building a forge; questions, scavaging, etc.

M

malignity

Well-Known Member
I'm looking into building my first forge, and am trying to collect my materials.

So far, I've got 24"x16"x1" ceramic wool insulation from Ebay, rated at 2600 degrees. I can't remember which brand. I think they're all about the same.

Ideally, I'd like my inner dimensions to be about 14" long, 6" diameter or so.

What I had planned on doing, was getting a circular base (not sure what size, not sure how to calculate that) do 2 layers of ceramic wool, a layer of refractory cement (pourable or some sort of motar) an inch or two thick, then plistix.

Rear will be closed off with fire brick.

I'm thinking I was going to do 2 burners. I want to be able to get welding heat, and I'm not sure I can achieve that with one burner.

Any thoughts or suggestions? Any ideas on what would make a good base for this? Maybe an old propane tank?

I'm new to this stuff. I've made 3 knives thus far, but used pre-hardened steel, and LOTS of time to keep temperatures down not to ruin the temper. I'd love to just soften it up, work it to my liking, then reharden and temper. Working with hardened steel wreaks havoc on my tools. Went through 12 dremel bits on my current knife.
 
I've got 24"x16"x1" ceramic wool insulation from Ebay, rated at 2600 degrees. I can't remember which brand. I think they're all about the same.
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I agree....brands really don't make a difference. What does is the density..... you didn't mention it, but personally I only use #8 density.

I'd like my inner dimensions to be about 14" long, 6" diameter or so.
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Depending on how thick your insulation is going to be, will determine the diameter you need for those dimensions. I personally do NOT recommend anything more then a single 1" layer of #8 density wool, with a light slurry coat of your choice. I don't know where the idea of thinking that mulitiple layers or ceramic fiber is "better" came from....I've done the experiments, and suspect that many don't understand the characteristics of ceramic fiber blanket. Each variant/thickness is designed to asborb a given amount of heat before it starts reflecting.... the amount absorbed before is starts reflecting, and the amount it reflects decreases as the thickness increases Compared to a single layer of 1", #8 density, 2" of the same material requires longer to achieve a desired heat/temp, and requires additional fuel/psi to maintain that temp. I suppose its all in how an individual looks at it, but in this case, more is not better.
So, were it me, I would go with an 8" ID "shell".....with 1" of "wool" on the inside, that will give you a 6" inside diameter. You didn't say if this was a vertical or horizontal design..... for vertical I would use 3" of castable in the bottom. For horizontal, just use some firebrick "splits" for the floor.

I'm thinking I was going to do 2 burners. I want to be able to get welding heat, and I'm not sure I can achieve that with one burner
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 If you're using venturi burners, you might need two to achieve welding heat, personally, I recommend a single burner with a blower......saves fuel, makes tuning the forge much easier, and reduces future problems. If you do go with multiple venturi burners, its far easier to use a manifold/fuel splitter just after the regulator, and run a hose to each burner then a single hose to a "splitter" just before the burners.......that setup always causes one burner to be "starved" versus the two hose method.

Any ideas on what would make a good base for this?
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My choice would be some type of steel "table", that will be solid and stable......I've been down the road of mounting a forge on a "pedistal"......and found its a train wreck waiting to happen. :)
 
I would also question having a 14" depth to the forge. That's going to heat up more steel than you can forge at one time. My main forge is only 7" deep and I do my forging and the vast majority of my heat treating in it. With an open port in the back I can heat treat a blade that is longer than 7" and that's getting up to a pretty sizable knife. At 7" I can get by just fine with a single blown burner.

Doug
 
Ed, I just looked, I have 8# density (whew!) It's CeraChem brand, found here:

http://www.ebay.com/itm/191604434061?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Do I need to do anything special where the seams hit each other? That'd be my main concern is that I'd create a hot spot there. Maybe not..



Doug,

I suppose that makes sense. My first knife was a 10" blade, very thick chopper. I figured "bigger the better" when it came to that, so I could make longer blades of similar style. I guess I don't really need one that big though.

I really enjoyed making that one, and it turned out to be pretty awesome. It's about as thick as a large steel file, has tons of heft, and doubles as a knife and machete in the bush. It's a mild to medium carbon steel of some sort (hot rolled steel I got from the scrap yard) and my friend heat treated it and tempered it for me once I did all of the work. I don't want to short change myself in making longer blades by having a forge too short. I suppose with an opening in the back though, that gives me some leeway.

Forgive my ignorance, but having it hang out the end while heating to critical temperature for quenching won't cause it to cool too much to provide an uneven hardening? I don't know the first thing about adding a blower or forge building to be honest. I was looking at the Zoeller and Reil style forges, and figured I'd do my best to copy off that, and try and stay budget. Ideally I'd like to stay around $100 or so building my own, and don't know if either of those designs are viable. Ideally like I said, I'd like to get forge welding temperatures, as I feel that canister damascus will be something in my future. I've got a ton of chainsaw and dirt bike chain laying around demanding to be used.

I appreciate the help thus far gentlemen. I don't have works of art like yours, but some aren't bad. I'll see about getting some pictures up in the next few days.
 
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I use a 9" length forge for my general work that's made out of two fire bricks. Due to the size hole I have I can forge up to 3" and as long as I want with it. It being open as a pass through allows this. As for heating evenly a longer blade I just keep it moving back and forth to keep it hot.

Works very well after a little practice.
 
When working with a blade that is longer than the depth of the forge you have to work the blade back and forth to keep the temperature even. Actually, when I'm working with a short blade I will still stick the point of the blade out of the back side so that I can heat up the thicker back end of the blade before the tip which, being thinner, can overheat It just takes a little art to keep the parts heating up the same. It helps to be able to see the decalessence that occurs as the iron phase changes as the steel heats up. It's like a shadow that passes over the steel and is easier to see under dim light.

Doug
 
Thank you. I'll probably be ordering some supplies soon from you Wayne.

I suppose if I'm only going to use one layer of ceramic wool insulation, I won't need a huge diameter pipe then. The scrapyard has plenty of steel pipe in various diameters for me to pick from. My thoughts were to put a layer of mortar or cement down before I did my plistix coating just to make it more resistant to flux. I suppose I could just put a piece of fire brick inside, but I don't know if having a square piece of firebrick in a round forge will make any unexpected hot spots.

Maybe I'm over-complicating this thing; I just want to do it once, and do it right. All of my knives thus far have been made from pre-hardened steel, and it's taking a toll on my drill and dremel bits, my tools, etc. I know I'm not doing it the 'right' way per say (if there is such a thing), and though I do get useful blades, I'm throwing money away without the ability to soften it and work with it how I wish before I re-strengthen the steel.
 
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I coated my ceramic fiber with a layer of Mizzou refractory cement and omitted the Plistix. The Mizzou is more resistant to being poked through with the knife blade while I'm working with it in the forge and it's more resistant to the flux than a mortar would be.

Doug
 
Instead of using pipe get a 20# Propane bottle or a Freon bottle. Read my attachments on the Forge Supplies page. The Plistix is not necessarily flux resistant but Kast-0-Lite is. The Plistix is an Infrared Reflective product and helps keep the heat inside the forge. Cast the floor with Kast-0-Lite. Fire Brick is a heat sink. Paint the Plistix over the 1/2" layer of Kast-0-Lite. Propane and Freon bottles are now readily available for free.
A scrap yard for the Propane bottle and the HVAC shop for Freon bottles.

Let me know if I can help you.
 
I'll ask my scrap yard if they'll let me take a propane tank. They may not since they can't guarantee it's safety, even though I'm not going to be using it for conventional purposes. . I've been hitting the place up for materials that I can recycle into other things, and looking for old files and such occasionally. Got a section of rail road track for an anvil. It's not ideal, but it was cheap and it's a start.

Ultimately, I think I should have waited to get my ceramic wool insulation. I don't know if it's the proper size for a propane tank. I've got 16"x24"x1". I may have to cut the tank a bit shorter, I don't know. I'll make it work. :)

How did that Metrikote end up working for you Wayne? Ideally, it'd be nice to find a layer of IR coating that's flux resistant, but I'm not sure such a thing exists. As long as I'm capable of forge welding, I suppose I can reapply the IR coating once in a while, whatever it may be.
 
Talking about safety with a used propane tank don't cut into it without making sure that any residual propane is gone out of it. Unscrew the valve and let it set upside down for a couple of days. You may even want to fill it with water a couple of times and draining it out.

Doug
 
For a 20# Propane Tank forge you should have 2' of ceramic blanket. How much is your time worth? It is probably cheaper to buy more ceramic blanket if you need it.
Metrikote works great for reflecting the infrared rays back into the forge, where it is needed. the Kast-0-Lite is a good, light weight, insulating castable refractory and is resistant to flux. If I get flux on the floor of my forge I just see a black area, no eaten holes.

Let me know if I can help you.
 
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This is what I had in mind. I figured if I didn't have enough ceramic blanket, I could always use a little more Kast-o-lite. The stuff I got on ebay was more expensive than yours. I wish I had found your site first. I'd have ordered it there. I'll work with what I have though.
 
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