New forge

I've been wanting to build a new forge for several years.  I finally got around to it, then forgot to show it off, so here it is:
It's roughly 2ft by 2ft by 18in tall, plus the legs.  The walls are 410 that I welded together, and the legs are riveted to the walls.  My apprentice (who is a better welder than I am) welded the cuff at the top and around the base of the lid.  That protects us and the duraboard from abrasion.  The inside is lined with fiberfrax duraboard, which (with some lung protection) can be cut on a regular table saw.  So this can get just as hot as the old forge, but without anywhere near the mess or airborne particulates of Kaowool.


Anonymous said…
What kind/size of venture burner are you using? Also, what psi do you run it at to reach hardening temperatures? Also, what psi do you use for tempering? Does your burner go in the side of the forge or up through the floor of the forge?
I use a Ron Reil style burner, though there are some good burners you can buy off the shelf these days. I use a high pressure propane regulator, though the psi matters less than the temp inside the forge. Your question is a little like asking how much current is going through the coils in your home oven when you bake cookies. Most cooks don't know, they just watch the temperature. My burner goes in the back of the forge. Driving it from the bottom is a safety issue. If something melts (this forge can melt brass without even trying) it would drain into the burner, making a molten metal potato cannon.
Anonymous said…
Melting brass? If that is being done with a single burner that sounds impressive. I have a generic 3/4" venturi burner made from pipe stock I use for raising; I was under the impression that heating a furnace sized space would require multiple burners or one huge one. I have located a source for the same refractory board and have given thought to fabricating a similar thing specifically for heat treating, but I am not sure if my current burner would do the job. Is there a trick to arranging or using some kind of sealant on the refractory board to reach those temperatures? I'm a relatively new Scadian from Aethelmearc by the way. I have been experimenting with making armour for several years and recently moved away from making welded pieces to making raised ones after successfully raising a couple simple helmets. I really want to take it to the next level and start experimenting with making tempered pieces.
The commercial gas forges are mostly marketed to blacksmiths, who need to get a smallish piece up to welding temperature quickly, so they load up on the burners. I think some of it is hype to help justify the prices though. A 12 cylinder engine isn't necessarily more powerful or faster than a well designed 8 cylinder.

Burner and insulation efficiency make a big difference. I didn't use a sealant of any kind in this forge, just hand fit the pieces together and they wedge themselves in place. I should post a shot of the inside for you.

Raising helmets is no small task! Do you have pics or a blog?
Anonymous said…
No I don't have pics or a blog, I just made a simple conical helmet and a relatively simple round Greek/Thracian helmet. Both were done in .048 for ease of making and cost. I ended up scrapping the conical helmet because it came out really crude and wrinkly, but I applied the lessons learnt from that to make the Greek-ish helmet which turned out ok. At the moment I'm working on a 0.075 cone shaped pilos helmet. Basically really simple non-complex stuff so far.I have sheets of 1050 laying around I bought from Admiral steel a couple of summers ago that I have never used which I would like to turn into a 1450's Milanese harness someday, like the ones in the San Romano paintings. Does the Lid on your forge simply close over top and act like and extra layer of insulation? What safety considerations does one want to consider with a lid, does it need vents or can the box just be closed up to trap heat?
I highly recommend keeping some kind of record of your work. It can be amazing how much better you get, and how much more you learn from writing things down and taking a few pictures.

As for the lid- it's two layers of duraboard, so it insulates quite well. My apprentice welded up a frame for it, and a sort of a cap for the top of the forge so the pieces of duraboard don't rub against each other. When the forge is running the lid has to be open a little to let the expanding gas out, or the back pressure will extinguish the burner. When I'm annealing a piece I'll step down the gas pressure, cooling it slowly until I can't run the burner any colder, then close up the lid, and let it cool down the rest of the way as slowly as I can. The forge insulates well enough that the process can take a couple hours, which softens the steel quite well.
Anonymous said…
Could you post some more photos of that forge? I just ordered a bunch of that refractory board and I would like to see more of your forge so I can figure out how its put together. Did you use two layers all around?

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