A light weight and mobile side blast forge without water jacket?

[DennisCA]

Hi. First post here, I guess this might have already been asked or talked about before, but I've searched and read and not really seen any examples of what I am thinking of.

I was looking at making my own forge for use with coke and perhaps charcoal, since for me it wold be simpler to manufacture and weld a forge fire pit from thick steel than it is to tackle a gas forge build and I like the idea of the solid fuel forge as well.

Now a bottom blast forge looks real simple and easy to build to me so I was leaning towards building one of those. Then I read that side blast forges have many advantages too, such as having more control over the fire and also working better with charcoal. From what I read a bottom blast forge will tend to go through the charcoal really fast becaue the oxygen stream c omes from the bottom and goes through the whole pile more easilt, whereas a side blast can be tuned down more and the air blast isn't aimed directly at the center mass of the coal fire. I dunno how true all this is, just what I reading on these forums. But it sounds interesting and I got the impression the side blast is what was traditionally used with older charcoal forges in the past.

So I started looking at side blast designs but I am a bit deflated looking at those designs, they seem to use a lot of mass, sand or firebricks and whatnot. I am looking to make a portable forge that I can wheel outside for forging, it will also sit in an uninsulated building so the water jacket isn't really sounding that great either, it gets real cold here in Finland.

Is there a reason I couldn't make a side blast furnace much like you'd make a bottom blast one from solid steel and no water jacket or massive insulation? In my head I was thinking a portable forge, a bottom blast design but just a different style of fire pit. I am imagening welding it up from say 10-12mm thick steel and just making one wall straight instead of sloping, then putting the air inlet on that wall. I tried to mock up something in paint, I could make something in CAD but not sure it's worth the effort if this is a dead end. Which I am kinda thinking because nobody else seems to have made it like this.

This is sorta like a bottom blast design, even has an ash dump / clinker breaker on the bottom, but the air inlet is on the side and that wall is made straight. I am wondering if this design doesn't work because it will blast air on the sloped forward surface and eat through even 10-12mm steel plate? Perhaps it's not possible to make a mobile forge on wheels with a side blast design? Or do you guys have any suggestions, should I go with a bottom blast or try to get a side blast forge?

 

 

 

[Irondragon Forge ClayWorks]

First of all, we won't remember you are in Finland once leaving this post, hence the suggestion to edit your profile to show location. This thread Read This First located up in the blue banner explains how to get the best out of the forum.

Second is all you have read about bottom blast VS side blast is true. Bottom works best with coal/coke and side blast is better with charcoal. With your sketch it should work but you don't need a sloping wall on the off side but it won't hurt. I have seen many side blast forges with both wall's at a slant and both straight, they all work very well. There is a thread by Charles Stevens with a steel side blast he built, I'll see if I can find it for you. The JABOD threads you have seen are built with wood boxes, hence the heavy insulation to prevent the wood from burning, not a problem with heavy steel plate. I couldn't find it maybe Charles will chime in and post some pictures. To answer the question about building a side blast without a bosh water cooled tuyere, is yes you can but the tuyere pipe will burn out eventually and is easy to replace. I make mine longer than needed and just push the tuyere farther in when the tip burns off.

[Chris Williams]

Mr. Stevens posted pictures of his forge in other people's threads to help them with questions, but I cannot find those threads. As they were located in multiple threads, I hope Mr. Stevens won't mind if I consolidate (at least some of) them here. 

You may also consider calvary or pack forges.

https://www.iforgeiron.com/topic/28685-portable-blacksmith-forge-military-circa-ww-i/

http://www.blacksmithworld.com/en/antique/ww2-forge-cavalerie-1944

The second one is a side blast without a water jacket. 

[Irondragon Forge ClayWorks]

That's the forge I was thinking of but couldn't find the pictures. I have an WWI Army Pack forge Made by Champion, which we use as a traveling forge to meetings & hammer in's.

[Chris Williams]

I saved the pictures the last time I went looking for them because of how long it took me to find them again. I still cannot find the other pictures of the treadle hammer in the first picture. 

How thick is the sheet steel in your pack forge? It looks like it wouldn't be very rigid, but I doubt that is the case based on when and for what it was manufactured. 

I have been wanting to make one like the WWII Broad Arrow forge in the second link. 

Edited July 23, 2020 by Chris Williams
Added specificity.

[Irondragon Forge ClayWorks]

It's about 10 gauge and very rigid, doesn't flex at all in use or transport. When it's packed up it takes two people to pick it up. That WWII Broad Arrow Forge is really neat, would love to have one myself.

[DennisCA]

Thanks guys! Those pictures look very promising. Also looks like someone put in my location while I was  sleeping.  That forge by Mr Stevens looks a lot like what I had imagined, though I figured the inlet would be placed higher and the pit might be deeper so the clinker can sink below the air inlet.

I was burning the midnight oil and watching some interesting videos last night, Joshua Delisle here has a "demo model" with water jacket that looks like it could be made to be mobile with some large wheels also looks simple to build. I am also reading that an advantage of the water jacketed tueyre is the clinker won't stick to it. I am wondering now if it's worth making it a little heavier to have the water cooled tuyere like he shows. I only need it to be mobile enough that it can be wheeled out and back in without too much trouble. Don't need to travel with it.

 

[Chris Williams]

Thanks IDF&C! I figured that it had to be rigid, but I just couldn't see it. I certainly hadn't imagined it being a two person lift. 

You're welcome Dennis. Charcoal doesn't make much clinker, so you can remove any between fires. I haven't used straight coke (i.e., my coke starts on my forge as bituminous coal), so I cannot speak to quantity of clinker for coke. 

 

[JHCC]

Is a water-cooled tuyere worth it?

YES!!!!

An uninsulated side-blast will have clinker sticking to it all the time and will eventually burn out. You do sometimes see old side-blasts that don't have water tuyeres, but those almost always have cast iron tuyeres with a lot of mass to give something of the same effect. The portable/cavalry forges shown above were intended to be used with a few shovels full of dirt, making them essentially portable JABODs.

My suggestion would be to modify the design in your drawing to include a water tuyere and bosh, and then add a drain valve at the bottom of the bosh. That way, you can roll out your forge, fill the bosh with water, forge, drain the bosh, and move the forge back inside. 

My forge is in an unheated garage, so I will always drain the bosh if we're expecting a deep freeze. 

[ThomasPowers]

Always drain the bosh if expecting a deep freeze!   Words to live by!

[DennisCA]

I kind of prefer the idea of a separate tank over that of a bosh, that way the tank can be separate and moved on it's own, making the forge lighter and smaller. Also less of the forge walls has to be in contact with the water so the rust issue should be reduced.

[JHCC]

That certainly works, and it makes the forge easier to move when it's in pieces. 

You might want to check out the thread from my own side-blast build, if only to see what mistakes to avoid.

[Charles R. Stevens]

If you look at the civil war traveling forge you will see that the tuyere is acualy rather complex, a hollow metal box with the bellows providing air into the box and the tuyere keying it out. A 1/4” or more steel plate with a hole drilled in it and your tuyere welder to the back will last a very long time, and siting off the air leads to the slag cooling and  popping off. Water cooled would certainly be best long term but eliminating the bosh for a portable  demo forge will save you set up time. 

[DennisCA]

Well I got this far on a sketch to get a general idea of what I might want. It's 450x700mm in size, took the size from a PDF I saw referenced in one of the links. Need to work on the tuyere, not sure what design I will go with but I think making a water cooled one won't be that much trouble, begun work on a square tapered one. Angle iron and 3mm (1/8th) steel plate construction.

Joshua De Lisle had an interesting design he used in a BBQ based side blast forge which was welded from stainless steel, looked quite doable as well. I wonder if bentonite clay is better than sand though, from what I understand it sets up a bit more firmly when fired but can be wetted and remolded.

I might have problems sourcing fuel though, in my area of the country it seems difficult to get coke or coal. 

[JHCC]

3mm (1/8") is perfectly acceptable, but a bit on the heavy side. My own forge is 1/16" sheet (1.5mm) and works great.

Given that you'll be moving the forge a lot, I would suggest you seriously consider the steel deck option. A BOD of that size is going to be HEAVY, whereas the metal deck version will be a lot lighter and easier to move. If you want the flexibility of the dirt firebowl, you could make a 460mm x 460mm (approximately 18" x 18") box in the middle with a steel deck around it.

[DennisCA]

I was wondering about how heavy it would become loaded up. And if one could have used hollow core fire bricks to help reduce the weight.  But a steel deck model would be a lot lighter. I can certainly draw up plans for both. I think I could make a steel version with a water jacket even.

There is no hurry I don't have a building to keep anything smithing related in, yet. Today I cast part of the foundation for it, using a mixer and doing it myself, so can't do it all in one go.

[pnut]

19 minutes ago, JHCC said:

Given that you'll be moving the forge a lot, I would suggest you seriously consider the steel deck option. A BOD of that size is going to be HEAVY, whereas the metal deck version will be a lot lighter and easier to move.

I opted for dry Kitty litter fill but it requires a fire pot. 

Pnut

[ThomasPowers]

That sq tuyere looks way too large.  Remember that the tuyere size helps control the speed of the air entering and that factors into the size and distribution of the hot spot in the forge fire.

Charcoal has been used to forge for over 3000  years while coal has been used in Europe for close to 1000 years. HOWEVER using charcoal in a forge designed for coal or coke is rather like using diesel in an engine designed for gasoline---you generally are not happy about the results!

My suggestion is to find a metal cart of some sort and build your forge to make use of it. (Extra points if you can buy the cart used!)

[DennisCA]

I thought it was the air inlet size which determined that, the rest of the size was just down to the water jacket. Mind you in the picture, it's not complete. Just the outer casing, a rough draft.

[ThomasPowers]

So you drew the part that doesn't mean much and not the important part that does?  OK.  Remember ghosting in a drawing dates back at least to Agricola in De Re Metallica,  1556. 

[DennisCA]

I did say it wasn't complete earlier.

I draw the simple stuff first to get an idea of the whole. The tuyere is the most complex part and I am not even sure how exactly I want it to look yet. But ok.

[ThomasPowers]

Such drawings tend to constrain things in your mind. I find it better to put in the essentials and let them drive the design.  Another way is to put in what you have or can easily source and try to make that work.   But to each their own path to madness!

[DennisCA]

I find I work a lot better when I can experiment in 3D first, when I try and do complicated stuff from the hip, it usually ends up as trash.

I am seriously considering going the BBQ route to start with. Like this:

 

[Frazer]

My first two forge builds both used a Weber grill as the body, similar to the thumbnail on the video.  My first attempt was a bottom blast, but I had major issues with the tuyere clogging up (I used 3/4" black iron pipe, bad choice) and with the sides being too tall to put long pieces in the fire. For version two I found a larger grill and that time I used the lid rather than the lower part. I also added some ball valves to adjust the air flow.

It was a little ugly, but I used that thing for a long time before I upgraded to the bottom blast I'm using now (details on that build here https://www.iforgeiron.com/topic/27046-show-me-your-forge/page/21/), but I don't think you will want to use that design since you said you'll be using charcoal.

I'll just say the side blast BBQ option worked for me, but I liked the shallow lid better than the deeper grill section. Yours could certainly look much better than mine did.  

 

[DennisCA]

I'd ideally be using coke if I can find it. I was imagening using charcoal on occasion though. But it's pretty difficult to get hold of good fuel. 50 euros for a 50lbs bag of coke (1600 euros for  metric ton), or 40 euros for a sack of bituminous coal (big lumps so they gotta be broken up), seems to be one company left in the whole country which can supply coal. Or at least the only one who bothers putting it on the internet. If it's gonna be impossible to source coke I am not sure I will build a coal forge. I would be willing to try coal but I got neighbors and I think it could be an issue.

At any rate I did design a welded steel pot closer to my first idea just to get a "taste" of what it could look like. But I went and made the air inlet water jacketed and I designed it from using bits and pieces I got in my shop, like square tubing for the water jacket. Inlet diameter is 20mm or bit bigger than 3/4" and it sits two inches below the top. But I am still thinking a design with sand or clay is better since the pot can shaped and reshaped as needed even if it's heavier.

The inlet pipe (bottom) goes almost the whole way to the back wall so cold water is delivered to where it'll be warmest. Also tilted 2 degrees since it's not tapered.