What works for you?

[Shabumi]

I've been seeing alot of posts where people need help with the size of their fire, or whether they have enough or too much air to their fire. There are not alot of answers out there for inquiring minds on these subjects, it seems to be a knowledge that comes with experience. Now I have a hunch that there are some experienced smiths here and I'd like to see if we as a community can come up with some basic parameters for solid fuel forges that anyone can use to help with their build. I'd be willing to chart the parameters of forges that are known to work, but as I don't have access to too many forges, i was hoping the collective of great minds here could help. What I am asking for is some info on the forge that works for you, like fuel type, firepot type(shape, dimensions), tuyere type(size, position), airflow, and any other info that might be helpful, like the min amount of air you need to keep anthracite coal going. If enough people are willing to share about their forges we may be able to find a 'sweet spot' for people to aim for when building forges for certain fuels. I'll start with mine. It's a jabod, charcoal fire, firepot is 3"L * 7"W * 3"D, ¾" side blast tuyere, ~15ft³/m airflow. It seems to work well enough for me, it gets metal hot enough to work, but it does take a few minutes to get ½" stock to heat and I doubt I would be able to forge weld in it. So please tell me, what works for you?

[Beavers]

As a complete noob I would find that kind of info extremely helpful. I'm also using charcoal and have designed my fire pit based on Charles Stevens JABOD designs.

I think my main question at this stage is how long should it take to heat up a certain size of stock with the forge design I'm using. It seems like it takes forever and I'm not sure if its user error or if that's normal for my forge. I think its Glenn that always says it the amount of air not the size of the fire. For a noob using a manual mattress pump I'm not sure what the right amount is for the forge/fuel I'm using and the size of stock. I also don't know how to measure airflow so 15ft/3m doesn't help me.

 

There is so much good info to help noobs here and I think I've read a lot of it. I haven't found much on this particular subject. 

I'm sure there's a ton of variables but a guide like Shabumi is suggesting seems like it would be helpful for us new guys. 

[Frosty]

<sigh> I wish there were a set of parameters we could lay out for new guys regarding many things, not just fires. What works for me is what I have available, I've been messing with fires since I was pretty young. The first time I used a coal forge it took me until the fire got hot to learn how to use it. The next morning I showed the . . . person who was letting me work with him at the demo a much faster way to light a coal fire. He probably still is a proponent of baling up 3 sheets of newspaper to light the fire, I tear a 1.5"-2" wide strip of corrugated cardboard long enough to make a 4" diameter roll,  let is open slightly and bury it in the coal. 

Sorry for the sidetrack. Managing a fire isn't a by the book practice it's done by: eyeball, feel and sound. From there you gain experience. 

Let's see. Fuel and air make fire, re. the fire triangle but it's got to be balanced. Sure more air will make the fire burn hotter but too much air can blow the heat right out of the fire. It's burning hotter but the heat isn't sticking around long enough to do any good. Make sense? 

Not enough air on the other hand and it isn't producing much heat so it dissipates before it can do you any good.

Size? Depends on what you're doing. Coal you can bank around the fire and let the escaping heat and exhaust pyrolize "coke" it. Coke is to coal what charcoal is to wood, nearly pure carbon that burns clean and very hot.  If you try banking charcoal on the other hand the fire will spread through the whole pile.

Coke also known as breeze if made in a forge is good insulation so having a pile around the fire helps keep the heat where you want it. Completely closed is a . . . wait for it!  . . . Closed fire or sometimes a beehive or domed, etc. lots of names for a pile of coal covering a pile of breeze covering a small hollow with a HOT ball of nearly pure carbon fueled fire. The bottom of the fireball (burn zone) near the air grate will be oxidizing, the excess oxygen will damage your work. The center or sweet spot of the fireball is the place where all the oxygen has been consumed by the currently burning fuel. The next zone farther away from the air grate is the carburizing or reducing zone where all the oxy has been consumed but there is free HOT carbon gas.

There is an excellent chart Glenn posts because some of us old galoots can't remember how to find it and never just save a link.

You can read the info and unless you light a fire and experience it it won't be anything but words. 

You have to have enough fuel on the pile or in the pot to provide enough to maintain the intensity of flame you need for the job at hand. PLUS enough covering the fire to prevent heat escaping before you can wring every btu out of it you can and also shield the work from outside air.

How long it'd take me to heat say a raw RR spike (to pick a uniform starting stock) to a given temp in any given fire would be I don't know how mush more quickly than you. And I'd be very surprised if anybody here with experience would take the same amount of time I do. After we worked together in one fire a while sure we'd probably become pretty consistent, even more so if we were working the same product. Everybody's different it's what makes it an art.

I'm sorry to inform you but what you're asking for isn't realistically possible. How do I know? What you'd like to know has been written about I don't know how many times in how many: scrolls, wall carvings, books papers, articles and posts here. . .

Frosty The Lucky.

[Beavers]

Thanks for the detailed response Frosty.

I guess I was hoping there was some kind of shortcut for experience.   I think I know the fire diagram from Glenn that you mentioned...it did teach me that my stock should be horizontal and not angled down into the fire like I had been doing.

I have tried to hook up with the local blacksmithing group but so far haven't had much luck.  I'll keep on them and continue playing with fire and reading IFI.

[Glenn]

The problem is each forge is a little different and requires a different air setting depending on the forge size, construction, fuel, and a whole list of other things. When you are given numbers of xx and a measure, you must take into account the source for the numbers, the date of the measurement, and the type and style of the forge, as well as the type and size of stock they are heating, and the product they are making. Are you working for one hour or ten hours at a stretch, using 1/4 inch round stock or 2 inch solid stock, JABOD forge or a old time rail road or industrial forge?

My forge is 24 inches in diameter (the 55 Forge) with either a 2-1/2 or 3 inch open tuyere with 2 each 3/8 inch diameter bolts across the open hole as a grate, and a squirrel cage blower as a air source. I have forged coat hanger wire to 1-1/4 inch solid material by just adding more fuel and more air. How long does it take to heat a piece of metal? That depends on the fire and whether you want to go tap tap tap or are in a production run. There is most always more than one piece of steel in the fire. One piece of steel is on the anvil, another piece in or near the sweet spot of the fire, and one or more on top of the fire warming up. It is a dance, with a piece of steel always ready to go to the anvil. 

Have you looked under the Solid Fuel Forges section for Bellows, Blowers and specifically for the thread called how much air to forge ?

[Beavers]

Thanks Glenn I had not found that thread yet.

I'll look back through all the JABOD threads...I think I remember someone posting a video of their forge running. Would be nice to see what a properly running charcoal fire looks like. It would at least give me a gauge as to how I'm doing with fire management. 

So much reading and learning to do

[Glenn]

Fuel is a consumable. The BTU output of the fuel needs to match the need for heat for the job at hand. Get a good fire going and then back off on the air until you have enough heat for the project at hand. If you are concerned about the decimal points of the air, fuel, etc your not forging. (grin)

Start another thread. Show us photos of your forge set up and we can make suggestions.

[Beavers]

The weather looks nice this weekend.   I have a bunch of charcoal and a whole bag of nails that need bent into hooks. 

With only a few hours of forge time under my belt it's probably time to stop reading and start forging. 

[Shabumi]

10 hours ago, Frosty said:

I tear a 1.5"-2" wide strip of corrugated cardboard long enough to make a 4" diameter roll,  let is open slightly and bury it in the coal.

This is what I do to start a fire too, I found that the wax boxes that produce is shipped in works the best.

10 hours ago, Glenn said:

My forge is 24 inches in diameter (the 55 Forge) with either a 2-1/2 or 3 inch open tuyere with 2 each 3/8 inch diameter bolts across the open hole as a grate, and a squirrel cage blower as a air source...

.I have forged coat hanger wire to 1-1/4 inch solid material by just adding more fuel and more air.

Thank you this is exactly the kind of info I was looking for. I do remember seeing this on your 55drum thread, and had already taken down the info, as well as info on 10 other forges in the first few pages of threads. I was just hoping not to have to spend the hours searching through each forge build to get enough to have a decent idea on a concensus of a size range for general all purpose work. Though I will if I need to. 

As someone who has forged in a variety of sizes I'm sure there is a minimum size to your fire. Or would you use a thimble sized fire to forge a needle?

I apologise if my questions seem like they've been asked a hundred times before, they sounded original to me, but as I see I'm getting the same answer as a hundred before me, they must not be too original. I'm just trying to make it more clear than "if the fires not hot enough, then you don't have enough air, Or too much air, or not enough fuel, unless your smothering it with too much fuel, or... "

10 hours ago, Frosty said:

I'm sorry to inform you but what you're asking for isn't realistically possible. Perhaps not, but you never know till you ask

[ThomasPowers]

Funny I have been smithing for 37 years now and have no idea on how much air an anthracite fire requires as I only burn Bituminous coal, charcoal, propane, breeze and industrial coke.

I've build special forges just for doing just 1 project to size the forge to the work---I wonder what the current owner of that house will make out of the back filled trench forge?

As I see it the problem is that people seem to think that there is *1* way to do things when blacksmithing almost always has a bunch of ways that work. 

Just the shape of your firepot will change how it works---for a JABOD U shaped or V shaped?  As I'm not in this for money I often detune my forge to be a bit slower to heat but produce less scale as well. Unless I'm working with real WI and then it's HOT HOT HOT!

[Irondragon Forge ClayWorks]

What works for me, won't necessarily work for someone else. That's why when you ask 10 Smith's one question you will likely get 19 answers.

[Shabumi]

Thank you for all the responses, after the comments here and some PMs I realize that I had already read all the info that would answer my questions, most of it was in the stickies. I had taken the advice given, and read them first in my search for knowledge, but it had been pushed out of my memory to make room for info more recently read. So here's some advice for those who are just starting out. Don't just read the stickies, go back and re-read them periodically. You never know what may have slipped your mind.

I got this table from "Machine Blacksmithing"(1913). I know I've seen it posted before, just not sure where. This is the kind of info I'd been asking about. This is for bottom blast, but would it carry over to side blast, with some adjustments to the distance from tuyere to top of fire?