You all have heard of the JABOD forge, Well for those without the "B" in JABOD. There is an alternative.  JAHIG (Just A Hole in Ground) forge.   Today, I had a need for a forge that could heat the length of a 20" blade. Evenly, without having to slide it back and forth through the fire.  So, I dug a trench in the ground long enough to accommodate the blade.  I used a three legged tuyre to allow even airflow over the length of the fire.  3 pieces of 11/4" tubing about 14" long, installed like chicken toes, in a side blast.  Fired it with charcoal, and air was a hair drier.  Worked very well.  

Forge on left, quench tank on right. 

The large flat rock to left of forge is where the three air pipes meet together.  Hair drier rested on the chunk of charcoal to the far left, pointing toward the flat stone.  Heated the blade to non magnetic in about 15 minutes, with a very low blast.  

 Quench tank is wood box, with water, and an inch of oil on top. 

I cleaned out the "fire box" to get a picture of the tyure. You can see the three openings in the bottom of the "fire box".

And here is what is under the rock.

I found that I could turn the hairdrier left, right, center, to control the blast over the length of the fire. and could move it closer, or farther to control the amount of air.   Nothing fancy, and works very well.