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I’m thinking of building a duel burner forge 10”x10”x20” with a 5”x5” opening either end with forge doors and I was wondering if two frosty T burners hooked to a standard propane tank with a 30 psi regulator would get hot enough to forge weld. Also what insulation is recommended I was thinking of using fire bricks. 

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Why do you need such a large forge and WHAT SIZE OF T BURNERS?  Also how much insulation, of what type will be on the walls and are those dimensions the inside dimensions after the insulation is installed?

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I want to try and make some short swords and larger projects. there will be 2.5” of insulation top bottom and sides. Outside dimensions is 10x10 the inside dimensions is 5x5. I was thinking of just going off of the original design so 3/4 8” pipe 1”x1”x3/4 t. 

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You do know that heating more metal than you can work at one time degrades the metal left unworked due to Decarburization, Grain Growth and Scale losses. So if you want to forge a 6' long great sword you should build a forge that heats say 6" of the blade at a time and has a door in the back so you can slide the area to be worked on into the hot spot as you go along.  The only time you need to heat the entire blade up to critical is heat treat and there are ways to get around that; like having a trench forge.  Building a huge forge just so it will be there for heat treating is like buying a Dump truck as your daily driver just because you want to get a load of gravel maybe twice a year.

Since propane forges are limited to the size they work best for; expect to build several as your smithing skills grow.  It helps to build one that doesn't spend all your money in propane when you don't need it.

The large interior forges tend to be used most by folks doing 3D ornamental work and are willing to pay for heating the space. (I've used one that was quite large to heat some 2.5" sq stock to use a 200# Chambersburg air hammer on----see my avatar picture.  I didn't own either the forge or the hammer and borrowed their use for a large project I wouldn't do with my set up.)

Will this be a sq cross section forge?  If so what insulation will you be using and how to you plan to support it?

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My plan was to have separate valves on each burner so I have the option to only use one burner at a time. And I can have a fire brick to reduce the length of heated space. Also I don’t think 5x5 internal is a large forge.  I’m not sure what insulation I will be using that’s why I’m asking for suggestions. I want to go big on the insulation to keep heat. 

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It's the 20" long that is a fairly large dimension.  I presume you will position the burners to cut down on Chimney effect heating of the ones not in use?  At the NMABA meeting I was a large 12 burner forge hidden away.  I hope it was natural gas!

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Welcome aboard Bisonforge, glad to have you. If you'll put your general location in the header you'll have a better chance of hooking up with members living within visiting distance. 

Where did you find the T burner plans? The mixing tube length to diameter ratio is considerably off. Guys who don't understand what ratio means tend to use 3/4" x 8" in their plans. The correct ratio is length = 8x the diameter. 8x 3/4 = 6" 

The illustrated plans are available here on Iforge and the fellow who developed them can be talked into helping with problems.

There are also proven plans for building propane forges under the "Forges 101" sub-section of the gas forge section here. 

Your concept is pretty unworkable in several ways because of it's excessive length. With only two burners it won't reach even temperature so won't be so good for heat treating, you can deal with that by using more smaller burners, six 1/2" burners would make even heat and be a nice amount of overkill. You can always turn the fire down but you can't turn it higher than max. Yes?

However, before you build and install burners, how are you going to apply a hard refractory flame face? Or heck spritz on the Kaowool rigidizer, 10" from the nearest opening? 

A propane forge this long and narrow isn't a very useful tool. There a number of professional bladesmiths in our club making blades including swords in propane forges 9" long, fired by a single 1/2" burner. Our club held a 2 day forge and burner workshop and everybody who participated went home with a darned effective forge for just under $100. Pic below.

They are made with 8 Morgan ceramics K26 insulating fire bricks, 2, 3,000f split fire bricks, about 4-5' of 2" angle iron, some strap stock, 8' maybe more, all thread rod, nuts washers, etc. If in the future you discover you really do need a 20" forge you can build another and butt them together end to end using 4, k26 IFBs on the porches to make a tunnel forge.

One of the things I REALLY like about a "brick pile" forge is being able to reconfigure them as needed. I keep a case of K26 IFBs (Insulating Fire Bricks) and another of hard fire bricks handy in the shop in case I need a weird sized fire. Hmmm?

We aren't trying to discourage you, we want to see you succeed and we offer you the benefits of OUR mistakes so you don't have to repeat them to learn old lessons. Make sense? Actually we're hoping you go forth and make some new mistakes for all of us to learn from. ;)

Frosty The Lucky.

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The only reason I got 20” is that’s the max length I can get out of my material I intend to use. I have a chunk of 5”x5” angle iron that I planned on cutting into 4 equal parts for the body. So going off what you have said I’ll just do two 10 inch forges and give one to a friend. I will also just do 2” of ceramic wool and so my opening will be 6x6 unless you think this is a bad idea. I can’t exactly remember where I found the design for the burners but I have been watching multiple YouTube videos for the burner info. I really appreciate your help and I hope to learn a lot more from you and the other members of this site. 

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If you put two 1" layers of Kaowool and 1/2" of castable hard refractory in your forge how large will the chamber be? Subtract 2" from EACH wall for the Kaowool and another 1/2" for the hard refractory making 2 1/2" thick forge liner on all 4 faces yes?

That's 5" of liner in a 5" x 5" shell. You'd probably have to compress the ceramic blanket to get it closed enough to weld. 

My recommendation for a good starter forge is a brick pile, not necessarily a bolt together like our club builds but a pile of IFBs on a refractory table. They're easy to build and you can change them around until you learn what works for you. Another solid prove design is the 20lb. propane tank forge though you'll need tools and basic shop skills. The plans are available here. The Freon / helium tank forge is similar but smaller though you'll need some experience with potentially dangerous chemicals, if you use a freon tank. Helium tanks are chemically inert and safe as houses.

I highly recommend you stop watching Youtube videos until you have enough knowledge to know good from bad designs. Most of what you see on Youtube is useless and some outright dangerous.  

When you build things it's REALLY helpful to draw it out with dimensions. One benefit is you won't propose a forge with a liner that completely fills the interior. I'm not picking on you, everybody has to break into a new trade and makes silly mistakes. When you look back on them. Honest, been there done that more than once. 

We like to help but you need to do most of the work, we aren't going to do it for you. Stop wanting to plan your forge based on the size of the shell, especially the outside measurements. What you will be using in a propane forge is the volume, that's the open space inside. All a shell has to do is hold the refractory and support the weight of your work so there is NO NEED for thick steel shell, you could use chicken wire if Kaowool wasn't a breathing hazard. 

Do a little reading in the Forges 101 section of Iforge and when you see something you feel is within your shop skills and tools to build it's time to start making a plan. Calculate how much materials you'll need, how you'll shape and install them, tools you'll need, etc. 

There's a big difference between having an idea and having a plan. Right now you're full of ideas and you need plans. Take your ideas, separate them into individual drawings and get out the calculator. I debug a lot of my builds on paper before picking up a tape measure. 

The T burner illustrated plans are pinned in the burner section and are by the developer of that adaptation of jet ejector burners.

Frosty The Lucky.

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