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In the County of the Isles, on Ironwood Island, there grow the Ironwood Trees. Ironwood is close to steel in strength, doesn't take an edge well, and is lighter than steel. The technology level of the Solar Kingdom may be taken to be approximately normal fantasy medieval, although I'm open to variations. Magic is not available, for various reasons (the trees are partly magical, but it's considered a good idea not to mention that).

Anyway, we have a lot of people in Ironville, and more come in seasonally. The island economy is mostly export of ironwood and ironwood products. The town palisade is made of ironwood, which has proven to be a good thing in the past. This is basically what I've committed myself to.

Anyway, people come out and cut down the trees. How? Steel axes aren't all that effective. People do things to it, not with steel knives or adzes or other steel tools. How do they do these things?

I need a way to cut down ironwood trees, cut up the logs and branches, and ideally do some carving.

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    $\begingroup$ It's worth noting that terminology is important here. Strength, toughness, and hardness are very different properties of a material. You say your ironwood is close to the strength of steel but that it doesn't take an edge well. If it doesn't take an edge then it is not very hard, and the hardness of a material is what dictates which one wins the abrasion battle. The tree could be five times stronger than steel, but if it is not as hard as steel then a steel tool would still be able to saw it or cut it. $\endgroup$ – J... Sep 17 '18 at 11:42
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    $\begingroup$ Hardness and toughness in steel, for example, trade off with composition and tempering. It's very easy to make steels which are extremely hard but brittle, or very tough but soft. We make steel tools to cut steel with - the tool steel is made specifically to be harder than the steel it needs to cut. Even old iron-age civilizations understood this. If steel can even be made to cut steel, it would be a difficult proposition to defend a wood which could not be cut with even a hardened steel - especially if the wood itself cannot itself be sharpened. $\endgroup$ – J... Sep 17 '18 at 11:48
  • $\begingroup$ Will answers that suggest changes to the wood itself be useful to you? $\endgroup$ – Onyz Sep 17 '18 at 12:45
  • $\begingroup$ It might be possible to use a primitive version of a waterknife. $\endgroup$ – Matthew Read Sep 17 '18 at 16:01
  • $\begingroup$ @J> Good points, and I can go with redefining terminology within limits (this is a role-playing game, and we're several sessions in). $\endgroup$ – David Thornley Sep 17 '18 at 20:23

10 Answers 10

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people come out and cut down the trees. How?

Quartz sand, water, metal saw and patience.

Using those above the Egyptians were able to saw granite rocks to make obelisks.

A blend of water and quartz sand, used to lubricate a saw moving back and forth in contact with the hard material will slowly ablate it, opening a cut in it. Applying the process for long enough, it is possible to cut the tree and also the trunk into planks.

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    $\begingroup$ This has the bonus of explaining why usage of the wood is not commonplace. This makes it extremely expensive to cut and use. Only the residents (who have regular access and possibly the opportunity to take some trees as tax) and rich nobles could afford it. $\endgroup$ – jpmc26 Sep 16 '18 at 9:25
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    $\begingroup$ Basically the way we work with granite IRL. Only instead of granite countertops you get ironwood at the end. Cool :) $\endgroup$ – Wayne Werner Sep 17 '18 at 16:15
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    $\begingroup$ Depending on how advanced you want the mechanical technologie to be you could have saw-mills (as they existed in medieval times) use a form of water-cutting already (it would make sense that they would develop it so early) $\endgroup$ – Hobbamok Sep 18 '18 at 7:47
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Fire would work, assuming the tree is still flammable, simple take a large brazier with you, light it. Use it to heat up a metal blade and the blade can then BURN through the wood.

Burning the wood sufficiently on the surface should also make it carvable.

Alternativly use the iron wood itself. Preferably the very hardest ironwood available or ironwood that has been further hardened artifically. Kinda like "only a diamond can cut a diamond.

For very fine work perhaps diamond or ruby tools should be used.

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    $\begingroup$ next youtube thumbnail: "1000° degrees dagger cuts tree " xd $\endgroup$ – user55267 Sep 17 '18 at 9:48
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A good first step would be to look at the Ironwood carvings by the Seri. The real ironwood is not as hard as steel, but it is notoriously hard to work with because it is so tough.

When it comes to cutting it, you want to pay attention to two things. The first is the weaknesses of the wood. Ummdustry suggested using fire to cut it in his answer. If you can control the fire well enough, that could be effective. Another approach we see in the ironwood carving business is cutting along the grain. Woods are inherently weaker along this direction, so a plain knife may be all you need to cut it.

Failing that, grinding would be highly effective. If your material really has properties similar to steel (rather than being similar to wood), then you can grind it. Most high-carbon tooling is ground because there are grinding materials which are much harder and sharper than wood or steel. Indeed, if we look at the ironwood carvings from the Seri, they typically use a rasp to form the shapes (which is sort of half way between a grinding stone and a saw), and a piece of glass to smooth its surface.

The second thing you need to pay attention to is the strengths -- how does the wood grow? If you can get the wood to grow in the general shape you need, then you don't need to spend as much time finishing it. The famous Crooked Forrest in Poland is believed to have been formed that way. It's believed that the planters of the trees intentionally shaped them with the intent of using them in shipbilding. You may also use this to make cutting easier. If you can leverage the growth patterns of the tree, you may be able to construct shapes that are easier to cut down, such as restricting the diameter of the tree at one point.

If your entire island culture is built upon the manufacturing of ironwood products, I would expect that they would be highly in tune with the growth and lifecycle of the ironwood trees. Elven style products, where they are grown in the desired shape, would be the norm, in my opinion.

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Just because it's close to steel in strength doesn't mean it's as hard as steel. It may have fantastic compressive and tensile strength, but still have very low mineral hardness... in which case steel axes, saws, and knives would still work just fine, although they may wear out faster than they do when working with other kinds of wood.

If, however, it has a similar mineral hardness to steel anyway, there are still other things you could make blades or files out of in order to work it. Quartz and corundum (i.e., ruby / sapphire) are both harder than steel, as is diamond, and industrial, non-gem quality diamonds aren't particularly precious, if they have a source to mine them from. Large chunks of quartz could be cut into axes blades all on their own, while smaller bits of diamond and/or corundum could be set into saw blades, much like modern diamond-bladed saws (which would be expensive with medieval-level technology, but not undoable), or more cheaply used to create rasps and files for carving the wood.

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    $\begingroup$ If it was as hard as steel it could, by definition, take an edge as good as steel. $\endgroup$ – J... Sep 17 '18 at 11:51
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braided steel cable.. not very high tech, easily replaced when broken and depending on length can fell a tree just by having a horse walk away from it(cable affixed to horse, wrapped once around the tree.). downsides are it's heavy and takes a few minutes to set up.

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Perhaps not quite what you want, but what about tree shaping? If you can coax your ironwood trees to grow into desired shape, you might not have to cut them... enter image description here

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Steam Bending

Wood has traditionally been shaped by placing it in a sealed box, filling it with warm steam, and leaving overnight. Or it can be left to soak in warm water.

This turns the wood into green wood, allowing it to shaped. The wood is pegged into the desired shape, and allowed to dry out.

In general, the harder the wood, the longer it takes to soften, and to take its new shape. Thus is may take a few days in the steam box, and a few weeks of being held in the shaper.

https://en.wikipedia.org/wiki/Steam_bending

With a bit of handwavium, you can say that this softens the wood enough to allow it to be cut with an axe, and then the edge smoothed with a rasp or chisel.

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  • $\begingroup$ Steambending. Is that a waterbender specialization? ;) $\endgroup$ – Mason Wheeler Sep 17 '18 at 14:50
  • $\begingroup$ @MasonWheeler it's what happens when a waterbender and a firebender have a baby $\endgroup$ – Wayne Werner Sep 17 '18 at 16:20
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Solar concentrator.

parabolic mirror wood

https://siamagazin.com/how-to-make-parabolic-mirrors-from-space-blankets/

You could fell a tree by setting up your mirror on a sunny day with the focal point on the trunk where you want to cut. Keep the wood above that point wet. The concentrated sun will burn a hole through the tree.

Similarly, carve your wood with hot spots of light. You will want a fan to clear the smoke or it will occlude your light. Refining the hot spot through a lens might be neat. I like the idea of the ironwood mill open to the light, with mirrors and lenses installed in various places inside. When the sun comes up the mill interior blazes to life with hot rays ready for various jobs. A "sawmill" like that would be a great setting for an action scene.

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Ironwood could have the property that it cuts like ordinary wood. Its remarkable strength emerges when it is subject to some annealing or curing process. It could be something that occurs naturally: passage of time after the wood is cut. Or perhaps a natural process that people have found a way to accelerate with heat or whatever.

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The usual materials engineering terms have already been defined -- most people think of "strength" as a single quantity, but there are several specific quantities that do not necessarily appear in all strong materials:

  • stiffness: how much the piece deforms under stress elastically (without a permanent change)
  • compressive and tensile strengths (usually most different when a material is "strong" but not tough) -- tensile strength is often measured to the point when the material starts to deform plastically (permanently) or to the point when the specimen breaks entirely
  • toughness (resistance to crack propagation, typically measured as the energy required to break a notched or smooth specimen)
  • hardness (resistance to deformation, typ. using a small ball as the indenter -- closely related to tensile strength, although an exact correlation depends on the material)

In addition, all of these are usually thought of as isotropic properties -- not varying in direction -- but they will depending on the material is formed. For wood, properties are highly anisotropic. Try bending a thin piece of wood with the grain and against it, for example. (One more aside: while complicated wood grains ("curly," burls, interlocked) are often prized for their beauty, woodworkers traditionally prefer to work with straight-grained stock because it's so much easier. Elm, for example, isn't often used commercially because it rarely has straight grained sections, and it's not pretty enough to be worth the effort.) Even steel and aluminum can have a "grain" -- usually the rolling direction -- and properties can differ significantly with and perpendicular to the rolling direction.

Ceramics and glasses can have high strength in compression, but even tiny flaws (almost always present) mean that they will fail in tension because they aren't tough. Once a crack has started, it takes very little energy to get bigger. They tend to make lousy tool materials as a result, although the trick of using sand or fine quartz for cutting hard materials is an excellent one -- you can cut glass with a hard grit using a copper tool because the hard grit tends to get embedded in the copper. I assume the same is true when using a cord to cut stone, although I thought that quite a bit of stone was quarried by cutting small slots and holes as stress concentrators, and wedges (or freezing water) used to split the rock at those holes or slots.

I would like to mention that "ironwood" is one of the most common names of various hard species throughout our world. It seems like just about every locale has its own ironwood. As for cutting and shaping, most of the usual methods have been mentioned.

Traditionally, even steel tools have their problems with the tougher and harder woods, especially if you don't like sharpening them after every other cut. The simplest fix is to work the wood before it dries. You can do so much with green wood: split along the grain, form, etc. There's a great book "How to make a chair from a tree" that details these methods.

Fire and hot tools to char or degrade the iron wood (as mentioned) are also possibilities -- native Americans and other indigenous peoples use fire to hollow out trunks for boats. You could also girdle saplings (cut the living layer on the outside of the tree) to get timber for palisades -- the hard part might be the inner heartwood.

In really old times, bronze tools (and earlier bone and quartz) were often used to prepare wood, so tool hardness and strength relative to wood was even lower. The usual non-metals were used as well: silica (sand, quartz), alumina (ruby and other corundums) were most common. One that I hadn't heard of until recently was shark skin -- it makes an excellent "sandpaper" and depending on how it is prepared, can range in roughness from quite coarse to very fine. You could certainly have a local animal that incorporates silica or another hard oxide in its skin.

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