I took nine hundred and ninety-five photos of this little event, culled out the best- or at least the good ones- and still had seventy-two. That's a bit much for even a Guild posting, so I trimmed that even further to a mere twenty.
I left 'em sorta large for detail, but most everyone's on broadband, so hopefully nobody chokes.
Now, this event was a demonstration, put on in part by the owner of a local steel-fab shop called Metal Magic. They hosted an expert from Houston, Texas, who had made the trip up, with stops for other demos along the way, including one in Denver, as I recall. This fellow, Pat, a second-generation iron guy, has a foundry in Houston and was very knowledgeable about his craft.
Most of the hardware shown was fabricated at Metal Magic, including the entire cupola (the "melting pot") and the ladles.
The rest of the participants are, as I understand it, an "artisan collective" sort of group from up in the Palmer-Wasilla area (north of Anchorage.) They all seemed to know what they were doing, everyone knew when to do, when to help and when to stay out of the way. A fun group I might have to chase down and chat with a bit more.
Anyway, the imagery:
-This was the initial firing of the cupola. The chamber was charged with coke, and broken scrap iron, lit off- I'm not sure how, it was already going when I got there- and then blown with a large squirrelcage fan. The wide band you see is an air chamber, with each of the caps being where the air can blow into the charge.
There's two tap holes, one shown here, and basically, once liquid iron starts to drip out, that charge is ready for tapping.
-These are the molds, arranged so there's plenty of room for the ladlemen (or ladlepersons in some cases) to move around for the pour. The sand is of course a safety thing, so any spilled hot iron- and yes, there were more than a few spills- wouldn't spall and damage the concrete, or go running along and try to melt it's way into somebody's shoe.
The molds are plain sand- they said local glacial sand- mixed with a commercial binder not unlike an epoxy. Multi-part molds were banded together with crate strapping.
-This doodad is basically just a big propane burner, used to preheat the ladle prior to tapping the cupola. That keeps the iron hotter, longer, giving more time to pour and I think reducing slag as well.
The ladle is just a five-gallon galvanized steel pail, in a custom-fit cradle, and lined with two or three inches of refractory- a mortarlike material designed to resist high temperatures.
-Tapping the cupola. There's a passage in the chamber's internal refractory lining, blocked by a wad of fireclay, or a similar material. When the charge is ready, the dam is chipped out with a bar, and the iron allowed to pour into the ladle. Note the "sluice" is also lined with refractory.
-Once the ladle is full, the taphole is once again blocked with a wad of clay, or sand, which is mashed into place. No quarter-turn valves here.
-Two people then carry the ladle to the molds. One simply supports it, the other has handles on the ladle arm to allow it to be poured. The third person there, with the scraper-like thing, is skimming slag- the darker material shown at the top of the iron. She's simply pushing it away from the spout of the ladle, so the mold gets clean iron.
-I don't know how much a full ladle weighed, but it was enough to pour several molds. The one in the back probably took forty pounds of iron all by itself. (We'll see that finished later.)
-Smoke, flames, sparks, molten iron... who needs fireworks?
-Tap it again for another pour.
-Molten iron is actually pretty runny. Not quite water, but it's sure not "syrupy" like some people think. It cools fast though, and the cooler it gets, of course, the more viscous it gets, which is why sometimes molds don't fill all the way, or have crases and folds in the finished part, where rapidly-cooling iron was forced into a space by the weight of the iron above it.
-Charging the cupola again. Dumping in a bucketful of broken iron, then dropping in another charge of coke. Start the blower back up and wait another five to ten minutes.
-Okay, that's just cool. Or rather, very, very hot.
-On most of these "open" molds, the heat would char the binder in the sand, which would outgas and catch fire. As noted earlier, I tried to play with the exposure a bit, to try and capture the texture of the flames. Fortunately I have a very good camera that is thankfully often smarter than me.
-Once all the molds are filled and the ladle emptied, the cupola is dumped. There's a swing-away panel at the base, which is knocked free, and then the sand floor of the chanber is chipped out with a pickaxe. The white-hot coke, slag, and liquid iron falls out the bottom, where it can be quenched, and in some cases reused.
The refractory lining of the cupola has to be replaced- or at least repaired- every couple of firings. This isn't a process you just decide to go do on a whim when you need a special part real quick.
-By this time, some of the first molds are cool enough to pop open. Here's that "NOTW" mold I mentioned yesterday, which came out well. The mold was overfilled, so it was kind of a blobby plaque rather than an outline, but the lady that had the mold made appeared very happy with it.
-Here's that big mold I mentioned. Metal Magic's company logo is an anvil with crossed hammers behind it. Scott- the owner and founder- made a mold using a real anvil and two actual hammers, to make a 3D version of the logo. It's hollowed on the backside, to allow for shrinkage, but it turned out great on the front.
-After the coke pile cooled, you can see that not everything had a chance to melt before it was dumped. Bigger pieces like these can be collected and remelted, and the larger chunks of coke can be used again, as well.
-One of several art peices done by the various artists. Yes, that's a crescent wrench and an old flattened sock. She apparently didn't find it humorous when I suggested she'd made a "sock-it wrench".
(It's two separate pieces- the round part in the center is the "gate", the channel for the iron to pour in to fill the mold.)
-This fellow cast a pair of copies of an old cap pistol. They came out pretty well, actually.
