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New side blast with water tuyere & bosh (pic heavy)


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The tuyere proper is made of 1/2” plate, making a tapered box:


The cap on the end is pierced by the air pipe, which is welded on both sides to prevent leaks. I spent a lot of time filling this with water, chasing down the leaks, grinding them out, and rewelding. I knew that I couldn't use any sealant on this part of the assembly, so all the joints had to be tight. Laborious, but worth it.


Here’s the rear view of the tuyere, welded onto the bottom of the bosh. Note the air pipe passing down the center of the tuyere.


Bosh all welded up. (This was a real learning experience. One thing I learned is that I’m not very good at welding 16 ga.) I welded on a short section of pipe to act as a drain, shown here with a cap to protect the threads.


The forge pan welded up:


And the frame, which is made of bed rails and random scrap. Lots of bracing, no wiggle-wiggle.


Bosh and pan in place. Note the integral tong rack:


Another view:


Rear view:


Air intake from the old JABOD. The cap on the bosh drain has been replaced with a salvaged pressure release valve from a water heater. This was also where I started to go a bit crazy with the silicone caulk, as the welds of the bosh had a bunch of leaks that I didn't want to bother chasing down. The silicone is rated to 400°F, and I knew that the bosh would never get above 212°F unless it boiled completely dry.


A variac (variable transformer) to control the speed of the blower):


Rear view with blower (stripped-down vacuum cleaner) and its connection (radiator hose):


Added a shroud over the variac to keep off scale and dust:


Put in place and filled with sand:




All in all, I’m very happy.

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No, I am going with the remake-the-fire-bowl-with-moistened-ash-and-cinders-every-day method (English-style),  at least for now. I am using the old sand and clay fill from my JABOD (broken up: it’s not a solid adobe mass anymore), and I understand that it will get even easier as the ash builds up from several fires.  So far at least, I like the flexibility and the fact that the clinker comes free so easily from the loose fill. 

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Boy that came out nice.. 

Is there anything you would do different "Now" after having made it?  Or is it to soon to say? 


I have for all my smithing journey always  had to make some concessions to my forge designs..   Especially with the transport of the trailer.. The forge in the trailer was the largest I could get away with and still keep the functions I wanted..  

Ideally I like a larger hearth so will be interesting once the shop goes up..    great job.. 

Love the shop also..    Very nice.. 

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Little too soon to say, but I'd probably go with a slightly larger hearth (currently 26" x 24") and a more horizontal bosh (as you noted elsewhere). The leakiness of the bosh is mostly a function of my inexperience at welding sheet, so that would hopefully be a bit better the next time. That's a long way off, though, unless I find myself in a different space than my current corner of the garage. In that case, however, I'd probably be thinking first about a hood and chimney stack.

One modification I'm considering for this one is be to cut the rim and fold it up, leaving the middle third as-is. That would help with sand and coal dribbling on the floor, while keeping the center sections at the right height. I'm also planning on adding an adjustable stock support to the front and maybe some firebrick as a shelf across the back of the hearth.

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You could just tack on some 1/8 or 1/4 by 2" to get a side above the hearth.. 

The forge in the trailer only had a 1" lip and the coal and coke used to end up all over the floor.. this time around I made part of the lip around the edge taller and also added a coal reserve against the far corner .. I also made removable lips at the drop in the forge bed for longer pieces can slide all the way through..  

I think your flat bed design would be great if doing long or larger pieces as the fire is right there.. 


I think i have 22 or 24 X 30" for the main part.. the hood takes up 14 or 16" of length overall but it was designed to hold the hood up.. 

For the stock support use 1/2" or larger and use the old fashioned ones with the kick lever on the floor.. 

I mounted the vise to the forge so can use this to support longer stock.. 

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Found some thin flat stock in the drop bin at the steel supplier and decided to go with that. Here it is with two short bits bent off the long side.  I’ll trim it up and weld it on some time in the next couple of days, along with two shorter pieces to go front and back on the left. 


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That’s a beautiful outcome!  I’m envious as usual.  It looks like you learned much from my many mistakes.  At least, I’m hoping that is the case so my forge build wasn’t all for naught.  The biggest issue I had with using the sand/ash base was having my coal buried and intermingled in it.  Every once in a while the cleanup was a pain.  It was rewarding to have the forge back to fresh...but my wife wasn’t pleased that I absconded with the metal colander.   Fortunately, I do a lot of the cooking so she gave in.

  I’ll be trying an overhaul to my forge this summer, I hope, but not until I get the propane forge built.  Please update with usage insights.  How much and where does your clinker build up?  Are the sides high enough or do you lose a lot of coal to the floor?  You know...stuff like that....

Thanks for the inspiration,


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I've got an idea for what to do about the mixing of fill and coal; I'll try it out and post a picture if it works.

I've only fired it up once so far, so the following may not be representative. I found that the clinker tended to build up mostly under the nozzle, but also with some significant lumps above it as well, much the same as the old JABOD. However (and I can't overemphasize how significant this is), it was SUPER EASY to remove the clinker: just build the fire up a bit to melt everything together, kill the blast and allow the clinker to harden up a bit, and fish it out with a poker. Easy peasy. With the JABOD, I had a lot of trouble with the clinker sticking to the adobe (despite the many different sand/clay proportions I tried), and it could take a lot of leverage to get it out (with the attendant risk of something breaking loose and scattering burning coal everywhere). It would almost always bring away pieces of the firebowl. Sometimes I even had to hack the stuff out with a hammer and chisel.

In short, because it's so easy to remove the clinker and the heat of the fire is not going to heat up the clinker or the adobe around the tuyere, it's much easier to keep a good fire going and to have its heat go into the metal where it belongs.

I haven't lost much coal over the edge, but that's just from being careful. It'll be easier once the rim is on. I've decided to add a little gate over the gap in the back rail, which I'll only open up when I need the pass-through for a long piece.

One of the biggest differences between your forge and mine is the depth of the hearth. Mine is significantly deeper, so the fireball sits in front of and slightly above the tuyere, whereas yours (if I remember correctly) is primarily in front. I think if you increased the height of the sides of your forge by about four inches and added a lot more fill, it might work better. I'll try and show you what I mean the next time we get together. (Which might be next week; you around on Tuesday or Wednesday evening?)

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  • 3 weeks later...

Nice forge! I don't know a lot about forge building, but as stated above I was curious about how big of an issue you had with your coal mixing in and getting buried in the sand. Aside from that, I can only see benefits like you said with Clinker. The sand being so loose you could practically pick it free with a poker or some tongs. Now question time; Do you think this would be a good forge to start out with? I've been looking around for forge ideas, and seeing as how sand would be fairly easy to come by, as would scrap steel. I've got a MIG welder, so I could probably fabricate something (that isn't beautiful, but functional) similar to this. Rather than using a variac, do you think I could get away with some conventional blower like a bed inflator, hair dryer, etc? Also; roughly how hot does your forge get?

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1 hour ago, Joshua Taylor said:

I was curious about how big of an issue you had with your coal mixing in and getting buried in the sand.

It's a bit of an issue, but not much. There's a bit of coal mixed into the sand, but not enough to bother about.

1 hour ago, Joshua Taylor said:

Do you think this would be a good forge to start out with?

For beginners, I ALWAYS recommend the JABOD forges, as described HERE, HERE, and HERE. Playing around with the JABOD taught me a lot of lessons that were very useful when the time came to build this beastie.

Since you have a MIG welder, I would suggest making a JABOD with a metal box, but holding off for now on building the bosh & tuyere. On the other hand, if your welding skills are already good, go for it! (You might want to consult Mark Aspery's article on Building the Side Blast Forge first. IFI member EverythingMac also has a good video about setting up his side blast.)

1 hour ago, Joshua Taylor said:

Rather than using a variac, do you think I could get away with some conventional blower like a bed inflator, hair dryer, etc?

The variac simply controls the speed of the blower; it doesn't produce the air blast itself. Before I got it, I used to regulate the blast on my old JABOD with a homemade gate valve, which you can see HERE. A hair dryer will work just fine, as will a bed inflator; Charles R. Stevens favors the double-acting hand pump, as shown in his Mark II JABOD post (linked above). I'm mostly using anthracite which needs a constant airflow, so I don't use a hand-powered blower. Still, you have lots of options. (The variac is great though. I love that thing.)

2 hours ago, Joshua Taylor said:

Also; roughly how hot does your forge get?

Really, really hot. If I'm not careful, too hot. 

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I think the coal mixing with sand is less important than it seems.  A bit of raking at the end of a session tends to pull the coal out of the sand.  Clinkers are a breeze to remove, especially if you've dug a little well in the sand below and in front of the tuyere.  Almost all of the clinker forms below the fire where it stays out of the way.  

One big difference if you're used to a bottom blast is that you can't pry against the pot to break things up. My first few fires I was a bit too forceful pushing stuff around and I ended up dousing my fire in sand.

Another difference is that the water cooled tuyere is a heat sink.  If the whole thing is buried in coal, the heart of the fire will be a few inches away from the tuyere.  Stock will rapidly cool if you get it too close to the tuyere.

 If you're looking for a cheap metal box to build with, consider contacting a commercial electrical contractor.  A lot of jobs end up with spare or salvaged panel tubs.  Some are pretty close to the necessary dimensions for a side blast forge.


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38 minutes ago, Charles R. Stevens said:

How fast dose the water boil off, John?

Never actually boils (at least, not yet). I'm thinking about sticking in a thermometer to see if the temperature would be right for a sous vide. I'll add a gallon or two of water before a forging session, but that's mostly to replace what drips out from the leaky drain valve.

13 minutes ago, rockstar.esq said:

If you're looking for a cheap metal box to build with, consider contacting a commercial electrical contractor.  A lot of jobs end up with spare or salvaged panel tubs. 

On my original JABOD, the box and the metal lining of the fireback were salvaged from a wall oven that I replaced.


17 minutes ago, rockstar.esq said:

I was a bit too forceful pushing stuff around and I ended up dousing my fire in sand.

Hook and pull, rather than push and pry!

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A small (short) metal bowl added to just in front of the tuyere can take a lot of this problem away...  As rockstar mentioned there is a sweet spot in front of the tuyere and once found the bowl can just be set before the level of the base of the fire and this bowl will collect a lot of the ickie and allow for one to get in the bottom of the fire without tearing the side walls apart..   

I will be building a Side blast when the shop goes up as you guys have inspired me.. :) 

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JHCC, no doubt about it you are correct!  I didn't realize it was a force of habit, now even though I know, I sometimes have to stop myself.  The hook and pull works a treat so long as I let the clinker cool a little beforehand.  After about five hours with the coal I use, the clinker forms a U shape around the tuyere.  

JLP,  I believe some side blast forges used a cast iron part called a "ducks nest" that served that purpose.  Clinker doesn't stick to cast iron so maybe one of those wee little cast iron skillets would be a decent option.



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  • 1 month later...

Since my last posting on this thread, I have added a super-sucker side-blast hood and a 10" flue, which works great. That process is detailed HERE.

I also just made a small change to the air intake. The blast goes from the blower to the back of the tuyere by way of a salvaged radiator hose, which is now zip-tied to the blower outlet. However, the fit between the hose and the tuyere was pretty tight, and it's been tricky to get the right amount of airflow, even with the variac. Today, I jammed a sliver of wood into that connection, which allows some excess air to escape. Seems to work pretty well.


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Realized that I’ve never shown an important detail. This is the gap at the back as a pass-through for long stock. Most of the time, it’s covered with a piece of flat stock (held on with some clips I bent up from heavy wire) to keep coal from dribbling out. 


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