Which steels benefit from a coarser, toothier edge?

From my experience I like to leave S35VN (on my CRK's) at around 600 grit; I will lightly hone them after sharpening on a 1000 ceramic. I don't do mirror edges on those as they aren't for show, and I like them a bit toothier for use.
 
Depends what you're cutting. D2, with its large chromium carbides, responds well to a coarse edge. Powder steels like S30V don't seem to cut any better with a polished edge; 600 grit seems to work just fine. Simple high carbon steels like 1095 will take a very fine edge, ideal for woodwork. Tool steels (3V,M4) will take a fine edge with a bit of effort, but 600 grit seems ideal.
 
I have always had better cutting as well as edge longevity with a very fine edge. I typically use a Wicked Edge sharpener to bring a mirror polished edge which glides through any material better than a rougher edge. I have used knives a lot in my personal life as well as at work in many scenarios, most recently working in the marine environment on the surface and underwater working as a Diver.
 
S110V is a shit edge if you go past 1K with silicon carbide but if you use diamonds or CBN it's much better even when finished with a Venev 1200 grit stone which is about the same as a 8K Jis stone.
 
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It's not necessarily just about the steel type, more about what you want to cut.

If it's something like a straight razor or a knife used for very delicate / very thin slicing cutting tool / knife then a polished, very fine edge is great. If it's a EDC or general purpose knife that needs to cut a lot of different materials, then a coarse edge is king.

High Vanadium carbide / similar steels generally work best for general purpose or every day knives with a fairly coarse edge.
 
Coarser ! Generally speaking , the softer budget steels ..
But in no way does it mean that your higher grade steels can not work .

I believe = Give the knife the edge it wants , rather than the edge you want ..
 
wade7575 said:
...Venev 1200 grit stone which is about the same as a 8K Jis stone.
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FEPA-F 1200 is more like 4K JIS according to the grit chart on this forum, but I agree otherwise.

I've got the Venev Alpha Centauri stones(I think that is what they are called). F240, F400, F800, F1200. I most often finish on the F400(something like 600-700 JIS) and deburr on a finer one and that works pretty well for me, but some steels like ZDP 189 I like finishing on the 800(2K JIS) and it seems to work pretty well. "Toothy" is a pretty wide range though IMO. I would still consider 2 or 3K JIS pretty toothy.

Everyone's usage will differ though. I think the best thing for anybody is to try a few different edges and see what works for you.
 
In general, any blade will do better with a coarse edge if slicing abrasive materials, but also anything 3%+ vanadium and steels like D2 that are known to be prone to large carbide formation. Because the best use case for those steels tends to be, again, slicing of abrasive materials, that aligns nicely.
 
I've also noticed that even simple, low-alloy stainless and other steels at relatively low-medium hardness seem to do better with a little more tooth in the edge. If polished to a high degree and thinned at the apex in proportion to that polish, they tend to be too delicate and prone to edge-rolling or other damage from light use. But if taken 2-3 points higher in hardness, then the teeth left at a coarser finish will tend to be more brittle (less tough) and therefore shed or break away more quickly, and the steel will tend to take & hold a somewhat finer (less toothy) edge which is less prone to rolling or denting at the apex.

I first became aware of this difference in comparing 420HC between two makers - one of them at HRC 55-57, and the other at HRC 57-59. The softer one does better and cuts more durably at a slightly more toothy finish (325-400), while the harder example does very well at something slightly finer (400-600+), but won't hold the toothy finish as long.
 
For what little it's worth, I think it's true that softer steels do tend to benefit more often from a coarser edge. When it comes to making an edge "toothy", I think that's a bit different. I think there's a distinction between having a toothy edge and simply having a coarser edge because you chose not to use a smoother stone while sharpening.
 
When I refer to 'toothy', I mean an edge with more noticeable slicing 'bite' that can be felt at the fingertips or detected in how the edge immediately grabs at first contact, in a slicing cut. More about cutting aggression, as opposed to the actual grit finish. Can be varying degrees of it as well. That sort of noticeable bite can come from something coarser, like most any diamond hone up through 1200 or so, or a Fine India stone (360-400-ish) or as 'fine' as a medium ceramic. At that end in particular, if I transition from the medium ceramic to a fine ceramic (like Spyderco's examples of each), that same 'bite' tends to go away, at least in terms of what I can feel in cutting tests with it. That's where I view the finish as trending more toward polished and less about it being 'toothy'. That transition is what I notice in the difference between the two versions of 420HC at differing hardness I mentioned earlier. With the medium ceramic used as the finisher on both of them, the softer steel retains more of that toothy bite, whereas the harder one starts to lose that same aggressive bite and starts to behave more like a near-polished edge.
 
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FortyTwoBlades said:
In general I find a good practice for producing crisp toothy edges is to sharpen at a coarse grit then lightly finish on a fine stone. Helps keep the apex from being too foil-like and burred.
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That's how I've liked to do it, in a sense. I like to leave an almost-nothing microbevel, using either a medium or fine ceramic and applied in a minimal number of passes, like (hopefully) 2 or less per side at the lightest-possible touch. For me, it accomplishes two things: (1) deburring the edge of any weak remnants left by the coarser hone, and (2) narrowing the apex width (increasing keenness of the edge) and adding some stability to the edge for durability's sake.

In fact, I've liked to do that with the two versions of 420HC I mentioned earlier. I became real interested in the method after using a Coarse DMT (325) or even an Extra-Coarse (220) to set the edge on each of them, and then using either a Medium or Fine ceramic for the microbevel. That combination made for a viciously-slicing edge that I really liked - better than anything else I've tried. And that's actually where I noticed the subtle difference in how 'toothy' the harder version remained after setting the microbevel. I had to be much more careful about not going too far with the ceramic on the harder steel, as it seemed to diminish the bite much more quickly than it did with the softer version of the same steel sharpened in exactly the same manner. I attributed that to the finer 'teeth' being more brittle at higher hardness, and therefore being scrubbed away more quickly by the finer ceramic. I also noticed the same tendency in stropping that steel after sharpening - the 'bite' from the fine teeth at the edge seemed to go away pretty fast, even doing that.
 
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