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Using the Natural Gas Forge

Basic information for running the Natural Gas Forge safely and efficiently:


Clothing should be only natural fabrics: Leather, Cotton, Wool, etc. Polyester, Acrylic, Nylon, Rayon, and other oil derived fabrics will burn when sparked, and fuse into your skin as they burn. They might have to cut you shirt out of you at the ER!

Gloves are very useful for keeping dirt off your hands, but can never be trusted to keep you from getting burnt! You can actually burn yourself worse grabbing a hot piece with a glove than without. Steel only starts to glow visibly at around 800 degrees F. 799 degree steel looks like room temperature steel. Use tongs if you are not absolutely sure something is cool enough to touch.

Long pants and closed toed shoes are highly recommended. Hot scale will fall from the anvil and occasionally give you 1st degree burns when it hits bare skin if you happen to have a really large flake come off.

Eye protection. Things can go flying, and they hurt if they hit you in the eye, hot or cold.

Keep the gas valve tightly closed unless you are using the forge! This is the valve on the forge manifold (yellow handle).

If anything goes wrong and you are unable to reach this valve. There is a emergency shutoff valve on the wall to the left of the forge, along side the hot work table, it has a blue handle.

If you cannot reach that shutoff, there is another shutoff valve that controls all tools in the forge area. It is further east, along the south wall of the room. It is labeled with a sign that says “main gas shutoff”.

You should be aware of what unburned natural gas 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

There is a gas safety alarm in the forge area. It will monitor 2 things we care about:

#1: Carbon Monoxide: If too much of this builds up, it kills people

#2: Explosive Gas:

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 fuel in the burner so that there is no remaining oxygen left after combustion.

Starting the forge

  1. Make sure the yellow gas valve on the blower manifold is closed.
  2. Turn on the fan at a very low speed, about 3 on the controller knob.
  3. 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.
  4. For now keep the fan at about 3 on the controller knob. The forge needs to run at a lower pressure as it warms up, or the flame will blow itself out.
  5. Slowly turn the gas valve closed to reduce the gas flow, you will see a marked change when the flame suddenly forms a cone under the burner and starts to sound like a rocket engine. Hold the gas flow at this level for now.
  6. Once you have a stable flame cone let the forge heat up to a red inside, it will be very temperamental until that happens.
  7. After about 5 minutes, you should be able to adjust gas flow to full and turn the fan upward to achieve a blue flame in the center of the forge.
  8. 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

  1. Always change the gas flow first to your desired level of heat output.
  2. 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” to “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.


  1. Turn off the gas at the tank, using the yellow valve on the gas line.
  2. Leave the blower fan running at 3 on the dial until the forge has cooled internally. Hot air can back up into the blower and melt the fan otherwise.
  3. This will take several hours, it fine to go home and leave the blower running on low overnight. Do not turn it off prematurely.
spacedocumentation/usingthepropaneforge.1582578899.txt.gz · Last modified: 2020/02/24 21:14 by dan_dude