Edge rollover with CPM S35VN

L

levernut

Well-Known Member
One of my EDC knives is a small 3" drop point made from CPM S35VN and hardened to Rc 60. I use it for everything including opening boxes, gardening and preparing vegetables. After only a short time, the edge rolls over and it no longer cuts well. A steel will straighten the edge after a few dozen strokes but the edge will soon roll again. My standard method of sharpening is with a Lansky sharpener using diamond stones and I finish with their black hard arkansas stone. I have tried finishing with a fine diamond stone and have tried different angles but nothing seems to make a difference. Any suggestions? Is this typical of this steel?
 
Hello, I could be totally wrong but it sounds like the burr is not being removed? Typically sharpening steels will not remove the burr, but line them up. I set my first bevels using my belt grinder until a burr forms on the edge, then use Spyderco's ceramic sticks to remove the burr. The only other thing I could think of is the hardness softer than you think? Hopefully you will hear from some other makers on this.
Clint
 
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Did you perhaps grind a too thin blade? My little bit of involvement with this steel has made me feel it is on of the better stainless ones. Frank
 
Without looking at the edge, you might just have a bur or the edge could be too thin and you are rolling the edge. Use a leather strop and compound to remove the bur. If the edge is too thin, increase the angle of the secondary bevel to a more obtuse angle. I make only single bevel knives using convex and scandi bevels to zero but I believe I understand your problem.
 
Bush Monkey said:
Without looking at the edge, you might just have a bur or the edge could be too thin and you are rolling the edge. Use a leather strop and compound to remove the bur. If the edge is too thin, increase the angle of the secondary bevel to a more obtuse angle. I make only single bevel knives using convex and scandi bevels to zero but I believe I understand your problem.
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I agree if you don't have a burr remaining your final bevel is too acute, fortunately that is a much quicker fix than if it was too obtuse.
 
That sucks. Sounds like something is wrong for sure. If the edge got too hot grinding, the temper could have be ruined, but the rest of the blade would test OK. Does the edge seem too thin? I've made several knives with that stee l and never had any trouble.
-John
 
Yep, it's a drag. I love the knife too. I didn't see any discoloration from being too hot when grinding the edge but I obviously didn't notice. The edge isn't too thin, about like my other knives. I've made much thinner without this problem. When steeling, the edge just flops from one side to the other, unlike my other knives from D2, a few strokes and I'm back in business. It reminds me of my son's cheap chinese knives he bought at the gun show for $10. I'm pretty convinced I got the edge too hot so I'm going to carefully grind the edge some more to see if I can get to the harder steel. Peters did the heat treat and they know what they're doing. It must be operator error.
Thanks everyone for their input.
Brad
 
Yes, I have stropped the blade and made sure there is no burr left. It didn't make any difference. I have also sharpened at different angles, both steeper and less steep, with medium grit stones and fine stones. The edge simply rolls over under normal use, no matter the sharpening method. I'm sure the edge is too soft.
 
Where on the blade did you check the hardness. Did you grind the blade before the heat treat?
-John
 
Peters did the heat treating and they checked it right behind the ricasso. Yes, I did 95% of the grinding before heat treat. After heat treat I did some clean up passes with 220 grit, then 400 grit.
 
One more thing to consider, Maybe the steel is not what it supposed to be? I have had the wrong steel sent to me on several occasions, sure messes a guy up when it comes to heat treating!!
Clint
 
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