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Coal Forge Airflow info.


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I recently have started building a coal forge. I have always wanted to make damasks steel and I have read online that coal can burn at temperatures of 4500 degrees Fahrenheit which is more that enough heat to make damasks! My question is how much air flow do I need in order to get it to burn that hot? I have a hair dryer got from Goodwill but will it be enough?

All the help I can get will be great!!

Thanks.

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Yes, No, Maybe depending on information you didn't provide----I have a vehicle; does it take 5 gallons of fuel to fill it up or 203400 gallons? Kind of hard to answer not knowing if it's a small motorcycle or a Saturn 5 rocket...  Things like size, design, fuel, even altitude play a part. (Of course the latter number is just the kerosene for the first stage...)

However in general a hairdryer puts out more air than a typical first forge requires and you will have to figure a way to meter it down---which is discussed in length in these threads.  Are you using bituminous coal vs anthracite?

Note however that you will need to learn to forge before worrying about making pattern welded damascus and so the forge you start on may not be the one you use for welding billets. It's a lot like learning to drive before entering a Formula 1 race; you probably wouldn't use the same car for both tasks...

On the gripping hand, if you are covid safe, stop by my smithy next Saturday afternoon and I can work you through your first billet in one of my coal forges.

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I run a hair dryer on mine. It goes into a 2 1/2" pipe to my turryer (?spelling?) it is closed down to about a 1/8" slit and behind the airdam is five 1/2" holes. I cover 2 of the 5 and i can get welding heat. 

But regardless, what you are asking is a fire maintenance question and like Thomas points out each forge  is different. These are also questions asked and answered a thousand times. Like was suggested to me when i first started, grab a cold beverage and some lunch and sit down and start reading these threads. Be warned, they sometimes drift into strange waters and we love puns. 

Anyway welcome, be safe and keep it fun. 

Thomas, my dad once had a 70' Chevelle SS, 396 with a 4 on the floor. He bought it used from a drivers ed school back in the mid 70's. 

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Until recently I had a hairdryer for a blower, with several holes in the air pipe, to act as a wategate.  It would get to welding heat pretty quickly when turned on high.

I now have a deeper fire pot, and a hand crank blower. I need to re-learn my fire tending due to the deeper pot, but the hand crank will get to welding heat pretty quickly as well.

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My dad traded that car in back during the oil embargo becuase gas was getting so high. He bought a Dodge Duster with a 390, yeah some savings. 

So it is not a good thing that my truck gets 16 MPG?  

Anyway to topic at hand, i have not turned that hair dryer on high. I actually cannot get to it very easy and have it wired to a switch on the front of my forge to turn it on and off with. I turn it off when not using the fire, kind of like not turning the hand crank. 

One thing i did do, the dryer does not blow hot. In my jumbled brain it seems that cold air being denser, is better than hot. Provides more oxygen. 

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Two possibilities: 

  1. Your fire gets hotter than you need it, and the risk of burning your workpiece gets significantly higher.
  2. With REALLY excessive air, you end up actually cooling your workpiece by convection. 

Neither of these is good.

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IF the hair dryer it putting out too much air, leave an air gap between the hair dryer and the pipe going to the forge.  Aim more toward the pipe for more air, and not so directly toward the air pipe for less air. You can spill what you do not need.

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Forgot to mention another problem that too much air can cause: blowing the fuel out of the fire. An over-vigorous blast can actually lift the fuel up and out of the forge, scattering burning bits of fuel all over your workspace. I've had this happen to me back when I was using anthracite: I saw the fire bulge up like a lava fountain and then blow apart, with glowing shards going everywhere within a six foot radius. That was not, shall we say, fun.

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Not to mention that you want a neutral to reducing hotspot to heat the workpiece in. An oxidizing fire will produce a lot more scale and also decarb if you are working high carbon steels.  (I like to makes blades and pattern welded steel so I even tune my gassers towards reducing.  I use a hand crank blower for my coal forges as I can control the blast to the fire and project easily.)

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If you have too much air and you are using charcoal you will have bad time with chasing fuel around. It is really frustrating when you need to chase fuel around. Or when you put your metal in bed of coals and you hope for 5 minutes or more you will get good heat, and you put out material back and you saw that you had bad heat.


I will say this fit for forges 

"Give me six hours to chop down a tree and I will spend the first four sharpening the axe."

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On 1/11/2021 at 4:07 PM, ThomasPowers said:

Note however that you will need to learn to forge before worrying about making pattern welded damascus and so the forge you start on may not be the one you use for welding billets. It's a lot like learning to drive before entering a Formula 1 race; you probably wouldn't use the same car for both tasks...

Listen to this man. You will try you will fail and get discouraged and abandon a very nice hobby.

Learn to walk before you run. Meaning you have to build up your skill, with fire and hammer. It all looks simple when someone else is doing it. I haven’t tried forge welding yet I don’t think I’m ready.

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Follow the advice and instructions given on the site.  Build something and learn how to use it so you have some experience on which to base your questions.  If you build a suggested forge, the site can assist you as they know what you are doing. 

Keep things as simple as possible until you know what to change and then only change ONE thing at a time.  Going slow is easy as it only creates small failures that can be fixed.  You learn how to improve from each failure.  No one ever did everything right the first time. 

We want you to succeed, and to be a small part of that success.  Accept the challenge of blacksmithing and enjoy the ride. 

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You can take pause from blacksmithing so you slow a litle bit and take time to think about it.

But is hard to escape and stop.it al together especially if you are working with tools.

Imagination will always be there, even when I was on my job and I saw they weld pipe with accetylene torch it reminded me on blacksmithing.

Pause is good so you can think better after week month or so , you dont need to push it if we are speaking about hoby.

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On 1/19/2021 at 9:11 AM, Glader Gold Fire said:

how should I be able tell if I dont hake enough airflow?

That takes some training. After a while you will be able to look at your fire and see clues like the color of the fire, dead spots, etc. These will tell you if you need more air, need to clean out the fire, or even need less air. Again most of what you are asking is fire management. This is something that you need to do and not just read. SOFA here has an introductory blacksmiths class that teaches the basics of fire management, but again it is hands on, not just someone explaining it. I could say something like to weld your fire needs to be a bright yellow, however usually bright yellow to me is a different color to everyone else. Some would say a high orange or some may say white. We all see these things slightly different. 

Have you built the forge yet? If not, why not? Have you fired it? again if not, why not?   You will learn more in a day playing with your fire than you will ever learn with someone just trying to explain it, and you will learn 10x as much if you have an experienced smith working with you. One thing you can try is get the forge running at absolute minimum air flow, see how long it takes to get a piece of metal to working temp. Let it cool or get a second piece. Say it takes a long time or does not even get to working temp, increase the air just a little and see how long it takes.  Keep increasing little by little until you hit that sweet spot. When i get my fire up and going good i can get a piece of 1/2" bar to heat in about 5 mins. from cold. After initially heated getting back to working temp is just minute or so. 

We want you to succeed, we want to see beautiful Damascus blades in the "What did you do today" thread. We want you to be a part his wonderful journey into blacksmithing, but you are going to have to get your hands dirty. I also know the frustration of not having experience as a guide. Took me 2 years to learn what could have been taught in 2 weeks. 

As a side note, i sent the pics of my plumbing to you but i forgot to answer one question. Yes i can do Damascus. I do not make many knives but i have made a couple Damascus blades. I have not tried a canister but that is just cuase i do not really want to. Also i see so much Damascus anymore i kind of look at it as a novelty now. 

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14 hours ago, BillyBones said:

how should I be able tell if I dont hake enough airflow?

You won't have a white heart in your fire. There won't be a hot spot that's too white hot to easily look at. 

Pnut

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