Need to heat treat some metals? Just wanna tinker in the back yard? Here is a fairly easy to make forge. What's needed? A metal drum or tank, kao wool, fire brick, a propane burner/torch and an air supply/bellows.
Step 1: Preping the Tank to Cut
Once you have found a suitable tank start by making sure it is empty, let the surrounding gasses escape then cut away the handle around the valve, this makes getting it off much easier and you can use an array of things to do so. The tank will likely smell and should be rinsed at that point. To cut your tank start by drawing a circumference line around the tank where you are going to cut, steady your tank and begin scoring with your metal cut off wheel, don't try to make a through cut at the start just keep removing material all the way around, this will help prevent binding and will improve the life of the wheel. When you cut through let the wheel do the work, do not apply a lot of force. Now let's get to the basic assembly.
Step 2: Lining With Kao Wool
Kao wool is a heat resistant ceramic insulating wool that helps keep the heat inside the forge where you want it. This wool can be coated in refractory cement such as satinite (not shown) or you can insert brick as shown.
Step 3: Inserting the Fire Bricks
Lay one brick lengthwise and place two atop from side to side. You can use different configurations according to your needs and amount of space needed. This setup is great for knife makers that want to heat treat their work.
Step 4: Enclosing the Forge
Fire brick is very easy to cut, you can notch out different openings to suit your needs. Using a cut out piece you can minimize the opening after placing material into the forge.
Step 5: Bellows and Heat Source
There are many things that can be used to supply air to your forge, a hair dryer is commonly used on smaller forges. A powerd air mattress pumps work well but you may need a bit more force at times. A propane torch with high btu's will work well for this application, upwards of 100,000 btu's. This is a whole other project which can be found elsewhere on the instructables site.