Good afternoon gentlemen, today I was concerned because it was time for me to sharpen 20 CV steel for the first time in my life. I could not believe how easy it was to get a hair shaving edge. The last knife I sharpened was in AUS 10A. And it was very difficult to sharpen. Does that mean that aus 10A is harder steel than 20 CV? I'm just trying to figure this out because right now I'm a little confused. Thanks in advance for your knowledge fellas
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A sharpening question
- Thread starter Vlade
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UncleBoots
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Heat treat is probably mattering more than composition here. I've seen a lot of variation in the ease of sharpening of various makers' VG10, for example. Some say that running VG10 harder makes it easier to sharpen.
With stainless steels, softness can mean a more persistent burr, and therefore more time spent to converge on a clean edge.
With stainless steels, softness can mean a more persistent burr, and therefore more time spent to converge on a clean edge.
It's hard to say without more information. How experienced are you with sharpening? Do you even know what the angle of the edge is vs the angle you were sharpening at? For example, if you have an acute angle like 15 degrees per side, it's going to be easy to sharpen if you mismatch angle by making it more obtuse than what you started with, whereas if you start with an angle of 20 degrees per side and you try to sharpen it at a more acute angle like 17 degrees per side, then it will take you a lot longer to get an apex. I hope that's clear enough.
The main takeaway is that it takes a lot longer to go from a more obtuse angle to a more acute angle, relatively speaking. It's simple geometry. You have to remove more steel to thin the edge from obtuse to acute, so sharpening will take a lot longer. But if you start with a more acute angle and you make it more obtuse, then initially it will just make a micro bevel, so it will sharpen very quickly and it will also strenghten the edge somewhat. This is one of multiple reasons why having an awareness of angles is important.
The main takeaway is that it takes a lot longer to go from a more obtuse angle to a more acute angle, relatively speaking. It's simple geometry. You have to remove more steel to thin the edge from obtuse to acute, so sharpening will take a lot longer. But if you start with a more acute angle and you make it more obtuse, then initially it will just make a micro bevel, so it will sharpen very quickly and it will also strenghten the edge somewhat. This is one of multiple reasons why having an awareness of angles is important.
So what was the original angle of the edge before you sharpened it?
SwissHeritageCo
Knifemaker / Craftsman / Service Provider
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Grind could have alot to do with it.
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Even 'simpler', less wear-resistant steels can be a pain to sharpen if the the grind behind the edge is thick and/or if the original edge angle is very wide. Anytime a lot of steel has to be ground off to attain decent cutting geometry, the going will be slower at the very least. Add to that, if the steel is also a softer, more ductile stainless (like AUS-XX types, 420/440-class steels, etc), you need to account for clogging of stones and staying ahead of that (lubricate the stone), and dealing with more burring issues as well. If a stone gets clogged with swarf from such steels, the progress slows exponentially. Newer, more modern wear-resistant steels at higher hardness won't usually present as much of that problem, which is one way they can actually be easier to sharpen than some would assume, especially if the right abrasives are used (diamond / cbn). Some high-wear steels can be stupid-simple to sharpen with the right choice of stone, and more so if the blade grind is nice & thin to start with and at a decent hardness to mitigate stubborn burring issues.
Seems like a lot of older knives I've seen in steels like AUS-6/8/10 etc were always pretty thick-edged to start with, as were a lot of knives of that era (1990s & earlier). That by itself often made them somewhat a hassle to get cutting really well. More makers these days are wising up to thinner grinds on factory blades, making them better cutters (even improving edge retention in going thinner) and much easier to make sharp and maintain them as such.
And I've seen some comparison between AUS-10 and 440C, both having (apparently) similar grain characteristics with fairly large chromium carbides. If the carbides are pretty big & chunky, like 440C's are, that sometimes tends to limit how fine the apex can get in sharpening. Newer CPM-grade steels utilize a finer particle metallurgy process, which makes the carbides much finer and more evenly distributed in the steel, making it both very wear-resistant and still easier to sharpen to a finer edge.
Seems like a lot of older knives I've seen in steels like AUS-6/8/10 etc were always pretty thick-edged to start with, as were a lot of knives of that era (1990s & earlier). That by itself often made them somewhat a hassle to get cutting really well. More makers these days are wising up to thinner grinds on factory blades, making them better cutters (even improving edge retention in going thinner) and much easier to make sharp and maintain them as such.
And I've seen some comparison between AUS-10 and 440C, both having (apparently) similar grain characteristics with fairly large chromium carbides. If the carbides are pretty big & chunky, like 440C's are, that sometimes tends to limit how fine the apex can get in sharpening. Newer CPM-grade steels utilize a finer particle metallurgy process, which makes the carbides much finer and more evenly distributed in the steel, making it both very wear-resistant and still easier to sharpen to a finer edge.