Hand Tools

Subject:
Re: Weaver grind v/s Japanese feathering

Winston
> I'm chasing what I've seen on the knives, where the idea of some perfect apex right at the edge isn't really that important.

From the testing and pictures I did with buffed chisels, I'm coming around to the idea that a one-atom thick apex isn't necessary for good performance cutting wood, and that it can harm edge durability. Of course, I wasn't able to see exactly what the edge profile is -- I think you'd need an electron microscope for that -- but the light reflections suggest that the edge is rounded over a bit after buffing, and also, a rounded edge is what one would expect from rubbing a soft abrasive object on a hard edge.

The fact that the rounded, higher-angle edge has less cutting resistance (as David experienced), or has about the same resistance (as I experienced) as a flat, unbuffed edge is interesting. It makes me wonder if much of the cut resistance with the flat unbuffed blades, comes from wedging very (very!) close to the edge, instead of forces right at the apex.

I said earlier that I think there are three possible things contributing to the edge durability for buffed blades: a higher angle at the edge, a rounded apex, and the smooth, uniform surface. (I know from the pictures that the buffed edge is significantly smoother and more uniform than what I get off a Shapton 12000.) I don't know the relative importance of each of these things, though.

Even if an unbuffed edge is sharper and cuts easier than a buffed one, I found that such an edge is visibly damaged even after a little paring of something as soft as pine, even with PM-V11. So for practical use, I don't think it would stay sharper than a buffed edge for long. But this does need more testing.

I'm curious if one can get the same effect with a strop. I think it would be kind of amusing if, after all the discussions people have had about stones, grits, bevel angles, and all that, it turns out that you don't have to worry much about the specific stone, or grit, or angle, and that just finishing with a strop makes more of an improvement than any of those other things.

I also wonder how well this works for plane blades. I had very brief experiment with buffing a plane blade, in which it was incredibly quick and easy to get a blade sharp enough to produce a maximally smooth wood surface. For me, getting blade sharpened to that level just on stones takes significantly more work. But it chipped out (probably due to either hitting something, or poor deburring) before I got much usage out of the blade. Even if buffed blades have clearance issues earlier than unbuffed ones, they might be suitable for finish planing, where you won't go for a long time anyway before resharpening.

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