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Beginner Gas forge Build


HUTT SMITH

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Hey guys, im just starting out in smithing and currently working on the design for my first gas forge....the outside shell is lasercut and formed out of 12g mild steel and im using 1.25 firebrick as a liner for top bottom and sides....the inside diameters for the forge are 13.5LX6.5WX4.5D......Will i need more then one burner to get the forge up to welding temp?

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1 hour ago, ThomasPowers said:

Would those be the hard firebricks and what kind and what size burner will you be using?  I've seen gas burners you could drop your forge in and read of others using hypodermic needles for the orifice.

I plan on using a .035 or .045 mig tip for the burner nozzle

 

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I had a look at the site you started from; being kind, I will just say that their conclusions are...dead wrong. The burner design they started from is, still being kind...an utterly outdated weak burner design. It is hardly surprising that their conclusions are skewed. Others can argue with  their 'facts.' The Burners 101 and Forges 101 threads lay out the truth, as best I can see it; read them, or don't. Their jumble of misinformation just makes me feel tired.

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So which burner design would work best for the forge size i described..keep in mind that i am compleatly new at this and am utterly depended on information i find in books and recive from experianced smithes ..so any advise will be helpfull and appreciated

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if i used two of the T-burners whos building instructutions are posted on this forum...would that be an efficiant design for the forge specs i mentioned? Please keep in mind that im trying to keep the building costs as low as possible and that includes how much gas the forge will use so it needs to be as efficiant as possible

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Fuel efficiency is related to the quality of burners you choose, but also to the insulation value of the forge lining and door system.  My personal feeling is that it is a lot easier to build and tune a fan powered burner and you get added efficiency because you can virtually close the doors completely and "lock in the heat" (you are planning on including good doors in your build, right?).  Also, hard firebricks are certainly cheap, but are a bit of a drain on fuel efficiency both due to their thermal mass (which takes a long time to heat up) and poor insulation value (which allows more heat to bleed through the forge skin).  It is all a trade off. 

You might consider just biting the bullet and buying a commercial burner.  There are a couple of good ones out there that aren't too expensive.  If you do plan on building a Zoeller Sidearm style burner (like in the linked file), try and follow the directions exactly, including using the correct fittings.

As a beginner you are planning on doing a lot of forge welding in your gas forge?  Even if you go fluxless the temperatures reached can be hard on a forge, and reduce it's lifespan.  Hopefully you will do the most efficient thing with your money and take an in person class or two.  Watching videos just doesn't compare, though if you are careful there are certainly some very good videos out there that can supplement your training.

In this instance I don't completely agree with Mikey regarding the information from the article.  I definitely agree with them about the requirement for volume matching and necessary forge diameter for developed length of flame.  I also feel that even thought here are advantages for limiting "hot spots" by having more than one burner, a single forge burner is usually much easier to tune properly (good compromise is a multiport burner...).

Good luck.

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Twenty-six years back I was working for a metal artist. His fan powered gas forge dumped so much heat in a very large shop that we had to keep a garage door open half way, with snow on the ground! Years later, I've learned that, it doesn't matter what kind of burner is used; only how well it is deigned and built. The only thing wrong with fan-powered forges is to few people designing them. lets have more of them :)

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yes i am planning on building two doors for my forge..a two piece door in the front so i can keep half the door closed and maybe just a firebrick slid into brackets at the back..is it nessasarry to have a small hole at the back for fuction ir is it just for working with longer stock/ im also planning on using 2 of the t style burners on my forge build

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Half firebricks sounds suspiciously like fireplace brick, which is a poor insulator, and not rated for the kind of heat a decent gas forge will put out. A small bag of Kast-O-lite 30, or a high alumina kiln shelf would make a much better floor.

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You can safely close one end completely without impeding the burner's performance. Being able to slide the rear baffle open to let long work be heated in the middle or slid back and forth to evenly heat a long piece is a big benefit.

Frosty The Lucky.

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Most hard firebricks will NOT meet your forge welding and efficient to run criteria.  I suggest you look into better more insulative ones---they are discussed here in the gas forge section.  A common thing we see here is folks telling us they need to do everything on the cheap and so to save US$50 on refractories they will end up spend hundreds of dollars extra on fuel.

I once used a blown ribbon burner forge at a smithy around 7000' altitude; it got my 2.5" square stock to welding heat with no problems. In fact we had an accidental forge weld when another person sharing the large forge slid their 3/4" round stock up against my piece and it welded and we had to use a hand sledge to get it off---no flux!   It does limit you to having to be near an outlet.

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A forge lining has four functions:

  1. Keeping the heat from escaping the forge.
  2. Keeping the workpiece from damaging the forge.
  3. Radiating absorbed heat back into the forge.
  4. Doing the previous three functions as long as possible within the harsh environment of the forge.

There really isn't one single material that does all of these well (at least not one that's within the budget of most blacksmiths). Hard firebrick (at least, the commonly available kind that is sold for relining wood stoves and fireplaces) doesn't really do any of them particularly well. Insulative (soft) firebricks do the first fairly well, but the lower quality ones are susceptible to damage and degrade over time. Ceramic wool (kaowool/inswool) does the first and fourth quite well, but not the second or third. Castable refractory does the second and fourth well and is okay with the third, but isn't great with the first. Adding an IR reflective coating will do the third well, but not the first, second, or (to a lesser extent) the fourth.

If you want to use firebrick, then you might consider the better insulative bricks with an IR coating and either a layer of hard refractory (like Kastolite 30) or a high-alumina kiln shelf to protect the floor.

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so..i got my forgeu built,,used two slightly modified T-burners(replaced the t fitting with a 4-way so a screw-in bushing can be used to mount the nozzle instead of drilling a hole in the fitting...i also added a forced air system by plugging one hole on each fitting and adding an airline with a regulator connected to the shop compressor into the other side..it was a definite improvement but i cant get a 1.25 wide 1/4 bar hotter then orange hot...any advice on how to achieve higher temps?

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If you are going to build a blown burner build a blown burner don't cobble together stuff from differing designs---that's like adding in diesel parts to your gas car engine and wondering why it's not working right!

Also compressed air is pretty much the worst way to provide a lot of low pressure air; certainly one of the most expensive/noisy  ways!

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On 10/8/2021 at 9:57 PM, HUTT SMITH said:

so..i got my forgeu built,,used two slightly modified T-burners,,,,,,,,, i cant get a 1.25 wide 1/4 bar hotter then orange hot...any advice on how to achieve higher temps?

Yes,read the first 3 threads under Gas Forges which is the forum you are in right now.  The titles are Forges 101 , Burners 101  and T Burner illustrated Directions.  If you still have a question after reading each thread ask it there.  After reading and asking your questions,follow the directions EXACTLY AS WRITTEN and ask questions as you go along to build your forge and burner.  If forge doesn't reach welding heat you have my word that you will get all the help you need until it will.  When you see what is involved you will understand why all the neccessary information doesn't need to be reposted for each individual that starts a new forge and burner. 

Best to you and looking foward to haveing you here at IFI for a long time, seeing your work and hearing your ideas.   

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Hutt: 1, Pick ONE forge design and follow it WITHOUT MODIFICATION!

        2, Pick ONE burner design and follow it WITHOUT MODIFICATION!

I don't want to be harsh here but you do not know enough to modify these things, burners especially. Some of us tinkered with the things starting with solid information from commercial manufacturers and it still took a couple few years to get right. 

Frosty The Lucky.

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