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How much fuel is too much fuel


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when I was using charcoal I'd go thru a 5 gallon bucket every 2 hours or so. If I recall correctly that was about 8 lbs of charcoal, more or less, so another hour for 10 seems reasonable within my own experience.  I did find I went through a LOT more water, damping down the fire and keeping it from spreading, working charcoal.  Easily half of my 4 gallon quench bucket would be gone after 2 hours. My forge was bottom blown, don't know if that makes any difference. The difference switching to coal/coke was astounding!

See how small a fire you can still work effectively in.  I walk away from a charcoal fire and come back in 5 minutes to find the whole pile of fuel burning.

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Honestly depends on the class of work your doing. Are you trying to forge 1” square or forge weld 3/4”? The latest version of the JABOD burns about 1/2 that and happily forges 3/4”x5/16” shoeing stock. It will forge up to 1” and frgeweld as well. But I have a 6x4 fire hole, a 7/8” I’d turn and a double acting manual pump. 



Electric blowers burn more fuel as you run the dang things at welding heat all the time (when your just heating to forge or when your forgeing) manual air sources you don’t go to welding heat until you are getting ready to weld and you don’t add air at idle. Another thing is charcoal is very happy at about 6” heat zone,.


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I am forging knives from schedule 60 rebar and some older scrap from tools and car springs usually the pieces are around 7” long at max. I use an electric leaf blower that honestly puts out a ton of air and yes the fire is HOT.  The coal bed is inside a brick housing on a wire grate and the air comes in under the coal bed from the side. 



This one is made of an 80d nail


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Welcome aboard brickforgebeginner!

My side-blast JABOD uses about 1 kg (2.2 pounds) of maple lump charcoal every hour. My burn area is about 5" wide by 9" long by 4" deep. So roughly half as much as you use.

I would say that the two main things that makes a difference is the size burn area and the amount of air.

First, you can get a much more efficient fire with charcoal by containing it to as small a volume as possible. Any charcoal that is in contact with your fire will burn, whether it contributes to heating up your steel or not. So adjust your brick so that you only have as small a fire as you need for what you are working on. If you could show us a picture of the inside of your forge, that would help. (For scale, the bricks in the following pictures are 4" by 9")


Second, charcoal doesn't need much air. I use japanese-style box bellows (hand pumped). So I can adjust how much air I pump in, depending on how hot I want my fire to be. And even more important, whenever I am working at the anvil on my hot steel, there is *no* air being pumped into the fire. So make sure you turn your blower off whenever you take your steel out of the fire.


Your blower is probably way too much air for your forge. By my calculations, my box bellows pump about 60 cubic feet of air per minute (cfm) when I am pumping it hard enough to get welding heat. When I just want my steel bright red to yellow, I am probably pumping at about 40 cfm. That gets an half-inch square bar from dead cold to bright red in about 3 minutes.

From what I know of leaf blowers (I recently purchased one), they blow about 400 cfm...

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Fuel is a consumable item.

The size of the fire, and the heat of the fire, depends on what you are doing.  Small stock only needs a fire large enough to do the job, where large stock only needs a fire large enough to do that job.  For instance, 1/4 inch square takes X amount of heat to get it hot. 1/2  inch square is like stacking 4 pieces of 1/4 inch square bars together and would take 4 times the heat. 1 inch square is like stacking 16 pieces of 1/4 square stock together and would take 16 times the heat. It would also takes much longer to get the 1 inch metal fully heated so the center and outside of the metal is at the same temperature.

Fuel does not make the fire hot, air makes the fire hot.

You have a blower that puts out way too much air for the fire you need. Separate the blower from the fire. You can use a 3 inch an expandable aluminum clothes dryer vent pipe connected to the forge on one end and open on the other end. With a 3 inch air gap between the blower and the end of the pipe, aim the blower more directly toward the pipe for more air, and less directly toward the pipe for less air. Adjust as needed to get the fire and heat from the fire you need for the job. As you are not wasting heat, you will be using less fuel. 

Look for a smaller size blower when you get the chance.


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You have way to big a fire, your trench should be no more than a brick wide and two or three long. For most knives 1/2 brick (4”) buy 1 brick is probably enugh. This will heat 1” stock 6” long. And with a good soak and just the right air weld 1/2” stock. Unlike Steve who welds up sword billets you are most likely working 4-6 inch blades with 4-6” hilts.

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I am not fluent in brick so I’m not sure what the scale is in the picture.  I’m sure some people here know what those bricks are and u derstand the dimensions because of it.  Still, the wide, flat “fire pot” will lead to charcoal burning out in all directions even away from your air blast.  The large volume of air you are supplying will speed that up.  I’m guessing you go through a lot of charcoal.  Shaping your burn area so it is more contained (as Charles indicated) would help you control the fire a lot better.  

Spend some time reading the threads in the solid fuel forge section to get ideas while you continue using this forge.  A JABOD will blow your mind for its simplicity and you can use those same style bricks to support your tuyere under the sand/clay/dirt if you want.  Like all of us, you will end up redesigning your current forge at least a few times and then building a new design just because you will find problems you couldn’t predict.  Experience is an excellent flaw identification tool.

You may be able to convert your current forge into a JABOD by redesigning the bottom area with clay.  You just have to use the right k8 d of clay...others here know better than I do.  Good luck and keep working toward the perfect forge...which doesn’t exist....


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The pictures of the inside help a lot. Your coal bed area is on the large side for what you seem to be doing. It is also oriented at a 90 degrees angle of what you need it to be, IMHO.

You want your stock the be laid lengthwise on your coal bed. That way, your stock is getting more of the heat from the fire. All of the fire that is more than 2" to the left or to the right of your stock is just wasted fuel.

So I would advise reconfiguring the inside of your forge to rotate the coal bed area 90 degrees and making it smaller (about 4" wide by 8" long). Try to position the air entry hole in the center of the 8". Eventually, you may also consider leaving a second hole in your wall so that you can pass through longer stock.

And definitively less air. As a side benefit, you will get smaller flames and can lower (or outright remove) the wall around your forge.

Have fun!


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I agree with the JABOD or Tim Lively washtub forge style based on what you are doing. Also if you look at traditional “Viking” style forges with the tall wings and narrow fire area (the Nepali Kukri makers still use this style) you will use far less fuel and heat your stock easier and with more control. As everyone here stated, charcoal needs far less air than coal, and a ton less than commercial coke. A manual air source is ideal for it. Coal barely burns without air blast, hard coke goes out, but charcoal goes on happily burning and spreading if there is extra fuel near it. Fire should be narrow, deep, and no longer than needed to heat the stock you can work in that “heat”.  Also your turbo air source actually robs heat as it can’t all be consumed, so it blows on your stock cooling it and causing it to scale more, especially with high carbon steels.

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