Controlling fire size

[Joel OF]

I've been reluctant to control the fire size with water as for a while I had problems with moist coke straight outta the bag spitting - my thoughts being that if I put water onto the coke whilst it's on the fire it'll just spit more, but it for whatever reason, it didn't.

 

Anyway, in the last couple days I decided to give controlling the fire size a go and I've had useful results with both concentrating the fire size + conserving fuel.

 

So my question is...at what point do you start adding water? Whilst you're filling the fire pot? Once the fire pot is full? Before the fuel's in the fire pot? Just curious...

Cheers

[Frosty]

The reason adding water doesn't react like damp coke is wet on the outside slows combustion while having soaked water up means it has to escape and if heated too fast it pops with little steam explosions.

 

I don't burn much coal or coke but I usually light the fire and once it's going wet the outside to assist coking and control the fire. In a coke fire it'd be for control.

 

Frosty The Lucky.

[Jim Coke]

Greetings Kurgan,,

 

I guess it depends on the type of coke you have.. Nut?  Most coke users have a hard time getting it going and have to add a lot of air to keep it that way..

I would suggest that you wet the coke in a pile off the fire and drag it to the outside as needed...  Adding water to the fire can be dangerous . A few times I have had an explosion in the  air tube.  About that of a fire cracker.. 

 

Forge on

Jim

[Quarry Dog]

I don't know much about burning straight coke, although there have been a few times where guys in the shop used it for their fire.  Mostly though we just use coal.  With coal I would advise sorting through the remnants of the last fire, getting the fire going really well.  Once the fire starts getting beyond the firepot, just add a little bit of water at a time to the green coal, until the fire is more controlled.  This will aid in coking the green coal, as well as keep the fire isolated to the firepot.

 

Two very important things to note:

1. Never poor water directly into the firepot.  If the firepot is hot, this may cause it to crack.  It may also go down the tuyere, which leads us to the next point.
2. When adding water to the fire, always keep on the blower for at least 1 minute afterward.  If you don't their is a good chance that unignited coal dust will run down into the tuyere.  Once this dust dries out, it will travel back to the bottom of the firepot, and ignite from contact with the flame.  The resulting explosion can be VERY loud.  We had a new guy do this about 4 months ago and I heard it 3 rooms over.  I walked into the classroom area and everyone was shaking off dust that had been knocked loose from the rafters.  The guy from the next forge over said he saw 4 inches of flame shoot out of the blower... 0_0

I hope this information helps anyone that plans on using coal.  I'm curious to know if this applies to coke as well, since coke firepots are usually heavier, and i'm not sure about the dust that is associated with coke.

[Joel OF]

Cheers folks, I'm burning coke singles, Jim.
 

 Most coke users have a hard time getting it going and have to add a lot of air to keep it that way..

I read that a lot and it always makes me wonder whether I'm unknowingly committing cardinal sins in getting the fire going as I don't have any trouble. I'm using a hand cranked blower too and I've read a countless times that hand cranked blower aren't suitable for coke forges. On top of that it's a hand cranked blower for a side blast forge but mine is a bottom blast...so I've had to adapt it into something that looks like an ugly cousin of a Buffalo hand cranked blower. (I don't use any fire accelerants or anything, just 3 pieces of newspaper + 2 handfuls of charcoal + coke.)

 

Blimey Jerome! Thankfully coke hardly produces any dust but I'll certainly keep that in mind because I do always have dust at the bottom of the fire pot from the charcoal I stick in first to get the fire going. I can't remember off the top of my head exactly how thick my fire pot is, I think it's about 12-15mm, I made it out of a couple bits of RSJ. It's about 9 and a half inches x 11 and a half inches and about 5 inches deep.

[Quarry Dog]

I believe I can see why hand cranked blowers are not suitable for coke fires.  The coke fires I saw were run on the masonry "Instructor Forge" which has an electric blower mounted to it with a switch + rheostat on one side and a switch on the other.  They kept the blast going a good bit almost the entire time.  I also hear that you have to constantly feed coke fresh air, or it dies really fast.

 

Coal dust isn't so much of a problem when you're starting a fire with a hand blower, as when you start the fire you crank it pretty good, thus blasting any loose coal dust past the fire you're starting.  The problem is when you wash a deposit down the tuyere, it dries out, startes breaking up, and ends up with the grain silo effect.

The video is in very, very slow motion, trust me.

[Joel OF]

They kept the blast going a good bit almost the entire time.  I also hear that you have to constantly feed coke fresh air, or it dies really fast.

Yeah this is another thing I don't get, the only time I crank the blower is when I put steel in the fire. I was concerned that I was cranking the blower too often but I always see people that use electric blowers telling others to turn off the blower when you're away from the fire/at the anvil...but for me that's a given because I'm using a hand cranked blower.

 

The problem is when you wash a deposit down the tuyere, it dries out, startes breaking up, and ends up with the grain silo effect.

Gotcha. Now I'm thinking I should buy a toilet cleaner brush to scrub out the tuyere before each day's forging! Haha.

[Quarry Dog]

Yeah this is another thing I don't get, the only time I crank the blower is when I put steel in the fire. I was concerned that I was cranking the blower too often but I always see people that use electric blowers telling others to turn off the blower when you're away from the fire/at the anvil...but for me that's a given because I'm using a hand cranked blower.

That's why it's called the "Instructor Forge".  Only people who've been around awhile are allowed to use it without supervision of some sort.  I usually get stuck on the durned thing.  To top it off, the blower only kicks on when there's enough juice to make enough blast to knock coked coal out of the pot.  It's just enough for industrial coke though, the stuff we have seems heavier than just normal coal.

 

Gotcha. Now I'm thinking I should buy a toilet cleaner brush to scrub out the tuyere before each day's forging! Haha.

The airblast works good enough on your tuyere.  Anything that doesn't move when you start up, ain't gonna move while you're working, it's the stuff that hasn't settled/adhered to the tuyere that you have to worry about.

 

P.S.:  How is tuyere supposed to be pronounced? TOO-yair? TOO-yeer? TWEER? TWAIR? TUAR-ay?  Am I even spelling it right?

[Joel OF]

How is tuyere supposed to be pronounced

In my opinion anything that sounds like you've got a mouthful of Pate du Campagne and a string of garlic around your neck is acceptable. I'm just as much French as I am English so I'm allowed to say that, before anyone starts...

[Dale M.]

If you use a sprinkling can and add a bit of water (fine spray/drizzle) to parameter of flame it will control size by not allowing it to expand outward (keeps fire ball forced inward)..... The "generic" adding water or wet coal/coke is kind of a real broad loose term/statement.... I do not think adding water to control flame is bad or will actually damage fire pot if done correctly, but its more how you use it (technique) and  what you are trying to accomplish.... And just dumping water on flame in broadest sense is not a good practice...

 

http://www.iforgeiron.com/page/index.html/_/blueprints/100-series/bp0157-watering-can-r389

 

Also if fire is becoming to big, reduce your air....

 

Dale

[Quarry Dog]

  I fully agree, and I guess I did leave a few points out for interpretation.  Well, as a general rule, I try not to use green coal in the middle of the fire, unless I'm trying to make a cave of coke.  The reasoning behind this is that green coal makes for a very dirty fire, and seems to produce more clinker.  It's better to let it cook into coke on the edges before you put it in the fire pot. 

  So yeah, again, avoid water directly in the firepot, because (a) it could crack the firepot(I've seen it happen, and it didn't take much water.  It's the same reason you never cool off a cast iron skillet with water.), (b) you're trying to slow roast the green coal, not actually burn it, and ©the firepot is best controlled by other means.  The dumping of water on the coal is more to keep the fire from spreading beyond the firepot, instead of letting it run free across all the coal that your trying to slowly process into coke.

  If you reduce your air, yes, your fire is easier to control, but it's not as hot either (unless you're already blasting coke out of the pot, which is not ideal to begin with).  You need all that heat, as well as a clean fire, for easier welding. 

  I've found the best way to control the fire inside the pot (which is primarily coke, even if it is the lighter breeze resulting from coal) lies in 4 factors:

1. How high you pile the coked coal.  This makes for a deeper fire that heats up stuff faster.  If you're going through too much fuel and don't need the extra heat, feel free to remove some coke and put it to the side so you can use it later.
2. Wherever your coke is piled deepest, is usually where it is hottest.  It's also usually easier to get your work covered in deeper areas, which also makes metal heat up faster, as compared to when you have it just sitting on top of the fire, where it heats a lot slower.
3. If you have a deep part of the fire without much airflow, it's not gonna be as hot as it could be.  The area with the best airflow is usually the brightest/hottest part of the fire, although if it is shallow, you might get a lot of scale heating metal at this spot.  If you don't like where your hot spot is, put your poker in where you want the hot spot, poke down toward your airhole until you feel it hit, and then wiggle it around.  This will result in an air jet going right where you want your hot spot.  I'll readily admit that I learned this on a bottom blast forge, and have no idea how to translate this for side-blast forges
4. Once you've got your depth, and your blast is where you want it, then you can worry about controlling the fire with the amount of air you push through the tuyere.  I also have noticed that if I cut off airflow about 5 seconds before removing the metal, I don't get as much scale.  I imagine even an industrial coke, or even an anthracite fire, can go at least 5 seconds without air flow.

As a last note, it seems that a little bit of water on the green coal just outside of the firepot makes it coke up into larger clumps.

 

I hope this clears up any points that I didn't make clear at first.

[Alan Evans]

Interesting reading. I have only ever used coke, first in side/back blast hearths with water cooled tuyeres (I have always heard it pronounced "twoy-err" Twoy rhyming with boy not hooey). Later in a home made dry bottom blast which is just a flat plate with two loose 50mm (2") square bars to form a nest.

 

I have never used water to control the fire. Just heap it up where I want it with a slice.

 

If you are using a side blast with a swans nest in front of the tuyere as per the sketch I posted on an earlier thread, you should not have a problem with the fire moving.

 

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I always heap up coke on the edges of the hearth so that it can be pre dried before it goes on the fire which reduces the spitting if you don't manage to keep your coke store dry.

 

Alan

 

ps I found the sketch image 

[matto]

I use a mop to wet down my coal/coke. Take an old dish towel and cut it into one or one and a half inch strips then take five or six of the strips or however many you want for the size of mop you want and stack them on top of each other. Set them aside for a moment and forge a handle like you would for a forge rake, then wrap The handle around your strip pile of towel this is done cold. Now you have a mop. Stick it in the slack tub and then mop the top of your coal/coke pile to control the fire size. Works slick. If i can get the camera from my wife i will take a couple pics.

[Dale M.]

Something else to consider is the air... Old forges with bellows or hand crank blower, the air was reduced when smith stepped away from forge to hammer...Modern technique to use electric blower allows for full time air flow and probable less attention to air flow vs fire then when smith stood there and gauged his heat by amount of air he manually induced into fire to adjust his heat, there for managing fire size and coal/coke usage...

 

Maybe if blower has a drop gate that cut off air when smith stepped way from forge or a foot switch to cut off blower,  one would be more attentive to what the "air" was doing and how it helped control fire size..

 

In out zeal to modernize we my have overlooked a subtle aspect of fire control...

 

Dale

[Joel OF]

Dale, that's exactly the reason I got a hand cranked blower. Good for evening out muscle building too if you crank the blower with your non-hammering arm!

[Quarry Dog]

The guy the runs the shop always gets on us if we leave the blower going when out steel isn't in the fire.  As far as judging how hot my fire is, I usually base that off of the color.  This is made easier by the fact that my safety glasses are around a 2 or a 3 shade lens, and the fact that the shop is well shaded so that you can see the colors very easily.  I also take a sacrificial piece of steel on occasion and burn the tip, and then let it cool down till I can't see it in the available light, and finally put it close to my face and cover it with my hand until I can't see it again.  This seems to be a very effective method of callibrating my color scale, but I guess it works so well because we hardly ever have enough clouds down here to block out any light.

[Joel OF]

we hardly ever have enough clouds down here to block out any light.

You are more than welcome to some of England's.

[Quarry Dog]

Well, considering that San Diego's average yearly rainfall is just under 11 inches, we could probably use some of yours.  Last year we got under 8, so that's officially desert status.  The only thing keeping lawns green all across southern California is the aquaduct running off of the Colorado river.  In fact that river runs dry 5 miles before it hits the Gulf of California because of all the water siphoned off by the aquaduct.

[Joel OF]

Ironically despite the amount of rain we get I live near Britain's only desert, Dungeness. It is a weird and wonderful place, it's like somewhere out of a post-apocalyptic movie. A nuclear power station, a house coated in latex, giant concrete sound mirrors from the 1930s to detect Nazi planes, a miniture railway, and a nature reserve...it's got it all.

 

I've made 3 anvil stakes and 2 hammers with of off-cuts from the railway so far.

[Quarry Dog]

Sounds like a good setting for the next Fallout video game.  Fallout: The New Kingdom... Yep, that was nerdy. <.<...>.>...0_o

[rockstar.esq]

I've found that since I switched to a box bellows the fire doesn't grow so quickly.  I've also found that mixing coal and coke has made forging with coke less difficult.  I get less smoke keeping the mix mostly coke and the fire stays lit because of the coal.