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Building a Frame Saw
Forging a Copper Kettle
Making a pair of leather work boots
Forging and Fletching a Bodkin
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Friday, March 8, 2013


As the day looms nearer for  casting the fittings of a long project, the time finally came to explore this strange and foreign art. After seeing Jim Kelso's presentation on Japanese water casting last fall, this has been something of a curiosity and desire to learn more of. Subtle interactions between alloyed copper and a host of plants and compounds produce some of the most beautiful works of art I have ever seen, not to mention the delicate engraving and inlay coupled with their natural lustre.

Such pieces are far beyond my level of skill and understanding, not to mention equipment to produce. As such, it is back to the most basic principle I must turn. For the piece, a Claidheamh Mòr, the fittings will be cast   from recycled brass ammunition casings. To practise the refinery techniques and to learn more about the process, I first had to gather the necessary materials.

First and foremost, I needed a crucible. Instead of ordering one, I decided to recycle some of the old and forgotten bits lying around the shop. In a shadowed shelf, I came across a collection of two dozen or so industrial gas cylinder covers used to protect the valves in shipping. Of course, those tanks to which they belonged are long gone, and they happen to be about the perfect size.

I cut the cap midway across the circular hole. For one, that brings it to the perfect height to fit in my small propane forge, and for another it allows the top edge to be folded down as a lip to guide the molten metal. This picture is deceiving, as the vice did not hold it there well enough to use the chop saw. Instead, I was forced to use a compressed air cut off disk and manually separate the two pieces. This took about half an hour, but came out clean enough.

With the two halves, I discarded the threaded end for use in another project somewhere in the distant future, and kept the now crucible shaped top. Because there are about thirty layers of paint covering the outside, I had to sand them off before firing it. Similarly, the rust accumulation on the inside was taken care of by hand. I have heard that a layer of rust on the inside of an iron/steel crucible will help prevent the casting metal from sticking, but I saw no practical difference, although I have here the wrong kind of rust.

Because the bottom is fairly rounded, I had to forge it flat. For one, it would not fit in the forge as it was, and for another it was largely unstable. While I hammered, I noticed that there is a welded plug in the crown, which I had to be careful not to over fatigue.

Flattened to the point of relative stability, I moved onto roll down the top edge. This was a tricky operation that involved using the largest bench vice I have and a great deal of effort bending it. Hammering alone proved futile, at least until it was bent enough that I could hit it down and to the side, forcing the brunt of the energy into the anvil instead of straight down into nothing. Another half an hour or so and it was ready for a test firing.

Typically, there is another brick lining the floor of the forge, which is hiding in the left side of the above picture. That extra inch, however, made the crucible too tall to fit inside. Since I am not doing any welding, the danger of the insulation being eaten away instantaneously is fairly small. Later on, I managed to spill some aluminium on the floor, but it rolled around and eventually cooled to no ill effects. One thing most notable about running the forge this way is that the chamber comes up to heat almost immediately. The brick absorbs vast amounts of energy in comparison, and takes anywhere from ten to thirty minutes to come to a steady state. The picture above was after about thirty seconds.

Lastly, I prepared a bucket of water to pour the casting into. Traditionally, I would use a cloth, but I only had paper towels on hand so I used those instead. With a bit of wire, I fastened the towels around a cutting of pipe and left a little bit of slack in the surface to make it concave. The idea is, or so I understand, to pour the liquefied metal down through the water and onto the cloth. The water cools the metal enough to prevent the cloth from burning, but not so much that it solidifies before forming a nice round ingot. Due to my inexperience, I only managed to get two small round ingots out of the day. The rest turned into some strange and interesting shapes. This was due, I suspect, to the level of water. I had the cloth too low, so the metal cooled too much and piled up on itself.

The first smelt was of four spent casings in the crucible for proof of concept. With the crudely fashioned set of wire tongs, I slid the lot of it into the forge and let sit. At first, I was weary that it would not get hot enough to melt, but a few minutes later I had a pool of yellowy metal beaded in the bottom of the crucible.

This is the result. Not much, but enough. Left in the crucible is about half this in slag. Having sat around for their fair share of years, the casings were extremely dirty and somewhat corroded. A major loss it was not, and there will certainly be more when I do a larger consolidation, but this was worth the effort. Here, the brass is far more pure than before, and can be re-cast into the hilt components without worrying about the quality of casting from a metallurgical standpoint.

With one attempt under my belt, I decided to dive right in. I had a sheet of scrap aluminium that had been laser cut into many things, leaving behind a gnarled old bit of unusable material. Instead of discarding it or recycling it, I decided to do my own recycling on it. In the coming days, I hope to cast it into something useful, but for now it is merely practise.

First, I aired on the side of caution and cut off only a few bits from the sheet and had at it. Like a dream, it melted quickly and evenly, leaving a fat ball of silvery metal in the crucible. After fitting the tongs around it and carefully pouring into the water, the result was promising.

Despite the strange shape, it was the second best of the day. This augmented shape is again likely because I had too much water in the bucket, although I am not certain. Perhaps it is an inherent property of aluminium. Soon, I will melt copper and not the differences. As best I can tell, this reacted in a very similar manner to the brass.

After this, I continued to cut away at the sheet and pour similar sized ingots until I decided to really push the limits of the forge, crucible, and bucket. Along with the above ingot and the other three I cast, I cut up the remaining aluminium and dropped it in the fire. In retrospect, this was far from a good idea, as it eventually overflowed and spilled on the forge floor, but it was worth the result.

Far from useful and consolidated, the product was an alien world of bubbles and bridges shining through the water back at me. So much metal poured into the bucket that the water inside began to boil, giving off plumes of steam and shimmering waves of heat distorted in the iridescent shop light. When last the surface became still, this is what I saw.

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