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I Forge Iron

Castable Refractory


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 I am making a new forge and I am trying to determine optimal placement as well as how many bolts I need to use in order to hold the Mizzou in place. I am starting with a 2 foot high 14 inch diameter pipe with 1/4 inch walls. Yes I know its thick but this is going to be a dual purpose forge..Anyone have suggestions.....I forgot to mention I was planning on making the bolt heads sticking out on the outside body to look like old style rivits like they used on boilers....so knowing the number needed and spacing to make them estetically pleasing as well. Also what size would be best.....


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If I understand correctly, you are making a vertical forge with castable liner?

Why not use a form to hold the fire chamber size (heavy cardboard tube like in carpet roll) or may even find a cardboard cement form tube the size you want at big box home improvement store and then simply cast the refractory in the void between metal shell and center form. It casts and sets up just like cement. Size I guess would depend on how thick you want the walls. 8" furnace in your 14" pipe yield about 3" thick walls. It will take some time to heat but would hold that heat for a week after you turn off the gas :D (Not really ;) However, my first forge as roughly 4 x 8 x 12" with 3" thick cast walls and it took 4 - 6 hours to cool enough to where I was comfortable to return it to the one-car garage and close the door.


My 2 cents :)


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I am thinking of doing the mock rivets to make it look like one of the old fashioned Boilers. I want it to not only estetic but functional, I mean yea I could do it that way Scott but then it would just be a plain old pipe forge, I want  it to be artistic as well....I know I am odd..

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My opinion;

I have made a number of gas forges using castable refractory. The castable I use is 3200 degree rated. I have forms made from sheet metal.

The interior form is wrapped in multipule layers (8 to 10) of sheet plastic to make it easy to get the form out after curing. Plastic sliding on plastic is the best release agent I have found.

The only place I use metal to re-enforce is the bottom or end of the forge. And I don't get too crazy with that. I generally weld in a few pieces of 1/4" rod to help hold in the end against putting in the fiber.

Consider this, the metal in the castable will expand and contract at a different rate and will cause cracking. That will happen anyhow to some extent but the more steel embeded in the castable will make it worse.

You can see from the photos I make a cast core and pack fiber between the forge body and the cast core. 1 1/2" of castable and 1 1/2" of fiber. The castable it then poured over the end encapsulating the fiber completely. There is no exposed fiber to break up and get into your breathing space. That stuff is a considerable lung hazard.

This gives me a good sized lumin and enough insulation so even running for hours at welding heat the exterior doesn't exceed 300 degrees.

The round forge was an earlier version, the mailbox shape is the current style I make, use, and sell

Make your fake rivets just keep them out of your castable lining.

Bob Menard








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I have used the same tech for a blast furnace to smelt bronze. I have also inadvertantly smelted steel in one of these forges. It got away from me a little bit. Those ribbon burners can get mighty hot.

The material is Castolite 30. As I mentioned above, 3200 degree rated. The fiber is regular kao wool though it is called something else.


Bob Menard

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It is a pine ridge burner. I have had very good results with them and if I have any questions they have been very helpful. 

The doors have held up well. The oldest forge I have built is now 5 years old. I still have not had to rebuild one. They are not a big problem to fix but the real wear part is the metal exposed to the heat of the interior. it does tend to scale and wear and I know I will eventually have to make a new one but that is easily done and not at great cost. The real money in this forge is the gas train. That part does not see wear. You can screw up the burner by shutting both the gas and air off at the same time. If the forge is screaming hot and there is no air flowing thru the burner it can melt the baffle plate right out of it. I usually let the blower run until the interior is black hot then shut it down

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