4/1/24: One Must Imagine Sisyphus Sanding

Connor O -

Now that the basic shape of the helmet is done, the only sections I need to do are the furniture that a crest would be attached to, the carry handle at the rear of the helmet, and the brass trim around the edges of the helmet. For guidance on the latter, I consulted Michael Allenson once again, who provided some insight into how brass can be forged to shape.

Normally, steel can be softened by annealing. Steel is a “ferrous” metal, meaning it contains iron. A quick TL;DR of steel’s phase changes will show that carbon dissolves into iron lattice structures rather sloppily. A good analogy would be like how salt dissolves into water — with proper energy added (mixing in water’s case, prolonged heat in steel’s case), the salt readily dissolves between the H20 molecules up until a certain threshold, and then after that the excess salt will collect at the bottom. Steel’s equivalent of that threshold is known as its “eutectoid” point. Carbon is much the same in a mixture of iron, except, instead of dissolving into a free-flowing liquid, it dissolves into geometric patterns much like that of a diamond. Now, the steel I am using in this project is mild steel, which means it is hypoeutectoid, or has less carbon than the threshold. If mild steel was a bottle of salty water, it would be clear. No excess.

Hypereutectoid steel is what I use for knives. The trick is, the excess carbon can be mixed around and then frozen into place using a careful process of heat treatment. Heating the steel to a point where all carbon is free flowing and not locked into lattice structures is known as Austentizing the steel. That point is at about a orange-red heat, usually a few hundred degrees hotter than when it loses its magnetism. Within steel, there can be two different structures: Ferrite, which is a tough material (like concrete) made of iron atoms lacking carbon, and Cementite, a hard material (like glass) made of carbon atoms. If steel has not been normalized, or mixed, the cementite can form little veins around ferrite chunks. When steel turns from ferrite to austenite, the lattice structures change from body-centered (1 carbon inside a 8-atom iron cube) to face-centered (6 carbon on each face of the 8-iron cornered cube). Essentially, ferrite begins to suck up as much carbon from cementite veins as possible, which forms austentite.

From austenite, steel can go one of two ways: it can be rapidly cooled down, forcing the iron to “buddy up” with as many carbon as it can, creating martensite, or hardened steel, or it can be cooled down slowly (annealed), allowing cementite to reform albeit in smaller veins around smaller chunks of ferrite, forming a very fine collection of evenly sized grains known as pearlite. As my helmet is made from hypoeutectoid steel, there isn’t any excess carbon that I would be able to freeze in place — rather than there being a surplus of carbon that can be frozen into martensite, there is a shortage that I can only change the amount of pearlite in.

Now that I’ve data-dumped all of ferric metallurgy in a few paragraphs, I’ll get to the point. While steel needs to be normalized and annealed to be softened to prevent cracking, brass is the opposite. To anneal brass (as well as other non-ferrous metals), the metal is heated to a dull red and then rapidly cooled by dunking in water. I have no idea how the chemistry behind it works, I haven’t figured out how yet, but it definitely does work, and I had a chance to try it.

While I waited for my shipment of brass to get here, I decided it would be best to get started on the most absurdist, unremarkable, loathsome process of any project I ever do: sanding.

I was able to do most of the sanding using my belt sander shown below, which runs off a 1.5 horsepower 3-phase motor, but around the eyebrows I’m still waiting on a tool to ship that I can use. One of the funny things about polishing a helmet like this is that it gives no advantage. A sanded surface is more expensive, more likely to rust, and cannot be concealed or camouflaged. There is actually a scene in book 9 of the Aeneid where a character named Euryalus had his position given away during a stealth mission by his helmet being so shiny. Also, according to Mr. McMath, Hector is described in the Iliad as “κορυθαίλος,” or “with a flashing helm.” Historians believe that as polishing a forged helmet is such an arduous process, it was likely done for its psychological effect. A modern-day equivalent would be somebody being able to wreck a Bugatti just for a video. It shows off that they are so wealthy they can afford to put money and time into something expendable, and in this case, it advertises the efficiency of Rome’s military production.

Once the brass arrived, I was intrigued by one of the papers that came with it. On it, the manufacturer lists the percent composition, accurate up to the thousandths, and even some info about the tensile strength and maximum strain. I also bought a little extra in case I want to add brass trim to any of my future projects.

The brass I bought is 24-gauge C260 Cartridge brass, which is extra thin because it only needs to protect the wearer’s skin from the harsh corners of the steel helmet, not from an actual impact. It’s about 0.607 mm thick, which is around the thickness of around 8 sheets of paper stacked on top of one another.

Here’s a sneak peek at the brass furniture. This piece in particular serves as a slot to which the crest would be attached.

Roman Imperial Gallic "H" Helm- 18 Gauge Steel - Picture 1 of 4

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Comments:

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    alex_h
    Do you plan on testing the helmet?
    Mr. McMath
    Connor, I am happy to see that Homer, Vergil, and even Camus have made their way into your post! As regards shining, flashing armor in the ancient world dazzles, blinds, and intimidates the enemy. For an interesting anecdote on the values of different armors, Glaucus and Diomedes around Iliad 6.119 put their duel on hold and exchange armor as a show of good hospitality. Diomedes gives his brazen armor to Glaucus, who gives his golden armor in return.
    valeria_r
    Interesting that sanding is such a dreadful process and yet it doesn't have the clearest purpose. At least it looks good!
    connor_o
    I do not plan on testing this armor as at the beginning of the project I was still developing my skills of welding. If it was made from one piece I would be a lot more confident.
    connor_o
    Mr. McMath, sometimes I forget that the Iliad has some ironic scenes such as that. Two guys come up to one another to kill each other and end up being like, "Oh nice hat" and do a little trade. Proof that the human psyche hasn't changed, only our technology.

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