Also, Fire is Hot. A burner like this puts out a significant amount of heat and using such a device improperly is likely to cause you injury and/or property damage. I suggest you use good safety procedures building and operating this burner, BUT AM NOT RESPONSIBLE FOR YOUR ACTIONS OR CHOICES NOR AM I RESPONSIBLE FOR ANY DAMAGE OR INJURY THAT MAY RESULT FROM YOU BUILDING AND USING THIS DEVICE.
There are countless designs for forge burners and furnace burners online. I like this one because it is simple to construct, and the materials are easily obtainable from most hardware stores.
This burner was built for this small forge. The forge is small enough that I can run the burner at under 5 psi and keep the interior at a good working temperature.However, this burner design does work well in larger forges, many large forges even use multiple burners.
In order to build this forge burner, You will need a drill, a set of bits, and a couple of files. If you don’t have a tap to install the set screws, there is an alternate method that I will address at the end of this article. Also, in order to forge the flare for this burner, you will need a functional forge already, or another heat source. If this is your first forge, there is obviously going to be a problem here. The alternate method for this too will be at the end of the article.
Also, it is important to note that you will need a gas regulator to run this burner. Simply running a hose from the burner assembly to your propane tank is not going to cut it. Regulators can be purchased locally at welding supply stores.
Step 1: TOOLS AND MATERIALS
The main burner assembly is made from black iron pipe fittings. I bought all of these off the shelf at Lowe’s. DO NOT use galvanized fittings as they will produce toxic fumes when heated.
The brass fittings are all 1/8″. The 4″ nipple, coupler and end cap on the left make up the segment that is installed into the intake of the burner. The rest of the fittings serve to distance the hose connection from the heat of the burner, and can be constructed in any configuration you want.
Step 2: BURNER INTAKE 1
The first task is to fit the 4″ brass nipple perpendicularly through the wide opening of the bell reducer. For the burner to perform optimally, the tube needs to be centered through the intake. It doesn’t have the be perfect, but it does need to be close. I marked out a center line on the face of the reducer using a carpenter’s square and a combination square as shown in the picture.
After marking the center line on the face of the burner intake (bell reducer), extend the lines down the side of the reducer. Then place the 1/8″ brass nipple against the wide rim of the reducer and mark across the center line where its approximate center is. Transfer this line to the opposite side with the combination square.
Step 3: BURNER INTAKE 2
Use a round file to allow the brass nipple to fit through both holes.
Step 4: BURNER INTAKE 3
Now that the gas tube fits through the intake of the burner, we need to find a way to secure it into position. During usage, the orifice must be pointing directly down the burner tube to burn correctly. To do this, we will install a set screw to keep the tube from rotating.
If you have never used a set screw before, the process consists of drilling a hole, then using a tap to cut threads into the sides of the hole so that the appropriate screw will fit inside.
The hole is easy enough to drill by hand, just pay attention to the angle you are drilling through the wall of the reducer. It is a slight inward angle toward the smaller opening of the reducer. I used a size 8/32 tap/screw which is drilled with a 9/64″ drill bit. You can go smaller than this if you want, but I would suggest you do not go any larger, as it would be easier to cut through the wall of the reducer.
Step 5: ORIFICE
The burner orifice is drilled with a #57 drill bit. As with the positioning of the gas tube, It is important that the hole is centered. I mark a line down the length of the 4″ nipple to help me gauge by eye where the center is. Smaller drill bits are pretty fragile, so if you are drilling by hand like I am, be careful not to apply too much force. Just let the bit do the work.
IMPORTANT: Make sure that the orifice is pointed down the burner tube (small end of reducer) before using the burner. I had mine position upward with the setscrew tightened because it was easier to hold it in the vice. MAKE SURE THAT YOU POINT THE ORIFICE DOWN THE BURNER TUBE BEFORE USAGE.
Step 6: Flare
With the help of the funnel shaped burner intake, the mirrored funnel of the flare at the burner’s tip helps to create the vacuum effect known as “venturi”.
The flare is made from a 3″ segment of 1″pipe that slides over the end of the 3/4″ burner tube. After heating the 3″ segment to a red heat, I hammer the rim of the pipe against a piece of round bar, rotating the pipe as I work. The flare should expand out to around 1 1/2″ at the opening. I recommend putting a set screw in flare as well, to provide a wider range of adjustments for your burner.
Step 7: Assembly
To orient the orifice, I took my #57 bit and inserted it, shank first, into the hole. Using the bit as a pointer, I directed it out of the SMALL end of the reducer (down the burner tube) and centered it as well as I could before tightening the set screw. It may take some more adjusting, but that is a good place to start.
As I said before, the fixtures coming off off the 4″ brass nipple (gas tube) serve primarily to distance the rubber gas hose from the heat of the burner and forge, so you can use whatever configuration you want. The last fitting on the brass assembly is a 1/8″ to 1/4″ bushing which attaches to a LP gas hose which attaches to a regulator running off a 20lb propane tank.
I do not claim to be an expert on much of anything, but specifically on forges. My authority on these subjects is that I have successfully done what I am talking about, and I am willing to take the time to document my experience and produce article, videos, and instructions to the best of my ability so that others can overcome obstacles that I have met. I am always open to advice from the many, many folks who know how to do this stuff better than I do, and I am always happy to give advice to anyone who asks.
So, for more honest to goodness instruction on forges, knifemaking, and metalworking, Check out my website at the link below:
Thanks for reading.
Step 8: Alternatives - Set Screws
In section I will talk about work-arounds for certain parts of this forge burner. The first is the set screw. If you do not have a tap set, you need to use another method to secure the gas tube. To substitute the setscrew, you can use the threaded end of a 1″ pipe segment screwed into the intake (bell reducer). Just tighten down the 1″ pipe against the tube to keep it in place. The disadvantage to this is that it narrows the intake, and therefore decreases the amount of air in the fuel mixture. This inst necessarily a bad thing, just something to remember.
Step 9: Alternatives - Forged Flare
Next, in order to forge the flare, you will need to already have a working forge. The alternative to the forged flare, is to simply not forge the flare. Using a 3″ piece of 1″ pipe over the burner tube will create the vacuum or “venturi” effect when. The “disadvantage is the same as before, it will not draw quite as much oxygen into the mix.