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I Forge Iron

Insulated fire brick forge.


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Ive seen a few one brick forges on you tube and the net but I am wanting to know if its reasonable to build a small forge out of insulated fire brick.

I currently have a coffee can forge that works......but it seems that my insulation isnt as rated as high as I need it. It is boiler insulation from work and as there are no markings on the roll or anything I have no idea what it is rated at.

This insulation is used inside of gas boiler fireboxes which Im sure dont get up to forging temps.

Anyhow, I would like to continue forging and was thinking of building a small forge with a 2 inch by 2 and 1/2 inch the length...9 inches of the bricks. I am making small tools and hardware such as hinges in the forge so I dont need much.....but I want something that will give good heat........ Im using mapp gas now.... but I also want something that will last a while.

Do you guys think that an insulated fire brick forge will last a while......Im thinking of g26 bricks 3 inches thick.

Im aware the bricks become fragile over time......and I will make sure to stack and secure them in a stable manner..... I just dont want to invest in bricks that are going to crumble or disentigrate after a few firings.

Im willing to spend money on the hobby.....I just want to get the most bang for my buck.

Any comments or suggestions would be greatly appreciated. Also any materials sources.

thank you

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Good Morning,

There is no perfect forge. There is no perfect size forge. The best forge is the one that will allow you to heat what you are trying to work with. A pile of bricks works just as well as an expensive forge, the advantage of a pile of bricks is that they can be configured in any fashion to get your job done. You don't need Hi-Temperature bricks to make a forge, any fire-brick will do. The hi-temp bricks have a refractory ability and sometimes the forge heats up quicker, depending on what burner you are using.

I have been using regular fire-bricks for a forge, for over 15 years. No problem. Don't buy into the thought that the hi-temp bricks are the ONLY WAY to go. Coal, Coke, Propane, Mapp Gas, Tiger-torch, RoseBud, use what you have available.

The one brick forge that Al Bakke showed the Vancouver Island Blacksmith Association, was a hi-temp firebrick. He is using the refractory ability to create welding temperatures for welding knife blanks, with a hardware store bought propane bottle and burner.

At CanIRON VI in Victoria, B.C. Al Bakke demonstrated using a post vice to weld a knife blank, instead of a power hammer or an anvil.

K.I.S.S. Don't doubt it until you try it. If it doesn't work, try it a different way!! Don't be afraid of trying, that is how inventions are created.


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My forge is nothing but 5 firebricks stacked to make a chamber that's just big enough for a large-ish knife blade. With a weed-burner torch, it works well. I'll be getting a few more fire bricks in the near future so I can increase the size to accommodate odd shapes.

I was thinking that painting the inside of the forge with some ITC-100 would help the bricks last longer and the forge to get hotter faster.

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This setup seems to work fine for me. I have the back bricked shut, but can move the brick for pass through items. Also, I was experiencing the woof woof problem, and solved it by rotating the burner 90 degrees to the side. Fire needs oxygen duh.

I also used a little bit of sairset between the gaps, and the output increased quite a bit.


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  • 2 weeks later...

I've used lots of soft fire brick in the past few years. They're fantastic insulators but they don't last long. As soon as mine develop a violet-colored tint on the side facing the flame, I know they're brittle and about to crack. But even cracked bricks can be reused. Soft fire brick is so easy to cut, it lends itself to many projects. I've scooped a channel out of one and use it to heat small steel rod. Much quicker than heating in air. I've even used pea-sized fire brick pieces as a component in a commercial refractory.
You might consider this: Get some Durablanket or similar ceramic insulating fiber. Dampen it and slather it with a refractory adhesive. I use Sairset. Wrap single or stacked fire bricks with this mixture. When it dries, the ceramic fiber and Sairset form a rigid "skin" around the fire brick. Now you have a forge container that combines the insulating value of both fire brick and ceramic wool... although the ceramic wool's insulating ability may change a bit since it's impregnated with Sairset and compressed. I've had good luck with this.

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I'm using a firebrick for my forge atm as well. One thing I would reccomend is adding some additional insulation on the bottom. I used some old ceramic blanket to line the bottom and added an extra floor of firebrick. kept the heat from getting to my workbench and warping the tabletop

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