Introduction: How to Build a Gas Forge Burner

Picture of How to Build a Gas Forge Burner

First and Foremost, This burner was designed by Mr. Ron Reil. All credit for this design goes to him. Visit Ron Reil’s page at the link below:

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.




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.


Picture of 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.


Picture of BURNER INTAKE 2

Before drilling the hole for the 1’8″ brass nipple, I align the center marks with the jaws of the vice to help me in orienting the drill bit. First drill a pilot hole through the “X” that we marked on the side of the reducer. Then I drill through with a 3/8″ bit.

Use a round file to allow the brass nipple to fit through both holes.


Picture of 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.


Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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.


MikeAlmogy (author)2017-03-14


Will this burner work with butane gas instead of propane? where i live propane is not that common. Thanks, Mike

harlyquin (author)MikeAlmogy2017-11-02

that will change your fuel/air ratios a little, and maybe the drilled orifice. I'll bet they are similar enough to just trial-and-error until you get a working fuel air mixture.
propane is c3h8, butane c4h10. The propane will want 5 O2 per molecule, where the butane will want ~7.5 O2 per molecule...
I'm not sure how this will scale up to this project, but I think the ratio is the same: you'll need 50% more oxygen to get a clean burn using Butane...

Please step in and correct me, someone, I am going off of Chem 1010 level knowledge from about 7 years ago...

harlyquin (author)harlyquin2017-11-02

Overall, I'm sure you just need to turn the pressure regulator down. Maybe using at 3.5 PSI (or .24 BAR) instead of 5 PSI (.35 BAR) ?

timjesse15 (author)2017-10-02

I made this, but instead of using a forged flare, I used a 3/4 to 1" bushing and a 1" to 1 1/2" bell reducer. Works great for the small forge I built. Just need to fine tune the jetting a bit. I was unsure of the size of the drill bit that I used for the orifice (looked small enough), got a ton of dragons breath so I'm guessing it was too big. Ordered some new drill bits and another pipe for it. Going to start at a #60 and go from there.

Will post updates and pictures once I get to it in a couple weekends.

tincup92 (author)2016-03-25

Can galv pipe be use for the just the part going through the bell. the piece that feeds the gas. Having a hard time finding 1/8 brass around here. plan to run 1/4 galv for that part.

BishCo (author)tincup922016-04-29

NO!! Galvanized pipe should not be heated. It gives off toxic fumes.

wouldn't it be ok if it is done in open air, I mean isn't it just small quantities of zinc that will be released?

From what I understand even a small amount of zinc will give you something called metal fume fever. Take all precautions to avoid this, it really sucks.

I thought the same thing that being outside would be enough. This is also what my friend thought. Unbeknownst to him He welded on galvanized & it swelled his eyes shut lol
In all seriousness, his eyes were swollen shut for 6 hours!

This is a for real No, not just a bad idea No. I wouldn't want to mess with zinc smoke/fumes in any quantities.

JadenT11 (author)tincup922017-07-29

how did the 1/4 work?

Bverysharp (author)tincup922016-09-14

If you can't get black pipe, you can throw the gal fittings into acid (even vinegar) and it will eat the zinc off. Once it stops bubbling, the zinc is gone, and heating should present no problems. (The flare at the gas injection end should never get hot enough to cause zinc fumes, due to the air flowing over it and being a long way from the flame)

JadenT11 (author)2017-07-27

I made this but couldn't make a flare so I tried without it and a bell reducer but it doesn't blow(not enough air in the mixture) its too weak of a flame, it is primarily blue but not as good as his. Any ideas?

RyanD230 (author)2017-06-13

Any advice on what regulator to use or how to connect the tank to the burner? I've made the burner, but need to hook it up still.

GaryA83 (author)2017-06-01

thinking of making a forge for knife making. Just looking for some input before i cut it up. Will this work well, old air compressor...think can leave wheels and handle on to make it a little mobile to pull in and out on my garage...

EricF162 made it! (author)2017-05-29

Thank you!! Built one today and it works AWESOME!!!

kozmonot (author)2016-10-29

I followed this to the T today, and can't figure out why mine won't burn blue. It just burns like a big candle.. any ideas? I was wondering if my bell wasn't smooth enough or even enough. So tomorrow I'm gonna try a reducer for the output/bell side

JackS178 (author)kozmonot2017-05-22

Sounds like it is not enough propane. Do you have a good regulator?

kokonutcreme (author)2017-04-24

Thank you very much for sharing your plans.

chuckmadere (author)2017-04-09

Thank you for such a great article on building a propane burner. I plan to give it a try as I am currently using bricketts for barbecuing. Thanks again.

TommyL55 (author)2017-01-29

I can't find the 4" 1/8 brass nipple... only 3" does its make a difference ?

grandpa2 (author)2017-01-05

I have just read and viewed your how to make a burner above and find it to be very good. I have written and taught for the US NAVY and a civilian company it is on par with all I have seen and written myself. A big BZ to you.

Dinoman217 (author)2016-12-21

Does the flare half to be hand forged, or could I just use a pipe coupler as a flare?

JohnstonBD (author)2016-10-24

How important is the orifice size hole? I've tried to do some quick reading and can't find anything definite. Lowe's did not have a #57 bit, the smallest bits they had that I could find were 1/16" which I have plenty of at home. I could order from Amazon, but don't feel like waiting. Thinking maybe I'll just try a 1/16" orifice and if it's not working well order a bit and just buy another short section of brass pipe.

TannerB2 (author)JohnstonBD2016-11-05

ace hardware or homedepot probably have it.

Adrescher (author)2016-09-28

Is the flared end needed for it to work correctly?

PaulW293 (author)Adrescher2016-10-22

Yes it is, otherwise the burner doesn't develop enough vacuum in the tube to draw enough air in for complete combustion, and also the flame will not burn very hot because the fuel/air mixture isn't right.

Adrescher (author)2016-09-28

Im haven't trouble getting this to have a flame come out of the end of the tube, is the flared end needed for it to work correctly?

Tom541 (author)2016-02-02

Lowe's List;

Outer Burner;

1 ea @ $3.48 = $3.48 Black Iron Pipe Nipple 3/4in x 8in

(ProLine #20512)(Lowe's #12946)

1 ea @ $5.78 = $5.78 Black Iron Reducer Coupling 1in x 3/4in

(ProLine #71313)(Lowe's #82770)

1 ea @ $3.08 = $3.08 Black Iron Pipe Nipple 1in x 6in

(ProLine #20610)(Lowe's #19758)

Inner Burner;

2 ea @ $5.99 = $11.98 Brass Pipe Nipple 1/8in MIP x 4in

(Watts LFA-721)(Lowe's #87758)

1ea @ $3.89 = $3.89 Brass Pipe Nipple 1/8in MIP x 2in

(Watts LFA-717)(Lowe's #87454)

2 ea @ $2.99 = $5.98 Brass Pipe Coupling 1/8in FIP x 1/8in

(Watts LFA-706)(Lowe's #85970)

1ea @ $5.58 = $5.58 Brass Pipe 90 Degree Elbow 1/8in x 1/8in

(Watts BF-700NL)(Lowe's #748348)

*I was unable to find an acorn nut to cap the end of the pipe nipples, I ended up using JB Weld (Lowe's #10301) $5.67 and a 39 cent, 5/16 in x 1/2 in (Lowe's #396437) screw to cap the end.

Set Screws;

12ea @ $1.98 = $1.98 Phillips Head Screw, 8-32 x 3/4in

(Weather Max #126944)(Lowe's #409482)

*Lowe's sells these in a package of 12, you will only need 2 of them on each piece as set screws.

Total Cost = $41.75

*with JB Weld & Screw $47.81

Nearly all of these parts are in Lowe's Plumbing Department. The JB Weld was in their Paint Department (go figure!), and the set screws were in their Hardware Department.

Hope it helps!

THANKS makingcustomknives!!! Great tutorial!

HAHA! We don't pay sales tax in Oregon ;-p

BlacktagMi (author)Tom5412016-08-20

Tom!! Seriously, thank you.
I've had great difficulty with other burners due to lack in clarity of parts & such, this will help lots.


CliftonR5 (author)Tom5412016-04-27

I was wondering if this is the full list of materials to build the burner ?

Tom541 (author)CliftonR52016-04-27


CliftonR5 (author)Tom5412016-04-27

I was wondering if this is the full list of materials to build the burner ?

CliftonR5 (author)Tom5412016-04-27

I was wondering if this is the full list of materials to build the burner ?

Tinka24 (author)2016-02-07

For anyone in Australia having a hard time finding the brass parts like I did (because apparently Bunnings and any other plumbing stores I went to didn't have them) pirtek has some brass all thread that works and is around $6 for 150mm piece and they have all the other fitting needed as well

CallumD3 (author)Tinka242016-07-23

Where did you find your un-galvanized pipe? I am having some trouble across the ditch here

lnel2 (author)Tinka242016-02-10


astrong0 (author)2016-06-25

I just might make this. I started blade smithing a few months ago and I have a brake drum forge that is heated with charcoal that I also make myself. It's getting almost impossible to fit, making the charcoal, forging, finishing making scales, into my schedule. I think that LP gas is the way to go for my time constraints.

McJarod_ImLovinIt (author)2016-05-20

IMPORTANT! if you attach an adjustable blower to the back of the burner, it can be adjusted to forge weld, did just that with mine and now i can melt steel if i wish :D

TheNotoriousHoppington (author)2016-04-27

I built a burner very much like the one here, but mine is of a smaller diameter. I've tried everything I could think of, but there doesn't even seem to be gas going through when I open the valve on the tank. I saw someone else in the comments fixed theirs with a higher output regulator. Is that what I need, or is my problem something else?

britbano (author)2016-04-14

Thank you for the response, i figured it out today. Got a 10 psi camping regulator from academy and now it works great!!

britbano (author)2016-04-10

Burner not working!!!! Please help. I'm using a dual bbq regulator with one side capped for an option to add a second. I used a #58 for the orifice. I haven't made the flare, and am just using a 3" section of 1" pipe. When I light it up, I'm not getting any noticing venturi effect. Does anyone knows what I can do? Any help, please!

jammin516 (author)britbano2016-04-14

You need a propane regulator with a higher output than the standard BBQ regulator. Like this one -

britbano (author)2016-04-10

Did you cut the threads off of the side of the 8" tube that the flare goes over?

Baer125 (author)2016-04-04

When i run my forge burner it runs a blue green color, but the color in the picture is a blue. The flame is coming out the pipe instead of the funnel. Does anyone have any ideas on how to correct this issue?

Scote621 (author)2016-03-30

Though after looking at the pics more closely I think the pipe is more like 1/4 or 3/8 in the finished product versus the pic shown in step 1...has that been confirmed?

Scote621 (author)2016-03-30

I was hoping for some help. I have gathered nearly all the parts for this but for the life of me can't find the fittings to go from a type 1 propane hose down to the 1/8inch female adapter i will need for my 1/8 brass nipples. I found that a 3/8inch male flare fitting fits the hose (which is strange I thought it was 1/4'' diameter). Anyways, if anyone has some advice on what or how they were able to connect the typical grill hose to the burner i would be very appreciative.

Mkp_knives (author)2016-03-28

You sound like you have lots of experience do you think I could make one half the size of so would I have to use a orfice hole that would let half the amount of gas out or a hole with the diameter half the size? I look forward to your response

NZCypher819 made it! (author)2016-03-25

Thanks! Made 3 of these today, super easy to do. Photo of running a twin burner setup. Now gotta finish the forge!

TheNotoriousHoppington (author)2016-03-22

Is it possible to reduce the pipes so they can fit on a 1/2inch nipple thread but still produce the same effect?

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