My JABOD

[DennisCA]

43 minutes ago, JHCC said:

Kaowool is a great insulator, but it's fragile and can shed microscopic particles into the air; these are VERY bad for you to breathe. 

The local suppler here sells something called superwool, which is said to be much safer than kaowool, I was looking at that for my diesel forge build. Expensive, but I was told I can use a layer of superwool and ordinary rockwool behind that.

Edited April 15, 2021 by Mod34
Excessive quoting

[pnut]

My forge is lined with fiberboard with a coat of plistix. Seems to be working fine. I'd be skeptical of claims that a ceramic liner doesn't need encapsulated. 

 

Pnut

[DennisCA]

I do believe it's recommended to encapsulate it with rigidizer, that is also sold alongside the insulation.

We really don't have much choice here at any rate, it's the only store I know of that sells anything related for making forges, and it's in the next country over.

[JHCC]

So if you have to travel eastwards to get the materials you need in a hurry, you'll be Russian to Finnish?

[Joe Bill Moad]

Yes i agree on the overage fuel cost of the larger forge for sure. I really meant to say what i was thinking which was the larger iron i may need to work may not fit the smaller gas forge. Thomas Powers hit the rivet on the muscle! 2 gas forges would be my style based on large plow parts and such, small 1” - 2 1/2” stock for the smaller. I still have my small 2 burner horseshoe forge but i cant run long bar through it. No opening on the back. Shouldnt have bought it because of that, but oh well.

jbm

[Frosty]

The clamp together brick forge I posted is made from Morgan Ceramics K-26 insulating fire brick. They are rated for a max sustained working temp of 2,600f, are not borax based welding flux susceptible, take rapid thermal cycling like found in a propane forge without damage, insulate almost as well as ceramic wool refractory and best of all are less expensive than the old probably defunct soft fire brick. 

A "brick pile" differs in that you don't clamp them together and can change the size and shape to suit they day's needs. Sometimes while it's in use if you need to.

Frosty The Lucky.

[ThomasPowers]

One of my favorite "odd ball tongs" is my "hot firebrick tongs"  made from a very crude old set of nippers/pulloffs? and sized to hold and move hot firebricks around while the forge is active.

[Bantou]

It works! I got impatient and decided to give it a test run with charcoal briquettes and some rebar a had laying around. Yes I know, both are horrible materials to forge with (you can slap my hand later). It got a 1/2” piece of rebar up to forging heat even with the limitations of briquettes (the neighbors probably thought I was setting off a fountain). I’m still waiting on my anvil so I didn’t move any metal tonight. However, as a proof of concept I’m happy with it. 
 

edit to add: I probably could have gotten the rebar hotter with better air control but I’m not going to waste anymore time on briquettes. I’ll learn more after I get my coal tomorrow. 
 

[Irondragon Forge ClayWorks]

Looking good and you will be surprised when you get some lump charcoal or coal fired up. They are so much better than briquets as far as building the fire. Back in the day, I forged a lot of stuff out of rebar, even forged welded it, when some folks told me it couldn't be done. I took a lot of ribbing here for making a D-guard out of rebar for a short brush cutting sword.

[DennisCA]

11 hours ago, Frosty said:

The clamp together brick forge I posted is made from Morgan Ceramics K-26 insulating fire brick. They are rated for a max sustained working temp of 2,600f, are not borax based welding flux susceptible, take rapid thermal cycling like found in a propane forge without damage, insulate almost as well as ceramic wool refractory and best of all are less expensive than the old probably defunct soft fire brick. 

A "brick pile" differs in that you don't clamp them together and can change the size and shape to suit they day's needs. Sometimes while it's in use if you need to.

Frosty The Lucky.

Sounds like a good candiate for a floor replacement in a conventional forge too if it solves the problem with flux that well.

[Bantou]

On 4/15/2021 at 9:08 PM, Irondragon ForgeClay Works said:

Looking good and you will be surprised when you get some lump charcoal or coal fired up. They are so much better than briquets as far as building the fire. Back in the day, I forged a lot of stuff out of rebar, even forged welded it, when some folks told me it couldn't be done. I took a lot of ribbing here for making a D-guard out of rebar for a short brush cutting sword.

I fired it up with coal today. I learned quite a few things:

1. The hot spot of my fire is about to 2” below the top of the box. I had to put the end of my 1/2” stock pretty deep in the fire to get it hot enough to melt (I did this on purpose). The charcoal hotspot was about even with the top of the box. 
        I’m going to try adjusting the size and slope of the fire pot first to try and correct this. It is currently ~7” in circumference with a slope similar to a tank damn. I’m going to try for 6” and steeper walls.  If that doesn’t work, I’ll try adjusting the angle of the tuyere. It is currently angled slightly downward and I had smoke pouring out of it a couple of times. I’m hoping that if I angle it upward it will move the hotspot up. Worst case, I can alway drill another hole and move it up.

2. I need to shrink the size of the fire pot. It burned through close to 2 medium sized coffee cans of coal in ~45 minutes. 

3. The rule of wind and smoke applies to a forge as much as a campfire. I turned the forge around to get the bellows out of the smoke and the wind changed directions on me. 

4. Because of lesson three, I NEED to put a chimney on the thing. I nearly scorched my beard when the wind picked up and blew the flames at me. Plus, green coal smoke is... less than pleasant to breathe. 

5. I either need a different air supply to start the fire, or need to get in better shape. I was sucking nearly as much air as the bellows by the time I got it going good.

6. Damp coal will sometimes exploded in the fire pot. I had several pieces pop and come flying out of the forge while I was pumping the bellows. I had raked some of it on top of my fire hoping to raise the hotspot some. 

7. I need to mount my air pump differently. The one I received has the hose connection on the handle instead of the air camber for some stupid reason. I currently have it mounted to the top of one of the kicker boards (see picture). It puts the handle about 3” above the top of the table at the end of the upstroke. As it sits, it exposes me to the fire when the wind shifts and is aggravating the tendinitis in my right wrist. 
 

[Irondragon Forge ClayWorks]

If you can lower the pump and at an angle, that way you will be pushing & pulling in a more of a straight line. For the tuyere I wouldn't angle it up, just a slightly less down angle and try raising the floor of the fire pot to just below the tuyere outlet.

[pnut]

I stole Charles R Stanley's idea and used metal strapping and mounted the pump at a 45⁰ angle in the plane that my arm naturally moved but I got tired of using that pump in the heat and humidity of summer in pretty short order and bought an AC mattress pump and scavenged a jump starter/power station that had an AC outlet. I have two of those hand pumps waiting to be given away to  someone wanting to build a forge. Here's a link to the thread that has a picture of the way Charles mounted it. It also might make you rethink the firepot.

https://www.iforgeiron.com/topic/55467-mark-iii-jabod-forge/

 

Pnut

[Bantou]

That was the way I wanted to mount it but the hose connection on mine is at the handle instead of at the base. If I mount it the way Charles mounted his, I’ll be dragging the hose over the fire as I pump. The pump I ordered looked exactly like the one Charles used. Apparently Intex changed the design and Amazon never updated their pictures. 

Shrinking the size of the fire pot helped significantly. I got out and played around with it after my last update. It is now ~5 1/2” in circumference with a lot less slope. The sweet spot is now ~1/2” below the top of the table. I’m going to try adjusting the tuyere angle up a little and raise the bottom of the pot an inch or so. 

I may wind up switching the fire pot to something like on the MkIII but I don’t have any brick laying around right now. I can scrounge some where I hunt, but it’s a 3 hour drive one way. I was also under the impression that coal needs a deeper fire than charcoal. It’s been a while since I looked over that thread though so I could be wrong. 

Changing how I used the pump also made an improvement. It seems to prefer short quick strokes over long hard ones... I was able to get the fire hotter faster doing it this way, without wearing myself out.  I went with the manual pump solely for fuel economy. I’m terrible about remember to close the valve while working the metal on a constant air supply. 

[Frosty]

Oh OUCH! It'd be torture pumping your bellows for any length of time at that angle! Mount it at an angle so your hand is below the forge box top at the highest. Pumping the handle away and towards you isn't nearly so tiring nor will it cause soft tissue damage to your shoulder.  We're typing at the same time your last post just downloaded. Put the pump on the same side as the tuyere, if the hose drags on the ground install a flexible support system. That's pretentious snooty talk for hang it from a string.

I formed the duck's nest in my coal forge by tamping the clayey soil in around a soup bowl. The rest of the forge table is flat and if I need a deeper or special shape I use fire bricks and arrange them as desired. I REALLY like a duck's nest forge much better than a fire pot.

When you're pyrolizing green coal don't rake it over the fire, rake it closer around it. That way the heat increases as it gets closer to the heart/fireball. First the moisture is driven off, the steam carries the more volatile components with it: esters, benzines, alcohols, etc. When the smoky components begin to burn off the: oils, tars, sulfur, phosphates, etc. the smoke is drawn into the exposed flame in the crater from the sides and is burned so there is little or no smoke. 

If you rake the green coal over the top of the heart, the smoke has nowhere to go but up and away from the fire into your breathable. Yes?

I make my green coal dome crater shaped and pack the outside with wet fines. The fines block air/flame/smoke flow so the only place it can escape is through the crater where the active flame finishes combustion. As it pyrolizes coal gets sticky from the tars and will support itself if there isn't too large a cavity in the heart. There is always a cavity where combustion has burned the breeze to ash in the center and if allowed to get too large the dome will collapse

When the heart needs more fuel (breeze is forge coke) I rake green coal up the outside and tamp on more fines. The process of tamping the green coal presses more breeze into the heart. I maintain the shape of the crater as I add coal.  

I insert stock through the side like I'm stabbing the dome. You don't want to be destroying the dome inserting and removing your work if you can help it, it mixes green coal into the heart making smoke.  

Frosty The Lucky.

[pnut]

33 minutes ago, Bantou said:

to mount it but the hose connection on mine is at the handle instead of at the base. If I mount it the way Charles mounted his, I’ll be dragging the hose over the fire as I pump. The pump I ordered looked exactly like the one Charles used. Apparently Intex changed the design and Amazon never updated their pictures. 

 

Mine was the same as yours. I didn't have a problem but if you are you could mount it lower and make an extension for the handle. 

Pnut

[Bantou]

I’ll take another look at it. When I mocked it up the first time, the hose kept drifting over the fire pot.

4 hours ago, Frosty said:

I formed the duck's nest in my coal forge by tamping the clayey soil in around a soup bowl. The rest of the forge table is flat and if I need a deeper or special shape I use fire bricks and arrange them as desired. I REALLY like a duck's nest forge much better than a fire pot.

I’ll have to look into the ducks nest. That isn’t a concept I’ve run across yet. 

The way you are describing banking the coal is more or less the way I was taught to do it. The first set of “pop rocks” came from starting the fire with green coal (I didn’t have any coke yet). The second set came from attempting to insulate the fire with coal on top. I read about guys doing it on here but I don’t think I had a good grasp on the concept.  

[Frosty]

I didn't tell you THE way to manage a coal fire, that's just how I do it. To "insulate" your work build the dome taller. The crater, flame cup, whatever, stays on top and burns the smoke so it doesn't annoy people. 

I have my own way of lighting a coal fire too. I cut a strip of corrugated cardboard about 2" (eyeballed) about 18-24" long. I roll it into a tight coil, position it over the air grate and surround it with "large" I like 3/4" max, coal. Once there's enough coal to hold it I let the coil spring open a little bit, just enough to let wooden match to slip into the gaps is good, so is a little wider. Then I build my dome around the coil with the crater extending just to the center of the coil. Then I pack the outside with wetted fines. 

I open the ash dump so there's a natural draw to start, strike a match and drop it into the coil getting it as deep as possible. A touch of blower might be necessary. Once the cardboard coil starts burning I give it GENTLE BLAST and cover it with 3/4" pieces but never so much as the flame goes out.

That's it, green coal is usually ready to work in maybe 10 minutes, if there's breeze available much less.

Cardboard burns hotter than paper, not as hot as dry wood but close enough. Being in a coil the blast can pass up through it making a torch flame that is directed through the coal. Having the coal directly against the coil means flame is blown through it too but is contained by the wetted fines so things get going nicely and pretty quickly without huge clouds of yellow green smoke.

Frosty The Lucky.

[Bantou]

Pnut, after a little tinkering, I was able to mount the air pump on the side. You were right, it is much easier and more comfortable to use that way. The only downside is that my handle has to point to the back of the forge making it difficult to tell what my metal is doing in the fire.

Frosty, I’ll have to give that a try. I’m still experimenting with fire management and whether to build a mound or a trench. The guy that taught my class had us mound the coal on both sides of the fire pot, more or less forming a trench, and then just scrape in the coked coal as we needed it. Glenn recommends building a mound in the sticky he made on the subject, though there was some heated debate about it from other members. 

[Bantou]

Well, I’m going to have to do something different with the fire pot. The dirt melted instead of hardening like I thought it would. Going to talk to a guy tomorrow that built a brick house last year. Hopefully he will still have some of the extras. 

[pnut]

I skimmed through the thread trying to find out if there was a specific reason you used topsoil vs sand but it's gotten pretty long. Is there a reason? Clay will usually vitrify at heat like firing it in a kiln but high organic content topsoil doesn't. You could always go with a bentonite (cheap kitty litter) clay as a fill material but it's tricky to work with if you wet it. Not really tricky but more of a hassle. I've been using plain old red clay bricks surrounded by dry kitty litter for a while now but I use charcoal most of the time. Coal slag might want to stick. That's another benefit of the addition of sand or wood ash to loose clay. It helps with that problem as well as shrink checking. Keep in mind that you will eventually melt the bricks too. I don't usually have a problem if the forge isn't lit for all day sessions. 

Pnut

[ThomasPowers]

Back in Ohio I had a clay bed in a stream I used to use, a couple of times a year I'd fill 2 5 gallon buckets and portage them to the truck.

Here I use the local adobe mix; I filled a 55 gallon barrel with the clay plates from the arroyo when it dried out to get some clay rich material too.

[Bantou]

7 hours ago, pnut said:

I skimmed through the thread trying to find out if there was a specific reason you used topsoil vs sand but it's gotten pretty long. Is there a reason? Clay will usually vitrify at heat like firing it in a kiln but high organic content topsoil doesn't.

Pnut

I used my top soil because it is supposed to be very high in clay content. It’s called Black Gumbo or Gumbo soil depending on where you are. When wet, it is so sticky that it will gum up motocross bikes. When dry, you need a rock bar to dig in it. If you catch it at the perfect consistency, you can work it like modeling clay. 
 

Plus, it was under my feet and free. 

[JHCC]

Sounds like a good option. 

[pnut]

Was it dry and hard when you fired your forge up? Different areas have different clays. The clay local to me vitrifies hard as glass when you fire it. It took a wrecking bar and sledgehammer to break apart my first jabod. I broke the box from around it and it was still in usable condition. It was like a big block. I reused all but the vitrified firepot section to build the next two. Anyways, did you try digging past the high organic content topsoil to get to a higher clay content layer? I'm just guessing because I have no idea of the topography and soil content where you are. It definitely shouldn't have easily melted using a manual mattress pump though. I'd look for a stream bed and try different clay or as already mentioned use brick and see if you have better results. 

Pnut