Smoked meat tastes good, and it lasts a long time. That is why people have been doing it for thousands of years. Smoking creates a steady supply of warm – not hot – smoke to penetrate the meat. The smoke dries the meat and has an anti-bacterial effect. Red meat and oily fishes lead the list of smoked meats. For the big smoking jobs, like a whole pig, you need a large smoker. DIY smoker-builders frequently choose the standard 275-gallon fuel oil tank to make these whole-animal smokers. You need to know how to weld.
Cut a 4-foot by 2-foot rectangle out of a flat side on the oil tank. The tank is five feet wide, with two rounded sides and two flat sides. Grind the sharp edges off the cut-out. The cut-out will be your smoker door. Place the flat piece inside the tank, then build a hardwood fire inside the tank. Let the fire burn for a couple of hours, keeping it very hot. This burns off oil residues. When you finish you can scrub the smoker with detergent and scouring pads.
Weld a bead along the sides and bottom of the door opening to ensure that the door cannot swing all the way into the smoker. Reposition the flat piece over the hole and weld two steel hinges across one four-foot cut. This is now the top of the door, and above that is a rounded side that will be the top of your smoker.
Cut a six-inches by six-inches vent hole in the top, near the side. Weld a bead around three sides of the hole. Weld one hinge on this piece to make a ventilation door and weld the hinge to the un-beaded edge of the vent hole.
Weld the 60" x 27" steel mesh (cooking rack) into the tank, flush with the bottom of the door opening. Weld the 60" x 20" steel mesh into the tank directly above the first rack and 12 inches higher.
Weld one angle iron rectangle together – 25" x 61". Weld a second rectangle with the angle iron, this one 30" x 66". Join the corners of the large and small rectangles with the four 3-foot lengths of angle iron. The 30" x 66" rectangle sits on the ground, and the 25" x 61" rectangle holds the tank. Position the tank on the stand. The tank, 27" x 60", will rest on the long bars. Weld the tank at the line where it rests on the long bars. This completes your smoking chamber.
Cut the steel 55-gallon drum in half, making two large cans. Cut the cap off one of the cans, leaving a steel cylinder and a round, flat lid. Keep the round, flat lid.
Cut a 12" x 12" door in the round, flat lid. Bead three sides of the hole. Weld the flap back on with a hinge, to make a door. Weld this lid-with-a-door assembly onto the open end of the other can. This is your firebox. It's dimensions are 22.5 inches in diameter and approximately 16.75-inches long.
Weld an angle-iron rectangle 17" x 18". Weld another angle-iron rectangle 23" x 24". Join the corners with the four 2-foot angle iron pieces. The 23" x 24" rectangle sits on the ground, and the 17" x 18" rectangle holds the fire box. Position the firebox on the stand. The firebox is 16.75" x 22.5" and will rest on the 17" bars. The round ends of the firebox will correspond with the 18" bars. Weld the tank at the line where it rests on the long bars.
Stand the completed firebox at one end of the completed smoking chamber end-to-end on a perfectly level surface. The firebox will be below the smoking chamber, but overlapping it. Mark the line where the firebox overlaps the chamber and where the chamber overlaps the firebox.
Separate the chamber and firebox. Mark a six-inch circle as close as possible to the center of the overlap area on the firebox. Cut out the hole as marked. Place the firebox end-to-end with the chamber again, aligning it with your overlap marks. Reaching through the door of the firebox, and using the 6" hole as a guide, mark a corresponding hole on the side of the smoking chamber.
Separate the firebox and smoking chamber. Weld the 12" length of 6" pipe to the 6" holes in the chamber and box.
Weld two eight-foot angle irons along either side, welding every intersection. Weld these tie-ins at the level of the top of the firebox stand and along the bottom. These horizontal tie-ins integrate the stands for the box and the chamber.