If you buy a Gransfors Bruks axe you also get The Axe Book, which is highly informative, especially for the novice woodsman/bushcrafter/lumberjack/generally burly man. Now, Gransfors Bruk axes ain't cheap, so you've really got to be into some type of woodsmanship before throwing down the cash for one. Since I moved into a house in the woods that had a large pile of rounds, I figured a nice splitting maul (an axe designed for splitting wood whose poll can be used as a hammer or be struck with a hammer to drive the axe deeper) was worth the investment, especially since I'm a quality over quantity type of person, and I've heard of people leaving Gransfors axes to their grandkids. I'm sure people leave all brands of axes to their grandkids (along with tons of useless crap), but you get what I mean.
So, the basic parts of the axe are the axe head and the handle. That's it, right? Wrong. Since axes have been around along time, there's a name for every feature, often more than one. The picture below is pretty self explanatory.
You might be wondering, what features make a good axe? And from a geometrical design perspective I'd have to retort, what are you using it for? But in terms of materials, the steel/forging process used for the axe head is the most important, since handles can be replaced with relative ease. When you buy an expensive axe, you're really paying for all the trial and error (i.e. science) that it took to determine a manufactureing process that produces an axe head that keeps a sharp edge (meaning it's very stiff = high Young's Modulus), yet tough (high impact strength = lower young's modulus) axe head. So generally, the cutting edge will have a different heat (or work hardening) treatment than the rest of the axe head, but the difference needs to be gradual to prevent stress concentrations and ensure the the higher stiffness of the cutting edge doesn't lead to a brittle fracture.
This all boils down to the composition and microstructure of the steel (iron with 0.1-2% carbon) throughout the axehead. Obviously, axes have been made long before anyone knew what effect microstructures have on material properties, so defining the forging process used to take far more trial and error than it does now. That is to say, if you wanted to start an axe company now and you knew some materials science/inorganic chemistry, it would take you a far shorter amount of time to produce a good axe, since now someone can change a process parameter (i.e. quenching rate) and analyze the resulting material properties. Companies like Gransfors Bruck that have been around a long time haven't had this luxury, so their testing methods probably largely relied on real world tree felling and wood splitting experience, and I'm sure they had many, many broken axes in the beginning.
Axe Construction Part 2 will focus on microstructure and phase diagrams of steel :)
So, the basic parts of the axe are the axe head and the handle. That's it, right? Wrong. Since axes have been around along time, there's a name for every feature, often more than one. The picture below is pretty self explanatory.
You might be wondering, what features make a good axe? And from a geometrical design perspective I'd have to retort, what are you using it for? But in terms of materials, the steel/forging process used for the axe head is the most important, since handles can be replaced with relative ease. When you buy an expensive axe, you're really paying for all the trial and error (i.e. science) that it took to determine a manufactureing process that produces an axe head that keeps a sharp edge (meaning it's very stiff = high Young's Modulus), yet tough (high impact strength = lower young's modulus) axe head. So generally, the cutting edge will have a different heat (or work hardening) treatment than the rest of the axe head, but the difference needs to be gradual to prevent stress concentrations and ensure the the higher stiffness of the cutting edge doesn't lead to a brittle fracture.
This all boils down to the composition and microstructure of the steel (iron with 0.1-2% carbon) throughout the axehead. Obviously, axes have been made long before anyone knew what effect microstructures have on material properties, so defining the forging process used to take far more trial and error than it does now. That is to say, if you wanted to start an axe company now and you knew some materials science/inorganic chemistry, it would take you a far shorter amount of time to produce a good axe, since now someone can change a process parameter (i.e. quenching rate) and analyze the resulting material properties. Companies like Gransfors Bruck that have been around a long time haven't had this luxury, so their testing methods probably largely relied on real world tree felling and wood splitting experience, and I'm sure they had many, many broken axes in the beginning.
Axe Construction Part 2 will focus on microstructure and phase diagrams of steel :)
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