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Ethan Yap

Planning a future proof forge?

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I've been planning a propane forge for a couple of months now. (After years of lurking on this an other forums) I live in Singapore, so there are a lot of compromises I have to make. One of them being the lack of space. What I mean by that is I have to build in someone else's space, and part of the deal is I build a forge that I won't outgrow as my skill progresses. The guy runs a metalworking business and the forge will be an upgrade to his space, in the makerspace part of his business where he lets people use equipment, so they also have to not outgrow it. He's a welder btw.

What I have so far is this:

Size: 30cm x 30cm x 100cm cuboid shape,

Insulation: Ceramic wool and sealed with refractory cement. I can't get satanite here unless I import it. What I plan to use is Plibrico Plicast 31, available in no less than 25kg bags.

Fuel source: 50kg propane tank

Gas fittings expanded to 3 burners probably

We're going to stick some ceramic wool and cement on a metal plate to partition the forge, so it'll only be 30x30x40cm most of the time, for years until someone gets good enough  to forge swords, then we'll need a super long forge to harden and temper. 

Now for the problems I'm having. I've been advised that you absolutely cannot harden or temper a sword in a horizontal forge, because it will droop as you take it out. How true is this? Because this will mean I can't future proof a forge like this, and what's probably going to happen is we'll build a vertical forge later on. I don't know if the welder will agree to this, because I'm getting a deal on his space usage to build a really nice forge.

Would it be at all possible to use these small burners on a large forge such as this? Or am I going to have to spend like a thousand dollars on burners? Gameco has a larger size, but it's expensive af. I was expecting to have 3 burners set up at 25cm intervals, with the forge heating up slower than most. Or will I straight up not reach temperature?

 

Can anyone help me with this?

 

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I've been forging for 37 years now and have never needed a forge that large.  You do realize that you will be paying many times the cost of building several more forges just to heat that one doing small work?  Forges are a consumable and will require being rebuilt with use.

The swordmaker I worked under had a vertical bore electric heat treating furnace with computerized controls and inert atmosphere to heat treat his blades. Of course he used alloys that required the computerized controls.  Not knowing what alloys you will be using makes it just a guess you know.

Have you read up on sword heat treating in Hrisoulas' books: "The Complete Bladesmith, the Master Bladesmith, The Pattern-Welded Blade" ?

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The problem here is unlike a solid fuel forge, you generally cannot just build a larger or smaller fire. In the case of a gasser, a large gasser will heat small stock just fine, but it isn’t very efferent. A small forge is more efferent for small stock, and a large forge is needed for large stock. 

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8 minutes ago, ThomasPowers said:

I've been forging for 37 years now and have never needed a forge that large.  You do realize that you will be paying many times the cost of building several more forges just to heat that one doing small work?  Forges are a consumable and will require being rebuilt with use.

The swordmaker I worked under had a vertical bore electric heat treating furnace with computerized controls and inert atmosphere to heat treat his blades. Of course he used alloys that required the computerized controls.  Not knowing what alloys you will be using makes it just a guess you know.

Have you read up on sword heat treating in Hrisoulas' books: "The Complete Bladesmith, the Master Bladesmith, The Pattern-Welded Blade" ?

I'm only going to be heating the first 30-40cm of it most of the time. I plan to put in a removable wall of refractory, ceramic wool, and steel which will in theory make the forge function the same as a small forge with some stuff sticking out the back. How consumable are they? They last in the order of years with moderate use, right? I know gas fittings are 5 years for hoses and 10 for metal parts.

I'll only be working with carbon steel for the foreseeable future. I definitely don't need computerised controls, just a way to keep it at about 260 degrees celsius for tempering and critical for hardening. I'm under the impression that you need a forge the full length of the blade (maybe excluding the tang) to harden effectively. Is that accurate?

I've done absolutely no research on ovens, but do you think you could give me a little to start off? What's the estimated cost of a simple oven  that does what I said above?

I haven't read that book, but I'll order one if I can find it for cheap. It'll cost me over $40 to ship it over here

What would you recommend I do? Do you think it's reasonable to ask the welder if we can do a small setup first, with a contract for me to upgrade as needed? Do you think that would be seriously screwing him over?

21 minutes ago, Charles R. Stevens said:

The problem here is unlike a solid fuel forge, you generally cannot just build a larger or smaller fire. In the case of a gasser, a large gasser will heat small stock just fine, but it isn’t very efferent. A small forge is more efferent for small stock, and a large forge is needed for large stock. 

Yes, I'll only be running the first burner for a long while, with an internal wall, of the same construction as the main forge walls. In theory, it should perform at the same efficiency as a small  forge, just that there's some extra, cold, forge parts sticking out the back. Is there anything I'm missing here?

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We have an active an active conversation going on under forges 101 and burners 101. Mike is an author who has written about them and Jerry has been experimenting with them for a 1/2 century or so. Read both threads. Most of your questions will he answered. 

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I could be wrong, but my understanding is that you do not need a forge the full length of the piece to heat treat. You can pass the piece through the hot spot of a smaller forge, working it until the full length is at critical heat. I also believe that this would be a more traditional way of doing it anyway. 

Now obviously a full length oven or forge would be able to provide a more even heat, but it's also inefficient and not necessary.

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Actually those are 3 books and we are eagerly awaiting the 4th one; (some of us have been waiting *years* JPH!)

I'd build a smaller one  in additional to a larger one if he's dead set on a gas guzzling large forge..

Most of the time when working a large blade YOU DO NOT WANT TO HEAT MORE THAN YOU CAN WORK THAT HEAT! As heating extra steel degrades it, especially the plain carbon steels, as they suffer grain growth, scale losses and decarburization.  The time you want to heat a long length is during heat treat so building a forge for that, which will happen rarely, to use every day is odd.

How long things will last? 1 day to 10 years depending on a whole slew of factors you haven't given.  (Construction materials, welding?, heat cycles, untrained users, etc  and so on. I've relined mine more times I can count though the shell and burners are about 20 years old and the burners need to be replaced. The shell of my forge is made from an oxygen welding tank and so it's doing fine!)

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The only forge that can meet your stated needs is a brick pile forge, because that is the only kind of forge that can accurately be described as completely variable; not just in dimensions, but also in body and burner orientation. HOWEVER, the real limiting factor in its usefulness will depend on what you use for bricks.

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and those waste lots of fuel heating up the pile, because the bricks are a heat sink

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Now you went and ruined it, Steve. He was supposed to ask what kind of brick; then I would suggest homemade high tech insulating bricks made from castable refractory :)

Then Frosty and a could rehash our previous discussions about brick pile forges.

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we can tell him anything, its not like he bothered to read anything already posted about it here  is it ?

 

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I like to think that there are others paying attention to these discussions and that it all has great meaning in some alternate universe maybe? The winter sun has sneaked out several times today, and I'm prepared to feel good about the meaning of life :)

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Ethan, I know you said you are in Singapore in your initial post. However we won't remember that for long. I suggest you edit your profile to show your location then read this thread to help with getting the best from the forum.

BTW Welcome...

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