The brick is a kiln insulating brick rated at 2600 degrees, NOT a standard firebrick. It's very soft. I hollow them out by drilling two holes at the ends (with a brace and bit no less) then taking a drywall knife to cut away what's in between. The whole process takes about 3 minutes. You could hollow it out with a spoon if you really needed to.
You can buy them
Here There's a hole in the side that's just big enough for the torch nozzle, about 1/3 of the way in from the front. That forge has a second torch 1/3 in from the back as well, but a smaller chamber only needs one torch.
I ignite the torch, stick it in the hole and let the forge warm up for a few minutes. It doesn't take long. Then I stick the blade/steel in the chamber.
If you're forging your blades, I don't think I need to tell you what to do next
For normalizing after forging I head the blade up to critical (the point where a magnet is no longer attracted to it) then take it out and let it cool. Then repeat a few times.
For annealing, I'd take it up to critical then cover it in a bucket of sand. Not really a good way to get a full anneal, but I'm cheap. Hardwood ashes with some hot coals thrown in would work better, or you could spend the $5 for a proper medium (again, I'm cheap).
To harden, take the blade up to critical and quench it in your favorite quench oil. I use corn oil b/c I don't like the smell of used motor oil. For everything but big blades the corn or veggie oil will work well. I'm mostly using 1095 steel which needs a very fast quench. Technically it's a water-hardening steel and it still hardens properly with the veggie oil.
After quenching, test the blade with a file. The file should skate right across. If it doesn't you probably didn't get the steel up to an even critical temperature or didn't get it in the quench tank fast enough. You can put it back in the forge and repeat the hardening step, or, more properly, go through and normalize it again, then harden.
After a proper hardening, clean off the oil and hit it with some sandpaper to get it down to bare metal (at least the edge). Temper immediately. I use a toaster oven I picked up for $10... with a oven thermometer so I know the real temperature, but you can temper blades with a torch or even on the stove top. You want to heat the blade up to a straw yellow color. It doesn't matter if the spine of the blade goes beyond that, but the edge shouldn't. It's best to let the blade cool slowly after tempering, but if you're using something other than an oven you'll probably have to dip it in water to prevent the edge from getting hotter.
After that you do your final grind on the knife. I leave lots of sacrificial steel to grind off. That way I know all my forge marks are gone in the final knife, but other guys like the marks and don't leave as much extra steel.
I take my blades to a 600 grit belt on the grinder (another el cheapo thing) then go to the bench and hand rub to an even 400 grit at an angle to make sure I got all the deeper scratches out. Then I switch to 600 grit with oil, going one direction only the full length of the blade. That gives me a nice satin finish. If you want it more polished that that go to finer grits... with oil to help prevent them from clogging. You'll go through about
half the sandpaper if you use oil.
That's the whole process other than the handle. Total cost to get me started was less than $50. The grinder I picked up after a few knives for cheap, but getting that first thing would be agood idea.
Topic: heat treat by torch (Read 1181 times)
