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Using the Propane Forge

Basic information for running the Propane Forge safely and efficiently:


Keep all gas valves tightly closed unless you are using the forge! This means both the valve on the forge manifold (yellow handle) As well as the valve on the tank itself!

You should be aware of what unburned propane smells like (rotten eggs is similar). In the event that you smell it:

  1. Immediately stop working
  2. Extinguish any flames
  3. Open the garage door
  4. Find the source of the leak

Gas Pressures

Safe to use between: 4 and 12 PSI. Good forging heat obtained at about 6-7 PSI after warming up.

Blower speeds

Use the minimum speed necessary to prevent a visible flame from shooting out the mouth of the forge. Any additional air supply will reduce the heating efficiency of the forge and greatly increase scale formation on your piece. Ideally you want a perfect ratio of oxygen to propane in the burner so that there is no remaining oxygen left after combustion.

Starting the forge

Make sure the yellow gas valve on the blower manifold is closed. Set the gas pressure to approximately 5 PSI. Leave the blower off. Hold a lit handheld torch in the mouth of the forge, and open the yellow gas valve. You should here a low “woosh” sound and a yellow flame will appear in the mouth of the forge. Increase the gas pressure to about 8 PSI. Turn on the fan at a very low speed, about 6 on the controller knob. The forge needs to run slightly rich (yellow flame) as it warms up, or the flame will blow itself out. After about 60 seconds, you should be able to adjust the fan upward to achieve a blue flame in the center of the forge. The forge will now build up retained heat over the next 30 minutes, you will need to adjust the fan speed up and down slightly as the heat inside the forge changes the natural draft of the blower.

Adjusting heat level of the forge

Always change the gas pressure first to your desired level of heat output. Then adjust the fan speed to match the gas flow. You should run the minimum level of air necessary.

How do I know when I have the correct heat?

This is an acquired skill, you need to eyeball the temperature of the forge and your steel by using the color of its glow. In general you'll want to be working at what is referred to as “yellow-orange” heat. You can get a rough guide by looking at this chart.

Keep in mind that ambient light will dramatically change your observed color. This reference was intended to be used in a much darker room than the makerspace.


Turn off the gas at the tank, using the high pressure valve before the regulator. Allow the gas line to purge itself by flaming out. Then close the yellow valve on the gas line. Keep the blower fan running at max speed for at least 30 minutes* after stopping the forge. Hot air can back up into the blower and melt the fan otherwise.

*If you are going to be leaving immediately after shutting down, you can turn down the fan to 6, and leave it there until the next person uses the forge.

spacedocumentation/usingthepropaneforge.1374079021.txt.gz · Last modified: 2013/07/17 16:37 by dan_dude