Unsharpenable Blade?

I had a problem once with a friend’s Buck 110 folder in 440C and again in August of ’18, when I sharpened a couple of Buck 120’s (a fixed blade hunter) in 420HC that were stubborn buggers.  Both times, the problems appeared in the coarser grits.  Whereas other knife alloys seem to “machine” nicely, with the grit cutting nice scratches with each pass, with these the grit seemed to dig in and then bounce off, leaving a scratch pattern than looked like a poorly plowed field.  It was difficult just establishing a bevel.  After reading Fisher’s comments on 440C I have to wonder if it’s the high amount of chromium and a less-than-ideal hardening.

From my experience, knives that tend to chip in use probably do it at a microscopic level too.   So my suggestion is to take double or triple the number of strokes at each grit level.  The objective being to remove edge chipping left by the prior grit.

NorCalQ wrote:

That article is way over my head. What it interesting is that while I was taking my strokes with the coarser grits, I could really feel the toughness of this steel. It felt like no other blade I’ve ever sharpened. It felt like my diamond stones were just gliding across the surface, rather than biting in. Again, I’ve sharpened several other 440C blades from this same maker, but never had that sensation. A bad batch of 440C? Hmmm…I have no idea. I’m glad to hear I’m not the only one to experience occasional difficulty with a particular blade.

I think some of the steel in them are harder than usual. The stones in my Hall’s Pro Edge Wet Hone would not even scratch the steel in my Buck 301X pocket knife. And my diamond stones barely would.