MMUK
Established Member
Jacob":2ok3inuf said:
Most of which are comments you've posted anyway :roll:
removing a back bevel
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Most of which are comments you've posted anyway :roll:
carlb40
Established Member
Which is always the same with any thread involving jacob. :evil:MMUK":3oc3rqjn said:
Jacob
New Luddism. Awake and resist!
I get used being trailed around by the same little gang of trolls all the time. They never have anything interesting or useful to say - I don't know why they bother. Just a waste of space. Reminds me of being back in junior school.
Jacob
New Luddism. Awake and resist!
There goes another one!
Racers
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Well Jacob all the other forum members I have met have had the same opinion of you, you know your stuff but you are a right pain.
If you could just drop the latter things would be alot better round here, I might even take you off my ignore list!
Pete
If you could just drop the latter things would be alot better round here, I might even take you off my ignore list!
Pete
Jacob
New Luddism. Awake and resist!
Please put me on your ignore list.
Cheshirechappie
Established Member
Corneel - you're quite right about Rob Lee's PMV-11 investigations, of course. It's not pure science, though it does seem to be about as close as anybody has come in recent years in the woodworking hand-tool field.
Jacob - if I did have unlimited time and money (ha ha!) to spend on scientific investigation, I'd look at what happens between a piece of toolsteel and a honing stone. What happens to the steel - pure abrasion, plastic deformation, or some combination of the two? - does abrasion happen by breaking of the grain boundaries, or are individual grains cut apart too? What is the effect of using different steels, or the same steel worked in different ways - multiple-strike forging, rolling, drop-forging or hydraulic pressing. I'd look at what happened to the abrasive, too; what's the influence of the abrasive, the bonding material, the different minerals in a natural stone. How exactly? Not really sure - start somewhere, and see where investigations led, I suppose. There might be some literature out there, but I haven't seen it yet.
Why? Curiosity, really. Like I said some posts ago, we know it works, but how and why? I rather doubt it would lead to much faster sharpening or better edges; such things would more than likely have been found by trial and error by now given the length of time craftsmen have been whapping tools up and down honing stones, but you never know. But - people keep making statements about tools and sharpening that have never really been properly investigated. For example, there was a slight difference of opinion in British Woodworking magazine a few months ago when David Savage stated his opinion that there has never been an equal to the old Sheffield tools for edge-taking ability. David Charlesworth begged to differ. It would be interesting to study things like that a bit, see if there's any facts to back up either's hunches. That's the beauty of science - you just never know for sure what you might find, and sometimes it might answer a few questions along those lines.
Jacob - if I did have unlimited time and money (ha ha!) to spend on scientific investigation, I'd look at what happens between a piece of toolsteel and a honing stone. What happens to the steel - pure abrasion, plastic deformation, or some combination of the two? - does abrasion happen by breaking of the grain boundaries, or are individual grains cut apart too? What is the effect of using different steels, or the same steel worked in different ways - multiple-strike forging, rolling, drop-forging or hydraulic pressing. I'd look at what happened to the abrasive, too; what's the influence of the abrasive, the bonding material, the different minerals in a natural stone. How exactly? Not really sure - start somewhere, and see where investigations led, I suppose. There might be some literature out there, but I haven't seen it yet.
Why? Curiosity, really. Like I said some posts ago, we know it works, but how and why? I rather doubt it would lead to much faster sharpening or better edges; such things would more than likely have been found by trial and error by now given the length of time craftsmen have been whapping tools up and down honing stones, but you never know. But - people keep making statements about tools and sharpening that have never really been properly investigated. For example, there was a slight difference of opinion in British Woodworking magazine a few months ago when David Savage stated his opinion that there has never been an equal to the old Sheffield tools for edge-taking ability. David Charlesworth begged to differ. It would be interesting to study things like that a bit, see if there's any facts to back up either's hunches. That's the beauty of science - you just never know for sure what you might find, and sometimes it might answer a few questions along those lines.
G S Haydon
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Jacob" The point is - most planes work really well if they are set up well and sharpened by whatever method said:
+1 for Jacob. It would be much duller around here without him.
It was reading threads on sharpening that hooked me and kept me coming back to this forum.
It's good to see the phony mystique blown away. There is an awful amount of self aggrandising twaddle spouted about sharpening - it really is not rocket science. It should be a means to an end, something to be mastered quickly so that you can get on with the interesting stuff.
Sent from my GT-I9100 using Tapatalk
It was reading threads on sharpening that hooked me and kept me coming back to this forum.
It's good to see the phony mystique blown away. There is an awful amount of self aggrandising twaddle spouted about sharpening - it really is not rocket science. It should be a means to an end, something to be mastered quickly so that you can get on with the interesting stuff.
Sent from my GT-I9100 using Tapatalk
Julian":2aqsyksu said:
Phony mystique indeed. Great post!
Carl P
Established Member
Julian":2aukdtek said:
Quite agree, but I'm also interested in the science - not as just another way of saying 'nyah nyah na nyah nyah', but because it's interesting to know as well as do stuff.
Cheerio,
Carl
Wow!
I go away for a few days and now I see that this thread has not only grown to great length, it has managed to stay largely polite and find some new ground to wonder about and explore. I'm no metallurgist but I do want to have some idea in my head of what I am doing when I sharpen, so the discussion about how a grain of abrasive can move a tiny bit of steel is useful. The suggestion that a rounded grain will plough a groove by pushing metal aside is interesting and I can imagine it making an edge which is more coherent, with fewer tiny cracks where use will make it fail, becoming blunt.
It makes me wonder about yet another variable in different sharpening methods, the direction of rubbing, relative to the edge.
If you put a stone on the bench, short side towards you, and just push a chisel up and down the stone (away from and towards your body) all the sharpening scratches will be at right angles to the cutting edge.
If you move the chisel in a long figure of eight, some of the time you will be rubbing at less than ninety degrees to the edge. The tiny scratches, or the consolidation effect, will be along the cutting edge, like a butcher's knife sharpened on a steel. Maybe that makes a longer lasting sharp edge?
So maybe this is another variable worth experimenting on. I expect that rubbing at right angles to the edge is commonest. Wide stones (wider than a plane iron) make it look normal, as do big sheets of paper and jigs with long rollers.
But I do recall a video someone found of a Japanese sharpening jig where the blade was hitched to a post and swung from side to side in a large arc, so the rubbing was nearly parallel to the edge, and it seemed to work well.
I go away for a few days and now I see that this thread has not only grown to great length, it has managed to stay largely polite and find some new ground to wonder about and explore. I'm no metallurgist but I do want to have some idea in my head of what I am doing when I sharpen, so the discussion about how a grain of abrasive can move a tiny bit of steel is useful. The suggestion that a rounded grain will plough a groove by pushing metal aside is interesting and I can imagine it making an edge which is more coherent, with fewer tiny cracks where use will make it fail, becoming blunt.
It makes me wonder about yet another variable in different sharpening methods, the direction of rubbing, relative to the edge.
If you put a stone on the bench, short side towards you, and just push a chisel up and down the stone (away from and towards your body) all the sharpening scratches will be at right angles to the cutting edge.
If you move the chisel in a long figure of eight, some of the time you will be rubbing at less than ninety degrees to the edge. The tiny scratches, or the consolidation effect, will be along the cutting edge, like a butcher's knife sharpened on a steel. Maybe that makes a longer lasting sharp edge?
So maybe this is another variable worth experimenting on. I expect that rubbing at right angles to the edge is commonest. Wide stones (wider than a plane iron) make it look normal, as do big sheets of paper and jigs with long rollers.
But I do recall a video someone found of a Japanese sharpening jig where the blade was hitched to a post and swung from side to side in a large arc, so the rubbing was nearly parallel to the edge, and it seemed to work well.
I think a figure eight pattern should result in scratches of multiple directions. Anyway, I abandoned figure of 8 sharpening years ago in favour of very short forward/backward strokes. The arm movement of the former being unnecessary complex.
Certain blades (usually small thumb plane types) I do sharpen parallel. No idea if it results in a longer lasting edge, exactly the same or worse!. It's not night and day, that's for sure.
Certain blades (usually small thumb plane types) I do sharpen parallel. No idea if it results in a longer lasting edge, exactly the same or worse!. It's not night and day, that's for sure.
woodbrains
Established Member
Hello,
I have been doing some research here and there, over the last few days and come up with a few interesting findings. I have bought a book on metalography too, so might find out a bit more when I have read that.
There are a few surprising things in my initial search. It seems that almost nothing was known about the metalographical effect of abrading and polishing metal, until the 1950's, so any results obtained, good or bad, when honing tools prior to that was purely serendipitous. I'm afraid those who think that old methods are the best are slightly misguided. Some obviously were, but no one could tell why until recently, just because it was old, traditional and done by countless craftsmen does not guarantee it was effective.
Polishing metal with abrasives on glass was documented to have been done first in about 1860. Essentially, 'scary sharp' is not a new fangled, fashion fad method of sharpening after all!
The coarseness or fineness of sharpening abrasive has a lot to do with affecting the sub structure of steel. I'm not entirely sure until I find out more, but I think it has something to do with the plastic and elastic state of the steel during sharpening. Basically there is some sub surface distortion caused when sharpening which causes edge failure at some point. This damage is reduced with successive honing on finer grit. There is a point to sharpening with fine abrasives to gain longevity of the sharpened edge, not just getting it sharper to begin with.
Also, referencing another thread here which did not fully answer the question; micro bevels actually do have a point, other than speeding up (or over complicating depending on your view) honing the extreme edge. Increasing the angle of the last hone on the finest stone, should more effectively remove the sub surface damage of the steel, than honing on the bevel alone, so give the tool better edge retention. I don't think even David Charlesworth who actively uses multiple bevel sharpening, realised this fact on his explanation there.
Mike.
I have been doing some research here and there, over the last few days and come up with a few interesting findings. I have bought a book on metalography too, so might find out a bit more when I have read that.
There are a few surprising things in my initial search. It seems that almost nothing was known about the metalographical effect of abrading and polishing metal, until the 1950's, so any results obtained, good or bad, when honing tools prior to that was purely serendipitous. I'm afraid those who think that old methods are the best are slightly misguided. Some obviously were, but no one could tell why until recently, just because it was old, traditional and done by countless craftsmen does not guarantee it was effective.
Polishing metal with abrasives on glass was documented to have been done first in about 1860. Essentially, 'scary sharp' is not a new fangled, fashion fad method of sharpening after all!
The coarseness or fineness of sharpening abrasive has a lot to do with affecting the sub structure of steel. I'm not entirely sure until I find out more, but I think it has something to do with the plastic and elastic state of the steel during sharpening. Basically there is some sub surface distortion caused when sharpening which causes edge failure at some point. This damage is reduced with successive honing on finer grit. There is a point to sharpening with fine abrasives to gain longevity of the sharpened edge, not just getting it sharper to begin with.
Also, referencing another thread here which did not fully answer the question; micro bevels actually do have a point, other than speeding up (or over complicating depending on your view) honing the extreme edge. Increasing the angle of the last hone on the finest stone, should more effectively remove the sub surface damage of the steel, than honing on the bevel alone, so give the tool better edge retention. I don't think even David Charlesworth who actively uses multiple bevel sharpening, realised this fact on his explanation there.
Mike.
woodbrains
Established Member
Hello,
Forgot to mention, the point density of the abrasive used can have an effect on the sub surface damage. Abrasives of the same effective size, but more closely packed will cause less disruption than less densely packed ones. Perhaps this is why diamond hones always feel a bit coarser than they are rated to be. This might suggest that particle shape can have an effect also, but I have not found anything conclusive. Perhaps a round particle could cause less damage than a pyramid shaped one, of the same size, but I haven't found anything on this in detail. It may be that when particles get so small, there is little difference.
Mike.
Forgot to mention, the point density of the abrasive used can have an effect on the sub surface damage. Abrasives of the same effective size, but more closely packed will cause less disruption than less densely packed ones. Perhaps this is why diamond hones always feel a bit coarser than they are rated to be. This might suggest that particle shape can have an effect also, but I have not found anything conclusive. Perhaps a round particle could cause less damage than a pyramid shaped one, of the same size, but I haven't found anything on this in detail. It may be that when particles get so small, there is little difference.
Mike.
Carl P
Established Member
Mike,
Sounds fascinating - I'm very glad you're posting a 'digested read', it'll save my indigestion!
Looking forward to any updates,
Carl
Sounds fascinating - I'm very glad you're posting a 'digested read', it'll save my indigestion!
Looking forward to any updates,
Carl
MMUK
Established Member
MIGNAL":2h45kfst said:
Nah, sod that! You want a figure of 64 for ultimate sharpness :wink:
Cheshirechappie
Established Member
Interesting stuff, Mike. May I ask you to post any references or books you find with relevant information in?
On that note, this reference (whilst not exactly tool steels on the usual woodworker's abrasives) may offer some insights - http://cdn.intechopen.com/pdfs-wm/31706.pdf
On that note, this reference (whilst not exactly tool steels on the usual woodworker's abrasives) may offer some insights - http://cdn.intechopen.com/pdfs-wm/31706.pdf
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