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How to OPERATE your coal Forge To get Awsome heat quickly!!!


Borntoolate

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I ain't gonna mince words so here goes.   IF YOU CAN'T MAXIMIZE THE HEAT WITHOUT BURNING... TOO MUCH... IN YOUR COAL FORGE THEN ALL THIS "ONE HEAT" TALK IS POINTLESS!

 

in my humble opinion there is not near enough talk, pics and so forth about how to "manage" your coal forge in order to deliver those awesome heats that allow you to "Start out" with enough heat to really make things happen with the hammer and anvil. 

 

Now you can peck away at things at a mediocre safe heat but this makes life hard (and progress slow) when all you may need is a small tweak to how you "OPERATE YOUR FORGE"  in order to really be able to move hot steel, at maximum temp, with minimal effort. 

 

Brian has said it doesn't take minutes to heat metal but rather seconds.   Brian if I have quoted you wrong please correct me.   But I am beginning to agree though understanding how to do this is not something I have seen on this forum. Doesn't mean it isn't here.  As I experiment and go through LENGTHY trial and error I am learning... Slowly....        But even if it is in this forum I bet it is NOT in an easily digestible form for most of us.   I recognize that it may not be easy to make this easily digestable.   BUT.   I challenge all of us to figure out how to make it at least more or less digestible... soonish.

 

Now there are always many variables.  This makes this subject hard to discuss.  But we really IMHO need to breach this subject.

 

I hope that this particular topic will become one of the threads that we send all new smiths too in order to learn about fire control and heat.   In other words "HOW TO OPERATE YOUR FORGE"!!!!

 

I have a few thoughts as a ~2 year amateur with some pics and  comments.   But it is late.   Rest assured I will be bringing this up some more...   Possibly often.

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I'm not quite sure what you are asking. There is a lot of info written or demonstrated on this site that taking a proper heat is one of the most important things a smith must learn. Of course, the term "taking a proper heat" means different things for various types of work - i.e. a knife maker may not want the same heat that an ornamental smith is after.

There is a video in my website (click here) that shows me working out of a coal forge. It is a Buffalo patent forge with electric blower and damper; it will easily burn steel if I don't pay attention. Nothing I'm doing in this video qualifies as "one-heat" but there are other processes that I can do easily in one heat cycle if the proper heat is taken. There are also a plethora of videos on this site and YouTube showing other smiths taking good heats and getting a lot of work completed in a short amount of time - whether it's one heat or more.

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Any given solid fuel holds (contains) a certain amount of heat (BTUs). You must release the BTUs by burning the fuel and transfer that heat to the metal. Air is the determining factor in how much fuel is burned and how many BTUs are released. You can run a fire *cold* releasing only a small amount of heat (conserving fuel). If you run a small cold fire it can take a long time or may never get the metal up to forging heat.

 

 You can run the fire hot releasing massive amounts of heat (which requires more fuel).  The larger fire generates a large bed of coals and when the metal is in contact with these hot coals it will absorb the heat quickly. With an electric blower and with practice, you can set the air to control the heat of the fire to almost any constant heat level.

 

The other factor is working the metal as hot as the metal can tolerate due to the chemistry of the metal, and returning it to the fire as soon as it reached the lower heat value of good workability. For mild steel I try to work high orange to yellow, and return it to the fire at low orange to red. If you wait until the metal is at black heat, you are not moving metal and it takes extra time to recover the heat from black to medium or high red, and then on up to forging temperatures.

 

Another factor is your forge and the shape of the fire pot. The fire pot should be designed and shaped for the work at hand. 

 

There is nothing wrong with having several irons in the fire at one time. One in the fire ball at forging temperature, one at the side of the fire ball almost at forging temperature, and a couple of irons on top of the fire soaking up any extra heat exiting the fire.  As you pull the iron out of the fire ball move each iron down one position. This is with an electric blower but I have used the same technique with a hand cranked blower.

 

Put it all together and you have a well choreographed dance with the iron, the fire, the blacksmith and the anvil. There is always a piece of iron hot, at forging temperature and ready for the anvil.

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so i have heard we should bank a bunch of coal around the firepot.   So that means semi large piles of coal piled up on the sides.   This makes coke.  And we should wet it so it doesn't burn away...  Then the coke formed ...  Which we rake into the fire and bank back up.  This also provides a wall of insulation on the sides to keep the heat in.  Well this works..    

 

But I find this to be a lot of bother and waste and it makes it harder to see the fire.  So I say that realizing I don't know what I am doing.    Glenn mentioned the "fire ball".    That is a new term but I think it really has some useful meaning.    Glenn please xplain more!

 

Well, I have been experimenting with not banking but rather just sprinkling enough green coal on top of a hot fire every heat.  Or every other heat depending on how much metal you are heating.   I can even sprinkle more where needed in order to keep a mature fire hot on top and high enough to put the metal into for quick heat both top and bottom.   There is always enough flame to burn away the smoke.    My forge "area" is cleaner meaning I don't have mounds of coal banked all around and I have morespace.  

 

The size of your coal makes a difference.

 

I don't have coal on the sides of my forge fusing together into a brick.   I don't have to poke and prod and disturb my firepot to use the banked coal as fuel by dragging and breaking it apart.  Usually, for me this disrupts the whole fire and you have to wait for it to recover.   Poking, prodding, and tweaking the fire pot which cools everything and can also make the coal stick to the metal and cool it is no longer necessary. 

 

I can see the "ball".  I think???   I can control the ball better???   I can keep the ball white hot if needed, easier..  Glenn, tell us about the "ball"

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As an amateur myself, a few things I have observed:

 

Keep the airway clear. Keep the ashdump only partially filled. Make sure there is a path for the air to go, so don't make too big of a pile on top of the burning coal. I have a whirlwind firepot, and sometimes to get a good heat I have to either bank the fire higher or angle the metal lower. By angling it lower I run the risk of putting it into the reducing layer of the fire. Also, I usually throw a good handful of coal around the edge every heat or two, just to maintain a good fire.

That's just my musings!

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Think of it like a big rosebud torch. To heat quickly, you set your flame or hot spot and position your piece you want to heat in that spot. Just like a torch, there is a sound to a properly set flame and a spot in that flame where you can heat quickly, and yes you can burn your metal if you leave it in that spot once you are up to temp, so move your piece. Set your hot spot with your blower where the flame blows through your material. You should hear the flame roar. Preheat and turn, then heat and don't burn.

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so i have heard we should bank a bunch of coal around the firepot.   So that means semi large piles of coal piled up on the sides.   This makes coke.  And we should wet it so it doesn't burn away...  Then the coke formed ...  Which we rake into the fire and bank back up.  This also provides a wall of insulation on the sides to keep the heat in.  Well this works..    

 

But I find this to be a lot of bother and waste and it makes it harder to see the fire.  So I say that realizing I don't know what I am doing.    Glenn mentioned the "fire ball".    That is a new term but I think it really has some useful meaning.    Glenn please xplain more!

 

Well, I have been experimenting with not banking but rather just sprinkling enough green coal on top of a hot fire every heat.  Or every other heat depending on how much metal you are heating.   I can even sprinkle more where needed in order to keep a mature fire hot on top and high enough to put the metal into for quick heat both top and bottom.   There is always enough flame to burn away the smoke.    My forge "area" is cleaner meaning I don't have mounds of coal banked all around and I have morespace.  

 

The size of your coal makes a difference.

 

I don't have coal on the sides of my forge fusing together into a brick.   I don't have to poke and prod and disturb my firepot to use the banked coal as fuel by dragging and breaking it apart.  Usually, for me this disrupts the whole fire and you have to wait for it to recover.   Poking, prodding, and tweaking the fire pot which cools everything and can also make the coal stick to the metal and cool it is no longer necessary. 

 

I can see the "ball".  I think???   I can control the ball better???   I can keep the ball white hot if needed, easier..  Glenn, tell us about the "ball"

I'd have to see your methods in action to know for sure... they seem less effective than the traditional ways that I work at first glance though.  It took me about two years to become skilled at fire management... and it makes a big difference!  I struggled with some of the issues that you mention early on... but they seem quite manageable now.  I will guess that you will gravitate toward more traditional fire management as you become more experienced.  I am a pretty Scotch smith with my coal so I keep a small fire when I work small stock and only rev up a big hot fire when I am working large stock or welding.  I like to keep my fireball buried in damp coking coal and have a small opening at the side to insert metal.  I believe that I burn LESS coal in this way and usually have nice chunks of coke that I can roof my fireball with or break up a bit and push in from the edges to refill a hollowing fireball. Fines and dust work as well as anything else for this type of fire management which is useful as my coal often has a lot of them in it.  The insulating effect of the coke chunks over and the damp coal around my fireball helps to conserve the heat for working metal and to keep the heat from roasting ME!  The side benefit of constantly creating fused coked chunks of prime fuel is useful as well.

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so i have heard we should bank a bunch of coal around the firepot.   So that means semi large piles of coal piled up on the sides.   This makes coke.  And we should wet it so it doesn't burn away...  Then the coke formed ...  Which we rake into the fire and bank back up.  This also provides a wall of insulation on the sides to keep the heat in.  Well this works..    

 

But I find this to be a lot of bother and waste and it makes it harder to see the fire.  So I say that realizing I don't know what I am doing.    Glenn mentioned the "fire ball".    That is a new term but I think it really has some useful meaning.    Glenn please xplain more!

 

Well, I have been experimenting with not banking but rather just sprinkling enough green coal on top of a hot fire every heat.  Or every other heat depending on how much metal you are heating.   I can even sprinkle more where needed in order to keep a mature fire hot on top and high enough to put the metal into for quick heat both top and bottom.   There is always enough flame to burn away the smoke.    My forge "area" is cleaner meaning I don't have mounds of coal banked all around and I have morespace.  

 

The size of your coal makes a difference.

 

I don't have coal on the sides of my forge fusing together into a brick.   I don't have to poke and prod and disturb my firepot to use the banked coal as fuel by dragging and breaking it apart.  Usually, for me this disrupts the whole fire and you have to wait for it to recover.   Poking, prodding, and tweaking the fire pot which cools everything and can also make the coal stick to the metal and cool it is no longer necessary. 

 

I can see the "ball".  I think???   I can control the ball better???   I can keep the ball white hot if needed, easier..  Glenn, tell us about the "ball"

 

 

Your basic observations are correct.  I typically build a fresh fire and bank wet coal on the sides of the firepot, which cokes and forms a solid mass.  Over many heats, this will eventually burn away and need to be replenished but the fire can be fed with loose fuel to keep it from burning hollow too soon.  I don't make a habit of tearing the fire down after every heat by driving the sides of the coke wall inward.  The video link I posted shows me doing this routinely as I manage the fire.

 

Fuel size does make a difference because solid fuel can only burn on the outside of the chunk.  Therefore, a 6" diameter piece of coal will burn longer but with less available heat than the same piece after being fractured into 1/2" pieces (total calories are the same - only the duration and peak change).  It's no different than putting a big log in a fireplace versus a bundle of smaller sticks.  The smaller sticks flare up and provide a very hot fire for a short period - the log will keep the fireplace warm all night but at a lower temperature.

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  • 2 weeks later...



There is a video in my website (click here) that shows me working out of a coal forge. It is a Buffalo patent forge with electric blower and damper; it will easily burn steel if I don't pay attention. Nothing I'm doing in this video qualifies as "one-heat" but there are other processes that I can do easily in one heat cycle if the proper heat is taken. There are also a plethora of videos on this site and YouTube showing other smiths taking good heats and getting a lot of work completed in a short amount of time - whether it's one heat or more.

So the vid shows you pulling out what looks like a very nice heat.   But the video does not show how to do this.   This is typical of videos.   No one really wants to watch a piece sit in the fire.

 

I think part of the problem is that it's difficult to show the details of what you see in a good fire using video.  The colors and details are hard to see in a video.  

 

And as I ponder my own question and think about the 4 or 5  different coal forges I have used there are a lot of variables with just the forge itself, air flow, fire pot size and shape, hand vs electric blower not to mention so many other variables already mentioned.    I am not even sure it is truly possible to answer my question without considering all these variables.     

 

I guess I have been a little frustrated in my lack of knowledge and experience.   After two years working this as a part time hobby I feel I am beginning to learn how to operate my own forge.   My inability to do this in the past has cost me a lot of time heating and extra hammering.   So any way we can help others get this quicker is a good thing.   As others have said elsewhere you probably need to find someone that knows how to do it and how to teach it first hand and not in words.

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We touched on some of this in the Jan 1, thread by Kogan. I might mention that there are four crappy fires that I can think of, off hand: clinker fire; hollow fire; low fire; wide, spreading fire. A clinker fire displaces coke and "chills'" the blast. A hollow fire may look good on top but is oxidizing underneath, so you get heavy scale and low heats. A low fire is the opposite of a deep or high fire, the latter desirable. A wide spreading fire is not compact. The fire should be pulled together and coned with green coal. A wide fire may be used for heating something big like, say, a shovel pan, but not for straight stock heats.

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We touched on some of this in the Jan 1, thread by Kogan. I might mention that there are four crappy fires that I can think of, off hand: clinker fire; hollow fire; low fire; wide, spreading fire. A clinker fire displaces coke and "chills'" the blast. A hollow fire may look good on top but is oxidizing underneath, so you get heavy scale and low heats. A low fire is the opposite of a deep or high fire, the latter desirable. A wide spreading fire is not compact. The fire should be pulled together and coned with green coal. A wide fire may be used for heating something big like, say, a shovel pan, but not for straight stock heats.

Thanks, thats another way to look at it.

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