Lie-Nielsen Toolworks
Published Dec 8, 2023See the process of making the Lie-Nielsen No. 62 Low Angle Jack Plane: initial pattern making; pouring the castings at the foundry; machining, grinding, and finishing all the parts; final assembly, inspection, and wrapping.
April 16, 2024
January 3, 2024
QotD: Iron and steel
I don’t want to get too bogged down in the exact chemistry of how the introduction of carbon changes the metallic matrix of the iron; you are welcome to read about it. As the carbon content of the iron increases, the iron’s basic characteristics – its ductility and hardness (among others) – changes. Pure iron, when it takes a heavy impact, tends to deform (bend) to absorb that impact (it is ductile and soft). Increasing the carbon-content makes the iron harder, causing it to both resist bending more and also to hold an edge better (hardness is the key characteristic for holding an edge through use). In the right amount, the steel is springy, bending to absorb impacts but rapidly returning to its original shape. But too much carbon and the steel becomes too hard and not ductile enough, causing it to become brittle.
Compared to the other materials available for tools and weapons, high carbon “spring steel” was essentially the super-material of the pre-modern world. High carbon steel is dramatically harder than iron, such that a good steel blade will bite – often surprisingly deeply – into an iron blade without much damage to itself. Moreover, good steel can take fairly high energy impacts and simply bend to absorb the energy before springing back into its original shape (rather than, as with iron, having plastic deformation, where it bends, but doesn’t bend back – which is still better than breaking, but not much). And for armor, you may recall from our previous look at arrow penetration, a steel plate’s ability to resist puncture is much higher than the same plate made of iron (bronze, by the by, performs about as well as iron, assuming both are work hardened). of course, different applications still prefer different carbon contents; armor, for instance, tended to benefit from somewhat lower carbon content than a sword blade.
It is sometimes contended that the ancients did not know the difference between iron and steel. This is mostly a philological argument based on the infrequency of a technical distinction between the two in ancient languages. Latin authors will frequently use ferrum (iron) to mean both iron and steel; Greek will use σίδηρος (sideros, “iron”) much the same way. The problem here is that high literature in the ancient world – which is almost all of the literature we have – has a strong aversion to technical terms in general; it would do no good for an elite writer to display knowledge more becoming to a tradesman than a senator. That said in a handful of spots, Latin authors use chalybs (from the Greek χάλυψ) to mean steel, as distinct from iron.
More to the point, while our elite authors – who are, at most dilettantish observers of metallurgy, never active participants – may or may not know the difference, ancient artisans clearly did. As Tylecote (op. cit.) notes, we see surface carburization on tools as clearly as 1000 B.C. in the Levant and Egypt, although the extent of its use and intentionality is hard to gauge to due rust and damage. There is no such problem with Gallic metallurgy from at least the La Tène period (450 BCE – 50 B.C.) or Roman metallurgy from c. 200 B.C., because we see evidence of smiths quite deliberately varying carbon content over the different parts of sword-blades (more carbon in the edges, less in the core) through pattern welding, which itself can leave a tell-tale “streaky” appearance to the blade (these streaks can be faked, but there’s little point in faking them if they are not already understood to signify a better weapon). There can be little doubt that the smith who welds a steel edge to an iron core to make a sword blade understands that there is something different about that edge (especially since he cannot, as we can, precisely test the hardness of the two every time – he must know a method that generally produces harder metal and be working from that assumption; high carbon steel, properly produced, can be much harder than iron, as we’ll see).
That said, our ancient – or even medieval – smiths do not understand the chemistry of all of this, of course. Understanding the effects of carbuzation and how to harness that to make better tools must have been something learned through experience and experimentation, not from theoretical knowledge – a thing passed from master to apprentice, with only slight modification in each generation (though it is equally clear that techniques could move quite quickly over cultural boundaries, since smiths with an inferior technique need only imitate a superior one).
Bret Devereaux, “Collections: Iron, How Did They Make It, Part IVa: Steel Yourself”, A Collection of Unmitigated Pedantry, 2020-10-09.
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November 15, 2023
“If you cannot make your own pig iron, you are just LARP’n as a real power”
CDR Salamander talks about the importance of an old industry to a modern industrial economy:
We probably need to start this out by explaining exactly what a blast furnace is and why it is important if you want to be a sovereign nation.
First of all, what it does;
The purpose of blast furnace is to chemically reduce and physically convert iron oxide into liquid iron called “hot metal” The blast furnace is a huge, steel stack lined with refractory brick where iron ore, coke and limestone are charged into the top and preheated air is blown into the bottom. The raw materials require 6 to 8 hours to descend to the bottom of the furnace where they become the final product of liquid slag and liquid iron. These liquid products are drained from the furnace at regular intervals. The hot air that was blown into the bottom of the surface ascends to the top in 6 to 8 seconds after going through numerous chemical reactions. Once the blast furnace is started it continuously runs for four to ten years with only short stops to perform planned maintenance.
Why are blast furnaces so important? Remember the middle part of Billy Joel’s “Iron, coke, chromium steel?”
“Coke” is in essence purified coal, almost pure carbon. It is about the only thing that can at scale make “new” or raw iron, aka “pig iron”. Only coke in a blast furnace can make enough heat to turn iron ore in to iron. You can’t get that heat with an electric furnace.
Pig iron is the foundation of everything that follows that makes an industrial power. If you cannot make your own pig iron, you are just LARP’n as a real power.
It takes a semester at least to understand this, but here is all you really need to know;
Primary differences
While the end product from each of these is comparable, there are clearly differences between their capabilities and process. Comparing each type of furnace, the major distinctions are:
Material source – blast furnaces can melt raw iron ore as well as recycled metal, while electric arc furnaces only melt recycled or scrap metal.
Power supply – blast furnaces primarily use coke to supply the energy needed to heat up the metal, while EAFs use electricity to accomplish this.
Environmental impact – because of the fuels used for each, EAFs can produce up to 85% less carbon dioxide than blast furnaces.
Cost – EAFs cost less than blast furnaces and take up less space in a factory.
Efficiency – EAFs also reach higher temperatures much faster and can melt and produce products more quickly, as well as having more precise control over the temperature compared to blast furnaces.
We’ll get to that environmental impact later, but the “Material source” section is your money quote.
Without a blast furnace, all you can do is recycle scrap iron.
You cannot fight wars at scale if all you have is scrap iron. You cannot be an industrial hub off of just scrap iron. If you are a nation of any size, you then become economically and security vulnerable at an existential level. I don’t care how much science fiction you get nakid and roll in; wars are won by steel, ungodly amounts of steel.
Where do you get the steel to build your warships? Your tanks? Your factories? Your buildings? Your factories?
If you can only use scrap, then you are simply a scavenger living off the hard work of previous generations. Eventually you run out. You will wind up like the cypress mills of old Florida where, once they ran out of cypress trees, they simply sold off the cypress lumber their mills were constructed of … and then went bankrupt.
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October 26, 2023
QotD: Making steel
So we are going to limit ourselves here to just carbon and iron. Now in video-game logic, that means you take one “unit” of carbon and one “unit” of iron and bash them together in a fire to make steel. As we’ll see, the process is at least moderately more complicated than that. But more to the point: those proportions are totally wrong. Steel is a combination of iron and carbon, but not equal parts or anything close to it. Instead, the general division goes this way (there are several classification systems but they all have the same general grades):
Below 0.05% carbon or so, we just refer to that as iron. There is going to be some small amount of carbon in most iron objects, picked up in the smelting or forging process.
From 0.05% carbon to 0.25% carbon is mild or low carbon steel.
From about 0.3% to about 0.6%, we might call medium carbon steel, although I see this classification only infrequently.
From 0.6% to around 1.25% carbon is high-carbon steel, also known as spring steel. For most armor, weapons and tools, this is the “good stuff” (but see below on pattern welding).
From 1.25% to 2% are “ultra-high-carbon steels” which, as far as I can tell didn’t see much use in the ancient or medieval world.
Above 2%, you have cast iron or pig iron; excessive carbon makes the steel much too hard and brittle, making it unsuitable for most purposes.Bret Devereaux, “Collections: Iron, How Did They Make It, Part IVa: Steel Yourself”, A Collection of Unmitigated Pedantry, 2020-10-09.
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October 21, 2023
October 10, 2023
QotD: The production of charcoal in pre-industrial societies
Charcoaling solves this problem. By heating the wood in conditions where there isn’t enough air for it to actually ignite and burn, the water is all boiled off and the remaining solid material reduced to lumps of pure carbon, which will burn much hotter (in excess of 1,150°C, which is the target for a bloomery). Moreover, as more or less pure carbon lumps, the charcoal doesn’t have bunches of impurities which might foul our iron (like the sulfur common in mineral coal).
That said, this is a tricky process. The wood needs to be heated around 300-350°C, well above its ignition temperature, but mostly kept from actually burning by lack of oxygen (if you let oxygen in, the wood is going to burn away all of its carbon to CO2, which will, among other things, cause you to miss your emissions target and also remove all of the carbon you need to actually have charcoal), which in practice means the pile needs some oxygen to maintain enough combustion to keep the heat correct, but not so much that it bursts into flame, nor so little that it is totally extinguished. The method for doing this changed little from the ancient world to the medieval period; the systems described by Pliny (NH 16.8.23) and Theophrastus (HP 5.9.4) is the same method we see used in the early modern period.
First, the wood is cut and sawn into logs of fairly moderate size. Branches are removed; the logs need to be straight and smooth because they need to be packed very densely. They are then assembled into a conical pile, with a hollow center shaft; the pile is sometimes dug down into the ground, sometimes assembled at ground-level (as a fun quirk of the ancient evidence, the Latin-language sources generally think of above-ground charcoaling, whereas the Greek-language sources tend to assume a shallow pit is used). The wood pile is then covered in a clay structure referred to a charcoal kiln; this is not a permanent structure, but is instead reconstructed for each charcoal burning. Finally, the hollow center is filled with brushwood or wood-chips to provide the fuel for the actual combustion; this fuel is lit and the shaft almost entirely sealed by an air-tight layer of earth.
The fuel ignites and begins consuming the oxygen from the interior of the kiln, both heating the wood but also stealing the oxygen the wood needs to combust itself. The charcoal burner (often called collier, before that term meant “coal miner” it meant “charcoal burner”) manages the charcoal pile through the process by watching the smoke it emits and using its color to gauge the level of combustion (dark, sooty smoke would indicate that the process wasn’t yet done, while white smoke meant that the combustion was now happening “clean” indicating that the carbonization was finished). The burner can then influence the process by either puncturing or sealing holes in the kiln to increase or decrease airflow, working to achieve a balance where there is just enough oxygen to keep the fuel burning, but not enough that the wood catches fire in earnest. A decent sized kiln typically took about six to eight days to complete the carbonization process. Once it cooled, the kiln could be broken open and the pile of effectively pure carbon extracted.
Raw charcoal generally has to be made fairly close to the point of use, because the mass of carbon is so friable that it is difficult to transport it very far. Modern charcoal (like the cooking charcoal one may get for a grill) is pressed into briquettes using binders, originally using wet clay and later tar or pitch, to make compact, non-friable bricks. This kind of packing seems to have originated with coal-mining; I can find no evidence of its use in the ancient or medieval period with charcoal. As a result, smelting operations, which require truly prodigious amounts of charcoal, had to take place near supplies of wood; Sim and Ridge (op cit.) note that transport beyond 5-6km would degrade the charcoal so badly as to make it worthless; distances below 4km seem to have been more typical. Moving the pre-burned wood was also undesirable because so much material was lost in the charcoaling process, making moving green wood grossly inefficient. Consequently, for instance, we know that when Roman iron-working operations on Elba exhausted the wood supplies there, the iron ore was moved by ship to Populonia, on the coast of Italy to be smelted closer to the wood supply.
It is worth getting a sense of the overall efficiency of this process. Modern charcoaling is more efficient and can often get yields (that is, the mass of the charcoal when compared to the mass of the wood) as high as 40%, but ancient and medieval charcoaling was far less efficient. Sim and Ridge (op cit.) note ratios of initial-mass to the final charcoal ranging from 4:1 to 12:1 (or 25% to 8.3% efficiency), with 7:1 being a typical average (14%).
We can actually get a sense of the labor intensity of this job. Sim and Ridge (op cit.) note that a skilled wood-cutter can cut about a cord of wood in a day, in optimal conditions; a cord is a volume measure, but most woods mass around 4,000lbs (1,814kg) per cord. Constructing the kiln and moving the wood is also likely to take time and while more than one charcoal kiln can be running at once, the operator has to stay with them (and thus cannot be cutting any wood, though a larger operation with multiple assistants might). A single-man operation thus might need 8-10 days to charcoal a cord of wood, which would in turn produce something like 560lbs (253.96kg) of charcoal. A larger operation which has both dedicated wood-cutters and colliers running multiple kilns might be able to cut the man-days-per-cord down to something like 3 or 4, potentially doubling or tripling output (but requiring a number more workers). In short, by and large our sources suggest this was a fairly labor intensive job in order to produce sufficient amounts of charcoal for iron production of any scale.
Bret Devereaux, “Iron, How Did They Make It? Part II, Trees for Blooms”, A Collection of Unmitigated Pedantry, 2020-09-25.
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September 5, 2023
September 2, 2023
August 3, 2023
QotD: Blacksmith forge techniques
A modern blacksmith can gauge the temperature of a metal using sophisticated modern thermometers, but pre-modern smiths had no recourse to such things (and most traditional smiths I’ve met don’t use them anyway). Instead, the temperature of the metal is gauged by looking at its color: as things get hotter, they glow from brown to dark red through to a light red into yellow and then finally white. For iron heated in a forge, a blacksmith can control the temperature of the forge’s fire by controlling the air-input through the bellows (pushing in more air means more combustion, which means more heat, but also more fuel consumed). As we’ve seen, charcoal (and we will need to use charcoal, not wood, to hit the necessary heat required), while not cripplingly expensive, was not trivial to produce either. A skilled smith is thus going to try to do the work in as few heats as possible and not excessively hot either (there are, in fact, other reasons to avoid excessive heats, this is just one).
Once hot the metal can be shaped by hammering. The thickness of a bar of metal could be thickened by upsetting (heating the center of the bar and them hammering down on it like a nail to compress the center, causing it to thicken) or thinned by drawing (hammering out the metal to create a longer, thinner shape). If the required shape needed the metal to be bent it could be heated and bent either over the side of the anvil or against a tool; many anvils had (and still have) a notch in the back where such a tool could be fitted. A good example of this kind of thing would be hammering out a sheet of iron over a dome-shape to create the bowl of a helmet (a task known as “raising” or “sinking” depending on precisely how it is done). A mass of iron can also be divided by heating it at the intended cutting point and then using a hammer and chisel to cut through the hot, soft metal.
But for understanding the entire process, the most important of these operations is the fire weld. Much like bloomery furnaces, the forges available to pre-modern blacksmiths could not reach the temperatures necessary to melt or cast iron, but it was necessary to be able to join smaller bits of iron into larger ones which was done through a fire weld (sometimes called a forge weld). In this process, the iron is heated very hot, typically to a “yellow” or “white” heat (around 1100 °C). The temperature range for the operation is quite precise: too cold and the iron will not weld, too hot and it will “burn” making the weld brittle. Once at the right temperature, the two pieces of iron are put next to each other and hammered into each other with heavy blows. If done properly, the two pieces of metal join completely, leaving a weld that is as strong as every other part of the bar.
Bret Devereaux, “Collections: Iron, How Did They Make It, Part III: Hammer-time”, A Collection of Unmitigated Pedantry, 2020-10-02.
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July 29, 2023
The brief – but vastly profitable – heyday of Parys Mountain
In the latest Age of Invention newsletter, Anton Howes discusses the engine behind the meteoric rise of Britain’s “Copper King”, Thomas Williams:
Parys Mine Shaft. View down a shaft at Parys Mine.
Photo by Stephen Elwyn Roddick – CC BY-SA 2.0
At the time More visited, Thomas Williams had only just begun his rapid rise to power. He was already a major industrialist and grown stupendously wealthy. When More asked about his stables, Williams apparently could not even estimate how many he possessed to the nearest ten. But Williams not yet even master of the mountain.
Nonetheless, the mining was well underway. The closest port, Amlwch, was already connected to the mountain by a new road that had been built for the Parys Mine Company’s sole use. Having not long ago been a village of just six houses, Amlwch had turned into a bustling port.
The mine itself was a source of fascination. “This differs from any mine I had ever seen or perhaps is anywhere else to be found, for the ore here instead of being met with in veins is collected into one great mass, so that it is dug in quarries and brought out in carts without any shafts being sunk”. Instead, the miners hollowed out the mountain itself, forming vast caverns that they supported by simply leaving vast columns of the ore untouched. He noted at least four or five of these caverns with ceilings forty feet high, with columns of yellow ore: “the whole seemed like the ruins of some magnificent building whose pillars had been of massy brass.”
It’s a fascinating insight into what Parys would have very briefly looked like, because today there is so little of the mountain left. Indeed, some of the caverns More got to see were already collapsing, with the rubble then needing to be sorted. He describes how one such piece of rubble — a two-ton chunk of ore — had to be bored, the cavity rammed with gunpowder and sealed with stones, and then exploded. “They are continually blowing up parts of the mine”, he noted, and was informed that the part of the mine he was visiting alone got through 10-12 tons of gunpowder per year. The mountain was disintegrating, punctuated by the occasional boom.
And as though that were not dramatic enough, the whole place smelled like hell. When More visited there were some seventy vast kilns upon the mountain for calcining the ore, burning off its sulphur. Each kiln held some 2,000 tons of ore, and when ignited with a little dried vegetation or coal it was so sulphurous that it took four months of furious burning for the ore to be sufficiently calcined. He noted that one had to keep to the windward side of the kilns, as “the fumes arising from them are very disagreeable and destroy all vegetables for a considerable distance around them.”
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