Basically, I've applied a layer of masking tape on the bottom frame, used paste wax for a mold release on the tape & then used high-temp silicone for a secondary layer, which has squeezed into the fiber gasket material. It will create an air tight gasket & as long as I don't burn wood or charcoal inside, the highest temps I'm running will be about 250f.

We'll have to see how this works, but it should be a nice tight fit now & the residue from cooking & smoke should help seal it once I start things up & season it. Picture to follow, once it sets up for a day or two...

 

[Noseoil]

It was a good idea, but a bad execution on my part. I used some carnuba wax to act as the release agent on the tape, but evidently the solvents in silicone were able to eat through the wax & bond pretty well to the tape. Had to use a series of small wedges to pry the lid ope & here was the result.

It pulled the gasket apart in a few places, so I've gone to a "plan B" which is the gasket repair. I put a layer of saran wrap in place on the lower frame, pumped in some additional silicone between the torn gasket surfaces & then lowered the lid in place again. I'm waiting now to open it toady to see how it mended. Thinking it will be fine once I start smoking in it, as the solids in the smoke will seep into every open space around the edges and soot everything shut to form a nice smoky gasket.

Slight setback for working today as the weather has turned a bit cold (12 degrees as I write this) & this is how it looks at the shop. I'm taking a day off as there's no heat in the shop & I'm being lazy for our 1st snow of the year...

 

[Noseoil]

Follow-up on a metal toluene container for use on BBQ smoking. Another "professional" dealing with these containers said it was the current industry standard to use a steam cleaner for purging this type of container. The large trucks, which carry industrial solvents, are all cleaned for different uses by pumping steam through the tanks.

I'm no expert on this information, but it's interesting to know what the government requires for the use of semi-trailers & their vessels from load to load. I would recommend you do your own research if using a solvent container for smoking.

 

[Noseoil]

Was out of town with our son last week (back from his 5th deployment to the Middle East, thankfully) so it's been a few days since I've posted to the thread. Got a couple of wheels & a fire box when we got back, started back up again on some welding & cutting. Started with setting up the fire box, which is about 1/3 of the volume of the smoker.

I'm going with a 4" inlet into the smoker & the 2" stack for the exhaust. I used a 2" street-L for the stack, as it's the thread size of the bung in the top of the drum. Figure the reduction in heat as it flows in & out will allow for a decent flow through the chamber. It should draw well enough, but have to see when it's lit the first time.

Here's a mock-up of the plumbing cuts & inlet into the cooking chamber. Thinking I'll probably add a short run of inlet (an extension), to bring the heat about 1/3 of the way inside, so it lets the heat come more towards the middle than the end. I may have to add some type of baffle to avoid a "hot spot" on the grill where the heat dumps, but we'll have to see on that as well. Easy enough to do it after things are running.

Here's a wheel attached to the leg. I'm going to put casters on the other end, as I have a few left over from some shelving. Once the wheels are in place on all 4 corners, I'll setup for the fire box attachment. More to come later, but this is where we are today.

 

[Noseoil]

Looks like I'll finally start heating & seasoning it a bit today. I got the casters located & placed yesterday, attached the fire box, caulked & roped the joints into the oven & basically tied up a few loose ends. I want to attach a steering grip on the caster end for moving it around & add a shelf between the legs under the fire box. But that's going to happen a bit later.

I welded a length of 1" angle (between the legs) opposite the fattest part of the fire box, then welded the box in 2 places to attach it to the angle on that side. Next, a couple of pieces of 3/4" flat stock were bent & bolted to the fire box at the top edge, then were welded in place on the legs. It's pretty solid now, so we'll have to see how the chamber does with a bit of heating & moving around when it expands, but it should be fine & last long enough to see how everything works together as a system. If I need to make changes or adjustments, I'll post what I've done as I go to this thread.

The fire box came with a pretty large gap in the door at the edges, so I used the left over 1" gasket material I had to seal it up. The door on the fire box was also hitting the elbow on the corner & was bumping it when it was swung up & opened all the way. I added a piece of 3/8" rod at the left hinge edge, to make an extra stop. It hits the factory stop now, so the 90 isn't being bumped each time it is propped open. I was concerned about the seals being cracked from constant bumping & leakage of the heat & smoke while tending the fire if the door hit the elbow.

Need to post one more image of the smoker making some smoke, but it looks like it's ready to go to work now. It's been 2 years since we moved from Tucson to Raton, so I'm ready to get back to smoking some meat & having good BBQ again. I gave our old smoker to our neighbors who came up from Mexico many years ago, so I'm hoping Irma & Nacho have enjoyed learning how to use it. I gave them the basics & some good dry mesquite to start with, so hopefully it is being used regularly still. We cooked a lot of meat on that thing over the years.

The grill we got with the "new" house is OK for a burger or steaks, but it's not the same as a slow cooked rack of ribs or a nice brisket which really takes a day to get ready to eat.

Here are the specs on this one, if anyone is interested in the numbers.
Smoking chamber volume is about 14,120 cubic inches (55 gallon drum, 8.2 cubic feet)
Fire box volume is about 3420 cubic inches (1.9 cubic feet), so it's slightly under-sized
Fire box exhaust into the oven is a 4" stainless steel lined 90 degree double-wall angle (according to the numbers 4.42", but 4" works for me)
The chimney is 2 1/2" pipe & 30" tall, but the opening into the chimney is actually only the 2" pipe fittings from plumbing stock

The damper on the exhaust will shut off most of the air-flow out of the chamber if it's closed completely, the fire box has a variable opening to regulate oxygen into the fire. It should run wide open for cooking. My theory is that the heat from the fire box will cool as it enters the cooker, so having a smaller outlet should help keep a bit of back-pressure on the drum, to help hold the heat and give it a chance to heat evenly. I added an extra length of 4" pipe inside the cooking chamber, to extend & dump the heat about a third of the way into the cooker. This may create a "hot spot" so a baffle might be needed to even out the heating. Since the heat will be cooling off on the way into & out of the cooker, the smaller exhaust & chimney will let the heat maintain a good temperature, but still make enough flow from the fire to the chamber for good, even heating. If there's a problem with this, I may need to put a larger exhaust on the right end to, let more heat flow through.

Enough theory & BS, it's time to light a fire & see if I'm talking through my a$$ or cooking with a smoker which works... Thanks for looking, best, tim.

 

[Noseoil]

Quick report, it's working pretty well! Started with some apple twigs & charcoal to get things moving, then waited a bit & added more wood for more smoke. Temperature seems fairly even, but the exhaust stack end is a bit warmer. Inside is getting a nice, smoky black finish now & I'm happy with how it draws & maintains the temperature. Not too many leaks, just a few small edges which will smoke & soot themselves shut with use.

 

[Noseoil]

Sunday's smoke adventure wasn't so good. The temperature had dropped a fair amount from Saturday afternoon & I had trouble getting up to a decent temperature. Glad I was just experimenting, as it didn't work very well this time. I was only able to maintain a steady temperature of about 175 degrees, just not enough heat for cooking... The fire box is a bit undersized (it's 25%, not 33% of the cooking chamber) so I was pondering what to do when I realized I had been spoiled by living in Tucson for 45 years. This is a picture I took in Tucson during the summer, with the old smoker in the sun one afternoon. There was no fire in it, just the sun to warm things inside.

I decided to read a little about winter smoking & realized I was S.O.L. on heat with this build design. It's not even cold yet & I'm running out of heat already! So what to do? I looked at insulated smokers & an idea popped into my head. I spent the better part of today changing things around a bit & here's what I came up with. I had a spare 55 gallon drum in the shop, so I measured & cut for a new top which sits on top of the original one, a double wall top for the cooker. Added some rock wool insulation I found out back in the shed when we bought the place & used some sheet metal screws to fasten the thing together. Here's an end view of what the top looks like now.

I cut a couple of holes to read the thermometers & stuffed the gap at the edges with more rock wool, it's ugly but functional.

The last thing was to take a partial cut of the drum & insert it into the bottom to act as a liner for the cooker. It's not a full cover of the bottom, but it should help cut down on the heat loss since it gives a layer of air between the heat source & the outer wall. I figured the bottom would suck a lot of heat if left as a single wall. The bumps in the barrel sides act as a stand-off for the air gap, but we'll have to see what happens.

So tomorrow I'm back at it again with another fire (third time's the charm, I hope?). Looking forward to see how much more efficient it makes this thing & how much more heat it can trap on the way out the smoke stack. I looked at a Youtube video of a guy reading outside temps on insulated boxes & he said the lined cookers were 33% more efficient, so here's hoping (175 plus 33% more heat means 230 degrees). Will report back again tomorrow afternoon...