Edge Matters ( How sharp? )

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  • Nice idea, but the issue would be, how do you measure it? This is still subjective as your medium sharp, might be my 5 or 6. I've had hair popping edges I would not consider scary sharp. EDIT: Scary sharp is so sharp that if you try to shave with it you cut yourself, so sharper than a new razor.

    I've been considering ways to measure sharpness, but the blade geometry and the edge angles affect each method I've ever come up with. A very thin kitchen knife that won't bite into a tomato skin will still cut most veg better than a scary sharp axe based purely on geometry.

  • Depends on the job. I like some of my EDC knives to be as sharp as I can make then, that's FUN. On the other extreme I find filleting a fish easier without too sharp an edge or point, I want the knife to follow the backbone not slice through it. Somewhere I saw someone comment that even a razor has an optimum sharpness, theoretically if too sharp it would just slice skin instead of following it.

    I think knives are an exception to the popular claim that a sharp tool is safer than a blunt one.

  • The mid range is always going to be a tricky because of the roughly y=c/x nature of edge wear, I think this is reason that actual wear resistance is hard to measure with a precise end point.

    Scary sharp is an interesting one, I think it's more to do with geometry than the edge itself.

    For example I sent a knife to Uncle Ian Longstrides for one of his famous convex edges.

    Uncle Ian is also a deer stalker so when i asked him for an edge that would stand up to this use ( bone contact on leg bones and vertebra on every deer gralloched) the edge he sent back was much more obtuse than the one he sends out to people who want a showing-off-how-sharp-it-is edge for their folder, as an example.

    Now this edge is as finely finished and as polished as any other he produces but at an included angle of around 40 degree, does not cut whilst shaving or things like that.

    With that in mind scary sharp I took to be in relation to the knife and it's usage in this context, rather than an absolute for which polished diamond at an incredibly thin angle must be 1.

  • A few accidents throughout my life with sharp knives taught me to stop short of super shaving sharp.

    I quit cutting cardboard boxes after many near misses with a super sharp S30V Spyderco Paramilitary.

    If I get them to cut paper then that is plenty enough, trying to cut hairs is just silly really.