Super Steel, Always Best To Sharpen With Diamond Rods?

Razor

Razor

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Dec 8, 1999
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I use my sharpmaker to sharpen all my knives. Is their any use to use anything but diamond rods on them when sharpening the super steels. I sometimes hit the knives a few times on a strop with diamond paste after the rods.
 
Can I sharpen the super steel at 30 degrees on the sharpmaker everytime and have a good sharp edge? Is their any reason to go to the 40 degrees angle? I can touch them up every night if need be or grab another knife.
 
I sharpen all my knives at 30 inclusive (15 per side) and have never had a problem with any of them. 420HC, S30V, M390, S110V, CPM154, 440C, S35VN. I’m sure there are others but those are what come to mind as my “comfortable to sharpen” steels in knives I own.
 
I never sharpen anything at higher than 30° inclusive. Literally any steel should handle that well for normal EDC usage. If it can't, it's not worth the trouble.

I've never used the 40° setting on the SM, so far as I can recall, except perhaps in using it to gauge how wide an edge is on a new knife. On occasions where I've had a new knife with an edge wider than 30° inclusive, I've always gotten around to reprofiling to within that limit or lower. I generally don't even carry a knife for regular use, until that's done. Once it is, it'll never see another sharpening at anything wider than 30°. Some of my knives are sharpened down to 25° inclusive or so. And with those, on the infrequent occasions I might add a microbevel, it also won't be added at anything wider than 30° inclusive.
 
A good rule of thumb is that if a steel has over ~3.5% vanadium content you'll want to use diamonds or CBN abrasives for grit ratings above ~400 ANSI/~360 FEPA F/~700 JIS. At or below that grit rating silicon carbide and aluminum oxide abrasives will scoop the fine vanadium carbides out along with the steel matrix, but above that grit rating the size of the abrasive vs. carbides gets too close to do that anymore. Pretty much anything outside of that scope can be handled by conventional synthetic abrasives, though.
 
40 degree setting is for a microbevel. Use 30 to get your main edge using diamonds, then do a quick micro on the 40 setting with the brown rods. Allows for quick touch ups as well. Works great for me on everything from 8cr and 420hc to 20cv and m390.
 
You have to do the bulk of the work with diamond or cbn, but finishing off with a few strokes on the fine or ultrafine rods with medium light isn't a bad idea. This will help align the apex which is left a little toothy and ragged from the coarse diamonds. It will also help break off any remaining burr. Just don't spend too much time on them, and be careful to maintain your angle.
 
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