Mark III JABOD forge

[Selph]

I hope that it's okay to ask a question here, I'm new to these forums and blacksmithing. I've taken a couple of classes and really enjoyed them, so I'm working on getting a setup together. I've looked over all the JABOD posts (on pnut's recommendation from a comment on Reddit) for inspiration.

On this mark III build, I was curious if the brick setup was because it's intended to travel or if it's more a refinement of design? I've been planning to give it a go exclusively with charcoal (if it ends up working out), and I wasn't sure if using a few soft firebricks for the structure around the charcoal fire would be any better or easier than the bentonite clay/sand option. Or maybe the clay/sand is actually better, but this is just easier to set up for portable demonstrations. I'm not worried about cost so much as I am interested in making it the most likely that lump charcoal will work out. Thanks for all the great information on these forums. It's a fantastic resource. 

[ThomasPowers]

Well for a travelling Y1K-ish forge I tend to build a basic forge of hard firebrick on a raised table and then encase it in a fairly thin layer of damp adobe so it will dry out fast in use.  My knees as well as the mutinous bellows thralls won't allow me to use a ground forge anymore. For long term use you can just use the adobe---as brick or as the mix to shape the forge and skip any brick.

I would not suggest using soft firebrick, not needed, an extra expense and they fail fairly fast.   

If you think of the fuel density; solid fuels pack a heck of a lot more energy per cubic inch than gasses do and so you don't need to be as concerned with insulating the firepot. 

[pnut]

Hello, same pnut, yeah the MarkIII was made to be portable. That's the reason for the bentonite around the bricks. It keeps them in place and you can pour it back into a bucket when done. Soft firebrick isn't necessary. Clay bricks will be fine. I would put them in an oven on the lowest setting to drive off any excess moisture. Charcoal is best if using clay because coal slag likes to stick to them. You'll probably have to replace them eventually anyways. I've melted clay bricks and firebrick in my jabod.

Pnut

[Selph]

Okay. If the bricks aren't really going to do much, I had might as well skip them. Or just use clay bricks to corral the charcoal it sounds like. I'm planning to make something that will last a while, hopefully. I'll probably end up wheeling it outside when I do the actual forging, then wheel it back in once the fire is out and cool when I'm done for the day. I'm getting together what I need for it now, which isn't much. Just need to run and get the kitty litter mostly. Our soil here is very sandy in spots, so I'll dig that up for sand. Will probably use some Aspen I've got for the frame, and maybe build a box bellows too. I'll try to take some pictures once I get going on it to post here. Thanks!

[pnut]

Are you planning on a brick firepot or a clay trench? If using bricks you just surround the bricks with dry kitty litter. If you're making a trench firepot from clay you will need to mix 3parts sand to one part kitty litter and add just a little water. Maybe 10% by weight and leave the mixture in a sealed bucket or bag overnight. Then check it by squeezing a piece in your hand. If it forms a lump that you can break without it crumbling or leaving mud on your hands it's ready. If it crumbles add a little more water and seal back up overnight and check again. If it leaves mud on your hands add a little more litter and seal back up and check it again The next day.  Keep doing this until you can break a lump without it crumbling or leaving mud on your hands. 

Pnut

[Selph]

Originally I was thinking a brick firepot, but if that doesn't get me anything above and beyond the clay trench, I'll probably just do a clay trench. I don't have any bricks, but I thought that maybe getting 3-4 to help corral the charcoal around the trench may make sense. I'll definitely follow the advice here on mixing up the adobe as I've never done something like that before. If I hadn't seen it explained here, I would have absolutely gone way too wet. Now, I'll try to err on the side of dry.

[pnut]

You can always add more water or sand/Clay. It might take a few tries to get the right consistency. Too wet and it will crack as it dries.  Bentonite is weird because if left alone it will evenly distribute the moisture throughout. The only thing you really gain from a brick firepot in my opinion is you don't have to mix the litter with anything. 

Pnut

[Selph]

Hmmm, really good point. That would certainly make it easier.

[Charles R. Stevens]

No you most defiantly can not ask questions!! 

Just kidding, ask that’s how you learn and often as not we will learn something new in the process. 

As pointed out, this version of the just a box of dirt (JABOD) forge was build as a traveling demo forge. You will find the original, a couple of other versions and an illustrated explanation in the stickies. 

If weight is an issue I might suggest using perlite or vermiculite instead of sand for most of the build . 

All clay will case (equals distribute moisture) if lest in a covered container. If it’s to wet let it sit open utile it dries to the right consistency and then cover it over it’s to rehydrate the crusties   (Technical term)

[Frosty]

You forgot the scowly  emoji when you told the new guy he couldn't ask questions Charles!

Welcome aboard Selph, glad to have you. I see you thinking one beginner's mistake nobody's addressed so far. Sorry, a JABOD isn't a very long term forge, until you get the soil sand mix right you might end up "repairing" it pretty regularly. Almost everything exposed directly to the kind of fire we use WILL be a wear item, it'll: melt, burn up, get stuck all over with clinker, scraped to pieces, etc. That's one of the beauties of the JABOD, it's easy to make, easy to adjust and effective. 

The brick is IMNHO an easy way to shape the fire though a hard rammed sand clay mix can be scraped to shape without much work. Still, just having a couple few bricks with soil holding them in position is less work. 

If you want a solid fuel forge you can store without waiting for all the coals to go out it needs to be made of steel with a tight fitting lid and a way to plug the tuyere. Not so practical but doable. If you use brick you CAN scrape all the charcoal and burning coals out, separate them and store in sealed steel cans. I wouldn't though. I do separate and extinguish the burning coals sometimes in a bucket of water sometimes in an "ash can" from the fireplace/stove store but I don't bring either in a building. A coal can stay burning for days after the fire is "out" and all it takes is a little air and more fuel to take off. 

Don't sweat thinking you can build a long lasting forge, we've all done that and they just don't last all that long. Even a cast iron rivet forge has a usable lifespan if you use all the precautions. Same for the propane forge you might be thinking about building, sometimes they last a couple few years of regular use but usually not so long. A gas forge that'll last a lifetime?     !! I sincerely wish a much longer life to you. 

Frosty The Lucky.

[Selph]

Oh yeah, that's a really, really good point. I tend to try to make everything as well as I can generally, and that crept in here. I've gotten into blacksmithing via woodworking, which I've been doing for 7 or 8 years now. I try to make a lot of my own wooden tools, but they aren't really consumable or reformable(?) the way this style of forge is. I'm used to spending a long time to make a nice tool, whether a marking gauge or whatever, but that experience doesn't really translate to forge building. I was spending way too much mental effort over how to do a charcoal forge before pnut pointed me here. I'm trying to approach this first forge as a "learn what does and doesn't work" experience, but I keep edging toward trying to find the elusive best way to do things, when best doesn't really exist.

But yes, I need to work on remembering that these heats are always going to be destructive, and the strength of this style is that you can easily reform or replace whenever you need to. Also, good points about fire safety. We've got a wood stove and it isn't uncommon for me to go to build a fire a day after our last, and find some coals still hiding in there ready to get the next one started. With the bricks, I could at least move the coals into a metal bucket, slap on a lid of some sort, and then leave that outside. Then the forge itself could come into the garage once all combustibles have been removed and it's cooled down.

[pnut]

Pretty much just give it a go. If it doesn't last long you'll only be out some dirt. You can use whatever soil is in your area to hold the bricks in place in a MarkIII jabod. My regular trench style jabod miraculously lasted nearly a year before I needed to tear it apart because of cracking. The first one started cracking immediately. The legs sunk in the mud and it fell over after about four days of steady rain and destroyed itself. I kept them outside in the open. I just covered it with a piece of sheet metal with a couple bricks to keep it from blowing away. I learned my lesson and put a paver under each leg after the first one though.  They're easy to make and if you don't get the clay mix right the first time they will usually still work for a while. When I put the next one together it will be the third one and I learned something important from each one. 

Pnut

[ThomasPowers]

Now Now Frosty, I bet we could design a long term forge and it wouldn't even cost as much as a Maserati!   Lots and lots of custom machined inconel, hmm maybe not as much as a top of the line Maserati...

Of course the cost/benefit ratio would be so skewed that the term asymptotic might creep in...and probably be misread as asymptomatic by some. 

As for a forge in Ann Arbor; have you given some thought of building it in a gas grill cart and just close the lid and leave it outside? I've used a gas grill cart to carry my propane forge around, replaced the grill body with a  piece of sheet metal.  I upgraded the wheels to over the years and recently added some cross bracing.  It's served me over a decade now and who knows what the previous owner had out of it. I see them free on craigslist fairly regularly out here and out for heavy trash pickup all the time.

(I recently had to jack up my large RR forge that had started to descend towards the dirt shop floor; found some track plates at the scrapyard that are just dandy for spreading out the load.  I scrounge jacks at the scrapyard too as they often come in handy in the shop---like spreading the rim of a helm...)

Looks like I will be out tomorrow; coworkers are beginning to source pitchforks and torches and the term "Typhoid Mary" has come up a lot---wrongly as Mary was asymptomatic and I'm coughing up crud and blowing my brains out my nose. Hope to be back Monday.

[Selph]

I may have a bit of an odd situation in that for me, wood is essentially free. We just moved to a house with a fairly wooded lot for being just outside a city, and then my parents and sister both live on wooded lots down in NW Ohio. My dad had a friend who was selling a small portable sawmill a few years ago, and he bought it off of him. So when any of us have trees that die or need to come down for some reason, we throw the logs on the mill and mill them up.

Leaving this outside permanently isn't a bad idea. I could make it out of some white oak or cherry or something, and it would hold up well to weather. Funny thing is, we have almost no softwoods. Otherwise I'd use cedar or pine for this. But I've got quite a bit of cherry lumber cut already, it's really rot resistant, and I've got two large cherry trees that came down before we bought this place that I need to get on the mill too. I would just need some kind of waterproof cap on the top, but I could figure that out and reuse the same frame when my forge mark II comes along.

[ThomasPowers]

Tusk tenoned, steam bent white oak and cherry frame with a really big eyebolt for the junkyard dog to keep it from wandering off?

I would suggest making the first one as fast, easy and cheaply as possible and start designing it's replacement as you find out what works best for what you want to do. (For example I know a number of smithies where the traditional beautifully made masonry forge is used mainly as a table to set the gas forge on, building them was an extreme waste of resources in getting started!)

[pnut]

The box can be literally anything. I used a nightstand from the hotel I work at set on it's back for one of my jabods. Have you taken a look at the sideblast 55 forge. Just cut 8 inches off the top or bottom of a 55 gallon drum and use it for the box. You can use some of the sheet metal From cutting the other end off and opening it up for the cover. After the first jabod you'll see suitable containers everywhere. 

Pnut

Here's a link to the 55 sideblast forge. You can use dirt or bricks to make a firepot just like a jabod. The next one I make I have a piece of drum for the container. https://www.iforgeiron.com/index2.html/blueprints/100-series/bp0238-simple-side-blast-55-forge-r184/

[Randy Griffin]

What Thomas said. Don't spend a lot of time on your first one. Just build it and learn from the experience. You will redesign it several times before you're satisfied. I modified mine 4 times and I think I'm finally satisfied. I am going to build a trench style in order to heat treat longer blades. Thanks Pnut.  

[Charles R. Stevens]

Forges and fires are a lot like wood, they have their own personalities, we can go against the grain and it wil work but simply flip things around go with the grain and it goes so much smother. All very tau. So just throw it together, palywith it and learn the way of it and then go hog wild and build another one of the good wood.

 

 

[pnut]

I think I've managed to wrangle enough pieces of brick out of the hill to cobble together a firepot and bellows stone. So as soon as they're dry I'll put it all together and get at it. I don't have an oven i can use or I would just dry them in the oven on it's lowest setting. Too bad.

Pnut

[ThomasPowers]

BBQ Grill?

[pnut]

I thought about building a fire but I'm feeling too lazy after fighting my way down the hill/cliff and digging them out and getting back up the hill with them. I probably will build a fire and let it dry them out but it won't be today. Just don't have the energy. 

Pnut

[ThomasPowers]

Out here we can just stick them in a junked car with the windows closed and have a solar drying oven---just flush out the damp air a couple times a day.  (I've had cookies backed on a dashboard before!)

[pnut]

It's only about 56F today and the humidity is a little high. When I lived in the high desert outside of Palmdale California I used a solar oven and I cooked a lot with a fresnel lens I took out of a projection screen TV. In the summer here in the Midwest if you leave something damp in your car you will regret it. It might rain in your vehicle when the sun goes down. 

Pnut

[Irondragon Forge ClayWorks]

Put em in a box you can close up, with a 100wt incandescent light bulb, they will dry in short order.

[Charles R. Stevens]

When things get straitened out I need to get with TP about a piece of soap stone. It’s is more heat resistant than brick