Thread: experiments

Originally Posted by kevint

You both are basing your opinion on what you think you see, rather than trusting his honesty? Even though he tells exactly what and how and why he did, (such as maintaing the position of the lighting)you both know better because of the photo, is that correct?

Why the animosity?

I stand corrected about what I first thought was an unhoned and a honed part. I see now, that it's all honed, only different steel.

But I still agree with Mparker and others. It remains extremely difficult to compare scratch patterns by taking magnified pictures. I have taken that route myself, and came to the conclusion that it's an unreliable method to compare different types of hones.

I can adjust a microscope in such way, that it will favour certain types of scratches as very smooth and other types as very coarse, without any re-adjusting in between shooting the pictures. Then, I can make one single adjustment, that will reverse the results if I reshoot the pictures at that point.

For comparing scratches of hones that come of the same quarry, this is less an advantage, but to compare synthetic hones to naturals, I don't accept this a good method.
I would have less objections against SEM-pictures, where an electron stream scans the surface in very controlled conditions, with high resolution and magnification. But even then, what does it matter?

At this level, the edge is as much shaped by plastic flow and debris deposit than by abrasion only. I believe the binder of a hone plays an important role in that. Without owning any, I'm still pretty sure that a Shapton 30K produces a keener edge than a Shapton 16K, that by itself produces a keener edge than a Shapton 8K. Where I have to situate my Nakayama, that I do own, in that list, remains to be seen.
Another, way more important, property of a particular hone, for our purposes, is the capability to produce an edge that skips skin and cuts whiskers. So far, for my skin and whiskers, I have not find anything that can beat a good old Coticule as a finishing hone. At the same time, I need a synthetic hone to push my edges to my desired keenness, before I can finish it on a Coticule or the Nakayama. I can also consider it finished, right of that synthetic, but those edges like to slice my hair papilae as much as my whiskers. Not a thousand magnified pictures can provide me with that information.

But I have no animus against Japanese Naturals, if that eases your mind. In fact I like them.

Best regards,
Bart.

Thank you for your reply Bart.

What I was referring to by animosity was the sudden turn to accusation of bias, fraud, ignorance. This in spite of the fact the description of the method specifically mentions the aspects of lighting and limitations of the equipment. Ignorant statements about how the appearance of scratches can be manipulated to appear smooth or deeply furrowed, combined with assurance that these cannot be 30k because they are too coarse in appearance is far less than I expect from an intelligent conversation.

This kind of response, and I have seen it before. Along with the mindless buddy system of thanking up the rep, like some middle school popularity contest truly makes me question my participation here.

Originally Posted by kevint

Thank you for your reply Bart.

What I was referring to by animosity was the sudden turn to accusation of bias, fraud, ignorance. This in spite of the fact the description of the method specifically mentions the aspects of lighting and limitations of the equipment. Ignorant statements about how the appearance of scratches can be manipulated to appear smooth or deeply furrowed, combined with assurance that these cannot be 30k because they are too coarse in appearance is far less than I expect from an intelligent conversation.

This kind of response, and I have seen it before. Along with the mindless buddy system of thanking up the rep, like some middle school popularity contest truly makes me question my participation here.

His photos do not demonstrate what he claims they demonstrate. To see submicron features requires a microscope capable of a very high magnification. There have been multiple papers published (Verhoeven's Knife Sharpening Experiments 2002 paper, and the Popular Mechanics article from the 20's) that show these scratches accurately, and both of these used 3000x magnification. Verhoeven used an electron microscope, and the PM article used a custom-built optical microscope.

The 25x magnification the linked poster used is simply inadequate by roughly two orders of magnitude. It is not ignorance nor mindlessness to point this out, nor is it ignorance nor a matter of popularity to note that this means that the linked poster is either unaware that he needs a much bigger scope or he is intentionally trying to deceive the readers. And it seems reasonable to point out that one factor that makes the ignorance option more likely (or at least more understandable) is the possibility that confirmation bias may have played a part. And it is not unintelligent to note that the sorts of effects that the photos do show are the sort that have tripped up previous attempts to analyse hone scratches with low-power microscopes. Nor is it out of line to describe how small differences in lighting can have a huge effect on the sorts of surface features that show up in the photos.

It is possible that the OP of the linked thread is absolutely correct in his conclusion that the Nakayama hone is markedly superior to the Shapton 30k. I've got both and think they're roughly equivalent, but it's possible that I'm wrong. But this conclusion is not bolstered by the photos in that linked article. I'm sorry to disappoint you, but the resolution is just too low. Even at 3000x the scratches are surprisingly small, and at 3000x you can look at the blade edge-on and measure the width of the cutting edge to the hundredth of a micron, and at that magnification the scratches are roughly the same size as the ones shown in the 30k shapton photo. So if the guy in the linked thread is right about those scratches, then somebody needs to tell Prof John Verhoeven at the University of Iowa that he needs to learn how to use an electron microscope. Or maybe, just maybe, it's the random internet poster with the 25x microscope that's wrong.

Maybe.

Originally Posted by mparker762

His photos do not demonstrate what he claims they demonstrate. To see submicron features requires a microscope capable of a very high magnification. There have been multiple papers published (Verhoeven's Knife Sharpening Experiments 2002 paper, and the Popular Mechanics article from the 20's) that show these scratches accurately, and both of these used 3000x magnification. Verhoeven used an electron microscope, and the PM article used a custom-built optical microscope.

The 25x magnification the linked poster used is simply inadequate by roughly two orders of magnitude. It is not ignorance nor mindlessness to point this out, nor is it ignorance nor a matter of popularity to note that this means that the linked poster is either unaware that he needs a much bigger scope or he is intentionally trying to deceive the readers. And it seems reasonable to point out that one factor that makes the ignorance option more likely (or at least more understandable) is the possibility that confirmation bias may have played a part. And it is not unintelligent to note that the sorts of effects that the photos do show are the sort that have tripped up previous attempts to analyse hone scratches with low-power microscopes. Nor is it out of line to describe how small differences in lighting can have a huge effect on the sorts of surface features that show up in the photos.

It is possible that the OP of the linked thread is absolutely correct in his conclusion that the Nakayama hone is markedly superior to the Shapton 30k. I've got both and think they're roughly equivalent, but it's possible that I'm wrong. But this conclusion is not bolstered by the photos in that linked article. I'm sorry to disappoint you, but the resolution is just too low. Even at 3000x the scratches are surprisingly small, and at 3000x you can look at the blade edge-on and measure the width of the cutting edge to the hundredth of a micron, and at that magnification the scratches are roughly the same size as the ones shown in the 30k shapton photo. So if the guy in the linked thread is right about those scratches, then somebody needs to tell Prof John Verhoeven at the University of Iowa that he needs to learn how to use an electron microscope. Or maybe, just maybe, it's the random internet poster with the 25x microscope that's wrong.

Maybe.

Mr. Parker. I considered the tone of replies to be quite negative. Your text overall; contradictory.

Originally Posted by kevint

Mr. Parker. I considered the tone of replies to be quite negative. Your text overall; contradictory.

Please, I fouind Mr. Parker's tone very much in line with yours to which I think he was responding. I found the content to be interesting, informative, and in my opinion, quite valid.
"This kind of response, and I have seen it before. Along with the mindless buddy system of thanking up the rep, like some middle school popularity contest truly makes me question my participation here."

So far the discussion has been directly to the topic. The analysis of the study, done by someone else, which you presented. I think it's fascinating, pertinent, and very worth dissecting. There's nothing wrong with attacking the data and/or methods used to reach a conclusion. I do not mean this to be inflammatory, but what did you find contradictory about Mr. Parker's text? If it was content, then please elaborate. If it was tone, then hopefully we can just let it drop.

(Don't let this valuable thread die over this.)

Finally found the Verhoeven paper, which should help correct the overemotional rhetoric and ad-hominem attacks in this thread.


Experiments on Knife Sharpening
September 2004
Prof. John Verhoeven
Emeritus Professor
Department of Materials Science and Engineering
Iowa State University

Experiments on Knife Sharpening


On page 19, figure 23, he shows a blade sharpened on a 6000 grit waterstone, at 3000x and 800x resolutions. Notice how small the grooves are, even at 800x magnification.

On page 30, figure 37, he shows a blade with a secondary bevel formed on chrome oxide. He doesn't give the grit, but he does describe it as the standard chrome oxide block sold in woodworking stores for honing chisels. At best this is the 0.5 micron Lee Valley block, at worst it's the coarse stuff that's blended with other abrasives. If it's the 0.5 micron chrome oxide then the grit is comparable to the grit of a 30k Shapton (my Shapton is 0.48 micron). Even at 3000x, the grooves in the secondary bevel are very thin and very shallow, and are therefore unlikely to be visible at 25x as the author of that linked article claims. Admittedly I'm comparing a 0.5 micron paste to a 0.5 micron stone, but Verhoeven shows an awful lot of photos of 1k, 6k, and 8k honing marks at a variety of resolutions, and the marks from even these relatively coarse hones are surprisingly small.

I do not apologize for being negative about the linked post, nor for being contradictory about his assertions. But if Prof. Verhoeven's pictures are accurate depictions of micron and submicron-scale honing marks, then it is clear that the centimeter-scale photos in the linked thread must be showing much larger honing marks and not the 0.5 micron - 0.2 micron striations that the Shapton and Nakayama hones would be producing.

I hope I haven't soured you on the Verhoeven paper, but it is well worth reading front to back. He shows comparative micrographs of commercial Gillette razor blades and a straight razor that was honed by somebody that used it, and the straight razor comes off looking quite well. And the photos are quite eye-popping.

One other issue with that guy's honing is that he is simply polishing the bevel, not getting the egde any sharper!

Check it out. The bevel is certainly seeing what seems to be improvement, but the dark line along the edge remains untouched.

Good example of what happens if you do not "set your bevel" and move up the progression anyhow. You get nice shiny bevels, and a razor that still won't cut right...

Not really sure what we're looking at there. Is it all bevel? with a hard/soft steel boundary or bevel and blade.

In any event, in the part that is blade or soft steel there are large discolorations/bumps/pits or whatever they are. There are two especially large ones close together almost dead center in the pictures. If you use one or more of those marks for reference it seems that the scratches above and below the marks are erased in the progression of pics but but the mark remains virtually uneffected. Would those be tiny pits in the metal?

Originally Posted by mparker762

Finally found the Verhoeven paper, which should help correct the overemotional rhetoric and ad-hominem attacks in this thread.


Experiments on Knife Sharpening
September 2004
Prof. John Verhoeven
Emeritus Professor
Department of Materials Science and Engineering
Iowa State University

Experiments on Knife Sharpening


On page 19, figure 23, he shows a blade sharpened on a 6000 grit waterstone, at 3000x and 800x resolutions. Notice how small the grooves are, even at 800x magnification.

On page 30, figure 37, he shows a blade with a secondary bevel formed on chrome oxide. He doesn't give the grit, but he does describe it as the standard chrome oxide block sold in woodworking stores for honing chisels. At best this is the 0.5 micron Lee Valley block, at worst it's the coarse stuff that's blended with other abrasives. If it's the 0.5 micron chrome oxide then the grit is comparable to the grit of a 30k Shapton (my Shapton is 0.48 micron). Even at 3000x, the grooves in the secondary bevel are very thin and very shallow, and are therefore unlikely to be visible at 25x as the author of that linked article claims. Admittedly I'm comparing a 0.5 micron paste to a 0.5 micron stone, but Verhoeven shows an awful lot of photos of 1k, 6k, and 8k honing marks at a variety of resolutions, and the marks from even these relatively coarse hones are surprisingly small.

I do not apologize for being negative about the linked post, nor for being contradictory about his assertions. But if Prof. Verhoeven's pictures are accurate depictions of micron and submicron-scale honing marks, then it is clear that the centimeter-scale photos in the linked thread must be showing much larger honing marks and not the 0.5 micron - 0.2 micron striations that the Shapton and Nakayama hones would be producing.

I hope I haven't soured you on the Verhoeven paper, but it is well worth reading front to back. He shows comparative micrographs of commercial Gillette razor blades and a straight razor that was honed by somebody that used it, and the straight razor comes off looking quite well. And the photos are quite eye-popping.

I have read the paper and discussed it here several times.