No-weld Double Barrel Smoker V1.1
If by some chance, you searched this site looking to build an UDS, an offset smoker, or a double drum smoker, and found this post before Javin007's "The No-Weld Double-Barrel Smoker (and How to Use It)" go there and read his first. From beginning to end. It's a great read; informative and funny, and the foundation for this 'ible. I built my NWDBS about 3 years ago based on his instructions, with some minor differences from his after thoughts, and some suggestions in the comments section. I used Grapho-Glass rope to seal the doors, a 6" stove pipe to connect the 2 chambers which I then coated with furnace cement, and I used angle iron instead of aluminum tubing for the frame. I also put an axle on one side with four 10" wheels - like a dually. I followed Javin007's firebrick (number and placement), flue, air intake, and exhaust placement design to a T.
It's been a little over 2 years since completion of the build, and I'd estimate I've used it 20-30 times. At least a couple of those cooks were scheduled on days that took last minute weather turns, necessitating a pop-up canopy for cover. I've cooked chicken a couple times on here - breast and wings, but I still haven't put any beef in it yet. Boston butts are most typical. As few as one 6lber, and as many as six - about 40lbs. I use jessyratfink'sDry Rub and cook till I reach an internal temp of 198-200. Most of the time it takes 9-10hrs to reach that temp.
At the end of last fall, I noticed a couple things that I thought needed touching up. I found gaps in both of my doors preventing a good seal in either chamber. Even with a welding blanket draped over the cook chamber, the temperature varied quite drastically. Paint was flaking off the rear of the fire chamber. No matter how much I tightened the bolt for the air intake vent, once it reached temperature, it expanded causing the vent to fall. Even with my air intake completely closed, I saw temperatures rise. Using a stick to prop the firebox door as forcefully closed as possible, didn't fix this problem either.
After my first use this spring, I saw cooking chamber temps vary from 205-275 degrees. My pig pinwheel allows me to see the speed and direction of the wind from inside my house, and the wheels on one end allow me to easily rotate the smoker during a cook. This helps, but still 70 degrees is too much variance. I decided it was time for an overhaul.
My goal is to stabilize the cooking chamber temperature. I think the instability is caused by air leaks in both chambers. To address this I plan on changing the doors and the air intake. I was inspired by purplewg'sThe Wild Pig Smoker design. I think having a metal door seals, that are attached to the inside of the chamber, allowing the door to sit flush with the chamber will help eliminate some of the air leaks. In the interest (aka requirement) of keeping the "No Weld" design, I decided to use some high temp sealant and pop rivets. I really wish I had saved the old doors, as they would've made perfectly aligned door seals. For some reason, I threw them away the day I started this rebuild. The plan is to use 2" wide strips of steel that span the lengths of all 4 sides of both door openings. The 3rd barrel I bought when I started this project was used up to make the replacement doors - sized to fit inside the existing door holes. I tried to find the guy on CL that sold me the 3 barrels 3 years ago…but yeah, good luck finding the same person on Craigslist 3 years later. I found a sheet of 2'x3' 22-gauge steel from a big box hardware store in town. Cutting of these 2"xN" as well as the replacement doors was all done with a Dremel and thin Metal Cutting discs. These are not cheap or fast. A pack of five cost over $10 and I went through 2-3 packs for the rebuild. They do cut the cleanest and straightest. My other options were a 4" angle grinder a hacksaw or a Sawzall with metal cutting blades. (I also have a jig saw, but no metal cutting blades). The angle grinder is big and rowdy, and was very hard to make slow precise cuts. The Sawzall bounces up and down misshaping the metal as it cuts it. The hacksaw laughed at me. The only way I could cut 20 gauge (the barrel) or 22 gauge (the sheet) in a straight line was with the smaller Dremel tool and its metal cutting discs. It takes anywhere from 5-10 seconds per inch to cut…so this was by far the most time-consuming part of the project. When I built this the first time, I think we used the Sawzall and settled for ugly cuts, because of time. This project really made me wish I had one of these.
For the air intake, I decided that any vent cover design using the existing axis is going to be subject to gravity and heat. To combat this, I moved the axis of the door to the center, and changed the shape to a circle. I cut 1 big opening that would expose all the holes when opened to the max. Then I lined that hole, and all the metal surrounding it with 8' of that Grapho glass rope. Instead of using that (miserable) adhesive that comes in the kit, I used some of my more user friendly high temp sealant to adhere it to the new cover. With some adjustment to the number of washers I used as spacers (on the bolt between the cover and the firebox) I think I've created a pretty good seal.
Lastly, I'm changing how I keep the doors closed. A bungee cord with 5lb of barbell weights hanging had been my trick for the cooking chamber door. The firebox door had a small metal tab of scrap metal, connected with a bolt, and offset by some washers. As heat, time and wear went on, I had to use the stick I mentioned above. Clicking around on Amazon one day led me to these, I bought 2 pair - a set for each door.
After all these changes, I'm going to load it up with wood and simulate a good 6-8 hr cook. I'll start without the welding blanket and see how it does. If temperatures still fluctuate wildly even with the blanket, I'll move on to revision 2.0 - insulation. Reading about Rocket Stoves led me to a homemade insulating concrete recipe that should absolutely stabilize my temps, but will make it so heavy, welding will almost certainly be required. If I go that route, I may start over with new barrels. The rocket stove I built with this mix weighs every bit of 60lbs and that's for a 7.5-gallon ash can. Green Egg smokers have the mass and insulation properties that I'm after, but I want to keep the indirect heat/smoke factor, the ability to fit whole logs in my firebox, as well as NOT opening the cook chamber to add fuel to the firebox.
I noticed early in my test burn - about the time I started seeing smoke rolling out the chimney, that smoke was escaping from small gaps a couple places in the cook chamber doors. Trying to bend a curved piece of 19"x30" piece of a steel drum - to match another curve is no easy task. When I set my new cooking chamber door on the updated opening, I saw the curvature didn't match on the lower right side.
No problem, I'll just bend it by hand…not so fast. Yes, you can bend steel of this gauge and size by hand, but finding that precise axis and applying the right angle eluded me. Each bend seemed to make it worse. Once I had the handle and door latches mounted, downward pressure on the handle allowed me to nearly match the curve once the latch is closed. The gap went from about a 1/4" before the handle and latch, to maybe a 1/16" - visible, but maybe not noticeable by a casual observer. I hoped I'd minimized the gap enough that it wouldn't matter. Once I saw the smoke, and knew it did, I used some clines to bend my door rests outward, hoping to further close the air gaps. There is another spot near the top of the cook chamber door - among the barrel ridges that also showed a smoke leak. I didn't even try to bend the doors here, I just bent the door rest outward. I worried that I'd need to add more Grapho glass to line the door rests, but draping the welding blanket over the door stabilized temps much better. For the test burn, I was able to keep the cooking chamber temp at a stable 225-230 degrees. With very small adjustments I was able to raise or lower the temperature. I was happy enough with these results to do a cook a few days later.
My burn basket is now too large, since adding the door rests closed that opening down by an inch on all sides. It still fits, but I have to tilt it to get it in. I used to be able to fit my charcoal chimney inside it, so I could dump glowing charcoal on top of the contents of the burn basket. Since that was no longer an option, I bent up a piece of barrel scrap to make this half funnel type of charcoal slide.
I learned on my last cook - before the rebuild, not to include any expensive (flavored) wood chunks in my first fill of the burn basket. I used to line the outside edges of the basket with Apple wood chunks, fill the rest of the basket with charcoal, then dump the glowing coals on the top center when they're ready. I'd wait until the cooking chamber hit about 300 before putting the meat on. I've found that a considerable amount of that expensive wood is burnt up while bringing it to temp. For this burn, I soaked those big Apple wood chunks in a bucket of water the night before (probably doesn't do a whole lot to slow their combustion), I put one log on the flue side of the basket (opposite the air intake), filled the middle with charcoal, and left a gap for the glowing charcoal to be added near the air intake. In theory, this would burn from left to right, hitting the log last and making a nice slow burn. It worked pretty well I guess, next time I may reverse it, to see if the intake air direction speeds up the burning of the fuels. The longer I can get out of the fuel the better. I opened the cook chamber and added the meat (6.5lb Boston Butt) when the temp was about 230. I always try to work quickly when I put the meat in (GIGGITY!) so I don't lose too much temp. The amount of time with the door wide open, while I place the butt, position the cooking chamber thermometer and the insert meat probe into the butt allowed for the temp to drop to 175. After closing the cooking chamber door, I knew I couldn't waste any Apple wood smoke. Opening the smoke chamber door fed the fire more oxygen, I also added some of the soaking wet wood chunks. I think this may be the way to get the most out of a $9 bag of wood chunks. I always get the biggest chunks I can find, that mulch sized stuff burns up way too quick for me.
I had the meat on at about 730a, and by 5pm, the meat temp was still only 185. For the last hour or two, I kept seeing my cooking temp drop to about 208, despite rotating the whole smoker so that the intake was facing the wind. I figured it out when I opened the cooking chamber - either the meat, or the cooking thermometer had shifted while moving it at some point, and the meat was touching the end of that thermometer - so I was more likely getting a meat surface temp than a cooking chamber air temp. I took it out of the smoker and finished it for 60-90mins in the oven at 400 degrees until internal temp hit 200. Once it did, I took it out, wrapped it in foil and let it rest an hour. It was about 730pm when I was pulling it off the bone. It came out perfect by my standards. 12hrs from the time it went in, until it was ready to eat (with the assistance of a 400-degree oven).
I've found that with the size of this contraption, it's capacity, and the amount of fuel it requires, you may be best suited to cook a lot at one time. I use almost an entire 18lb of charcoal, a whole $9 bag of wood chunks, and 6-8 logs throughout this cook. I'd use the same amount to cook a single 6lb butt as I would for 6 of these. In the future, I'll probably cook at least 2 at a time.
After this cook, I'm very happy with these mods. It was so much fun designing, building, and testing this project I may make another smaller version. I'd like to incorporate my insulation cement recipe into a single drum aka Ugly Drum Smoker - in a way that would allow me to add fuel without removing the lid.
Step 1: Here Are Some Minor Changes When I Built This a Few Years Ago
Pic 1 shows the Grapho glass used instead for the Sealant. The curing time is much shorter, but the adhesive included with the kit was a nightmare. We followed the instructions placing it in warm water, but it still had the consistency of almost-set Quik Steel. And it was very messy.
Pic 2 shows my air intake - pretty similar to the original design. Notice how it didn't sit flat against the barrel. None of the "flat" surfaces of the barrels were really flat.
Pic 3 - based on Javin's recommendation, I removed some of the paint I knew would be impossible to reach once I'd added the furnace cement to adjoin the flue to the 2 barrels.
Pic 4 is what turned out to be the best tool to remove paint from the barrels. A drill with a locking trigger made it easier to position my hands to apply pressure in all the little nooks and crannies. If I were to make this all over again, I would absolutely strip 100% of the paint from both barrels before I made the first cut.
Pic 5 is after initial assembly was complete. It was recommended that we try to get the Grapho Glass adhesive to...IDK, 500 degrees for 30 minutes for it to completely cure. We had fires in both boxes and maybe saw 400 something in surface temps per an infrared laser thermometer. (Another reason not to use that miserable adhesive, you don't have to do that with the red High Temp stuff I mentioned in the intro)
Pic 6 is after the initial firing. We scraped off the red paint that had bubbled off (with that Quick-Strip disc) - a very-not-fun part of the project, then hit it with 2 coats of High Temp grill paint.
Pic 7 is the last change I made to Javin's design, regarding the flue. I went with a one foot section of 6" stove pipe. I cut a 6" hole in the top barrel, jammed the pipe through it, then traced where it hit the bottom barrel. We got both holes lined up well enough so that the pipe would link them. Since the pipe was a foot long and the gap was only a couple inches, there was a plenty of pipe extending into each barrel. I cut vertical slats on each end and bent them down in kind of a sunburst fashion, in an attempt to improve the fit. With the tools we had available, these cuts resulted in a fit that was nowhere close to air tight. I bought 2 tubs of this furnace cement and used it on both ends of the pipe, all that I could reach on the exposed area of the flue, and also on the chimney pipe. I'm pretty happy with this material, although I found it did eventually leak grease - when I cooked 40lbs at once.
Step 2: A Few Years and Many Cooks Later, Time for an Overhaul.
Like a dummy, I removed the old doors, and threw them away the day I moved this into my workshop.
Tackling the air intake first, I measured the distance from the center of the drum, out to the furthest hole I had drilled, then added 1" to that. That would be the radius of the new circular cover. Since I saved the 3rd drum I bought for the original build, I still had one good end to source that piece. I stripped all the paint before I cut out the circle. Once I had it cut, I drilled a hole in the center and hung it in position with the machine screws I used throughout the build. With the circle in place, I marked the exterior holes with a marker shown in Pics 2 and 3 .
I estimated about an inch gap around all these holes and drew my cut line you see in pic 4. Pic 5 is how I typically cut the metal - using bar clamps a scrap piece of 1x2, being held down onto an old door - aka my second workshop table.
Pic 6 is post-cut.
Pic 7 shows the Grapho Glass and sealant I used.