Thursday, July 10, 2014

Survival Knife: Steel hardness and sharpening‏

Maybe you can shed some light on this on your blog.  I have a Spyderco Endura, VG10 steel.  It was razor sharp out of the box, but in time the blade got dull, and I have never been able to sharpen it with my wet stone back to factory standards.  Meanwhile, I also have a Boker Magnum (looks like a Buck110 knock-off).  It’s probably some cheap stainless steel, judging from the price I paid for it, but it takes a razor sharp edge with a couple of passes on the same wet stone and it retains the edge relatively well.  So what make the VG10 steel better than say 1080, if it’s so hard to sharpen?



Hello Jose,
The knife market is saturated with products and everyone wants the strongest and sharpest. These days, in many ways knives companies live or die depending on what a guy on youtube says. Does one knife cut 20 pieces of cardboard before failing to cut paper while another cuts 15? Guess which one ends up making the crazy sales after one of those videos hits 100.000 views.
Because of this knife companies are looking to make sharper knives, that cut better (although sometimes they sacrifice a tougher blade geometry in the process, like in the case of full flat grind knives) and hold an edge longer (although this same thing makes it much harder to sharpen). The Endura is a great knife, but I prefer the saber grin over the more fragile full flat grind.
Hardness is another hot topic. Everyone wants to have the harder knife. Joke about it but its true. “My knife is 60HRC” “Oh, yeah? Mine’s 61!”.  In the good old days a knife was simply a high carbon steel blade similar to 1055 or 1080 and hardened to 50-55HRC. It would be tough as nails, hold an edge well enough, and a breeze to sharpen.
Today, we have knife enthusiasts that can’t even sharpen a knife themselves and want a knife that holds an edge longer before sending it over to someone to sharpen it for them. That’s how we end up with knives that are too hard, even brittle and may fail catastrophically or in the best case a knife that is at least a pain to resharpen.
Answering your question, what makes VG10 is the same thing that makes it a pain to sharpen: It’s a tough steel that holds an edge well, but holding an edge well means that it has resistance to wear, that the blade material, may that be for losing the edge or for putting it back, its harder to remove.  VG10 is a high end knife steel that doesnt need resharpening often, but it will take more work to sharpen well when needed.

Spyderco Endura 4 Folding Plain Edge FRN Knife

I see this as more of an advantage in smaller blades that you want to use but you don’t want to sharpen often. For bigger knives its more of a pain, and sharpening becomes an even harder job. 1080 is a very nice, no frills high carbon steel. As you notice, its tough but not as hard as VG10. This means its easier to sharpen as well. My daily pocket knife is a  surplus German Army Knife by Victorinox. Its X55CrMo14 hardened to 56 HRC. That’s a nice balance of edge durability and ease of resharpening.  That pocket knife is a joy to use and although I use it and resharpen it often, its easy to keep razor sharp.
At the same time, my most used multitool is  a Leatherman Charge. This one has an S30V blade and like VG10  its not as easy to resharpen, but it does hold the edge longer.


1 comment:

Jose Garcia said...

Thanks for the great response to my question. Yes, the Boker that takes an edge very easily does feel like it can break easily while the Endura I have abused it to the point of using it as an ice pick.

I do notice, though, that while the saber geometry lends lots of strength to the blade, it's not optimal for slicing.