Hand techniques

Ah, the sharpening. Here's where you can discuss sharpening stones and media, along with sharpening techniques.
dmccurtis
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Re: Hand techniques

Mon Jul 06, 2015 11:57 am

I don't agree with his conclusions. It's empirically obvious that natural stones, finishers at least, finish finer than they start. I haven't, however, heard a good explanation of the mechanism by which that happens, so it's interesting to see some imagery of the process. Of course, that could be because there are no English translations of Japanese research, which I would love to see. I think he discounts the contributions that the broken-down clay binder makes to the sharpening process, which I suspect plays a large role in cushioning the steel from coarser particles, and is perhaps capable of at least abrading soft iron. The fact that he uses a razor, with a small surface area in contact with the stone, may also contribute to his conclusions. I think it's possible that a wide beveled tool would work the slurry more, further breaking it down.

As far as surfacing stones, I flatten and round corners with diamond plates, and then use nagura and tomo nagura to smooth the stone face. After surfacing, the stone is reflective when viewed at an angle. I find that a properly conditioned stone feels more engaged with the blade, cuts faster, and yields slurry faster.
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Chris Hall
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Re: Hand techniques

Mon Jul 06, 2015 1:43 pm

The fact that he uses a razor, with a small surface area in contact with the stone, may also contribute to his conclusions. I think it's possible that a wide beveled tool would work the slurry more, further breaking it down.
I wondered the same thing too.

Here's a razor guy who uses a natural stone for a long time, working the slurry, and the finish he gets on the blade is intriguing:

https://www.youtube.com/watch?v=AJqy49-yHXw
dmccurtis
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Re: Hand techniques

Mon Jul 06, 2015 2:39 pm

I've watched that video, and Dr. Matt's others. It's intriguing, but I find it hard to draw conclusions from. HIs postulation that adding CBN to the stone catalyzes slurry break-down, and that may be, but it seems to be a solution in need of a problem. The image he shows of the non-'supercharged' Nakayama edge looks surprisingly poor, and I don't think indicative of a normal result. It's hard to tell from small pictures, but to me, it looks like the results from a stone either too hard for normal use, or too hard for its user.

Not to make things too personal, but I tend to take sharpening advice from razor sharpeners with a grain of salt. The razor community has lots of flavour of the month products and wonder-techniques, and lots of contradictory ideas about what works and why. It's even worse when Japanese naturals are added to the mix, with so little good information about them readily available.
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Brian
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Re: Hand techniques

Mon Jul 06, 2015 4:56 pm

I thought the CBN on Nakayama was interesting as well, just didn't know if it would have any relevance in woodworking. I have a jewelers loupe in my house....and have contemplated inspecting my edges with it. I forget if it was this forum, but I think a few of you guys do this as well?
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Chris Hall
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Re: Hand techniques

Mon Jul 06, 2015 5:10 pm

I use a 200x Peak magnifier
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Brian
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Re: Hand techniques

Mon Jul 06, 2015 5:17 pm

Awesome! Alright, I'll give the loop a go.
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Re: Hand techniques

Mon Jul 06, 2015 5:43 pm

I've used a loupe for years and wouldn't be without one when experimenting. It can be a shock to see your prized finish up close.
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Chris Hall
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Re: Hand techniques

Mon Jul 06, 2015 5:45 pm

Yes, be prepared for some disturbing imagery...
dmccurtis
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Re: Hand techniques

Mon Jul 06, 2015 6:32 pm

Brace yourself especially if you peek at your edge after some use.
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Brian
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Re: Hand techniques

Mon Jul 06, 2015 10:55 pm

Will do! I'm expecting the truly grotesque.

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