Scrap wood can be converted into charcoal in this homemade burner.
PHOTO: RALPH RUMBLEY
Coal is not readily available in my community, so I use charcoal to fire my forge for blacksmithing. I had read books on making your own charcoal, but I wasn’t satisfied with the ovens others had used, so I went to the drawing board to develop a burner that would last a long time and could be built inexpensively.
The main part of my burner is a 200-gallon butane tank. Inside the burner is a 10-inch-diameter pipe that holds the wood, which will be cooked by a wood-fueled fire, to become charcoal. I welded two water tanks to the butane tank for a chimney. The process produces about one and a half feed sacks full of charcoal.
This charcoal is perfect for my blacksmithing work but also could be used in a barbecue grill.
Building the Charcoal Stove
I’ve read books on making charcoal and looked on YouTube to see how others make it. Some people use brick for the oven, but that would be expensive. Others use 55-gallon drums, but they would burn out fairly rapidly. So, I went back to the drawing board to find a design that would be inexpensive and last a long time. I finally settled on butane tanks.
The first piece of the “cooker” was a 200-gallon butane tank. It was three-eighths-inch thick and had a hole in one end from rust. I cut the end with the hole from the tank. Next, I cut a 22-inch hole in the center of the tank’s side. I stabilized the tank by welding two pieces of 2-inch tubing onto the bottom supports.
I then cut a 10 1/4-inch hole in the good end of the tank. The top of the hole was 1 1/2 inches from the top of the tank. Next, I welded together two pieces of 10-inch quarter-inch pipe. One piece is 52 inches long and the other is 72 inches long. I cut one end of each at a 90-degree angle. The angled ends were welded together to make an L-shape. This will be the holder for the wood that will become charcoal.
In order to get the L into the butane tank, I cut the 72-inch piece off 12 inches above the elbow. I left some tooth-shaped reference marks when I made the cut so I could line up the pieces after they were installed. Using a come-along, I placed the 52-inch end through the hole in the tank tip and stuck it through the 10 1/4-inch hole in the end of the butane tank. After leveling it, I welded the 10 1/4-inch hole closed. I used iron straps to attach the chimney to the top edge of the butane tank. Then, I welded the cut off vertical piece back onto the short end of the elbow.
Next, I fabricated the chimney base using quarter-inch angle iron and flat plate welded to the top of the butane tank. The chimney itself is made up of two used pressure tanks. One has a diameter of 20 inches and the other 18 inches. The larger tank has both the top and bottom cut out and sits on top of the chimney base. The smaller tank has the bottom cut off and the top has a 10-inch hole cut in it. Together these two pipes form a chimney that is 4 inches taller than the 72-inch pipe inside it. The 4-inch lip left on the top of the smaller chimney piece allows the exhaust to gather around the top of the 10-inch pipe holding the wood. Weld everything well.
For the two caps that cover the ends of the 10-inch pipe, fabricate these from16-gauge steel. Cut two pieces each 6-inches-by-36 inches long. Wrap these around the 10-inch pipe, mark for length, cut off the end and weld the band together. Make these caps to fit as tightly as possible, but still be removable. Cut two pieces of 11-inch circles for the ends and weld to the bands. Don’t remove the overhang because you can use it to tap the cap off.
In the cap that will cover the end of the horizontal burning chamber, drill a hole and braze a half-inch galvanized, threaded hose barb onto it. Bend a piece of half-inch pipe to fit over the barb. Bend the pipe around and attach it to a barb in the upright portion of the chimney (see photo in the Image Gallery). There will be some very bad smoke coming out of your coal wood, so be sure to have plenty of ventilation and open space around the cooker.
Fill the 10-inch pipe with hardwood cut into small chunks. I make mine in two sizes. One is for the 52-inch piece of pipe. This wood is about 3 inches long and one inch thick. I built a rammer out of a 4-foot piece of pipe and welded it to a 10-inch saw blade. I carefully stack the 3-inch pieces and use the rammer to slowly push these back to the 90-degree joint. This way I can fill the 52-inch pipe completely full. Put the cap on the end. Now, drop wood into the upright end of the cooker and fill it. These pieces can be random lengths. However, I keep mine small and can use the chunks without having to break them up. Just fill up the 72-inch piece and put the cap on.
The tank fire can be made from any kind of wood except treated lumber. I use old boards, pallets and deadfall. No need to pull nails or cut the wood to a specific size. I even use dried clipped vines and broken furniture. The fire should burn for three and a half hours. I then pull out the deep bed of hot coals, putting them on two pieces of tin laid on the ground, douse them with water and let them cool for 24 hours. When the material is completely cool, I sift the coals, separating the chucks from the dust. This is also usable charcoal, although not of the quality of the material in the cooker pipes. I use the dust and fines on my garden as biochar.
To make the charcoal, I have used oak, cedar, pecan, hickory, grape vines, poplar, sweet gum and privet hedge. All the woods work well and the charcoal is great for the grill as well as the fuel in a blacksmith forge. The lump charcoal in the 10-inch pipe looses about one third of its volume, which leaves about one-and-a-half feed sacks full of charcoal.