Propane forge burner

[Canute Rex]

While we are on a series of posts about heating and melting I thought I'd show you the propane forge burner I made yesterday. It is mostly plumbing parts. The burner tube is an 8" x 3/4" black iron nipple. It is bushed into a 1 1/2" tee. The other side of the tee has a threaded plug with a 9/16" hole in it for a 1/4" nipple with a cap on the inside end. The cap is drilled and tapped for a 1/4" x 28 thread and has a 0.035" MIG welder tip screwed into it for a propane orifice. A 10-32 set screw drilled and tapped in from the side of the plug holds the 1/4" nipple in place. I turned the nozzle from a 3/4" coupler so it has a 5 degree angle inside - that slows the gas slightly and stabilizes the flame. The pipe fitting partway down the burner tube is a 1 1/4" nipple with one end sawn off and three 3/8" setscrews threaded into it. That allows the whole thing to be mounted in the side of the forge body with a couple of ring nuts.

The rest is the standard propane fittings you can get at the hardware store or Tractor Supply. The regulator on the 20 lb. tank is a high pressure (1-60 psi) 400,000 BTU model. Note the use of yellow gas-compatible teflon tape.

After I finished it I realized that I could have used a shorter 1/4" nipple, but I wanted to be able to adjust the position of the orifice inside the tee. Accidentally got it right the first time.

In practice this would be inserted in the side of a metal cylinder (a freon can works well) with holes in the ends and lined with 2" of Kaowool insulation. All the parts together cost maybe $75, and about a third of that was the regulator. I think the plumbing parts were $35.

I gave this to my neighbor, who is an aspiring amateur blacksmith, and he is a happy camper. You can do a lot of forging and heat treating with a propane forge powered by one of these. A 20 pound tank will last 6-8 hours if it's not in a cold environment.

Note that the ball valve isn't fully open. Full blast gives a foot and a half of zombie-ready blue flame.

[blaksmth]

Canute Rex,

 Nice looking burner how hot do you suppose it will heat the metal do you think it would get to a welding heat?

 I have never messed with the propane burners before so I am wondering ? if not it would still be great for general smithing with out the hassels of a coal forge

[Angus]

That's what every shop needs!

Two questions:
-How far into the T does the mig tip need to be?
-The 5 degree taper, is that a bell flare on the inside or the reverse of like a forcing cone?

Thanks for posting.

[Canute Rex]

Thanks, blaksmith. If you put a big enough burner in a small enough chamber you can get up to a bright yellow-white.

Angus: The placement of the tip depends on a few things. In this one it is about a half an inch back from the "downstream" side of the side opening of the tee. I happened to get it right by accident. Change the propane pressure and the optimum spot will change. That's why the 1/4" nipple is held with a setscrew. It's important to get the MIG tip centered and straight for a stable flame.

If you want to get fancy you can put a circular gate on the side air hole. Then you can adjust the air intake as well as the gas pressure. Let's say you are working on a delicate blade. You can lower the gas pressure and then restrict the air so the flame is just barely reducing (instead of oxidizing) and keep it from scaling. If you are going to do this SPEND THE $50 ON A CARBON MONOXIDE DETECTOR! That stuff will kill you before you know it.

The 5 degree taper flares out like a trumpet. That slows down the gas a little, which creates a low pressure zone. That keeps the flame from either poofing out the front or going back up into the tube. If you don't have a lathe you can forge out a piece of 1" pipe into a flare and put it on the 3/4" pipe with set screws.

You have to size the burner to the insulated chamber. This thing would produce a welding heat in a freon can. About 250 cubic inches per 3/4" burner. You'll need at least 4 square inches of open vent for the flames to come out, but then you need that to get the steel in. 3" of Kaowool is better than 2".

Here's a link to all you will ever need to know about propane forge burners: http://ronreil.abana.org/design1.shtml

[cmac]

I made a propane forge up with a weed burner some years ago. It works well but I prefer the coal still. I second the carbon monoxide detector!

[Canute Rex]

I use either coal and propane, depending on the job.

With a coal forge you have a chimney venting the smoke out and sucking air into the building, just like a fireplace. When using propane you have to think about ventilation and oxygen supply. I set my propane forge right on the coal forge with the back opening blowing into the forge hood. That creates a draft to suck fresh air into the room.

[P.W.Berkuta]

My forge 10" dia. X 16" long - building instructions from the web - works very well. I use it mostly for heat treating knife steel's.

[David R. Pennington]

I guess I'm just too old fashioned. Part of the enjoyment I get from forging is handling the fire. I don't see what hassles there are with coal. I could see I guess if you had fussy neighbors that might complain.

[Angus]

Are you guys also coating with ITC-100?

[P.W.Berkuta]

Are you guys also coating with ITC-100?

Yes----

[blaksmth]

David R

 I like coal also, but out here in Colo. It is hard to locate so I am probably going to have to make Charcoal  for the forge, but a propane forge would be nice addition.

I dearly love the smell of coal when smithing and it seems like The Folks in D.C.  don't want us using it which is sad .

 I ever get a chance to get back east  I am gonna try and get some Cumberland Elkhorn coal  and bring a good amount home.

 If I ever get to get back there
 

[Canute Rex]

I'm a big fan of coal as well, for a lot of things. Sometimes, though, propane does the trick. Forge welding Damascus steel billets is much easier in a clean, enclosed propane forge. Forge welding in general is easier with propane. Heat treating is easier.

Still, coal is king when it comes to odd shaped pieces and general forging. The smell of coal is the smell of happiness to me.

By the way, P.W. B, I like your burner design with the butterfly air adjustment. Very slick.

[Nordnecker]

I'm with you guys…..I like the smell of coal. I like rearranging the fire to suit what I'm doing. I don't like it when I loose a small part in the fire and burn it up, though. I have a 3 burner propane forge and use it when I want an even heat over a large area. I don't like the noise it makes and I really don't like the cost of refilling the tanks. I have never tried to forge weld with it, I didn't even know it was practical. The propane forge, mine anyway, scales the metal much worse than a coal fire does.