Finally Achieved hair-whittling sharp!!!

Bladenoobie1

Bladenoobie1

Joined
Jul 20, 2012
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I bought a cheap Kershaw gutting knife from my local sporting store today and decided to sharpen it. Using the Sharpmaker medium rods, a strop man strop (black and white compound), and a green knives plus strop block I can finally split a hair. The only thing that's bothering is that I can't get a hair-whittling edge on my Spyderco Paramilitary 2. Right now it has a convex edge put on by Richard J. I tried refining the edge today to my avail. It still slices printer paper decently, but it's no where on the level of the gutting knife sharpness. I seem to be able to get a "sticky" edge on the Kershaw with ease, but despite going through the same process on the PM2, its edge won't get that fine. Any idea on what I'm doing wrong? :confused:
 
What steel is the PM2? And for comparison, what steel is the Kershaw (or what model, if you're not sure of the steel)?

I'm betting it's likely you're seeing the difference in ease of sharpening (abrasion resistance) between the PM2's 'super steel' (assuming something like S30V, D2, etc.), and the low/mid-range stainless of the Kershaw. The PM2's blade probably includes a lot of vanadium carbides, which are much harder and won't abrade (sand/grind/sharpen) near as easily as the Kershaw's stainless, which likely features little or no vanadium carbides. Diamond is usually the best medium for sharpening vanadium carbide-rich steels, for this reason. It is possible to get hair-whittling edges on these, but they take a LOT more work and patience, to get it there. If an existing factory edge is good (fully apexed, good geometry), sometimes it's possible to do it fairly quickly on ceramics (Sharpmaker), assuming it's done very lightly and carefully. But it's also very easy to blunt or round off a good edge the same way, if angle control is inconsistent or pressure is too heavy.

It's also possible you're seeing the difference in grain size of the steel, between the (generally) larger vanadium carbides in the PM2, and the (possibly) much finer grain of the steel in the Kershaw. The chromium carbides in many stainless steels can also be rather large sometimes, but they're also much easier to grind (not nearly as hard as vanadium carbides). Larger & harder carbides, and therefore larger grain size, will make it more challenging to put a really fine edge on the PM2's blade. Again, it's not impossible, but it takes more work.
 
Bladenoobie1 said:
its s30v for the pm2 and for the cheap kershaw gutting knife, its 420J2 stainless steel
Click to expand...

OK. That pretty much confirms what I said earlier. S30V is full of vanadium carbides (vanadium content is very high, at 4%), and 420J2 has none at all (0% vanadium in the alloy). 420J2 is also very low carbon content (0.15 - 0.36%), which makes it all the 'softer' to sharpen. Compare that to S30V's carbon at about 1.45%. It's the combination of carbon and vanadium that makes the ultra-hard vanadium carbides. These two steels are virtually at opposite ends of the 'abrasion-resistant' spectrum.
 
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:rolleyes: Well thanks for the information, the gutting knife is really fun to play with though haha and it's cheap so I don't have to worry about breaking it.
 
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