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  1. #13
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    Quote Originally Posted by Visibility View Post
    Well I own most of those stones he is using, and have a microscope, (not the pocket kind, though I have that too) and I see the same thing that he has photographed. I have no alliance to that guy, I don't even know who he is, but thos pictures show pretty accurately the difference in sctratch pattern. DO you have a couple to check?
    Sure. I have a couple of microscopes as well. And I see similar sorts of scratches, depending on the angle of the light. But what I'm seeing are *not* the scratches from the shapton 30k - they're the scratches from the lower-grit hones, brought into sharp relief by the polishing action of the shapton which polishes the tops of the high ridges. In the photos you linked to, notice that in the shapton shot there are large, fairly contiguous areas on that bevel that look a bit flattened and polished, where the grooves aren't as prominent. There are three irregular bands of these going across the length of the bevel, one at the very edge that may be a microbevel, and two more farther back on the bevel. One or all of those bands is likely where the shapton is honing - my suspicion is it's the one at the edge itself, because...

    The nakayama-finished blade actually has a rougher edge - don't look at the bevel, look at the edge itself - there is a distinct regular sawtooth pattern on the nakayama edge that isn't present on the S30k edge. This again demonstrates pretty solidly that neither the nakayama nor shapton edges were effectively sharpened on those hones, and that the edges are still hopelessly compromised by the remnants of their 1k honing striations. Verhoeven demonstrated in his paper that when viewed under an electron microscope, blades only show a regular sawtooth pattern up to about 2k grit, beyond that the edge gets thin enough that the steel at the edge is simply too weak to sustain the sawteeth. When I compare edge roughness between hones, I set the lighting and contrast so that only the reflection off the edge shows up, this reduces the distraction of the bevel appearance since all you have to look at is the thin white line interrupted by the occasional microchip. Any sawtooth pattern that is showing up means that I need to go back to the 4k or 8k hone and clean things up before going back to the finishing steps.

    The real reason the nakayama bevel looks "finer" is the loose particles in the slurry are rolling around underneath the bevel and leave behind a finish that under magnification looks like it's been sandblasted, and this changes the way the light reflects off the surface minimising the appearance of the underlying low-grit scratches. If those edges had been honed properly then neither razor would show any grooving pattern at all at that magnification, there would be no sawtooth pattern at the edge. From looking at those partially-honed bands on the S30k picture, you might predict that the properly-honed S30k bevel would look like a mirror (and you would be right), and from looking at the sandblasted-grooves on the Nakayama picture you might predict that the Nakayama bevel would look like a sandblasted mirror (and you would also be right).


    Quote Originally Posted by Visibility View Post
    I understand what you are saying about the angles, but all things being equal, the s30k produces a much rougher edge when magnified. The Nakayama particles are always breaking down, you are getting particles much finer than the shaptons and that process just keeps continuing the longer you hone, it's just in effect a higher grit stone. Mine in particular is so high I use the 30k before it, not because I necessarily need to, it just makes the time on that stone less because it's so damn hard and cuts so slow.
    Sorry, but unless you've got a microscope at least 1,000x, then what you're seeing aren't the scratches from the nakayama or shapton, and I'm doubtful that even at 1000x that an optical microscope could resolve scratches of this size.

    Secondly, while it's true that the particles from the Nakayama are always breaking down, it's also true that new large particles are always coming out. So this isn't a win-win scenario - those small broken-down particles may well be smaller than the ones on the Shapton30k, but those new fresh particles coming out are larger than the ones in the Shapton. And I've never heard anyone claim that the particles in the Shapton don't break down. Certainly on mine it gets finer and finer over repeated uses after I've lapped it, which makes me think that the abrasives are breaking down as well.



    Quote Originally Posted by Visibility View Post
    I'm not dissing shapton at all, I have their whole set and sold everything else I had except for the lapping film. Their DGLP is the best lapping plate I've ever seen. I've been to Harrelson's house, walked through his workshop and seen his collection of blades. I sing their praises from the rooftops.

    I won't be getting rid of my 30k cuz I love it so much and it's useful in applications that the nakayama just isn't. I do more than sharpen razors though. A tool for every job...and for razor applications, the nakayama has an edge over the shapton.
    I don't think you're dissing shapton, I just don't believe that those photos you linked to are particularly useful except as a negative example.

    I get similar levels of sharpness out of my shapton 30k and nakayama asagi. If either is superior it isn't by much, certainly not enough to worry about since there are ways of getting much higher levels of sharpness. So if I'm going for sharpness I really don't care if the nakayama is 10% or even 30% better than the shapton, because the edge is only gonna be there for the few minutes it takes to haul out the newspaper or 0.1 micron diamond or 0.05 micron aluminum oxide.
    Last edited by mparker762; 09-28-2009 at 01:42 PM.

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