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I Forge Iron

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I went and bought a couple of 55 gallon drums last night so I could start building a simple forge using dirt, bricks, cat litter or whatever. This way I hope t get started cheaper and faster and I wont have to wait for my new shed to be completed, which won't happen until next year at best.

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Side blast design is what I am going with, I am going to start with coke but want to keep my options open for charcoal. But other than that I am quite open ended about the design. I am leaning towards cutting the drum so it will have an integrated hood and chimney. I think it might be worth going with a hood & chimney to get some shade and hopefully annoy the neighbors a bit less with coal smoke. And I can keep it outside 24/7/365 if it has a built in roof.

I am contemplating using two drums stacked on top of each other, and use the lower for coal storage as well as a stand. It probably needs to be cut down ot get the right height. I got the idea of stacking from another thread (link below), but he was building a bottom blast and going about it quite differentely than I will.

I will keep the bottom of the top drum intact to fill with bricks/sand/clay and the bottom drum I will cut to the right height I think by cutting the top and adding a side hatch that I can open to both deposit and withdraw coal. As for material for filling the forge I am looking at firebricks that are rated for 1730C (3150F) I can buy for 1.8 euros a piece. I could also buy second hand red bricks for 20 cents a piece but I am not sure how well they will withstand the heat. My SO wants me to buy a batch of the red ones at any rate for raised garden beds. There is also bentonite cat litter but I am readig mixed things about it, at least if you use it "pure", mixed with sand and other stuff like straw, it might be good I understand?

I need to research chimney and hood setup some more yet but I understand 10" is what I should aim for.

I am aware of the dangers of cutting drums like this, steps will be taken before any cutting.

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The link you posted has a couple of design issues. First the opening is way too large. The single drum being used as a forge AND a chimney works by can be improved greatly.

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We are fortunate to have good bituminous coal available.  When stored in a steel 55 gallon drum, it has caused the drum to rust and fail.  A better solution would be to store the fuel in plastic containers such as 5 gallon buckets.  They do not rust and the fuel supply can be moved when needed.  One bucket of coal is about 35 pounds and can be placed beside the forge for use.

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If you are concerned about the bricks, place then in the forge pan as you like and use a layer of ash or clay rich dirt to insulate them from the heat of the fire.

I found that the  55 gallon drum and hood combination did not work as well as expected.  This is from the original blueprint of the 55 forge with a supercharger attached.

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The two bottom drums are only for supporting the top drums.  The final opening was 4 inches below the 2nd ring, 2 inches above the bottom,  16 inches wide, with an arch on the top of the opening.  This can easily be configured to bottom blast, shown, or side blast.

All fire and metal being heated was done INSIDE the drum. This worked well for most projects. A small hole can be cut in the back of the drum for pass through projects.  The chimney was another 55 gallon drum placed on top of the first one making a 24 inch diameter hood and a 24 inch diameter chimney. Yes it was a big chimney and was therefore called the 55 Forge with a Supercharger. It would suck the fleas off the dogs back as he walked past. (well almost anyway).

The 55 Forge was designed as a place to start and then a test platform for improvements.  There have been many modifications, some working better than others.  Keep the ones that work.  And yes, testing on the 55 Forge continues.

 

With a side blast 55 Forge, place a standard brick on edge and use a 3/4 or 1 inch pipe in from the side to rest on top of the house brick.  This 3-4 inch height will allow ash to build up and insulate the bottom of the pan as well as create a depression for the fire ball.

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Yes I thought the opening looked too big on the first link, the 2nd link has a design with a smaller opening and a small chimney, the chimney looks a bit small on that one, but otherwise it seems a lot like what I had imagined.

That's a big chimney, don't think I will go quite that big, the chimney in the 2nd link looks a bit too small to do much good on the other hand.

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The 2 drum (55 gallon drums) configuration works and works well.  

The suggestion for chimney diameter is 10 to 12 inches in diameter when used to get the smoke out of an inside location.  You can purchase standard chimney pipe and assemble two pieces into one piece for a larger diameter if needed.  Always use caution when going through a wall or roof.

Outside forges are a little different.  I have used the same side draft forge hood and tried chimneys from 8 inch to 18 inches in diameter.  Bigger is not always better in this configuration.  The 55 Forge with the supercharger chimney is easy to build and works well.  24 inches diameter is indeed a BIG chimney but only the heads need cut from a drum in order to make the chimney.  No fussing, no calculations, no problems.  Knock the heads out and go.  

Many of the designs are made with 3rd world blacksmiths in mind.  What resources do they have available, what tools are available, and what designs just plain work.  Yes, you can improve things by using the electric powered tools, but some 3rd world locations do not have electric yet.  

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The top drum has both heads removed and is just an open cylinder.  The bottom drum uses one head as the bottom of the drum where the fire is located. The other head of the drum is removed.  There are no restrictions.  It is a straight path (24 inches diameter) from the fire to the sky.

The opening (access to the fire) on the bottom drum is located 4 inches below the 2nd ring,  2 inches above the bottom,  16 inches wide, with an arch on the top of the opening.

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The 55 Forge drums last (here) 2-3 years being outside in the weather. You can throw a solid cover over the top of the top of the chimney if it is a concern.  I put the open bung holes down in the floor of the forge so any water can drain out. 

With bottom blast configuration, keeping the ashes cleaned out of the forge help it last a little longer.  With side blast I put a cover over the top of the chimney to keep the rain out. Corrugate roofing tin or plywood will work.

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OK I think I will experiment a bit with chimney sizes first, I have some pipes in various sizes. You said bigger is not always better so if I took the implication of that to mean there is a more optimal size than the 24", but that doing this is the simplest way. Not that it matters that much that I get the last ounce of performance I can squeeze out of this setup, but more for curiositys sake. It's an experimenting platform as you said.

Today I am going and getting some bricks, found someone giving them away and what's better than free. The SO wants them too for making raised gardening beds. Hope there are some left.

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For the 55 Forge with a Supercharger, the optimum size for the chimney is the diameter of the open drum, 24 inches.  It is the easiest to build, simple, and works. 

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The mention of the other chimney sizes were for use with other forges with different designs.  Please do not confuse the two comments.  

You need to stick with building ONE forge of a known design that works.  Once you have a working forge, you have a standard to base any modifications on to and see if the modification is better or worse in performance from the original design.  If you combine several elements from several forge designs, who knows what you will end up with, or if it will even work at all.  That is not to say one way is the only way, just that that design works.  You are welcome to experiment all you want. Please let us know of your results.  We want the ideas that work so we can try them out. 

 

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Well got some progress today, cut open one of the drums.

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Filled the bottom with bricks and tried to imagine roughly how the pit should be formed. The air blast should be located on the side and not in the back like in the picture though.  I might make the opening taller yet.

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Also got my coke today:

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You may want to recalibrate your ruler.  

4 inches below the second ring is 10.16 cm.  2 inches above the bottom is 5.08 cm.  The width of the opening was 16 inches or 40.65 cm.  I should have converted and posted both measurements to avoid any confusion. Brick floor is fine but it requires bricks which were not on the original materials list. 

It should work even with your modifications.

You WILL need to be careful of the sharp cut edges of the metal.

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I'm not really following any precise dimensions here, I just went with what I thought looked "right" and sorta like the pictures, that's the level of precision I was working with.

I was mostly concerned that the bottom part would be deep enough to work with the additional bricks put in there, that's why everything got moved upwards. But I liked the idea of bricks on the floor of the pit. 

All edges were deburred too

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I mixed up sand and some bentonite powder today, maybe it was 1 part clay to 3 parts sand. It made a moldable mess however, and I covered the bricks I got  in there and then started building up the sides and then I formed the fire pit using a small bowl. I rammed down the sand with a piece of wood to help pack it down. I could yet add more mixture to bring more of the inside up so it's even with the edge I cut, that would give me a deeper fire pit too, current depth is 3 inches. 

The pipe is an OD of 20mm and ID of maybe 18mm. It's a bit on the thin side I think but I have lots of pipe like this laying around. I figure once the sand and clay sets up I can withdraw the pipe a bit . 

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I already went and added more clay/sand mix so now it's all level with the cut and the fire pit is a little deeper. This way I don't have cut out any metal to lay a piece flat into the fire.

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My methodology for determening this was simply that I google searched this site and looked at picture after picture of fire pits and forges and tried to find references to fire pit depth and then I made mine to resemble what I found. I figured that's the best way to find a jumping off point rather than random chance. It's probably 5 inches deep now, tuyere sits the short dimension of one house brick above the bottom.

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I was only using natural aspiration for the wood burn in. Haven't yet figured out what I should do about an air source. Last night I just hooked the hair drier over the tube and tried with coke, it did seem to work

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I probably should have added more coke, there was a lot of charcoal mixed in and it went away quickly so the pile shrank. But this was only a short experimental burn, it was getting kinda late so I only ran it 20 minutes or so. But I managed to beat a small hook on that piece of flat bar to scrape coals with. But a hair dryer certainly seemed to be able to provide enough air flow

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Hair dryers generally provide too much air.  Do you have a tuyere to get air into the middle/base of the fire?   If so getting a good fire going and closing the open door should use the chimney effect to pull air in through the tue pipe!  (You will have to learn how long to leave the front door closed between working the metal though.)

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I have a pipe that I packed the clay mix around, I just hung my SOs hair dryer on that, most of the air went elsewhere but enough went into the pipe to provide a good enough flow. I took your suggestion and I put back the opening I cut out on hinges. So now I have a door. I had to give it another burn today because it rained during the night and I had forgotten the chimney cover so the inside was all soggy wet again.

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Looks like you may need to adjust the depth of the firepot so it's a tad shallower and you don't have to angle the stock down into the sweet spot. Looks good else wise. 

Pnut. 

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