I was looking for info on knife honing and come upon this:
straight razor | scienceofsharp
Good info on a lot of the aspects of honing
Printable View
I was looking for info on knife honing and come upon this:
straight razor | scienceofsharp
Good info on a lot of the aspects of honing
Very interesting read. Thanks for sharing. Some amazing photography. Of course the analysis really does boil down to (sorry can't attribute this quote as can't remember the member who said it :( ) rub on stone until sharp, anything else is just an improvement in efficiency. (Or something like that) lol
I really like how it emphasizes the importance of linen (or other cloth like material) strop when preparing the edge for shaving. You can really see the difference the strop does to the edge before it even touches the leather.
Who is the website's author?
Nice resource
I wonder about the J-nat slurry though. The shape of the particles is weird, I took images of slurry a few years a go and it looks a bit different.
Here a pic from a book by the Kyoto stone association
http://i1020.photobucket.com/albums/...psb4466d5a.jpg
you can see the layered structure of the slurry and the theory is that that is where the break down occurs with honing.
His description of the slurry getting black with metal swarf is also not very consistent with a finishing stone. Those usually do not abrade so much as to darken the slurry significantly.
Any way there is no hard evidence that I know of what happens really with the slurry.
Great read
He also referred to the Nakayama Asagi (the source of the analyzed slurry) as having a "red-orange colour." That seems odd.Quote:
Originally Posted by mainaman
Ron I missed that good catch.Quote:
Originally Posted by Utopian
Always looking for new honing help, thanks!
Some Jnats seem to encourage rusting during the honing process. My Yaginoshima does this but not my Nakayama.Quote:
Originally Posted by Utopian
I'm also curious as to why the bevel gets more polished & the scratches get finer if the slurry doesn't break down as the blog postulates.
He has identified himself as Todd.Quote:
Originally Posted by Hirlau
I think it has great potential, but he is limiting it by choosing a format more suitable for a soapbox than discussion. He has access to expensive equipment and experience in using it, but I noticed number of occasions where the conclusions are not supported by the evidence he is presenting or amount to simple definitions of terminology rather than the new insight that is claimed.
The peer review process of scientific publications is not just a nuisance, and this blog is a good example for how the lack of qualified and vigorous review results in lower quality product. I wish it can be given to an undergraduate student as a project with the goal of peer reviewed publication.
Still, it's has a lot of good stuff, especially given that very few of us have access to the imaging equipment he has, the skills to use it, or the time to spend researching these topics.
I found the comments interesting and seeing as this is a recent blog you may have your questions/requests answered ?
Things like this tell me he doesn't use a straight or hone, he just compiles data.
""I will be presenting the pasted-strop data and discussing "overhoning" in future posts. But you are correct, the data indicate that there is no reason to go beyond 4 micron (Shapton 4k) if you finish with a diamond strop.""
Thank you for the response to my question.Quote:
Originally Posted by gugi
I just have a bug up my a$$ with anyone who posts information/research on a topic & does not put his identity to his work. Whenever I attend a class of instruction on any subject, I want to know who is teaching me & his/her background in the subject.
Whenever I teach one of the few subjects that I have knowledge on, my audience will know all about me before the first instruction.
I'm not ungrateful for the O.P. & the link to the work,,,, so thanks for the information.
Hi, Late as always. His name is Todd Simpson and he is a materials researcher specializing in electron microscopy. He was somewhere down south US but now in Canada. I'm retired from Oak Ridge National Laboratory where one of my jobs was to support EM safety, and he did his post doc work there. I may have met him but can't recall, that's been a few years ago.
You can find a mention here:
http://www.uwo.ca/fab/resources/News...15-Issue-1.pdf
It's nice to be able to clearly see what's going on with the edge off different media. BTW, he does the sectioning with a device that's part of the microscope called a focused ion beam or FIB. Actually seeing an edge folded over from glassing, etc is an interesting thing.
So thanks to Dr. Simpson for taking the time to do this. It isn't exactly an easy thing to do in terms of the time and effort expended.
Cheers, Steve
"Sharp and keen part II" published: https://scienceofsharp.wordpress.com...d-keen-part-2/
I've enjoyed the reading, so far.
Rgds.
Martin
I'm a little late to this, but I want to say something because I've always been confused by this, too....I've never been too vocal about it because there's no reason to be rude, but it's my speculation that the particles don't get smaller, they just get dull - *especially* the particles that are still attached to the surface of the stone. Silicon dioxide is fairly durable in terms of not being brittle, but the sharp edges of the particles themselves are not much harder than hardened steel. I think they probably get dull rather than small.Quote:
Originally Posted by onimaru55
I also say this because I have never seen a comparison picture of before and after slurry where the slurry is uniformly some fraction of the size of the original particle.
It's always been my opinion that an easy way to tell if a stone can finish is if the particles are natural and some sort of silicon dioxide, they don't come off of the stone in clumps and act like a large particles, they're five microns or smaller, and the stone is hard enough to hold on to them.
I haven't heard of particles smaller than about 3 microns naturally, but that's no big deal if you can make them a little dull so that they and the steel are in a little war burnishing each other.
The somewhat odd thing is that novaculite gets so tired that anything harder than about 60 without striations or 62 with striations left in it will not want to be cut on a hard poreless novaculite stone. Most jnats seem to go up a few ticks from there, but at the same time, most will refuse to cut somewhere around the high end of hardness (65 or so) on japanese tools if the jigane doesn't pull a few particles from the surface.
There's probably more to it, like getting a good edge with worked slurry being due to the inability of a particular particle to sit down somewhere on the stone and cut a straight groove.
I don't know, but of the talk about the shrinking slurry, I'd sure like to see smaller slurry that's materially smaller before I drop my *duller particles* idea.
There's one hole in my theory above, and that is one particular stone that I have, okudo suita, seems that it will cut stuff a lot harder than other stones of the same hardness. I don't know what makes its cutting power so good, but it is well known (okudo's cutting power).
It isn't stated anywhere in the blog entry on Japanese natural slurry that "the slurry doesn't break down". What he says is:Quote:
Originally Posted by onimaru55
Note: No firm conclusion, just that he did not find evidence of silica particles breaking down or becoming refined through use using his methods. No more, no less.Quote:
Originally Posted by Todd@scienceofsharp
He addresses it further in a comment:
He is quite clear in this.Quote:
Originally Posted by Todd@scienceofsharp
As far as the scientific criticism goes, I think he could be doing much worse. He defines his terminology, carefully examines his subject and clearly states his methods, so they can be reproduced. On claiming new insights, I couldn't find other than he states that "The goal is to provide an understanding of what is happening a [sic] the blade’s edge", but I might have missed something.
I don't feel he's 'soapboxing' by any means. He engages in discussion in the comment section and doesn't come off as preachy or highly opinionated. I haven't yet read all of it, but what I did read was interesting at the very least.
I think there's no firm conclusion on the mechanism that causes a finer edge on a stone where the slurry has been worked a while, but the conclusion that the silica particles aren't breaking down is firm.
I think they dull. I think they're too durable to be friable and just break apart, but the edges get dulled just like an ice cube would get dulled if it was rolled around on a rink for a while. We don't get significant pressure on any one particle on the stone when we hone. It's no surprise that the binder would break down, it's soft and friable, otherwise it wouldn't let go of particles.
Did any of the blog entries show particles before and after? I think that would pretty easily show that the particles aren't shrinking. My own supposition above is just by the fact that microscopes have been around for a long time, but I've never seen a picture of slurry before and after where the after is crushed in general and very small.
I'm agnostic on what's actually happening, as long as the razor is getting sharp. There are some old wives tales in japanese stones and tools. A friend of mine who has gotten me some rare stuff tool wise from tokyo mentioned that one of the carpenters he met a few decades ago told him that if his chisels touched a synthetic stone (even medium and finish stones) that they would be irrepairably damaged and would have to be thrown away.
Sure, he could just make up stuff without any evidence like so many do. Given that he has free access to multimillion dollar equipment, the ability to use it well and extensive professional training - a PhD degree and post-doctoral experience - the quality of findings is highly unsatisfactory.Quote:
Originally Posted by Pithor
Like any other scientist I've been reviewing other peoples research for publications since graduate school (and had mine reviews) and this is just low level 'look at the pretty picture' type of data collection. The analysis of the data is poor and does not provide understanding.
For example take your quotes - he doesn't see that the size of the abrasive particles in the slurry changes with use and states that the slurry becoming "less abrasive" is an "accepted observation". So the abrasiveness of the particles in the slurry isn't determined by their size but by something else that changes with use. What is this? The first obvious hypothesis would be 'the shape', but that's not pursued in even the crudest manner, or even posited it. That's not a good science by any objective measure.
I don't remember everything I had issues with because it was almost three months ago, but there was more than one case. Ah, there was "This result indicates that the bevel set is completed at the 4k level, not the 1k level as commonly believed." This is an example of an arbitrary definition of what 'setting a bevel' means as the geometry changes in the honing progression are contiguous not abrupt.Quote:
Originally Posted by Pithor
He has picked two length scales relevant to the edge and is calling one of them 'sharp' the other 'keen'. There is absolutely no motivation for picking these particular length scales vs. something else (other than they're trivial for the microscope to measure). The obvious correlation between these two length scales along with an arbitrary parameter of 3microns makes his choice to treat them as independent parameters very unsatisfactory.
The difference is that he is a scientist and the bar is much higher than what he is presenting.
I don't care much about his conclusions, just the pictures that he puts up. I doubt that for most of us, it's going to change much. Pictures are interesting, though.
Great read, the burr has been giving me problems honing. I am considering trying spine leading strokes for bevel correction and edge leading for the rest of my progression.
If you do enough laps on your fine stone to remove the entire amount of scuzz left on the edge by the coarse stone, it shouldn't matter too much.
Actually, it shouldn't matter that much what you do with the coarse stones as long as you don't leave damage that the next stones can't remove. I've never had any regard for what those stones are doing until I get to a finish stone, just as long as whatever evidence is left on the blade is metal and no marks that weren't created by the last stone.
Yes, and any tiny microscopic remnants of the wire edge should be removed by stropping.