By request, here’s a post about the simple fire-brick forge that I made.
First of all, this is not designed to be a blacksmithing forge. I guess you could do some small blacksmithing with it, but I’m really just making it to heat treat knife blades.
The idea is to stack up insulating fire bricks in such a way as to form a small chamber. Inside that chamber, you can heat your steel with a torch, and it will retain its heat better because it’s not losing to the air like it normally would. This allows you to heat an entire knife blank with a simple plumbing torch.
So, first thing was to buy some fire bricks. I went to a wood stove store and bought several of these for three bucks apiece. They’re approximately 8″ x 4″ x 1.5″:
Then, to make things a little slicker, I cut them. This step wasn’t necessary, but it allowed me to make a small forge with only 4 bricks instead of the 7 that I started out with.
To cut them, I mounted up a cut-off wheel into my drill press, and using the tabble, scored a cut around the perimeter of the brick, approximately 0.25″ – 0.5″. Once it was scored, I was able to snap the bricks in half.
Now for the assembly:
Here are all four of the bricks. One is not cut, one is cut along the length, and two along the width.
You end up with an inner chamber just the right size for a medium-sized knife blank, and by moving the bricks around, you can easily make up to 3 openings — 2 on the ends, and one in the top.
Using it is easy — stick the lit torch in one opening, and open up at least one more to get things flowing.