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I Forge Iron

Just a box of dirt, or a simple side blast forge


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3 hours ago, Randy Griffin said:

I'll post the results here

Please do. I'm interested in how it works out. I'm about to build a new forge. I finally have the okay since I can store it in my vehicle when not in use so it's going to be a MarkIII type of setup I think. 

Pnut

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Or do a variant of my first forge.  I had a pipe going along the bottom of a trench with holes drilled in it and the air coming from one end and a ramrod controlling how long an area got air to it.  (Steel pulley mounted on a steel rod for the ramrod.) It would be possible to make this with 2 ramrods one from each end and the air supply from the middle of the forge.  

I made and used this forge in 1981.

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I built an almost Jabod today.   I have a bunch of old fire brick that have been laying around my place for at least 10 years .  I took an old 2x12 that was 8 foot long and made a 25-1/2 inch square  and screwed a piece of scrap plywood on the bottom.  Since I had the bricks I lined the sides with bricks to a 10" height from the plywood floor .  I used 1-1/4" pipe with a pvc fitting to slide a hair dryer into. The pipe went thru the box at 4-1/2 from the floor . I then filled it partially up with some red clay type soil . It had enough clay in it to pack well. I stuck the page a couple inches past the brick and packed the clay soil around it and formed a shallow trough for the fire.IMG_6044.thumb.jpg.583f0173d67186bd8748df02cc12d2d7.jpg

IMG_6043.jpg

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The bricks trapped the pipe in place while I packed the clay soil in place and formed the trench. Unfortunately the excitement caused by the ease of construction and the overwhelming desire to have FIRE caused me to forget to take any other build pictures.:(

I started the fire with a little coal that a friend gave me and then put coke on top. From start of build to fire was around an hour. Cost was zero !  I had the old boards and bricks and screws used to assemble it and the dirt.

The beginning of the story is it GOT HOT!   I cooked some steel to the sparkler stage.  The end of the story is I should have done this sooner!

That said I am not happy with the size of the "coal bed" or size of the hot spot. I believe that I might need to change the size of the trench some what. Maybe be able to control the air flow from the hair dryer. The fire is super hot right where the air pipe enters the trench and I built it in such a way that I can't  move the point of the stock past the hot spot easily. I also believe that the side walls are to tall. The happy thought is that I have 0$ invested in it and a minimal amount of time. So I can modify or rebuild to my hearts content. 

I will post a couple more pictures tomorrow . With just the dirt in it and also with a fire . I would like any suggestions.

Thanks

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  • 2 weeks later...

With my bellows and forge dimension test run through, I'm ready to get going on a better setup that isn't just insulating bricks. A few questions though:

The adobe mix I've seen is roughly 20-30% clay, with the rest sand. We've got pretty sandy soil, so I'll just dig up some of that for my sand and use kitty litter for the clay. The sand will probably be a little wet since it rained a couple nights ago and has been cold, so from other places in this thread I should probably only add 1-2% of the total weight as water, right? Then let it sit overnight and check in on it in the morning? For the box of dirt itself, is it okay to use some of these cracked insulating bricks to form a structure that I mold the clay over? I figured it would give the wooden frame a bit more space and protection, and since they're cracked, there's not much other use for some of them. Then, do I need to wait for the mix to dry naturally or can I use it right after I'm done forming? Lots of questions, thanks for all the advice so far!

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If the sand is wet now it's probably plenty wet. You only want it DAMP enough to pack hard. You don't want to be molding it like modeling clay, you want to have to hammer on it to make it hard. Too much water in soil being compacted starts taking the place of aggregate instead of just lubricating it. Water in mud leaves open spaces between all the aggregate particles as it evaporates so the soil checks or crumbles. JUST enough moisture acts as a lubricant so particles can be forced closer together and when it dries it stays hard. 

If you use kitty litter you'll need to let it temper over night to dissolve the litter chips so it'll mix and coat the sand to stick it together. Bentonite (AKA Kitty Litter) is NOT adobe clay, it's in another universe. Figure 10% is pushing the upper limit for bentonite content, a LITTLE water will make it into the slimiest mud gravy you've ever seen and it's WAY easier to add a LITTLE more water than it is to try and dry it out adding more kitty litter.

Do NOT add water unless it will NOT pack under a mallet. Then just a LITTLE sprinkle of water, mix and let it temper over night and try hammering it again.

Hammered hard and you can start a fire almost immediately. If you made mud bentonite can take days or weeks to dry. It's amazing stuff, seriously amazing.

Frosty The Lucky.

 

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Oh, okay, great information then. I may have put in too much kitty litter., but I could always add more sand.

I just checked on the mixture I currently have and it's definitely a bit dry. It doesn't compact at all when I grab and squeeze it, just kind of crumples apart. I think I'll add maybe another 2 cups of water, mix it in, and wait another day to check on it again. Right now I've got half a 5-gallon-bucket half full of my mixture, so 2 cups shouldn't be too much. I can't really do much with it right now anyway, we're getting our routine April snows right now and it's only 20 out. :)

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  • 11 months later...

Has anybody tried a JABOD with Black Gumbo soil? If so, did it work better a loose fill or dampened down and tamped? The dirt around where I live is all gumbo, which to my understanding is predominantly clay. My concern is that it will crack if I tamp it in instead of loose filling (it cracks like crazy in the Texas heat). However, I don’t have any bricks laying around to form the fire pot on a loose fill. Right now, I either have or can easily scrounge up the other materials I need. 

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My local dirt is also a heavy clay. I’ve had decent success with mixing in a fair amount of sand. 

Cracking comes from shrinkage; shrinkage comes from having too much water to start with. If you don’t have access to sand, try adding the dirt and tamping it down without adding any additional moisture. 

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Some types or clay absorb water and expand when wet and contract as they dry out.  That is why you see mud cracks in dried up puddles, ponds, etc..  So, ideally, you only want as much clay in your sand to bind it together and not enough water to make it expand. It you have a heavy clay soil only add enough water to barely bind it together, no water = no expansion, no expansion = no contraction/cracking.

"By hammer and hand all arts do stand."

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Remember that for several thousand years a forge was a simple hole in the ground with no fancy additions.  It will work even with cracks!  Ash from forging can also be mixed in to make it crack less...  For Y1K demos I tend to make a forge from adobe, used to be bricks but is now a hillock in the yard as they weather. I dig up a bucket and take it with me so I can build a forge off the ground based on the Hylestad Stave Church carvings and much easier on my knees.

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