Redesigning my forge, asking for advice.

[Gendry]

So my forge has always worked well enough to do what I need, but I've never been able to achieve a welding temperature. I've always burned lump charcoal in it, and it will get a 1 inch bar to a very bright orange, but that is it.
Anyways, there is actually a coal mine a hundred miles out of town, so a buddy took me down with his half ton and we got a full truck box of coal (regular $50 for that, be we came on a weekend accidentally and since we came all that way they did us a favor to "sell it" to us. Seeing as it was such a "small" quantity they said they would pretend we were never there! Score.)

First of all, I can't believe the price difference between charcoal and coal. Just wow.
Second of all, I believe it is lignite coal, not positive. I forgot to ask at the time, but buddy thinks that's what it is. I know one of them is more ideal for smithing then the others, and I don't think it's this one. Is it still usable though?

Now, my forge:

Those are old pic's, I quickly realized that steel plate with a concrete backing did nothing to keep the heat in, so instead I made a 1 and a half foot diameter round block to put over top.

Anyways, I've already tore it apart a bit. I took everything out (except all the ash), and then pushed a much larger area clear of debris. Laid a firebrick in the back, and then 2 stacks of regular bricks along to the edge. So I have basically a 7 inch deep pit around my air inlet, and it' near a foot and a half in diameter... I packed the ash and old charcoal around the formation tightly, and poured some watery concrete along the edges to solidify it all, and now I suppose I have to build a bowl of concrete in there to contain it all.
I know I should use "refractory cement", but I went to home depot and they had tons of types of cement, but none that looked like any kind of furnace cement. I should note I make my cement mostly out of crushed up kitty litter, with some cement mix a bit of rock and some sand. I read somewhere once that kitty litter made a decent refractory cement, if that's true or not I do not know.

The forge is powered by a hair dryer which shoots air up the pipe below from a hole in the side. The bottom of the pipe has no cap, so I can pretty much regulate how much airflow there is to the fire by removing a few of the metal plates I stack ontop of the brick underneath the uncapped pipe.

So, yeah I want to make this into a coal burning forge which is capable of welding heat, I want to try some Damascus.

Any pointers you can give me? What obvious flaws are there in this plan?

 

[A.McPherson]

First off, I'm not a coal/charcoal expert, but from what I understand, if you can't get to welding heat with charcoal you aren't doing it right. Sounds to me like you need more air.

 

[TN metalman]

No expert here as well, but I can melt my steel with charcoal, given that there is a boatload of air. Granted, it's pine, but still.

 

[Stacy E. Apelt - Bladesmith]

Biggest problem I see is the lignite coal for forging. It will create tons of clinkers and sulfur. Not the best for making knives and surely not right for welding.

If you aren't getting a welding heat out of charcoal, something is wrong in either your fire or your technique. have a smith who forge welds on coal come over and see what is wrong.


Just out of curiosity, are you placing the iron on the coals or in the coals? That is usually where a smith goes wrong.

 

[Gendry]

Well I put it in the coals, but not so deep that the blower air is going to cool it, basically I just cover it.
Perhaps my fire tending technique is simply poor, I know I can get enough air because it's a hair dryer and if I didn't regulate it, it would be blowing most of the stuff right out of the fire pit lol.

 

[Stacy E. Apelt - Bladesmith]

I would think a hair drier isn't enough air. Too much air will not "cool" the blade. It will make the fire hole so hot it will melt/burn the steel.

For forging coal you want bituminous, preferably Pocahontas #3. Lump charcoal should work nearly as well.