Doug Ayen (blackanvil) wrote,
Doug Ayen

More on knife design

What is a knife? To borrow and mutilate a phrase from the New England Bladesmith's Society, it's a short-bladed hand tool. (A sword, in comparison, is a long-bladed hand tool, but that's a thought for another day.)

One of the reasons I'm working on designing a chef's knife is that I think the professional knifemaking industry has fallen behind. It's not really their fault -- ask most professional chefs what they want in a knife, and they'll say something along the lines of "make it so I can steel it and keep it sharp that way. Don't make it too hard to sharpen." Some of the smarter ones will add in factors such as seamless grips, balance, and overall weight, but that's about it.

Folks, this is 14th century tech they want. At last years NEBS conference, one of the guest makers had made a skinning knife for a hunter, who complimented the maker on his knife because it only needed re-sharpening twice on the trip. Oh, he was hunting elephants and other African wild game. The sharpening was required after skinning an entire elephant -- and elephant skin is very tough, very abrasive, and very thick (1" to 2" in spots). The steel he used? O1, one of the most commonly used high-carbon simple steels.

Now, a steel works by straightening up an edge that has rolled over -- i.e. it was so soft that rather than staying straight with use, it bends. As for "easy to sharpen," well, if it's too easy to sharpen, then it's going to be too soft to keep an edge as well. This practice developed during the middle ages, when the quality of steel was usually quite variable, even in a single knife, with hard spots and such. Many knives either had a welded on steel edge, or were plain iron. Steeling these made sense.

Modern steels don't have this variability, and with proper heat treatment, steel selection, and handling will rarely need sharpening. Oh, toss in some design factors as well - proper primary bevel angle, good clean profiling - and proper sharpening technique, and we've pretty much covered the basics. These edges won't bend over, and won't break.

The two steels I'm planning on using for the chef's knife project are L6 and O1. L6 has a lot of nickle, a good amount of carbon, and a bit of chromium and other alloys to round it out. O1 is pretty much iron and carbon, a chunk of moly, and a bit of vanadium and tungsten to finish it off. Of the two, I'd prefer to use 01 for everything, but I have to admit the consumer desire for a stainless or stain resistant steel is strong enough to make me include at least one semi-stainless steel as standard.

I could go with the ultra-modern, CPM alloyed steels, but honestly, is it worth it? Unless you're a salt-water diver, what's the point? If you can't remember to wipe a blade clean after use, should you even be allowed to have a knife? Sure, a carbon steel blade with develop a dark patina with use, but even a semi-stainless steel will prevent that. Even a "stainless" steel such as BG-42, ATS-34, 154CM, or the dreaded 440C will stain, darken, and rust if you abuse it -- ask anyone who's cut an orange or lemon with such a knife then put it in it's sheath, or a diver who forgot to rinse the salt off his "stainless" dive knife.

(Then there's titanium. Titanium is wonderful, but it is too soft to keep an edge long. Still, for a diving knife, I'd probably go titanium. And what is with those titanium hammers??? What's the point!)

Anyway, now that I've thoroughly justified my selection of steel, how about edge geometry? I'll talk about that next time, on Blackanvil Blogger.
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