Forge welding with charcoal

[Seek]

Hi all,

 

When I was at the blacksmith shop lastmonth, he demonstrated how he made a forge weld. He uses normal coal. He build a large mound of coal, let it burn through, created a cavity and inserted the iron pieces. You could see very well how the surface of the steel got fluid. He also used very little air, but it was like an oven, very hotin that cavity.

Now I am back in my own little corner in the back of the garden. I use charcoal (don't want to pester the neighbours). I have a couple of firebricks around my brake disc. Air comes from the botto. The firebricks make the fire about 7-8" deep. I pile it up and then have to crank up the air to get it really hot. Then I push the steel bars in the pile of charcoal, hopefully in the middle of the heat. But I can';t see anything in there. So from time to time I pull it out to have a look. It is a short stretch from hot enough to sparklers, so I feel a bit uneasy with this procedure.

Another point is that I must blow a lot of air into the fire to get it hot enough. Much more then the blacksmith was using with his coal fire. This blows around a lot of ash, which also settles on the steel parts. Any problem in that?

I am still trying to make some hinges, quite a few trials and errors until now. The welds aren't great, but it isn't very critical in this aplication, so I don't worry too much about it. But I would like to get better at this forge welding. Any tips how to treat a charcoal fire for good forge welding?

 

[ThomasPowers]

Is your forge designed for it?  Is your blower appropriate for it?  What size charcoal are you using?  Generally charcoal takes less air than coal---or at least gentler.  Are you raising the temp slowly and without oxidizing the work piece?  More hurry, less progress.

All the Frankish/Viking pattern welded swords were welded up using charcoal.  Traditional Japanese swords are still forge welded using charcoal---in fact you might want to look up the section on making a katana on youtube "Living Treasures of Japan" National Geographic and see how their fire/set-up  looks.

[Seek]

My forge isn't really designed! I think I made quite a mess of the design, but right now it is what it is. The blower is one of these bouncy castle things. I run it on half power at the moment, with an old fashioned big rheostat. The blower is blowing from a little distance into a piece of tubing, which is afixed to the bottom blast tuyere. So, I did everything to reduce the pressure of the blast.

The idea of my forge is here. In the meantime I have made the fire area smaller, set the bricks closer together.

https://www.youtube.com/channel/UCZ3RNXESpIKrm1d5u5p2xbA

Good idea about heating up slowly. that is something I didn't think about.

I think my next forge will be a sideblast. i must still figure out how and where.

 

 

[ausfire]

Glad to see this topic.

I use a side blast hand cranked forge with charcoal. Welding has always been a hit/miss affair for me. I find that you need to pile the charcoal up to avoid too much oxidation and use multiple and liberal applications of borax to be successful. Lots of brushing to remove scale.

I never include welding in my demos for two reasons: too many sparks flying around, and lack of confidence that the weld will take.

And as seek points out, it's a thin line between not hot enough and sparkler time! Wii be interested to hear other members' comments on this one.

[Frosty]

A bounce castle blower would run at least 10 charcoal forges with air to spare. Hit garage, yard, etc. sales and buy an old blow drier. It's not practical to get charcoal to cave up for you, too dry so how about putting a couple bricks over the top of your brick fire pot thingy? Turn that baby into an oven you can shovel charcoal into the front.

Bust your charcoal into pieces smaller than your thumbnail. The more surface area the faster it'll react to the oxygen coming in making more heat in a shorter time AND consuming more oxy faster. More heat, less free oxy to your steel. Hmmmm? If the pieces are too large you have to pump more air to get the heat but you're also blowing unconsumed oxy through the stack. Also the unconsumed oxy represents a quantity of air that isn't HOT so it's cooling the hot stuff.

Don't pull your work out of the fire to check it's temp, slide your shovel along the stock and lift it so you can peak under it and see the steel.

Aus: Same to you, small pieces of charcoal and ease back on the blast. If you judge your fire correctly you don't need flux, the little bit of ash or unburned charcoal that may get into the joint is insignificant.

Frosty The Lucky.

[Charles R. Stevens]

A visit to Steve Sells' shop renfoced a few things, clean steel, clean fire, flat surfaces (a good firm tap takes care of mating the serfaces well) a good soak to make dang sure it's hot, clean serfaces, clean fire....

A36 is mystery metal and some times refuses to weld, charcoal doesn't like bottom blasts, and to much air sends embers flying and cools the steel and fuel. I have one I have been playing with that has a manual double action bed inflator, a half inch tuyere and a 3" deap fire bowl. It routinely melts nailes I mis in my pallet wood charcoal to slaggy little lumps  

[Seek]

Great! Thanks for all the tips.

 

One more question. What is a fast way to chop down charcoal? One by one with a hatchet on a chop block? A big hammer, and putting the charcoal in a bag? I find that just burning makes them a lot smaller too. Lower down in the fire the pieces are smaller then higher up.

 

[dancho]

I work  with char coal ONLY  for many years.  This is in my view definetely the best fuel for forge welding and working with steel and just as sustainable local resourse.

My experince:

1) Side blast is the best.  Bottom blast will work but not as good.

2)Average size of char coal is wallnut.  Smaller sieve away (sieve diameter 5 mm). Bigger crack by hands in gloves..

3) Not too much air.   Bring the to the heat slowly step by step.

Good luck!

 

 

 

[ThomasPowers]

how to size charcoal---the traditional way was APPRENTICES!   I know a fellow that has a piece of catwalk formed of strips of steel oriented vertically,  He pushes charcoal though it to size it but a lot is wasted as dust from the crush.

[Seek]

Anyone want to apprentice? You can sleep in the shed and share the meals with the dogs....

[Frosty]

Put it in a cloth sack and use a frying pan, don't get carried away. The unrecoverably fine dust can go into the pile when you char the next load, go into the garden or on the lawn. Really powder it and add it to your iron finish. It'll make the pieces very black and you can rub the high spots for highlights.

Frosty The Lucky.

[Seek]

Frying pan! That's a good fine sieve too.

I think I still have some cloth sacks around. So now I have plenty of things to try. But first I go to Rome for a long weekend, ain't too bad either 

 

Oh wait, I am mixing up English words agian, a frying pan is something else then what I had in mind. But I understand now.

[Wayne]

Frosty,

How much difference does adding powdered charcoal to your finish do? Normally I just use oil or bees wax but I have been looking for something darker

Wayne

[Nick O]

you could try and add some coal to your charcoal I would put a hand full in probably 2lb of charcoal its something that will just have to be experimented with. surly your neighbors wouldn't mind if you burned just a little coal

[Charles R. Stevens]

Charcoal will, as mentioned break up as it burns and the smaller stuff works its way down. Traditional Japanese and British charcoals made from managed coppice wood lots are close to ideal. As are the coals from a live fire. 

[Sweany]

google Japanese box blower plans. The box blower works well with charcoal. Charcoal forge's are usually longer and deeper than a coal forge., again google.

[Charles R. Stevens]

Muchof the comertial charcoal I see is not fully "coked" so as to provide a "smoky" product. I use constriction wast and pine wood pallets, and usually take a page from Frosty and Tomas and just keep a small fire going. 

[Grafvitnir]

https://www.youtube.com/watch?v=_jwUl3Z2-cc

[Charles R. Stevens]

I do have a bottom blast trench forge that I can feed raw wood to, and the flames are rather impressive, but it uses way more fuel than my simple side blast.

a bowl that is 3-4 inches from the top of the tuyere with a pile of burning coals of about the same with just enough air to make the center of the pile painful to look in to (high yellow to write) will do you, but low yellow and a good soak is safer. Either way make shire the steel is heated evenly all the way threw. 

 

[Frosty]

On 12/17/2015 at 3:52 AM, Wayne said:

Frosty,

How much difference does adding powdered charcoal to your finish do? Normally I just use oil or bees wax but I have been looking for something darker

Wayne

My first batch of finishing wax was taken from Alex Bealer, "Art of Blacksmithing" which is wax, turpentine and soot. It's very black but I don't know if Mr. Bealer's "reasons" are accurate. He was writing down what he'd been told so I guess it really isn't on him. He said in the book the soot filled the pores of the heated iron and trapped the wax as it cooled making a durable finish.

I don't know if soot filling the pores is true but it's very black and made for nice highlights. I used paraffin and have had plant hangers outside here for going on 18 years with no rust on any of them. Soot might be the secret, I don't know.

I tried powdered charcoal once and it seemed similar to soot but I haven't had anything finished with it hung outside so can't say about it's durability.

Frosty The Lucky.