Charcoal heat time

[Deep Forest Tinker]

Hi everybody,

I did a quick search and didnt see anything about this so here goes. I built myself a small forge for working with charcoal. Since the charcoal sparks a lot, i built a hood for it and it seems to work fairly well (it just has a mesh grate at the top of the stack). However, I feel like i'm spending a lot of time heating my material and maybe its not getting hot enough. It seems like it takes several minutes to heat a chunk of 1/2" steel to I'd say about a dull orange. 

I have a lot of open ended questions and would just like advice. Questions:

- main question - how the heck long should it take to heat material?
- is it just the design of my forge?
- is it that charcoal sucks?
- is it my material? (hot rolled steel)
- is the blowing I"m doing not good enough? (ive used a shop vac and an air compressor and both seem ok but how would i know?)

I attached a picture of my evil little forge. the firepot is about 2.5 inches deep, has about a 2.5 inch perforated section for blowing, and maybe 8 inches across at teh top, 5 at the bottom. 

I greatly appreciate any advice 

 

[Glenn]

Make the depth of the fire pot about 9 to 12 inches deep and FILL it with charcoal. Fuel does not make the fire hot, air makes the fire hot. Do not blow the fuel out of the fire pot, just add enough air to get things hot.

The metal should be yellow (mild steel) to high orange when you start hitting it with a hammer. When it gets into red, put it back into the fire.

Read the solid fuel forge section and the anvil section of the site for more details and ideas.

[Jim Coke]

Greetings and welcome Jordan,

You have a lot of work to do to be successful at forging . First I would suggest alot of research on this sight for forge design. For starters move the cars out of harms way. Next your anvil height is way to high.. Others will chime in but a lot of reading is in order.. Take your time and you will do well .. 

Forge on and make beautiful things

Jim

[Deep Forest Tinker]

8 minutes ago, Glenn said:

Make the depth of the fire pot about 9 to 12 inches deep and FILL it with charcoal. Fuel does not make the fire hot, air makes the fire hot. Do not blow the fuel out of the fire pot, just add enough air to get things hot.

The metal should be yellow (mild steel) to high orange when you start hitting it with a hammer. When it gets into red, put it back into the fire.

Read the solid fuel forge section and the anvil section of the site for more details and ideas.

Thanks for the reply. So to have a firepot that deep, does it need to be like a foot wide as well? Are there design ideas in the solid fuel forge section? I feel like I'm pretty off the beaten path with charcoal - does it require a different forge design?

8 minutes ago, Jim Coke said:

Greetings and welcome Jordan,

You have a lot of work to do to be successful at forging . First I would suggest alot of research on this sight for forge design. For starters move the cars out of harms way. Next your anvil height is way to high.. Others will chime in but a lot of reading is in order.. Take your time and you will do well .. 

Forge on and make beautiful things

Jim

Thanks, Jim!

[Frosty]

I love the forge, sort of an Angry Forge look. It's not a very good charcoal forge design though, better ratios have been mentioned already. NO the fire pot should NOT be as wide as it is deep, especially not for charcoal.

I'm sure someone will chime in with a side draft forge and how much better it is for charcoal.

Your blower is WAY more than you'd need to burn charcoal by the pickup truck full at a time, a blow drier typically needs to be choked down. With that one the blast is strong enough to blow the heat right out of the fire without much more than warming the steels.

Pull up a comfy chair, pack a lunch and beverages and settle down for some serious reading. Yo bet Iforge has a solid forge section that contains designs, plans, discussion and arguments pro and con for different ones. There's in depth discussions abut fuels, what and why one is preferred over another. Etc. etc. Figure a couple days of reading, take notes and don't be afraid to check books out of the library even if you have to ILL them. Yeah, there's a reading suggestion section too.

I'm not sure how long IFI has been online, Glenn's told me, us several times but I don't remember lots of things well. Anyway it's been online more than a decade and yakky guys like Me have been posting. A lot of the guys contributing are world known names in the craft many published authors. Anyway, virtually anything you can think of to ask has not only been asked but answered many times.

Reading up may not tell you what you need to know at any given moment but it will give you a handle on the craft and more importantly a handle on the language. It REALLY helps to know what a thing or process is called so you can ask good questions and better still understand the answers.

Frosty The Lucky.

 

[dickb]

Before rebuilding the forge, you could try loading it up with as much fuel as it will hold and reducing the air blast.

 

[Deep Forest Tinker]

10 hours ago, Frosty said:

I love the forge, sort of an Angry Forge look. It's not a very good charcoal forge design though, better ratios have been mentioned already. NO the fire pot should NOT be as wide as it is deep, especially not for charcoal.

I'm sure someone will chime in with a side draft forge and how much better it is for charcoal.

Your blower is WAY more than you'd need to burn charcoal by the pickup truck full at a time, a blow drier typically needs to be choked down. With that one the blast is strong enough to blow the heat right out of the fire without much more than warming the steels.

Pull up a comfy chair, pack a lunch and beverages and settle down for some serious reading. Yo bet Iforge has a solid forge section that contains designs, plans, discussion and arguments pro and con for different ones. There's in depth discussions abut fuels, what and why one is preferred over another. Etc. etc. Figure a couple days of reading, take notes and don't be afraid to check books out of the library even if you have to ILL them. Yeah, there's a reading suggestion section too.

I'm not sure how long IFI has been online, Glenn's told me, us several times but I don't remember lots of things well. Anyway it's been online more than a decade and yakky guys like Me have been posting. A lot of the guys contributing are world known names in the craft many published authors. Anyway, virtually anything you can think of to ask has not only been asked but answered many times.

Reading up may not tell you what you need to know at any given moment but it will give you a handle on the craft and more importantly a handle on the language. It REALLY helps to know what a thing or process is called so you can ask good questions and better still understand the answers.

Frosty The Lucky.

 

Thanks for the comments! I don't use the shop vac anymore, i had been using a toe switch to pulse it, which worked ok. Now I use an air compressor hose with an air gap before it hits the intake to suck more air in. it actually seems to work pretty well, but I run out of air fairly quickly.

I'll spend time in the solid fuel forums. 

How long should it take to heat a piece of 1/2" steel from cold to orange? I still don't have any idea if my forge is working reasonably or not.

[Charles R. Stevens]

A hairdryer can provide to much air for charcoal, if the fire fleas are out you either have to much air, incompletely coked charcoal, a chunk of rock in the fire (from my fire pit) or your burning the steel. The last two are more like "fire mites" but anyway, point is to much air, or more precisely to high of pressure/speed. 

A traditinal side blast (say a Viking area forge) uses a 3/4-1" tuyere and produces a working fire ball of about 6", this is a wreathed shallow bowl of 4" deap and 6-8" across. Bottom blast, in a traditinal bottom last forge is a bit tricky, first you have to regulate the air down, just to the point you maintain a yellow-white hot center, and you have to build a deeper fire, say 6" deep (with both forges you have a mound of charcoal 3" tall over the top of the bowl) for fuel effecency reduce the bowl to 6-8" around (mud works just fine) aim for a funnel shape. 

To much air leads to a slew of issues, one you acualy blow away the heat and cool the fire, fire fleas and hot embers blowing around and exesive scaling do to excess O2. 

Lastly when you get the air and shape right, the first best takes a wile, the second heat (even if you let I cool to black heat) takes much less time. 

Bottom blast makes a hungry charcoal forge, I have a 8" trench forge that I use for big stuff, but for general forging a small side last is more effecent. 

[Frosty]

Glad you chimed in Charles you have a lot more experience with side draft forges.

No, an air hose isn't a good air blast, you want low velocity and moderate volume. All the gleaties (fire flies) are a result of too much or too fast a blast. Charcoal will throw sparks normally, quantity depends on a couple factors, type of wood and air volume.

A charcoal fire needs to be deep and as narrow as practical. It WILL grow as wide as the fuel pile so keep the fire pot, trench, etc. as narrow as possible. Deep is good for a couple reasons, first it shields the steel from atmospheric oxy, the fire has consumed all the oxy and positive presure through the pile keeps the ambient out. Second is insulation, it helps hold the heat in a controlled volume and not heat the room instead of your stock.

Frosty The Lucky.

[Deep Forest Tinker]

22 hours ago, Frosty said:

Glad you chimed in Charles you have a lot more experience with side draft forges.

No, an air hose isn't a good air blast, you want low velocity and moderate volume. All the gleaties (fire flies) are a result of too much or too fast a blast. Charcoal will throw sparks normally, quantity depends on a couple factors, type of wood and air volume.

A charcoal fire needs to be deep and as narrow as practical. It WILL grow as wide as the fuel pile so keep the fire pot, trench, etc. as narrow as possible. Deep is good for a couple reasons, first it shields the steel from atmospheric oxy, the fire has consumed all the oxy and positive presure through the pile keeps the ambient out. Second is insulation, it helps hold the heat in a controlled volume and not heat the room instead of your stock.

Frosty The Lucky.

Huh, interesting, thanks. I'll dig around the solid fuel forum. google image search for charcoal forge doesnt turn up anything but coal forges :\

[ThomasPowers]

Or you might look at the example in "The Complete Modern Blacksmith" by Weygers; your local library should support ILL for it.

[Frosty]

9 minutes ago, ThomasPowers said:

Or you might look at the example in "The Complete Modern Blacksmith" by Weygers; your local library should support ILL for it.

Thanks Thomas, I don't know why I didn't think to suggest,"The Complete Modern Blacksmith". It's got to be the best book about setting up a shop and making tools with what ever's available I know of. Maybe I should add it to my sign off?

Frosty The Lucky.

[ThomasPowers]

I have a soft spot in my head for it as "The Modern Blacksmith" was my first smithing book. 

[Deep Forest Tinker]

I just got the backyard blacksmith for Christmas, it's good but doesnt have a lot of detail about anything but the way she does it. 

I'd be very interested in that book if it talks about several options, I'll probably just buy a copy of it if it's that good.

[Frosty]

1 hour ago, Deep Forest Tinker said:

I just got the backyard blacksmith for Christmas, it's good but doesnt have a lot of detail about anything but the way she does it. 

I'd be very interested in that book if it talks about several options, I'll probably just buy a copy of it if it's that good.

Uh, do you find something wrong with the way Lorelei Sims does things?

Mr. Weygers doesn't talk about different options, he shows you how HE deals with situations where there isn't any choice but do it yourself with what's available. That's a long way from different options. His choices were often make do or forget it.

Weygers book isn't about blacksmithing per se, he was a multi media artist, carver mostly and he traveled the world looking for . . . whatever it is artists look for. His carving tools were just too darned heavy and bulky to pack with, so he made his tools where ever he found . . . Whatever he was looking for or at. He didn't carry a machine shop with either.

Alexander Weygers is a hero of mine simply because he would do whatever he set his mind on if he had to build a machine shop to do it. I can't think of a better book to show folks how to bootstrap themselves. A LOT of my field expedient shops were based on some of his and I'd like to think I figured out a trick or two he'd like to hear about.

Frosty The Lucky.

[ThomasPowers]

Actually I was thinking of one of his drawings of a purpose built charcoal forge he saw in Malaysia that I thought was a lovely design even though Mr Weygers, who was a polymath, didn't use it. 

[JHCC]

I use a shop vac as a blower myself, but (A) for anthracite, which needs more air than charcoal and (B) with a HUGE offset between the end of the hose and the air inlet of my tuyere, so only a fraction of the air actually makes it up into the fireball. Charcoal is a lot less dense than anthracite, so you need a lot less air to get the same fuel:oxygen ratio.

A hearty second (third?) to Weygers, for all the reasons stated above. There is also a great quote of his I ran across in an old "Fine Woodworking" magazine, reported by someone who took one of his toolmaking classes: "Little corrections, always be making little corrections. With the little corrections, we avoid having to make the big corrections."

Also, check out this thread, in which Charles R. Stevens describes how to make a dirt-cheap side blast forge.

[Bhutton]

Hi Deep...My forge design is similar but just a little larger...I can drag the forge outside & fired up and have a piece of 1/2" rebar bright orange in about 12-13 minutes. As all these guys have said to much air is your enemy. (I use bath fan and dimmer switch) Be sure to keep your stock level when heating...don't cram it down into the firepot at an angle, keep your air blast authoritive but not overblasting if that makes since? 

I have found that reducing the diameter of the firepot makes a difference with charcoal. I have my firepot (Brake drum) lined with brick and the firepot is approximately 6"X 6" X 4"-5" deep. I keep the charcoal piled up and have found the hottest part of the fire is about the top of the firepot to 1/2"-3/4" above the firepot. This gives me good heats but i dont think its anywhere near welding heat. 

Sounds like to me that you just need to do some tweaking......Nice looking build by the way.   Im a greenhorn and very inexperienced take my advice with a grain of salt...Im looking to get the Modern blacksmith as well. I have attached a couple of photos of my firepot/forge.

[ThomasPowers]

When I switch from coal to charcoal I tend to take a bunch of firebricks and make a trough across the firepot, so narrower and deeper.  When I build a Y1K forge from adobe I make a fairly narrow and deep trough with my twin single action bellows blowing from the side.

[Charles R. Stevens]

Wygers was also a machinists mate in one of the Scandinavian naveys, that's where he learned to drill square holes...

try google image searches for "ground forge", "Viking era" "Iron Age" ect. Marcawits (spelling?) who did the iron work for "outlander" and the lessern meadows recreation of the Ericsson base in candida has some good info. 

I ended up just building one on my best guess and information here and out on the web, then, as it's just a box full of dirt I experimented till I found the hot spot. Started out to deap but dug down

African termite mound forges work real well as well

[ThomasPowers]

Wareham Forge, Darrell Markewitz of Ontario Canada; good fellow and one of the tops on viking stuff; used to meet up with him at Quad-State semi regularly.

[Charles R. Stevens]

Thank you Thomas for filling in the blanks, his blog has a wealth of information

[ThomasPowers]

Hey, I had to hunt down the correct spelling of his name and I know the guy!  (and I agree with you which is why I wanted folks looking his way and not getting lost...)

[Charles R. Stevens]

Lol, glad you agree.

 

[rockstar.esq]

I hadn't brought out my forge since winter set in and my first try at getting going yesterday was instructive on this topic.  I use an old soup can with the ends cut off as a chimney starter.  I put newspaper in the bottom, charcoal on top, then coke on top of that.  I've got a champion flat-bottom blast forge and crank blower.

My first try I got fire flea's jumping and figured I could pull the chimney out.  Now the charcoal was lit, it just didn't have sufficient time to really get the coke going.

Despite my best efforts to make the fire grow, it simply stayed wimpy.  My cranking arm was tired and I could BARELY get metal to orange.

I stopped, started from scratch, and let the charcoal really get the coke going before I pulled the can.  I had a full-strength fire right off the bat. 

There might be a better term for this, but I've found that forge fires have to hit a critical mass for them to be useful.  Without sufficient fuel alight, additional air-flow seems to just blow the heat out of it. 

It's a bit counter-intuitive, but a slower and gentler kindling stage gets more fuel lit.  More fuel lit seems to require less air to get things heated up.  It also keeps the thing from going out when you're forging.