High Speed Steel Puukko

Great work, from personal experience cutting rope in a knife comparison I know it would be easy to wear blisters in your hands without gloves or a very ergonomic knife. It takes tons of time to do what you did, and I really appreciate seeing that difference between all hard M2 and 154CM borne out by actual testing. If you have M4 that would be a great test as well. My Krein custom in M4 is 62 RC, and I hear the Spyderco Mule M4 I just got from Tom Krein should be about the same. It would be interesting to see how much the additional hardness of the M2 could overcome the additional carbides of the M4. Lots of work for another time. If I ever get off my ass and build myself a knife out of the M2 blades Sodak gave me I promise to compare them.

Mike
 
It really doesnt take that long, only about an hour to dull the 154CM, and I usually space it out over a couple of nights of tv watching. The other trick/limit is that I test for edges that I like to use and stop when I would sharpen it, or at least touch it up. The results for different steels would be completely different if I went to the dullness that most people accept before deciding to sharpen their kitchen knives. S30V, D2, M4, S90V, A11, and Talonite would be worlds ahead, I think, if I tested to the point that the knife wouldnt cut paper or steak.

Oh, and one more conclusion that I forgot earlier. Shaving sharp edges last a lot longer than typically believed. Cardboard is generally viewed as quite detrimental to an edge. The M2 would still cut hair above the skin after cutting about 20 feet of it, and neither knife lost its ability to shave arm hair. One modification to the batoning conclusion. This knife would probably not have survived its beating if the blade had a full flat grind, illustrating my belief that geometry and cross section are at least as important as steel choice and heat treatment. However, its still quite thin with a high hardness, and even I believed it would shatter pretty readily before the testing began.
 
Yes, a high quality steelproperly sharpened will retain it's shaving edge a long time, and once my knives start getting rough with their shaving off to the hones they go. I can't stand to use a dull knife anymore, which is one reason I carry 4 knives, including 2 in ZDP-189. Still getting tree topping after 20 feet of cardboard is impressive, I'll have to see if my M4 knives can do that. That is some very good edge stability. I start off with a .05 micron edge, so our finishes shouldn't be too different.

Mike
 
Our final compounds are about an order of magnitude different in size, but I dont know what the results would be if I went that fine. My finest finish is 0.3 micron film. For keeping a shaving sharp edge longer, I think hardness is more important than wear resistance. The M4 should work fine, but at 3-4 points softer, I doubt it would retain that level of sharpness longer than the M2, but you never know.
 
me2 said:
Our final compounds are about an order of magnitude different in size, but I dont know what the results would be if I went that fine. My finest finish is 0.3 micron film. For keeping a shaving sharp edge longer, I think hardness is more important than wear resistance. The M4 should work fine, but at 3-4 points softer, I doubt it would retain that level of sharpness longer than the M2, but you never know.
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If you're interested in playing with 66-67 rc CPM-M4 I can cut you a piece for the benefit of knife science.
 
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