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First Gas Forge Design


Rubyoffthe

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Hi! I'm a reenactor who has decided to build their first forge. I've done a bit of work on coal but for working at home I decided that gas would be the much easier choice. I read the thread on Forge 101 and it warned about not starting too big but now I'm worried as to what you guys consider "too big". The size of what I've drawn up (diagram below) is based on the size of the things I need to be producing for reenactment (mostly larger axe heads) but please let me know if you think I've been too ambitious. The burner I'm planning to use is the 1" gameco bkit3 burner. 

All sides of the steel box in the diagram will be lined with 2 inches of kaowool and one inch of refactory cement. And it will stand on a base of the same. This gives an internal size of 10" x 10" x 5". 

If anyone can see any problems with this I'd love to hear them and I will adapt the design accordingly because I want to get this right.

Many thanks

Ruby

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Welcome aboard Ruby, glad to have you. If you'll put your general location in the header you might be surprised how many of the Iforge gang live within visiting distance. 

The oversight I see in your drawing and description is for a floor but I'll assume you intended to make room for the hard refractory flame face and 2" backer and just forgot to include it in the drawing you posted. N sweat I do that all the time.

1" of hard refractory is a bit much for a flame face, for the most part we're having good luck with 1/2" even on large flat span roofs. My newest forge roof measures 10" x 19". I ran sheet metal screws down through the shell into the Kaowool backer for support and it hasn't sagged. The flame face is 1/2" over all with the addition of a home brew kiln wash of 2pts. Zircopax to 1pt. sifted to remove the aggregate Kast-O-Lite 30, the hard refractory I use.

I don't see anything about your forge that won't work. At 500 cu/in it's well within the range of a 1" linear burner. I've never used or seen the one you refer to though I looked it up online. It should be enough to bring that much chamber to welding temperature as well insulated as you propose.

That IS however a lot of volume to expect a single burner to heat evenly, It's going to have a HOT spot and the temperature will go down the farther from it's impingement zone you travel in the forge. However, it that burner produces a large soft slow flame that stays in the chamber long enough the temp will even out after a while. 

Without knowing more about the kind of work you wish to do in it I'd be making pretty unsupported suggestions. But in the nature of undefined speculation I'd probably still use two, 3/4" burners to distribute the heat more evenly. End spec. . . for now. ;)

It may not be the best but it should work pretty well. 

Frosty The Lucky.

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Concrete wouldn't survive long enough to take the picture so it has to have a proper refractory for the table top. This pic looks like a dedicated forge so I'm not sure why the whole top would lift off. I probably just don't have the picture yet.

Frosty The Lucky.

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Hard Refractory concrete should have specified that. At least that is what he states in the build video.  (2 inches of wool and from what it looks like 1 or 2 inches of hard refractory)I tried to find a better picture but could not. Personally I like the idea of a removable top, would make it possible to adjust the volume as well. Reminds me of this thread: 

 

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 Frosty thanks, all of your advice is super useful! Basically the reasoning on the 1" inch burner was I know they're good burners and living in the Uk shipping costs of the burners I've heard about was insane, and those burners are available in 1" and 1/2" sizes over here so there wasn't silly amounts of shipping on top.

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Wow, that thread brings back memories Maarten. I was sure you meant hard refractory but we get posts from folk using Portland cement concrete for refractory pretty frequently so I make a point of mentioning how unsuitable it is. It takes a special mix even for relatively low temperature applications like fire place mortars.

I"m attracted to the idea of a lift off forge like these but having worked with a clam shell forge ONE time was enough. You wouldn't believe how unpleasant and downright dangerous it is to be close to one when opened, the IR will set you on fire pretty quickly. I have an aluminized fire suit but don't really want to have to wear it at the anvil. 

You're more than welcome Ruby. While it's not what I would've built it looks like a good forge.  I've been reading posts from folk in the UK trying to build burners and evidently plumbing fixtures common this side of the pond aren't available on yours. Heck, evidently propane is harder to come by, here virtually every filling station fills propane tanks. I live semi rural and there are at least 12 within 10 miles., if I drive 15 miles there must be 30 including 3 large bulk delivery fuel tank farms. 

Different places eh?

Frosty The Lucky.

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