CPM 420V or D2 ? Which would you choose and why?

Originally posted by OwenM
Tough choice. I'm really curious to try out S30V, and see how it compares. Based on what I've read, it might suit me better than either 420V or D2, but that remains to be seen. Maybe one of these days...
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My thoughts exactly. Me thinks that S30V at Rc60+ (maybe up to Rc62) may be my default choice for anything under 4.25" in length.
 
Originally posted by rockspyder
I don't know either. It just seems unlikely that you can actually sharpen the carbides with particles that are magnitudes larger than those carbides. Sharpen the steel matrix, yet. Expose more carbides, yes. Sharpen those carbides?
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Yeah, I'm in the "I dunno" crowd too. And I think you are right ... even the fine diamonds are a lot larger than the carbides. Good question.

At times like these, I just resort to "ATAMO".

I pulled out my 420V blade, started scrubbing with my diamond stone, ATAMO. (And Then A Miracle Occurred).

There was an old fart instrument technician here at work (Louisiana, he was a Cajun/Coonass type). When I used to ask why certain systems or devices did certain things at times, he'd just say "Coo, I doan know ... it juss doo dat sometime".

Same thing. The Diamond stones just seem to cut a lot faster on hard and/or high alloy steels.

Now, trying harder to think... maybe it is that when the regular stones run past the carbides, instead of pulling them out of the matrix, the carbides abrade away tiny amounts of the sharpening stones themselves...reverse sharpening, or abrading the sharpening stones. So things progress more slowly.
 
R
Yes I have tried s30v.
I am building some of the new balis and other knives with this steel choice.
Im glad crusible realized there faults with 3v and upgraded this steel.
As for d2 and 420v . There both great steels.
I feel adding s30v to my line up for certain applications is a good choice.
My choice between bg42,154cm and ats34 is 154cm.
I just like the way crusible makes there steel.
They process it right. It costs more but its worth it!
 
Originally posted by rdangerer
Same thing. The Diamond stones just seem to cut a lot faster on hard and/or high alloy steels.
Now, trying harder to think... maybe it is that when the regular stones run past the carbides, instead of pulling them out of the matrix, the carbides abrade away tiny amounts of the sharpening stones themselves...reverse sharpening, or abrading the sharpening stones. So things progress more slowly.
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Yeah, I might buy that explanation. It is as good an explanation as I've heard. But I'm still a little... skeptical. Either way, I would buy that the diamond cuts faster. What type of diamond are you using, though? Fine? Medium? Coarse? Especially in relation to whatever stone of choice you use?

Originally posted by tom mayo
Diamonds DO sharpen carbide...........I know......I do it for a living!
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Are you talking sharpening carbide tools? Or are you saying that you are actually sharpening the carbide particles in the steel matrix? If the latter, how do you know? Are you inspecting with a microscope? I'm not trying to be contrary, or troll, or otherwise, and I HIGHLY respect your knowledge and talent. But, I want to learn. And I'm confused. (obviously. Reference my earlier post. :rolleyes: ) I have diamond coated blocks (ezlap, I think, or whatever), as well as a diamond coated rod. The ezlap I would say is "FINE" I think. Certainly feels "FINE." The rod is more toward "MEDIUM." I also have a carborundum (sp?) stone. "MEDIUM" on one side, more like "COARSE" on the other. Certainly the medium side is fine enough that I could use it to finish an edge, to a very toothy edge. When it comes to sharpening BG42, D2, M2, or 440V, the medium stone works much better than any of the diamond coated stuff. Now maybe I'm comparing too many apples to oranges. But I just don't understand how the diamond sharpeners actually sharpen carbide particles.

I guess it is a moot question for the most part, though; certainly what rdangerer says makes the most sense. Don know why, it juss works dat way.
 
Originally posted by rockspyder
What type of diamond are you using, though? Fine? Medium? Coarse?
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Yes. All of those, add X-coarse. They are mediocre Lansky stones... they don't last all that long. I hear from people who have compared that DMT stones last longer. Coarse and x-coarse for reprofiling, and medium or the worn medium and the fine for touch ups...nice toothy but shaving edge.

Originally posted by rockspyder
Especially in relation to whatever stone of choice you use?
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I'm not sure what you are asking, but in any case, I don't use bench stones, never tried to learn to use them seriously, only got frustrated with them early on before I learned what a burr was. But I never went back to learn them.

I do use a bench grinder w/ hard fiberboard wheels, and am getting good enough on those to do the 'good stuff' on them without fear of ruinage/ruination/ruinous results.

Use a 204 a little bit, and a motorized cheater sharpener for kitchen knives (ChefsChoice 120). I'll probably start using the bench grinder for kitchen knives though, since I'm nearing the point of being able to put an "ok" looking convex final edge on with the grinder.

:end diversion
~~~~~~~~~~~~~~~

Ok, back on topic....how about D2 vs. 420V?
 
Originally posted by rdangerer

Originally posted by rockspyder
Especially in relation to whatever stone of choice you use?

I'm not sure what you are asking, but in any case, I don't use bench stones, never tried to learn to use them seriously, only got frustrated with them early on before I learned what a burr was. But I never went back to learn them.
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Pretty much what you answered: how coarse are the diamond media vs. any bench stones that you (might) use? (which you have already now said you don't use, so the question is not relevant. :)

Sorry, all, for my digressive questioning. Forgot it was a D2 vs. 420V thread. I especially apologize to you, geode, for hijacking your thread for my own purposes. :o
 
I buy thousands of dollars worth ( a LOT of thousands) of diamond wheels every year. I have a 1500 lb tool and cutter grinder and a big saw sharpening machine. I use mostly only 400 grit diamond wheels at high speed under a flood coolant.
I sharpen all of my knife steels on my variable speed 2x72" belt sander, using mostly Orange 3M ceramic belts (usually 220 grit to get them sharp and then I go over them with a dull blue 400 grit belt to get all the 220 grit scratches out). Then I run them on my medium felt wheel which is on one side of my buffer, with some green chrome rouge and finally to a tightly sew muslin wheel loaded with green chrome rouge which is on the other side. I realize that none of you (except the knifemakers) have this equipment, but I am doing this for a living. :)
 
Thanks for all the detail, Tom. I meant no offense or insult, but truly didn't know just what you meant.

Man, what I wouldn't do to have THAT kind of equipment to touch up the edges on my knives. Whew! :eek: No wonder you can make Talonite and Stellite sing and dance!
 
The average grit size on really fine diamond abrasives is between 5-10 microns. Iron carbide in fine grained steel is very small, about 0.1 microns. However large segregated clumps of alloy carbides can be much larger than the fine diamond particles in the abrasive. That being said, an abrasive particle can easily cut a carbide particle that is smaller than it, as the edge of the abrasive particle can cut into it, the whole abrasive particle doesn't have to "pass through" the carbide particle.

In regards to sharpening, you can sharpen a material with an abrasive that is softer than it, so just because you can grind something this doesn't infer the abrasive is able to cut it. All that is happening is that the harder material being shaped is being worn away by cutting up the abrasive. You could for example shape a knife edge on a wooden wheel as the knife edge will wear away eventually, it will just take a long time (and a few wooden wheels). You generally don't want to do this for the main reason that it goes much faster the other way, and the harder you can make the abrasive the faster it goes (lot of other factors as well such as loading rates etc.). With a knife edge there is another problem as a soft abrasive leaves the carbides in a rounded state and thus even though the edge will be well formed and very sharp for push cutting, the slicing aggression will be lower than optimal.

You can see the same thing if you over strop edges. The edge still looks perfect under a scope, very even with no imperfections, and will be very "shaving sharp". But has little or no edge aggression. The worst case of this I have saw was when I kept stropping my SHBM for a few months and towards the end, even though it could still shave, a full stroke across a piece of cloth under its full weight had no effect on the cloth, yet when at its optimal finish, it would cut through the same cloth in <1" of blade length.

-Cliff
 
Thank you, Cliff. I can accept that, now that you have put so much detail into an explanation.

DANG! Now I'm going to have to go get more diamond! :mad:

;)
 
I like D-2. I can put a wicked edge on it, and it holds up to what ever I throw at it. A good "old school" steel. :thumbsup:
 
I think it was the first powdered steel to hit the knife market. Also went by S60V to avoid the confusion with regular 420 (S90V was also known as CPM440V at the time). It was highly touted for it's wear resistance. I only remember it being used in the Spyderco Military. I think it was difficult to work with & had a reputation for being chippy. S30V replaced it.

I remember some minor drama over this because S30V didn't have the same edge holding as S60V despite being pushed as an updated replacement for it. Either way, they quit making it once S30V got going. S30V was more easily machinable & less chippy once folks got the heat treat down & it wound up being a big winner.

S60V was last heard of a few years back when Jared West was still with Mantis & was claiming to use this extinct steel in one of his sub-$100 Chinese made atrocities. Much fun was had over this.

Man, I feel old now.
 
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Yeah, it is a zombie thread alright.

Crucible has brought back CPM S60V/440V after it being discontinued for almost decade or so.
 
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