Over the last few years, my son and I have watched a show off and on titled Forged with Fire. It’s a competitive blacksmithing show that really made us both want to go fire up some metal and bang on it. But blacksmithing seemed difficult, intimidating. Even if I could get all the equipment an figure out how to flatten some metal, could I really make anything useful? I put the thought aside for a while.
In the last quarter or so of this year, the urge struck me again and I decided maybe I could make a simple forge using things I had on hand. There’s a type of forge called a JABOD (just a box of dirt) that will do in a pinch. At the most basic level, what you need to build a forge is a chamber to hold some fuel and air pumped into that chamber to make the fire burn hotter. Steel needs to heat to something like 1200 Fahrenheit before it’ll be hot enough to shape.
Well, I had an old grill that seemed like it’d make an ok forge chassis. And I have a shop-vac to blow air. All I needed was some way to heat-proof the grill a bit and pipe air into it to stoke the flames. I was going to use lump charcoal (not briquettes) because it seemed the easiest way into the hobby (anthracite coal would’ve been another option).
Now, the floor of my grill was not solid or sturdy. It was basically a sloping grease trap made of thin metal. It would need to be reinforced somehow. I opted for cutting some plywood to provide a level floor, figuring that putting refractory material over top of the wood would protect it. I didn’t get a good photo of the grill before recycling it, but here it is with the piece of plywood I would cut to size.
Here I’ve begun ripping off the dials and pipes and wires and such that I wouldn’t need.
The board, cut to size and braced (it’s thin plywood):
Here’s the new plumbing I planned to add to the grill to bring air from the shop-vac to the fire bowl inside the forge. I didn’t wind up using all the pieces, as I tinkered with my original design as I went.
I had to drill some holes in the side of the grill to fit the flange. Here you can see the holes, and then the flange installed, with a pipe screwed into it. Don’t mind the wire — I got rid of that later.
Now I had something that was beginning to look like the skeleton of a forge, with the leveling board inserted and the plumbing installed. You can see the hole on the left-hand wall and the light shining through the knob holes on the front surface. I would need to patch these up somehow or else I’d have lots of fire shooting out of them. I didn’t think that simply mashing refractory material into the holes would work. It’d likely fall out before it could harden, and at any rate, it’d be a pretty thin barrier.
Remember that box of miscellaneous grill parts? I thought there might be something useful in it. Indeed there was! I got out my tin snips and cut out little patches I could wedge in front of the holes. Some needed a little bending to fit around curves in the grill wall’s surface. These were not perfect, but I hoped they’d give the refractory material something more to cling to.
I’ve mentioned refractory material a few times and am aware that I haven’t defined it. I take its purpose to be both serving as a barrier between meltable/burnable parts of the forge an to keep some of the heat in the forge. You can get fire bricks for this, or you can buy refractory concrete. If you’re building a JABOD forge, you can use dirt or clay for refractory material (or maybe you just don’t need proper refractory material because the worst you’ll do is cook some dirt, provided you’ve picked any rocks out of it). I didn’t want to dig a bunch of holes in my yard to get dirt, but I did want to go the cheap route, so I got some plain old cheap cat litter and some playground sand. For best results, you want to powder the litter. What you really want out of it is the clay (so you don’t want the stuff with crystals in it). Mix that with sand, ashes if you have them (they’re good insulating material), and water and you can make sort of a mud you can use to make your forge more heat resistant. This was a real pain. I stated with a mallet for pounding clay (breathing a lot in while I pounded) and graduated to a cheap blender, which broke after doing a few pitchers full. I had loads more sand, and I had plenty of ash from our fire pit, but I got tired of pounding the litter, so I had less refractory material than I really wanted.
I had my refractory material now an needed to try to make a fire bowl and some horizontal surface around it. I just made this part up and had no idea whether it’d work or not. It turned out better than I had initially figured it might. I first spread the goop over the plywood and around the pipe, leaving sort of a hollow around the tip of the pipe. I wanted a nicer looking fire bowl, so I used a real bowl to shape the hole. Once I had the basic shape, I wanted to build the flat, raised surface out farther and higher. You can see how the bowl looks shallower in one picture and deeper in another — in the latter, I had built material up to the rim of the bowl. I built a wood fire on top of the material to try to help it dry and cure. It worked only ok. If you look down in the bowl in some of these pictures, you can see the opening for the air input pipe, which delivers air right to the center of the bottom of the bowl.
With that settled, now I needed to rig up my shop-vac to be able to blow air into the forge body. I knew going in that the shop-vac’s hose would not naturally fit the pipe I had selected. I also harbored a hope that I could 3D print an adapter. So I learned a little bit about design specifications for threaded pipes, etc., and I did the math and modeling required to make an adapter that would thread onto my pipe at one end and onto my shop-vac’s hose at the other. Problem is, I’m not great at math. Even though I felt as if I had honored the spec perfectly, my plastic pipe fitting was just a hair too large for the pipe, which would sort of thread into the adapter but would not do so perfectly. It seemed close enough for a first-run. I might lose some air given the looser connection to the pipe (the connection to the shop-vac was pretty good), but I didn’t think I’d lose too much.
Now the thing was assembled. Time to fire it up! One thing I learned was that I did not need to worry about losing air through my adapter. I had more than enough air and, alas, a shop-vac with only “on” and “off” settings. I loaded the fire bowl up with some chunks of lump charcoal (basically wood burned in a low-oxygen environment) and some newspaper and lit it on fire. The shop-vac proved too much for the small lumps of charcoal. It would get them pretty hot and then blow them out of my fire bowl. I kept the grill’s lid down for some of this time to try to keep fuel in the forge, but the air was too much and I wound up with a rain of sparks and embers flying out of holes in the back and sides of the forge.
The fire did get hot enough to get a little dark red glow on my steel — you really want a bright orange maybe even tending toward yellow — but battling with the fuel and the airflow made it hard to keep the temperature up to anywhere approaching where it needed to be. I suspect that coal would’ve done better. After heating and trying to shape a piece of rebar a little bit, I finally gave up. It was clear that I wasn’t going to make a full success of the venture. Coals started tumbling/shooting out of the bottom of the grill, which indicated that my wood floor and the refractory material coating it had not held up to the fire. This is when I called it quits. My goal had been to move some metal, and I did accomplish that, but what I had in the end was a very slightly smushed piece of rebar.
Here’s the state of the forge after all of this effort:
The hole at the bottom of the bowl has enlarged, and indeed flames burned through the board underneath and chewed away at the refractory material too. You can see here some of the smaller lumps that my larger lumps of charcoal turned into. At top left, you can also see some lump near-charcoal I inadvertently made as part of this whole process while using a little hunk of wood to prop the forge lid open a little.
Naturally, after all of that, I failed to snap a photo of the smushed rebar, and it’s been a week or two. The result is sufficiently sad that it’s not worth showing it off anyway.
Still, I knew precious little about blacksmithing or forge-making when I started this enterprise. In the end, I made a functioning-ish forge and felt at times while building the thing as if I was in an A-Team montage. I’m pleased with this outcome. And I still want to make something that resembles a blade. So I bought an inexpensive forge that will work with a standard propane tank. Just today, I fired that sucker up, and I did get a better outcome (though still a pretty sad one). I’ll post about that separately.