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Thread: Longer-lasting Sharpness?

  1. #16
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    Quote Originally Posted by Prashun Patel View Post
    Luke, I hope you can sift through the debate here and distill some practical, useful info for your situation. I wanted to elaborate on my point:

    Since I stopped dragging my plane on the back stroke (thanks, Warren), taking more deliberate passes (thanks, David Charlesworth), and setting the chip breaker and lateral adjusters properly (thanks Brian H/David Weaver) I find that I'm struggling less and less with my strokes; it takes fewer to accomplish what I'm after. This ends up in far more blade longevity than would have adding an intermediate stone or changing the way I strop.

    I also find that I'm stroking on my stones less, with more deliberation. Everything slowly becoming more efficient. All this adds up to less manipulation of the blade, and less use. Don't get me wrong, materials and details about metal structure must be critically important, but I submit that this is only the case when you've reached a level of proficiency of Patrick, Stanley, Derek, and Warren. If you are earlier on the learning slope as I am, then my money is on 'honing' your technique, not changing your materials.
    This is good advice. I've definitely noticed a more than expected increase in edge retention as I've become less "ham handed" in how i handle the tools. Some (perhaps even most) of that can probably be attributed to increased efficiency (less cuts obviously means a longer edge). I do think there is also some impact by cutting "smarter" so the edge takes less impact though.

    It is possible that you have too soft of chisels and they're just wearing back faster than desired.. That's hard to know for sure. But even across a fairly broad range of tools I've found that really razor edge retention is fairly fleeting unless you're cutting something pretty easy (like basswood) and there is some merit in simply embracing the "sharpen early, sharpen often" mantra. Adjusting the bevel angle has some impact on this of course with all the attendant trade-offs. For carving chisels (where I'm most interested in super clean cuts and also tend to use a pretty shallow angle so the edge is relatively fragile) I find that stropping is required every couple dozen cuts or even more often if there is any end grain involved or the wood is abrasive or really hard.

  2. #17
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    Quote Originally Posted by Robert Engel View Post
    I'm sure I'll be corrected if I'm wrong...
    You greatly underestimate us; you'll also be corrected if you're right!
    AKA - "The human termite"

  3. #18
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    > Stanley, Patrick, Warren, Prashun, Ryan

    All excellent points and information. When I make a post like this, I'm usually just in a position to soak up various information more so than to reply to specific points.

    One thing that is for sure is that I've been using a wide range of steels and sharpening media, as I've been so keen to give everything a try to see what I like/don't like. I guess that leaves one in a position not to easily master any one thing, I guess. I have chisels and plane irons in everything from O1, to A2, some low-end but very hard Japanese steel tools, and even some mystery steel that seems a bit different from all the above. Moreover, as I mentioned in my previous post, I've been using just about every sharpening media under the sun. I do get very different results with the different steels that I'm using; my A2 chisels tend to fracture easily when I chop mortises, which perhaps suggests that I should increase the angle I sharpen them at a bit, or perhaps that there's something I'm doing poorly technique-wise. My O1 tools never fracture, but they do wear down easily, and I've had instances of my plane iron getting dinged up badly from hard knots in one particular SYP board that was hell to work with. My cheap Japanese tools have held up the best; I haven't had any of the chisels fracture from mortising, and they seem to stay sharp longer than my other tools. They are, of course, a bit harder to sharpen.

    I get very consistent results sharpening O1, but some of my harder steels are kind of hit-or-miss, and sometimes I spend longer on them than I should. I'm sure that's just a symptom of changing my methods so often and using a wide variety of steels, though.

    I think I'll stick with oil-stones for a while, as I'm liking them quite a bit, even if they're arguably not the fastest. I receive my Arkansas stones from Dan's, and they seem to handle even my really hard Japanese tools pretty well. I'm sure in time I'll learn how to use them most efficiently, and I'll continue experimenting with my methods to find what works best for what.

    I can definitely see how technique and tool-use could make a difference as well. I'm still not all that efficient in how I work, perhaps, but comparing myself to 3, 4, or 5 months ago, I'm certainly much more efficient than I was then, even. The great thing about being a novice is that you improve quickly
    Last edited by Luke Dupont; 07-22-2016 at 2:54 PM.

  4. #19
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    Quote Originally Posted by Luke Dupont View Post
    > Stanley, Patrick, Warren, Prashun, Ryan
    I think I'll stick with oil-stones for a while, as I'm liking them quite a bit, even if they're arguably not the fastest. I receive my Arkansas stones from Dan's, and they seem to handle even my really hard Japanese tools pretty well. I'm sure in time I'll learn how to use them most efficiently, and I'll continue experimenting with my methods to find what works best for what.
    There's a LOT to be said for sticking with (and iterating on) what works for you.

    One minor nitpick: When it comes to sharpening the average hardness of the steel actually isn't the biggest determinant. It's the maximum hardness, and specifically the presence of carbides that are well up into the Rc70s, that causes trouble. Japanese HCS chisels have very low carbide content, so the maximum is actually fairly low and they're fairly easy to sharpen. That's why SiOx media like oilstones and JNats work on them. That's not so for something like A2, though.

  5. #20
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    Quote Originally Posted by Patrick Chase View Post
    It's the maximum hardness, and specifically the presence of carbides that are well up into the Rc70s, that causes trouble. <snip> That's not so for something like A2, though.
    I was a bit surprised to learn that A2 had relatively small carbide and sparse carbide crystals compared to a lot of steels (more and bigger than O1, but still relatively few). Personally I find A2 a bit easier to sharpen on water stones than oil (but hate the mess), and the "feel" is different a bit stickier perhaps on oil than water. The O1 steel seem more comparable, just a bit slower.

    The point about maximum hardness is pretty useful, especially considering carbide grain sizes and whether or not you're pulling them out of the matrix, or shearing them off. As far as I can tell you mostly don't cut carbides with oil stones so they'll leave a better edge with things that don't have big honkin carbide crystals in them (for microscopic versions of big and honkin) like O1 or some of the Japanese steels otherwise you have fracture points along the edge where the stone pulled carbides out of the matrix.

    I kind of went down the "harder steel is better steel" route for a bit, but I'm coming around to the "easier to sharpen is kind of nice" and "hey maybe that old O1 isn't so bad after all" theory (I only have a couple of powdered steel pieces and not enough use to form an opinion). It certainly depends on what kind of material you're working, how your work area is setup, and what you like/enjoy doing though so it seems a bit dubious to make a strong statement any one theory being better than another in the general sense.

    If its working, stick with it. If its not, then figure out whats busted and how to adjust that part and fix that.

    On the mortise chisels I ended up with the Narex ones and a couple (especially the 1/4" which I use all the time) were simply buggers for chipping out when new. Once I sharpened them back a bit from the edge they behaved a whole lot better and settled in (actually the 3/8 is still a pita, but I haven't used it as much so I'm giving it a chance ). I believe that some of the tip of the chisels was a smidge over hardened and once I worked past that the problem area it was less of a problem.

  6. #21
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    Quote Originally Posted by Ryan Mooney View Post
    I was a bit surprised to learn that A2 had relatively small carbide and sparse carbide crystals compared to a lot of steels (more and bigger than O1, but still relatively few). Personally I find A2 a bit easier to sharpen on water stones than oil (but hate the mess), and the "feel" is different a bit stickier perhaps on oil than water. The O1 steel seem more comparable, just a bit slower.
    It's all relative. A2 has high carbide content and coarse grain compared to O1, "white steel", or even "blue steel". As you point out it isn't even close to D2, HSS, or any of the stainless alloys. The problem with honing A2 on SiOx media (Arks, JNats) is that they tend to erode the soft metal around the carbides and leave a "micro-chipped" edge. It may feel sharp coming off the stone, but it won't last. A lot depends on the angle, though - at higher edge angles erosion doesn't cause as much trouble.

    Quote Originally Posted by Ryan Mooney View Post
    The point about maximum hardness is pretty useful, especially considering carbide grain sizes and whether or not you're pulling them out of the matrix, or shearing them off. As far as I can tell you mostly don't cut carbides with oil stones so they'll leave a better edge with things that don't have big honkin carbide crystals in them (for microscopic versions of big and honkin) like O1 or some of the Japanese steels otherwise you have fracture points along the edge where the stone pulled carbides out of the matrix.
    I think that's a fair statement. Even water stones can get dodgy with exotic steels, though some are better at it (Sigma Select II) than others (Shapton). FWIW I use diamond films and pastes on tough steels these days. They sharpen carbides almost as well as the surrounding metal.

    w.r.t. choosing steels based on hardness, it's a tricky balance. For Western-style tools many makers have settled on moderately hard steels with medium to high carbide content. L-N's A2 alloy and LV's PM-V11 both fall into this category. Simplifying quite a bit, they keep the metal soft (compared to Japanese tools at least) to provide toughness and avoid chipping etc, while relying on the much harder carbides to provide abrasion resistance.and edge life. PM-V11 in particular has very high carbide content (higher than D2, close to 440C), but its PM processing keeps the grain structure fine so that you don't have chipping issues. It's arguably the best of all worlds in that regard.
    Last edited by Patrick Chase; 07-23-2016 at 12:25 AM.

  7. #22
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    I was really surprised to read the last couple of comments -- that A2 would be more difficult to sharpen than Japanese HCS, and would not leave as fine an edge off of Arkansas stones. So, curious, I did some test sharpenings of my Japanese and A2 chisels back to back.

    Sure enough, I think Patrick is right. My stones seem to cut the steel in my Japanese chisels faster than my A2. It also seems (and I noticed this even before reading the more recent comments in regard to sharpness), that the stones left my Japanese chisels with a finer edge, or, at least, that it was easier to get a very fine edge straight off the stone than my Narex chisels, which just don't seem to get quite as sharp. The difference isn't much, but...

    All of this time I thought everything just came down to the RC hardness rating, and didn't really know what people were talking about when they mentioned "carbides" and "complex steels." So, basically, A2 has super hard "impurities," if you choose to think of it that way. Or, I guess that's the case for all steels? I assume carbides are the carbon content included, and that's what hardens as opposed to the iron, then? Sorry, I'm quite ignorant of how this works. Interesting, though.

    One of my reasons for getting these stones is for use with Japanese tools, which I see more of in my future. I wanted something finer than my standard India > Strop regiment for them, and I'm not fond of man-made waterstones. So, in any case, it's good to see that they cut Japanese steel well enough. I was a bit concerned since I knew that Arkansas stones are a bit slow, and Japanese tools tend to be pretty hard.

    I'll try out my O-1 plane irons next.
    Last edited by Luke Dupont; 07-23-2016 at 4:58 AM.

  8. #23
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    Patrick's comments are very correct. The carbide are much harder than the matrix. A sharpening medium needs to be picked to be able to cut both the matrix and carbide. The carbide are not impurities but intentional part of the steel. In powder metallurgy grades, the size and distribution can be well controlled. But in any case, the heat treatment needs to prevent the carbide from growing and becoming too coarse.

    A last comment, the heat treatment of A2 is fairly complex and requires careful control and cryogenic treatment to get the most out of it. While everyone is focused on grades, one should be aware that in some grades there can be huge variations in properties due to the heat treatment. Even the same grade such as A2 with the same hardness can have different structure and properties.

  9. #24
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    Quote Originally Posted by Luke Dupont View Post
    All of this time I thought everything just came down to the RC hardness rating, and didn't really know what people were talking about when they mentioned "carbides" and "complex steels." So, basically, A2 has super hard "impurities," if you choose to think of it that way. Or, I guess that's the case for all steels? I assume carbides are the carbon content included, and that's what hardens as opposed to the iron, then? Sorry, I'm quite ignorant of how this works. Interesting, though.
    Here's a VERY simplified version: A few different things can happen to the Carbon in steel, depending on the composition of the steel and how it's heat-treated.

    In a low-alloy high-carbon steel like O1 or Japanese "white steel" the Carbon ends up mixed with the Iron in a few different ways, forming Martensite, Cementite, or Ferrite. The Carbon content and specific heat treatment determines the ratios. Martensite is what makes steel uniformly hard, so heat treatment generally strives to convert as much of the iron to Martensite as possible. Cementite tends to form from excess Carbon at higher Carbon concentrations and is in fact iron carbide, so even low-alloy HCS can contain "carbides", but they tend to be small and well dispersed and not so much of an issue for sharpening.

    When you have a higher-alloy steel like A2 the excess Carbon tends to combine with those alloyants (mostly Chromium in A2) to form their respective Carbides (Chromium Carbide). It isn't an "impurity" inasmuch as it's very much done on purpose. Chromium Carbides are (mostly) what gives A2 its well known wear resistance.

  10. #25
    Quote Originally Posted by Patrick Chase View Post
    Here's a VERY simplified version: A few different things can happen to the Carbon in steel, depending on the composition of the steel and how it's heat-treated.

    In a low-alloy high-carbon steel like O1 or Japanese "white steel" the Carbon ends up mixed with the Iron in a few different ways, forming Martensite, Cementite, or Ferrite. The Carbon content and specific heat treatment determines the ratios. Martensite is what makes steel uniformly hard, so heat treatment generally strives to convert as much of the iron to Martensite as possible. Cementite tends to form from excess Carbon at higher Carbon concentrations and is in fact iron carbide, so even low-alloy HCS can contain "carbides", but they tend to be small and well dispersed and not so much of an issue for sharpening.

    When you have a higher-alloy steel like A2 the excess Carbon tends to combine with those alloyants (mostly Chromium in A2) to form their respective Carbides (Chromium Carbide). It isn't an "impurity" inasmuch as it's very much done on purpose. Chromium Carbides are (mostly) what gives A2 its well known wear resistance.
    Very nice summary and explanation. I'll just add a couple nerdy bits for Luke et al about the low alloy stuff, which is what I have direct experience with (the higher-alloys not so much).

    The steel used in a lot of late 19th c. – early 20th c. tools, particularly stuff marked "cast steel" as well as most laminated tools, is what's called "eutectic" steel, which means it has only as much carbon (about 0.7 - 0.8%) as can be eventually converted to martensite during heat treating. This means there's very few carbides in the final product, so such steel tends to be very fine-grained, takes an incredible edge, but doesn't have the wear resistance of steels with more carbides. A modern example of eutectic steel is 1075, which is approx. 0.75 % carbon.

    On the other hand, steels like 1095 (0.95% carbon), ) O1 (1%), or Japanese white and blue (1.1 - 1.3%), are "hypereutectic" steels. They have more carbon than can be converted, so some of the excess carbon ends up as carbides, as Patrick explains, which is why these steels have greater wear resistance than eutectic steel. They are still very fine-grained, but not as fine as eutectic steel.

    Then, as soon as you start adding stuff like chromium, manganese, etc., you start trading fine grain for wear resistance. This is barely noticeable in something like O1 but becomes more of an issue in steels like A2, and even more in something like D2, as previously mentioned in this thread.
    "For me, chairs and chairmaking are a means to an end. My real goal is to spend my days in a quiet, dustless shop doing hand work on an object that is beautiful, useful and fun to make." --Peter Galbert

  11. #26
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    My understanding of A2 is that its also prone to uneven matrix formation and retained austenite (incomplete martensite formation), so you can end up with pieces that while more or less evenly "hard" still have a annoying fracture lines or points in them that can cause issues with edge retention. Less a "wear" problem and more a "tear out" problem (for some values of wear and tear out.. heh). Some A2 treatments would seem less prone to this than others, but knowing what a particular vendor is doing is challenging (to put it mildly) and the best measure in the end is how well the tools work in use (which as noted above depends somewhat on the use their put to).

    Carbide crystals also tend to have poorer bonding points with the surrounding matrix than the a more uniform matrix does with itself so even if they aren't pulled out during sharpening (or left sitting "proud" of the surrounding area) they're still a somewhat more likely point of edge failure under some usage conditions. Whether or not those usage conditions are prevalent in hand tool use I'm hesitant to say. I'm also not sure if the crystal formation is large enough in A2 for this effect to actually matter for our purposes.

  12. #27
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    Quote Originally Posted by Ryan Mooney View Post
    My understanding of A2 is that its also prone to uneven matrix formation and retained austenite (incomplete martensite formation), so you can end up with pieces that while more or less evenly "hard" still have a annoying fracture lines or points in them that can cause issues with edge retention.
    That very much depends on the processing. Cryo treatment as done by LN and Hock is reputed to largely address the problem of retained austenite in A2.

  13. #28
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    Quote Originally Posted by Patrick Chase View Post
    That very much depends on the processing. Cryo treatment as done by LN and Hock is reputed to largely address the problem of retained austenite in A2.
    Hence "Some A2 treatments would seem less prone to this than others", I might have a small tendency towards understatement.

  14. #29
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    Quote Originally Posted by Steve Voigt View Post
    Very nice summary and explanation. I'll just add a couple nerdy bits for Luke et al about the low alloy stuff, which is what I have direct experience with (the higher-alloys not so much).

    The steel used in a lot of late 19th c. – early 20th c. tools, particularly stuff marked "cast steel" as well as most laminated tools, is what's called "eutectic" steel, which means it has only as much carbon (about 0.7 - 0.8%) as can be eventually converted to martensite during heat treating. This means there's very few carbides in the final product, so such steel tends to be very fine-grained, takes an incredible edge, but doesn't have the wear resistance of steels with more carbides. A modern example of eutectic steel is 1075, which is approx. 0.75 % carbon.

    On the other hand, steels like 1095 (0.95% carbon), ) O1 (1%), or Japanese white and blue (1.1 - 1.3%), are "hypereutectic" steels. They have more carbon than can be converted, so some of the excess carbon ends up as carbides, as Patrick explains, which is why these steels have greater wear resistance than eutectic steel. They are still very fine-grained, but not as fine as eutectic steel.

    Then, as soon as you start adding stuff like chromium, manganese, etc., you start trading fine grain for wear resistance. This is barely noticeable in something like O1 but becomes more of an issue in steels like A2, and even more in something like D2, as previously mentioned in this thread.
    Wow, that's a really nice writeup. I avoided the whole eutectoid vs hypereutectic thing and hand-waved about "excess Carbon" instead because I didn't think I could explain it concisely. You did.

  15. #30
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    I never spend any time thinking about these sort of details you guys are posting about. Someday, I may be using wood that it matters on, but my last hand planning project used Bald Cypress. I sharpened the stock Stanley irons after planning for three hours, but don't know if I really needed to or not. I was going back to work after lunch, and decided I might as well hone the irons of the two planes I was mainly using. The starting point then was the 6k stone first.

    I do like to sharpen something as sharp as I can get it. I've seen people say that stopping at 6,000 grit makes a cutting edge sharp enough, but my thinking is that a couple of minutes getting it a lot sharper will pay a dividend of many more minutes, or even an hour or more, of workable sharpness until it gets down to the stage that the 6k stone would have given you at the starting point.

    I guess you guys probably do a lot more planing than I do though to worry about the metallurgic details.

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