JHCC

New JABOD box of dirt forge (picture heavy)

37 posts in this topic

I've been wanting to make a JABOD (Just A Box Of Dirt) forge ever since Charles R. Stevens first posted his original description. It just occurred to me that a sheet metal box salvaged from my oven replacement project would be a good base, so here goes. 

I started by making a base from an old pallet cut to the proper width:

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Using the cut-off section for one end:

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Legs in the other corners (more pallet wood) and a robust diagonal brace:

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The sheet metal box with the sides built up with some more pallet wood:

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(This photo shows how I built up the back fairly high and added another piece of oven side to protect the wood, as well as the pipe that I'll be using for the tuyere. The handle for the gate valve is visible on the left.)

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Here is the gate valve on the back:

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When the gate is pushed all the way in, all the air goes into the tuyere. When it's pulled out, the blast vents out of the rectangular slot on the top. It's pretty much infinitely adjustable between those two extremes.

The little metal clip keeps the gate from coming out too far.

I'll upload some more photos of the forge once I've got the clay in place.

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I've made another thread that shows the insides of the gate; see here.

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Started putting in the dirt. This is taking a LOT more dirt than the old rivet forge. 

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When I lived in Ohio I would get clay from a local creek that was lovely stuff to work with; I'd mix it with wood ashes and form it into the forge shapes I needed.

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6 minutes ago, ThomasPowers said:

When I lived in Ohio I would get clay from a local creek that was lovely stuff to work with; I'd mix it with wood ashes and form it into the forge shapes I needed.

Yep, that's been my strategy too. The rubble in this picture is all local clay, and a lot of it is clay/sand/wood ash from previous clayings of my rivet forge. I'm filling in about half of the new forge with this, and then I'm going to put a good, thick layer of new clay and ash to form the firepot and top surface.

One of the old side-blast forge threads mentioned using dampened ashes alone to line the firepot -- not particularly durable and needing occasional reshaping, but I'm wondering if this might be a way around the problem of clinker sticking to the clay.

In other words, make a clay firepot somewhat bigger than necessary, and then add a layer of damp ash about 1" thick to bring it to proper dimensions.

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And clay in place. The firepot is 5 inches deep and about 8 inches across at the top, maybe 3 or 4 at the bottom.

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Railroad spike for scale:

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We'll let this dry for a couple of days, and then give it a go.

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Dry, did I say? Well, first it has to thaw!

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(Gotta love those cold snaps and unheated garages.)

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One detail I forgot to mention: the vertical piece of oven side was eventually moved down and had a hole cut in it for the tuyere before I started adding clay. 

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Besides being unfriendly to coal (or overly friendly with clinker) clay dries hard and makes temperary modifications of the fire bowl shape difficult, but by the time you need a trench fire or a larger diamiter fire you will have the basic skills you need (and a forge to fabricate parts) to build a "better (looking)" forge. 

JHCC, rough and ready, I like it. 

As I side note, one of the fire bricks I use on the table (mostly as a wind screen, but also to help corral the charcoal) has gotten "melty" lol

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Thanks, Charles. I've re-clayed the rivet forge often enough that I've gotten a pretty good handle on the size and shape of the fire bowl. Let's see how the ash layer works out, perhaps with just barely enough clay to give it some cohesiveness.

Still waiting to give it a try. The good news is that the temperature has warmed up enough for the clay to thaw; now I just need it to dry!

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For an extra 50 bucks, you could make a refractory fire pot. Just a thought.

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If I had 50 bucks to spare, I'd spend it on steel and coal!

 

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The clay will vitrify sarounding the fire, and as clay is a refractory material that would be redundant, lol. Besides the whole point is to show the new guys how cheep and simple a forge is. 

But hey, $50 and I would go find me a 6 to 2" reducing bell and a go for the 2" pipe tuyere. Walla

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One substantial modification that I do plan to make is to reduce the height. My initial calculations were off (didn't factor in the rim, for one thing), and it's about 4-5" higher than it needs to be. I figure that I'll just drop the left-hand side down on top of the little shelf (from the center piece of the pallet) and trim the legs on the right by a corresponding amount.

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Well, the clay  still isn't dry enough to forge, but I decided to fire it up with some kindling to test the gate valve. Worked really well; I'll try to upload a video later. 

It looks there was a lot of shrinkage in the clay, and there's been some cracking. I'll wait until it's completely dry, and then put in that ash layer.

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Trying out the gate valve.

 

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A fitting to attach the blower hose to the gate valve. 

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No pictures today, but I've made the first real fire in the JABOD and done some actual forging. Here are the results:

PROS:

The air control from the gate valve is great. Zero to inferno in half a second, with infinite adjustment in between.

The firebowl is a good size, and heated everything from 1/4" to 2" with ease. 

CONS:

The catch that kept the slide on the gate valve from coming out too far wasn't up to the task and had to be removed.

Still learning how to manage the clinker. Didn't collect at the bottom quite the way I expected. Still on the upslope of the learning curve.

I had used a rag to seal off the hole around the tuyere, where it passes through the wooden back. Unfortunately, I forgot that it was there, and a spark got back to it somehow and set it on fire, right at the end of the forging session. Rather scary, having sparks and smoke coming from where they shouldn't be! I'll need to figure out how to get it out of there before I fire things up again.

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So, broke down the gate valve, fished out the rag, and reclayed the transition from the valve to the tuyere. 

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Another forging session yesterday, which went very well. The clinker seems to want to form around and above the tuyere opening as well as at the bottom of the bowl. No idea why, but it's not a major hassle. 

Here's the bowl after clean out. 

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And here's another video of the effect of the gate valve:

 

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Added a new blower made from a salvaged vacuum cleaner. The styrofoam, fiberglass insulation, and steel box (scavenged from an Omaha Steaks delivery, a friend's remodeling project, and the grocery store parking lot, respectively) bring down the noise level by about 15db, from 97 to 82. A bit more noisy (by 6-7db) than the old shop vac, but more compact and out of the way. Plus, now I can use the shop vac in, you know, the shop. 

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Since posting the above, I've salvaged a neat old variable transformer (variac) and connected it up to the blower. It works very well, and gives even better control over the airflow than the gate valve. It also reduces the noise of the blower, since the motor is now rarely going full-out.

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Big thanks to the Theater Department for letting me raid the dumpster when they cleared out the old equipment.

I don't know if this is a function of better speed control, a different batch of coal, or something else, but in my last forging session, the forge appeared to be running even hotter than usual. I burned a couple of pieces of 5/16" x 1-1/4" mild a LOT faster than I would have in the previous setup. 

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