Here is my journey building my propane forge. I’m not looking at this as a coal forge replacement,  but an addition to my blacksmithing tool set.
This forge is a compilation of watching a whole bunch of YouTube videos, reading blogs and websites. You don’t typically find two the same, so it seems it’s best to pick a design and go with it.

http://www.zoellerforge.com/
https://www.instructables.com/id/How-to-Make-a-Propane-Forge/
https://www.youtube.com/watch?v=hqFDRBZZPWQ
https://www.youtube.com/watch?v=thNOSEhcQog
https://www.youtube.com/watch?v=_bnMj4TjKjk

zoellerforge.com was especially helpful and I wound up ordering everything I couldn’t find local from there.
Here is a list of what I used:
A 7 gallon  air tank (an old tank that’s been around forever)
For the burners
(2) 3/4″ black iron pipe tee
(2) 3/4″ x 8″ black iron pipe
(2) 3/4″ to 1″ adapter (this is because I couldn’t find a 3/4″ x 1 1/4″ adapter)
(2) 1″ to 1 1/4″ adapter (flare)
(2) 1/4″ plug (drilled and tapped with 1/4″ x 28 for nozzle)
(2) .035 nozzle for mig welder.
(2) The ball valve came with the connection kit from Zoeller Forge
Here was what I bought from Zoeller Forge (for 2 burners)
(1) Two burner connection kit
(4) 9″ x 4 1/2″ x 3/4″  3000°F heavy duty fire bricks  (2 extra for when I use flux to forge weld)
(2) 2 1/2″ x 9″ x 4 1/2″  2600°F insulated firebricks
4 lbs Plistix 900F
(2 each) Propane Quick Disconnect and Coupler
(4 running feet) 1″  8# density 2300°F Durablanket 24″ wide
Building the burner.
This was pretty simple once I figured it out. I drilled a 1/2″ hole in the top of the tee. With just a little filling, the plug fit through the hole. Next time I think I will tap it for the plug.
I drilled and tapped the plug 1/4″ x 28 to accept the .035 nozzle. The plug fits through the hole and the ball valve threads on it to hole it in place nice and tight.
The propane connections added per Larry’s instructions.
Building the forge body
I cut the front of the tank off following the original weld line. This is just to facilitate the ability to work inside it. This cut was made with a 4 1/2″ grinder with a cut off wheel.
I used a 2″ hole saw to cut the holes for the burners.  You can obviously use a different technique  like drilling a series of holes around and knocking it out and grinding or filing it round.
The black pipe adapters were welded to the tank
I just made a few brackets to bolt the front back on.
I have seen a few designs where the door was hinged. The front opening on mine isn’t much smaller than the size of the box, so I didn’t see an advantage
I made the back opening the size of the insulated fire brick. This allows me to slide the brick in to reduce the box size and use a single burner.
The shelves on the front and back are just 1/8″ plate steel.
The front opening  is also the height of the firebrick, but wider. I can use the brick as a door to  close down the opening when appropriate.

MY PROPANE FORGE BUILD 001

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Here is the back view. The firebrick is just closing the door. This allows me to slide the brick in to reduce the box size and use a single burner.

MY PROPANE FORGE BUILD 003

The firebrick can be slid to open or close the front opening

MY PROPANE FORGE BUILD 004

Here is the 3/4″ to 1″ adapter (this is because I couldn’t find a 3/4″ x 1 1/4″ adapter) then the 1″ to 1 1/4″ adapter to create the flare

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MY PROPANE FORGE BUILD Parts

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MY PROPANE FORGE BUILD Valve

A simple bracket to hold the front back on. The tank is threaded to accept the 1/4″ x 20 bolts cut to length.

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I had trouble getting one burner to work correctly. It wound up being the nozzle was partially plugged. After figuring it out, I replaced the nozzle and everything was good.

 

 




This is my make shift back yard red neck coal burning forge. What a learning experience this has been.
This is an old wood stove that was in my shop. I used it to heat the shop for a couple years but it was was bit worn out. The fire box leaks and it’s warped bad. The doors no longer shut right and I replaced it with a better stove several years ago. It actually sat in my shop, thinking someday I’d make a forge out of it.
I gave it away 3 or 4 times but nobody ever came to pick it up. Finally i stripped the outer sheet metal shell and started to convert.
While in Tractor Supply I grabbed a bag of Nut coal. The smart thing to do would have been to do a little research first, but I was there and they had two choices, rice coal or nut coal. It seems i picked wrong.
My first attempt was to just light a fire on top. I’ve never burnt coal before so I just assumed it was similar to wood…….NOPE.

Coal Forge 01

This attempted failed and failed again. I think I used a half a tank of propane, then a half a tank of mapp gas trying to get it going.

Coal Forge 02

A bit of advice i picked up after the fact:You have to make sure you have the right kind of coal. You need bituminous and most coal sold at tractor supply is anthracite,( it too hard) it’s meant for heating homes, blacksmithing coal is softer and needs less oxygen, and for the best results if you can try and get the air to come up from underneath the fire.”

 

Doing a little research on the subject I thought this read was very helpful, https://www.sustainlife.org/coal-for-blacksmithing/

Coal Forge 03

My only goal for this fine Saturday morning was to turn this bolt into a coat hook. Seemed simple enough, right?

Coal Forge 04

I found this bolt on an early morning walk in the middle of a partly dirt, partly black top road. A quick session on the wire wheel and it looked a little better.

Coal Forge 05

Others say the rice coal Tractor Supply burns a little better. (I’ll let you know in future post)

Coal Forge 06

Many attempts to light this failed. Even scrapping the whole thing and starting wood fire first failed. After a quick google search I found that one of the complaint of Nut Coal is it’s very hard to get burning. I probably should have done that research first.

Coal Forge 07

Coal Forge 07

So scraping the idea of a small fire on top I turned to the inside. I started a bit bigger wood fire and added some coal.

Coal Forge 08

So now it seems to actually be working. The rigging I had for the air underneath didn’t do anything, so a new plan emerged.
This is a heat gun. I really didn’t dare borrow  my wife’s hair dryer and I assumed this would work. And it did for a while.

Coal Forge 09

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But problems prevailed. I just couldn’t keep the fire going. I eventually gave up and grabbed the propane forge to finish the coat hook. Not a master piece, but once hung, it will hold a coat.

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But tomorrow will prove to be a little better. Look for the next installment when I talk about making my first partially forged adze. I did manage to make this set up work (well sorta)
And thanks to my friends at Blacksmith for Beginners  I see this in my future.

Coal Forge 014

I’ve heard a rotor from a car and a mower deck works for this setup. Off to find some junk!!

 

 




After my initial design and a few days of forging I decided it was time to make some major changes to the forge.

I’ve left images of several iterations I went through before landing on this final configuration. It was truly a learning experience. I put the forge on wheels so I can wheel it outdoors. My anvil is close to an overhead door, so the coal forge can be outside. When I’m done forging, I just shut the air down, separate the coal, let it cool for just a few minutes and wheel it inside.

I like it better than the propane forge that cost almost 10 times as much and took a bunch more work to build. The propane is noisier, and try making a dinner bell in it! All in all however, I’m glad I now have both. If I get the urge to forge in bad weather I can use propane.

My only supply of coal I can find local is Tractor Supply. They have Nut coal and Rice coal. I started with the Nut Coal. It was near impossible to get started and keep burning. I tried the Rice Coal and that was much better. In trying to just use up the bag of Nut Coal I found that mixing the two worked best. Both of these coals are anthracite coal. I hope to find Bituminous coal, which is softer and works much better (so I’ve heard).

Coal Forge 1

Coal Forge 2

My air flow is a broken vacuum cleaner. I removed all the unwanted parts from it and cobbed up an air hose. I do want to find a way to regulate the air flow.

The bottom of this forge is actually the top of the wood stove turned upside down. It just makes up the stand for the fire box section.

So here is a few things I’ve learned.

  • The sides should be just high enough to stop the coal from falling off. If its to high it makes it hard to get the piece in the hot spot. The lower the sides, the more convenient it will be. If a table top was big enough to not need and side, that would be awesome.
  • You don’t want the firebox to deep. I always wondered why some of the commercial made forges didn’t have a firebox at all. No firebox will work far better than a firebox to deep.
  • How big the forge is isn’t of great importance,  you typically only work about 6″ or so of heated metal at a time. Support outside the forge can be helpful to help hold longer pieces however.
  • Bituminous coal is blacksmith coal.
  • If you are going to put a coal forge inside, think of it like a hood over a cook stove, not a chimney on a wood stove.
  • I didn’t believe you could burn metal quicker in a coal forge than a propane forge. Believe it!

Coal Forge 4

I ordered some 2″ black pipe fitting to get the air from under the fire. Getting the air under the fire seems to be the best way to go.

Coal Forge 5

Here is all you need.

  • 2″ Black Cap
  • 2″ Black Floor Flange
  • 2″ x 2-1/2″ Black Nipple
  • 2″ x 4″ Black Nipple
  • 2″ x 5″ Black Nipple
  • 2″ Black Cast Iron Steam Tee

Think of how you will connect your air. You may want the side intake longer. I also reduced mine with a shop vac end.

I forgot to order the floor drain so I wound up making the screen section to keep the coal from falling down into the pipe.

Coal Forge 6

Here are some of the “Not so good” ideas……….

Coal Forge 7

To say this didn’t really work very well was a bit of an understatement. I still wanted to use this old wood stove, if for no other reason than pure stubbornness, but I also felt if modified correctly, it could work out well.

Coal Forge 6

Next was to find a rotor. The best way to go about a forge is to have a fire basket. And I soon learned bigger isn’t necessarily better. This truck rotor is actually a little to big based on most opinions I’ve heard, but not really by much. I believe it would have worked, but I found one a little shallower and I went with that one.

The larger deeper rotor would have burnt more coal to get the fire high enough to use.

Coal Forge 9

Here is the one I ended up using.

Coal Forge 10

I started the transition by cutting the opening in the front. This was more or less a design on the fly kind of project, which is typically what my projects are anyhow. It wasn’t a good design for a forge. A fireplace maybe, but not a forge.

Coal Forge 11

Coal Forge 12

Coal Forge 13

Coal Forge 15

Coal Forge 16

Coal Forge 16

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So lots of things wrong with this original design. But doing it all wrong taught me why what I ended with was right. Low sides, High fire hot spot, and lots of air.

And the first real projects from the finished product. Dinner Bells made from some 100 year old rod.

Hand Forged Dinner Bell