The forge is made from 10 inch pipe with a hole cut out close to the top such that when the burner is installed the flame will be tangent to the top of the blanket. A piece of 2 1/2 inch pipe is welded at this position with a 3/8 NC nut welded to the top to accept a short bolt to hold the burner in place. A one inch thick layer of Durablanket or KAO wool eight pound density is installed on the inside of the 10 inch pipe. A hacksaw blade it used to cut the blanket where the burner is installed.
The burner assembly is made from 2-inch pipe fittings with an air gate valve to control airflow. The blower is a 120 to 150 CFM blower. The nozzle is a brass plug with a 1/16 inch hole drilled in it.
CAUTION!!!!!!!! Durablanket or KAO Wool gives off a fine dust when cut or handled during installation. The dust has been shown to cause cancer in animals at high concentrations of dust. On the basis of these animal tests OSHA has designated the material a carcinogen for humans. There have been no reported cases of cancer in humans who have been exposed to the dust from this material. The material has been in use since the mid fifties. Therefore, when installing or cutting this material, spray with a plant mister to dampen and wear a 3M 9970 of equivalent disposable respirator. Once the blanket is installed, avoid disturbing by it placing a one-inch thick brick in the bottom of the forge and avoid jabbing the blanket when in use. There is no hazard once the blanket is installed. A controlled test was conducted over a 10-hour period of use with appropriate sensors with one of these forges. The measured particulate matter is well below the OSHA standards. Once the blanket has been exposed to high heat some of the surface is converted to cristobalite, a type of crystalline silica, which is also designated a carcinogen. Therefore, when removing, wet the blanket thoroughly with water.
Set the forge on a non-combustible surface. Install the burner assembly so that the fan is the vertical down position so that the flame from the forge cannot enter the blower. Wrap some duct tape around the pipe where the burner assembly enters the forge. If the forge has no back block off the back with firebricks. On the front of the forge arrange the fire bricks so that you have an opening about 3 inches wide.
OPERATING THE FORGE:
Connect the pressure regulator (0 - 20 PSI) to the propane tank and the hose to the burner assembly. Open the air control valve about one third. Next turn the regulator valve all the way out (off). Turn on the blower. Then using a propane torch stand to one side holding the flame next to the opening. Now turn on the gas on the propane tank and the burner assembly. Slowly turn the pressure regulator in until the forge lights. Adjust the gas pressure and air until the interior of the forge is the brightest. CAUTION!!!!!!! Always operate the forge in a well-ventilated shop to prevent carbon monoxide poisoning. Once you have the forge adjusted, to shut down simply turn off the two gas valves and the blower. To re-light turn on the blower and holding the flame of a small propane torch near to the opening and open both gas valves.