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I Forge Iron

First Gas Forge Build


iron quake

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Finish building my first forge. I like the features included: A burner idle circuit, a valve to turn off the third burner, front and rear doors that move up or swing out of the way, stand that has a moving front support thats part of the base for holding up long heavy stock. The side door is soft fire brick that when removed gives open access to the “8x4x24 clam shaped chamber. I used 2” blanket for the doors and body coated it with Matrikote. The floor is a zone 11 kiln shelf.  I cast a couple other floors but really didn’t like them. The burners are from Thermal Art Design and very stable. I tried machining some myself, based on a design shown by Dave Hammer but I couldn't get them to behave through ranges of pressure and in idle. These from TAD are working very well.

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Thanks Frosty, It works well so far. It might look like a bit of over kill having three burners for that volume but with all three sides open I think I'll need them all. Have you ever used an electric carving knife to cut blanket? They work really well for that.

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Im trying to put together my first gas forge at the moment. Up until now I have just used a solid fuel forge but because I would like to forge more often in my current situation the best option for me was to build a gas forge. I decided to attempt a build on a forced air burner. From what I read they seemed better option for controling the fire. I just want to build a small forge and am still uncertain what Diameter I should make all my pipe and fittings, for greatest efficiency, so any insight would be greatly appreciated.

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Welcome aboard toadstool glad to have you. If you'll put your general location in the header you might be surprised at how many IFI members live within visiting distance.

 

As a rule of thumb, figure a 3/4" burner outlet will bring about 350 cu/in volume to welding heat. I expect we'll hear from the guys who read my rambling that ratio is for a naturally aspirated burner but I use it because that's the ratio my Johson Appliance forge uses and it seems to hold for both.

 

A word about gas inlet placement: the gas and air will mix much more thoroughly if you mount the gas inlet before a bend in the pipe. The turbulence of going around a 90* turn will stir it better.

 

Frosty The Lucky.

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Thanks for the quick reply and the tips Frosty. Is there anything specific I should be using for a regulator or gas line? I have seen some people make mention that it is important to be able to regulate your flame like on a torch. But I didnt know if spending money on a nice regulator would produce a noticeable difference.

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Yes, a regulator is a good thing, it will maintain an even pressure even while the propane in the tank cools an the tank pressure falls. A 0-30psi regulator ought to do unless you're building a big forge in which case you'd need a higher volume reg and need to talk to the propane supplier. A gauge is a really good idea, it'll help you repeat temperatures consistently.

 

To adjust the output of a gun burner (blown) you need to control both halves of the fuel air ratio. Increase the fuel and you must increase the air by the proper ratio. With practice you'll be able to eyeball the burn. Changing gas is easy, it's the adjusting the air input that can be a trick. A rheostat is nice if it won't burn out the motor and a simple valve on the air intake is good if the motor isn't cooled by blower air. A bypass on the output works too.

 

Controlling the air is one of those fiddly bits that can hang you up for a while but once you figure it out you wonder why it took so long. My solution was to make naturally aspirated burners, a PITA to get tuned but once they are they don't change fuel air ratio enough to make a difference the air is induced into the forge by the gas flow.

 

Frosty The Lucky.

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You notice how he gave sizing with respect to how much volume the burner would heat?

 

This is because to some people on this site "small" is stuff under a foot  sq  and to others "large" is over 1/2" sq; so one person's small forge can be very much larger than another person's large forge.

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You'll be turning a 3/4" burner down low in a 250cu/in forge to keep from melting things, the steel, the liner, etc. It fits my basic philosophy of useful stuff perfectly, "It's better to have it and not need it than need it and not have it."

 

It's not WAY too much burner for that volume, it's just more than necessary so you'll be running it turned down but if you need screaming HOT it'll be on tap.

 

Frosty The Lucky.

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That is kinda what I was looking for in this forge build, I am a minimalist at heart. Going to town today to pick up the pieces I need to put everything together.

 

Having more burner than you need for the volume is an interesting definition of minimalist but I agree. having one tool that will do more than you think it needs to is a good way to minimize things.

 

Don't forget to post pics of it running at - A - Minimum. <grin>

 

Frosty The Lucky.

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haha yeah not the best use of the word minimalist. Simply put the fewer rescources I can use to accomplish a task the better. The more efficient I can accomplish a task the happier I am. But I got everything I needed today in town except for my propane hose, I have to order that one it turns out. Should give me time to get the forge set up and ready.

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Naw, it's a fine use I just like pointing out little ironies like that. Faster, better, cheaper, easier, is the golden rule of the blacksmith businessman. Improve any one and increase your profit margin. A more modern tern of phrase would be "More Bang for the buck". Your use of minimalist fits the spirit of them both from the cheaper easier part of the first and the entire second one.

 

Same spirit, different letter. The rule of the game remains the same.

 

Frosty The Lucky.

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