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I Forge Iron

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Hey guys... after a lot of reading, mostly here, I decided to build a JABOD charcoal forge. Here is my start.

In order to maximize my goals for reuse and thrift, I used all materials I already had. The wood is pressure treated 2x12 that is around 25 years old. It was a sand box I made for my kids when they were little. The stand is made of old deck boards. The bottom was hard packed topsoil from the back yard (mostly clay with probably 30% sand).  For about an inch and a half coating over the base layer and pavers, I made an adobe. I used clay from the back yard mixed with sand from a paver project and wood ash from my smoker. The pavers and black pipe were also things I already had, so the grand total was $0 so far.

I decided to not clean up the wood other than sweeping it off and ripping 1/4" off of each edge. I like that the forge looks like it is ancient. Someday I'll have a nice metal shop, but for now the rustic feel is cool. Besides... not spending any money makes it no issue with the boss. :D

Right now I have a tarp draped over the forge to slow the drying and because we are supposed to have rain later in the week. 

Thanks to Charles and everyone else for all of the research and pointers! I welcome any feedback/input.

You guys said you like pictures.. so here it goes...

 

The rough 2x12s from the sand box


Squaring up the corners and fastened with 3 screws per corner

 

Simple base made from old 2x6 decking

 

3" of soil hard tamped in box

 

Cutting hole in pavers for blower tube

 

Pavers set in place to give channel structure

 

View of box from front prior to adobe

 

Getting ready to mix adobe

 

Adobe.. getting ready to throw!

 

Second layer of adobe all thrown and smoothed

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Everything looks good except you'll want to pull the pipe back flush with the side of the trench or it's going to burn off in pretty short order. Other than that it looks like it's missing the most important thing.    A fire.;)

Pnut 

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Thanks! Yeah, it's sticking out right now mainly because I used it to kind of core the hole out after applying the adobe and also because I don't have anything supporting the pipe yet. :)

I hope to get a fire going later in the week or next weekend! So excited!

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A jabod will make it obvious if there's anything you need to do to it after you fire it up. Mine lasted about a year with only very minor cracking. I used worm castings to patch any cracks when they formed. Where I live there's usually pretty high humidity during the spring through the fall. It wasn't until we got a real dry spell and a hard freeze that it started to show any cracks that made a difference. 

Pnut

 

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On February 16, 2020 at 11:20 PM, Charles R. Stevens said:

Go ahead and cut the far side now...

Yeah, you guys are right. I had planned on cutting both sides out, but I was being lazy and figured I would do it when the project required. I also know how annoying that will be at the time so I'll cut it out this evening! 

 

On February 16, 2020 at 10:13 PM, pnut said:

... Mine lasted about a year with only very minor cracking. ...

I hope it provides me with a nice life like that. If nothing else, it will be easy to reline since I have all of the materials on hand.

 

Thanks for the support and comments guys!

 

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When I needed to make minor repairs I just grabbed a little mound of worm castings because they were right there and the right moisture/consistency and size.  When I seen your mixture I did wonder if it was too moist. That will cause some cracking or "checking" as it dries. You'll just have to wait and see though and if it does you'll know next time. 

Pnut

 

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Nice job Clint! You can just burn a through hole while you work, saws are just soooo not blacksmitherly.  :rolleyes: Just joking, a pass through is a good thing.

The only thing I see is your adobe was way too wet, if you can hand form it it's too wet. It only needs to pack in and stay put. Being plastic, (hand formable) means there is enough water between soil particles the mix can flow with a little help. What happens when it dries is the soils shrink and check (crack like a dry mud puddle) to fill the space left by the missing water. Plastic soils also tend to be more impermeable to water. This means steam can't escape easily when it reaches temps higher than 212 f. and can cause more checking (cracking) or even spalling.

Don't tear it out and reline it! Just be aware of what's happening and why, there's plenty of time to try different mixes and water content later. Liners are wear items no matter what you use. Next time be stingy with the water, start with a couple few % IF the soil is dry. Mix thoroughly and let it sit over night in a sealed container. Clay soils will become moisture static, every particle will end up with the same amount of moisture, that's just one of the weirdnesses of clays. You really only need enough clay to bind the sand and ash but you don't want it to fall apart when it dries, I like 1 pt clay to 3 pts sand but that's just me and the clay I have available. Anyway, the next morning squeeze a handful of your mix hard. If it makes a hard clod and breaks cleanly its ready to ram into your JABOD. If it leaves your hand dirty or damp it's too wet, add some sand, mix and allow over night to temper and test in the morning. If it crumbles when you break it add a LITTLE water, seriously, a quick sprinkle with a watering can. Mix, allow to temper and test in the morning.

I know it sounds like a real PITA but it's actually easier than mixing it like pottery clay and your liner will be tougher and last longer. Putting the tempered mix in the forge is a matter of ramming it in in lifts of about 2" at a time. A mallet is good, hammers are okay but can be a little aggressive, I like using the end of a baseball bat. I pick up wooden baseball bats at yard, garage, etc. sales if they're cheap enough. They're handy to have around, they make excellent mallets and thwockers for straightening forged work without damaging texture or forging it farther.

If you ram your liner till the mallet, bat, 2" x 4", etc end, on bounces it's good, you can scrape, etc. to make fine adjustments but it's ready to light a fire and go to work. As it heats steam will escape without spalling and popping hot bits around. 

Frosty The Lucky.

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Thanks Frosty. Sounds like the 3" base layer was closer to the consistency I should have had for the adobe. Some of what you said also applies to our soil here in general. ALL houses have foundation issues because of the amount of movement we deal with. In the summer, if I don't water, I can end up with cracks in the yard 1.5" wide. 

Lots of learning here. At least it is easy to repair/replace vs a much more permanent design and cast refractory. 

I definitely appreciate everyone's knowledge and willingness to share. Some time in the future I'll be able to give back. :)

 

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You're welcome Clint, my pleasure. I'm just passing things along, I picked it up from other folks, knowledge isn't mine to keep. ;) Asking good questions is giving it back, there are guys out there who don't know and for whatever the reason haven't asked. Maybe they're shy or are afraid of the wrath of the curmudgeons. I've described how I prefer to clay a forge many times and I'm sure the casters are saying, "He's just describing how to temper casting sand." S'true I learned how to temper casting sand in jr. high school and the same method works as well as anything for claying forges or developing road beds. My time in the materials lab taught me the particulars of how and why though it's been so long I don't remember the details but a working handle is all I need. I can look up details if necessary. 

Oh don't get me started on soils and foundations! I worked for Ak DOT for 30 years, the first 20 with bridges and foundations section of geology Materials HQ. We lived soils and all the variables involved. You should try adding freeze thaw to clayey soils, talk about move. If you want a building to stay put drive piles till they stop. 

Frosty The Lucky.

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I left a tarp covering the overly wet adobe coating for a day, since then I have added a decent layer of sand on top and just covered with a couple of small sections of plywood. This allows moisture to vent out without rain soaking things. I've also been tamping the surface gently each day to help minimize the cracking as it started occurring. I'm sure I will have some cracks to fill (maybe with worm castings as recommended, but I don't have that many.. might mix another drier batch of adobe). I'll post more pics once things have actually cured and I can get a fire going.

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I only used worm castings because I literally looked over and seen about eight or ten little mounds of them around some holes. It was out of convenience. I would recommend using a mixture that matches your adobe. The worm castings were From the same clay I used so I thought, why not. Luckily it worked. Keep us posted on how it's going. 

Pnut

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Thanks Bill, it warms my heart to see your byline, how are you and the misses? 

I need to redo my rail iron anvil stand and make it to a meeting (need to pay my dues again as well, Miss your better half being on the board! 

Don't over think it, Clint just do it. It’s just a hole in the ground raised to waist high.

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Charles, I’m still griping about stuff, but, at least I’m still around to gripe! My wife is as mean as ever! This week she has moms house rented to a bunch of ladies for a quilting retreat. She’s cooking for them so she’s busy! She enjoys it though! Hope y’all are doing ok!

Bill D. 

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  • 2 weeks later...

Sorry for the delay in updates. Work has been kicking my butt the past week. 

As a status update on the forge itself, no real cracks have appeared anywhere other than where the adobe meets the wooden box. Maybe me forcing it to dry slowly under the tarp and tamping it helped. *shrug*

I did cut an opening out on the other side for long work pieces. 

I did a test firing last weekend and used a hair dryer for my blower. I snuck my wife's out there. :D  Anyway, even on low, it was WAY too strong as predicted. Between the fire fleas and burning the chunk of steel I put in there, it was clear I needed a baffle or other way to control the air flow. I toyed with the idea of using a 40mm computer fan, but my tests showed that while it has decent flow, the static pressure just isn't there. So, back to a hair dryer.

My next thought was using a cheap hair dyer and the right angle EMT junction I have seen others use. However, I really wanted to figure out a way to not need an extension cord. While I was reading up on disabling the heating coil, I discovered that most all hair dryers use a universal DC motor. The heating element is fed 120VAC and uses three diodes to rectify the current down to DC. That was a lightbulb moment for me. I have a slew of Dewalt 20v batteries and tools. So, I figured out how I can power the hair dyer, sans heater element, with my Dewalt batteries. Even the smallest should power the blower for ~4-5 hours on a charge. I found a DC motor control board for about $7 on amazon and a small hair dryer at Goodwill for $3. So.. I now have an infinitely controllable blower (from off to literally blow the coals out of the forge) for around $10. AND... no need for power/extension cord!

I removed the wiring harness, switches and heater from the dryer and put the motor, impeller and shroud back in the dryer housing after soldering some new power wires to the motor. It is MUCH lighter now and now I don't see a need to support the pipe anymore.

I used a battery cover that shipped with some of my batteries to act as a connector. I inserted a couple of spade connectors into the battery then put the cover on. I gently tapped the cover which made indentations where the barrels of the spade connectors made contact. I used these marks to drill holes through the cover. After crimping the connectors onto some wire, I filled the cavities with hot glue to hold the spades in place. 

I may make a housing for the whole thing, but we will have to see. 

I got everything hooked up this morning and forged out my first tool at home. I made a little coal rake out of a chunk of rebar I had. I'm so happy with how the blower turned out, how well the forge is working now and that I made my first tool in my back yard!

Oh yeah.. I also threw in a picture of my anvil stand made from 6x6 and 3/8" allthread. It is mounted with two 3/16" steel straps and a lot of silicone... it is dead quiet.

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1 hour ago, ClintMakes said:

did a test firing last weekend and used a hair dryer for my blower. I snuck my wife's out there. :D  Anyway, even on low, it was WAY too strong as predicted.

If your new solution turns out not to work just Don't connect the hair dryer to the pipe. Just aim it at the opening of the pipe. More directly for more air less so for less blast. You'll have to have something to set the dryer on though. I used an electric mattress pump and a ball valve until I got a real blower. I'd just turn the ball valve to adjust the air. It really was the easiest solution. I used a five inch piece of rubber drain hose from a washing machine to connect the hose from the pump to the ball valve.

Pnut

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2 minutes ago, pnut said:

If your new solution turns out not to work just Don't connect the hair dryer to the pipe. ...

Thanks pnut. I considered a lot of these options and honestly, the motor control and built-in potentiometer is performing flawlessly and meets my criteria! The level of control, range and how intuitive it is to adjust is pretty amazing. 

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