420V sharpness?

B

blademan 13

Joined
Jan 25, 2000
Messages
4,492
I recently acquired my first 420V blade. As usual, after using the knife as purchased for a short while, I just have to sharpen the thing to my satisfaction. I usually am able to obtain excellent results using my Sharpmaker and stropping afterwards. I can get the 420V blade so that it will shave, but just not to the level of sharpness I can with some of my other blades. Is there something inherent in 420V that will not allow it to take a very fine edge? Does the large amount of Vanadium Carbide present prevent it from obtaining the next level of sharpness? This is more a question out of curiousity rather than need. The blade cuts like crazy as it is and probably will hold an edge longer in this state also. For the sake of comparison, how does your 420V blades fare in the sharpness category when compared to 5 of my most familiar steels; BG-42 (Sebenza), 52100 (Marbles), A-2 & 0170-6(Blackjack) and ATS-34 (Benchmade)? Looking forward to your input.
 
It is possible that the metal which is defining the edge contains worn vanadium carbides which the Sharpmaker might not aggressively cut into. I would try a couple of things. First just do a little more work than usual. For example after you have the burr defined give it another 25 or so strokes. If this doesn't help then try using a DMT diamond hone. These will readily cut throught the 420V, vanadium and all. Using them I can get 10V, 420V and 3V very sharp, hair popping and all that.

-Cliff
 
On two occasions now I've attacked blades sporting CPM steels with my Edge Pro. One is a Kit Carson large Mod 4 in 420V and the second a Whitewing in 3V. In both instances I was disappointed with my results the first time around.

Although I used the same techniques I've employed while sharpening all the other knives I own (ensuring I get a burr, working my way through the grits, etc., etc.), for some reason they just didn't feel as sharp when I was done.

It should be noted that both knives came with sharp edges from the makers and that my true intent here was to reprofile and thin out the edge geometries. For any who might be interested, I went to an included angle of approximately 35 degrees on the Mod 4 and something closer to 25 degrees on the Whitewing.

Anyway, my solution to this apparent absence of a razor edge was to simply go back and try it again. Obviously the task was simpler the second time around as I could concentrate on improving the existing edge and didn't have to devote the considerable additional amount of time to the stock removal/reprofiling task. The end result is that there was a dramatic improvement the second time around. My theory is that even though I was getting a burr during my first attempt, it was probably not as even as it should have been; no doubt due to the fact that I was using too much elbow grease in an attempt to compensate for the incredible wear resistance of the CPM steels. I think Cliff and Tom have hit the nail on the head here (not surprisingly). Just resign yourself to the fact that it's going to take a lot longer to properly sharpen 420V than it takes to sharpen 1095
smile.gif
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Semper Fi

-Bill
 
I have a really nice Green River type camp knife from Richard Rogers(who, by the way, is on another level as far as fit and finish is concerned), and this knife is ground thin out of CPM3V with the full cryo treatment. I had one heck of a time getting the scary type of edge I like on it, but now its truly Sharp as S##t! You just have to be patient, and remember this stuff isnt like the steel on your grandpa's pocketknife. Its meant to last almost forever in Industrial applications. I havent tried the 420V yet, but have a little dangler type knife coming from Bailey Bradshaw made from 420V, and I imagine it will be a bear to sharpen also. Should be well worth any extra effort though.

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Danbo, soul brother of Rambo
 
CPM steels are fine grained by design, and it is extremely unlikely that a maker working with the best steels would screw up the heat treatment. CPM steels are extremely wear resistant, and you have to use a felt marker to make sure you are getting to the very edge. My 420V Apogee cuts like a scalpel after working on the white Sharpmaker rods.
 
Bill to clarify, when I said do a little more work than usual, this isn't something that is necessary every time you sharpen. The problem is that becaues 420V is both strong and durable, the edge may blunt just by wear. If this is the case, which can happen to any steel depending on how you use it, you have to grind away all the worn and weakened metal to get the edge back to 100%.

If the steel is not quite as strong nor quite as durable then a lot of the edge can break away either from direct fractures or snaps from repeated bending. When you sharpen this it is obvious that you have to remove a decent amount of metal to restore the edge. However if it doesn't happen then you can easily undersharpen.

It is more of a problem with the high Vanadium CPM's becuase those carbides are very hard and there is so much of them that they define a large part of the edge. Once they wear down you will notice a large drop in slicing ability, but not much in push cutting which is kind of interesting the first time you see it.

To be more specific, after I have recut a fresh edge on 10V with a diamond hone I often maintain it with a ceramic rod. This will keep the edge aligned and very polished. However over time the slicing ability drops as the ceramic will not cut the carbides and once they round then the edge starts to slip.

There are two solutions to this, the first as I said above is to grind away all the weakened metal and expose fresh carbides. The problem with this though is that many of the softer hones (AO) are not aggressive enough to cut into the very hard carbides and may in fact be rounding them out. And of course it takes some time.

If this doesn't work then you need to try a Diamond or SiC abrasive. While the CPM's may be very wear resistant for steels, and the Vanadium carbides very hard for a carbide, it is all like butter when compared to diamond. SiC will cut through it as well but not as aggressively.

-Cliff

[This message has been edited by Cliff Stamp (edited 09-01-2000).]
 
So far I've found that the 420V blades in my Kit Carson and Darrel Ralph knives take a very sharp edge via touching up on the Spyderco Sharpmaker.

Of course, I don't let them get too dull before touching them up either.

Blues

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Live Free or Die

Blues' Knife Pix

[This message has been edited by Blues (edited 09-01-2000).]
 
I had, for a very short period, a 420V folder by PJ Tomes and it was extremely sharp, an overused phrase to be sure but accurate in this case. Also I called PJ and asked him about his knives and of the steels he is using right now, he said that he is very impressed with the 420V material, that speaks volumes to me coming from a well know knife maker. And Darrel Ralph also is very fond of that material as well.

So, as mentioned above, perhaps it wasn't heat treated properly or you've not gone far enough in the sharpening process. I'd be willing to try and put an edge on it for you if you'd like.
G2

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"The Road to Hell is Paved with Good Intentions!"
Take the time to read your Bible Now, don't be left behind...

G2 LeatherWorks
 
I had to change the angle on a 420-V knife from ~60(+)° to 40°. Took me a while with a diamond hone. But eventually I managed to get it perfectly sharp.
Remember: vanadium carbide is harder than the average ceramic stone.
Happy sharpening
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D.T. UTZINGER
 
Steve,

I have the Sharpmaker and an Apogee. I was wondering what angle you use on the Sharpmaker and what steps did you perform the first time you used it on the Apogee?

Regards,

Tom Carey
 
Cliff, your point is well taken. I think I may have been more accurate had I stated that 'reprofiling' a 420V blade will take significantly longer than doing the same with a blade made of 1095. Since then, I honestly haven't had the need to resharpen these blades because of dulling through use, so I can't really add anything to that discussion.

Furthermore, my experience reprofiling blades made of CPM steels is strictly limited to my use of an Edge Pro Apex whose stones are ceramic based if I remember correctly. The thought that these ceramic stones might not be hard enough to actually cut into the individual grains of vanadium carbide hadn't occured to me before. I'd love to know the actual relative hardness of the two substances.

As it is, the Apex, using the supplied ceramic stones, is capable of putting an edge on my 420V blade that can cut hairs off my arm without firmly contacting the blade to my skin. I'm not sure if this is a useful description or not. However, while I may find it difficult to communicate the relative "sharpness" of a blade in objective terms, I don't want to give anyone the impression that the Edge Pro isn't equal to the task of 'functionally' sharpening CPM steels. Still, I also believe I remember hearing Ben Dale mention diamond hones of another manufacture that were compatible with his outstanding sharpening system. This may be worth investigating further as some point.

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Semper Fi

-Bill
 
Thanks JB. Doesn't sound too promising.

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Semper Fi

-Bill
 
Happy to report, problem solved! Thanks guys. Just thinned the profile a little with a diamond hone, back to the Sharpmaker again and PRESTO! A very sharp blade indeed. Now let's see how long this 420V stuff is going to hold an edge.
 
My experience w/ CPM steel is only with the 440V in my Spyderco Militaries. I find it very easy to sharpen, much more so than ATS-34 for example.
Today for example I opened several feed bags (canvas/ mylar) and cut the binding on about 20 bales of hay (plainedge Military). I then used it to make dinner, cutting about a heap of sausage, mushrooms, peppers and onion on granite counter top. The edge was just starting to drag when shaving arm hair. Five seconds with a wustoff-trident steel and ten seconds on a charged strop (edge trailing) had the edge mirror polished and hair popping sharp. The only other steel that sharpens easier for me is CRKT AUS6, and that, of course, doesn't hold an edge nearly as well.
That is just my experience. Is the big difference 440V v. 420V or is it in the heat treat, I believe Spyderco hardens their 440V so that it is still impact resistant (but maybe not as abrasion resistant), in any case I find it about perfect.
Be safe,
Chad

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"People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf."
George Orwell
"Those who hold the thin blue line keep order, and insure that anarchy and chaos will not prevail."
 
The edgepro hones are AO waterstones which is technically a ceramic, but this is the same abrasive that is in Japanese waterstones, and is not as hard as the harder carbides in blade steels. Unless of course Ben Dale has changed them in the past year as it was some time ago that I discussed hones with him.

Note concerning Diamond wear, on the Edge Pro diamonds will wear quite fast because of the way it works you can put quite a bit of pressure on the blades. This is the way I usually sharpen them. If you do this with a diamond abrasive you will soon have a bare plate.

However I have a number of DMT hones that are years old and have sharpened many more than 20-30 knives. Joe Talmadge has been using his for quite some time and I think uses a 6" coarse DMT for most profiling.

What I would recommend is that you do any rough profiling on a large benchstone. You do not have to be precise and get a consistent angle. Just grind off the shoulders of the edge and make it roughly the profile you want. When you want to actually sharpen it, then switch to the Edge Pro. Things will go much faster this way.

-Cliff
 
Hello everybody. I somewhen managed to get the following data on hardness:

Knoop hardness numbers of average samples:
Nickel(tech.): 550
Steel(HRc 58): 690
Steel(HRc 62): 770
Steel(Hrc 64): 820
Quarz (crist): 820
Chromium(hard):935
Zirconia :1160
Ti nitride :1800
Cr carbide :~1800 (there are several types)
W carbide :1880
Ta carbide :2000
Al oxyde :~2200 (there are several types)
Ti carbide :2470
Si carbide :2480
V carbide :2520
B carbide :2750
C diamond :7000
Please enjoy.
Happy sharpening
smile.gif


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D.T. UTZINGER

[This message has been edited by ZUT&ZUT (edited 09-02-2000).]
 
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