CPM-440V Sharpening Questions

callahwj · Apr 5, 2001

Hi:

I have a Kershaw Ken Onion Boa in this steel and was curious about what results people have gotten sharpening this steel with different sharpeners. I have a lansky sytem, by the way. I've heard it said before that you can't realy get an ultra-fine edge on a high vanadium blade because it forms large-grain carbides. The blade is barely shaving sharp right now, and I just wanted to get recomendations on what the best type of edge is for defensive purposes is and how I should go about sharpening. Oh, by the way, the blade is plain edge.

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William Callahan

"I can picture in my mind a world without war, a world without
hate. And I can picture us attacking that world, because they'd
never expect it."
-Jack Handey

Cliff Stamp · Apr 6, 2001

The CPM steels are near the top of the list in regards to grain size, there are a couple a little better like 52100, but I have never seen them described as coarse grained.

I have used CPM-420V at 59 RC heat treated by Phil Wilson, full cryo, multiple temper. It will take a very fine shaving sharp edge.

-Cliff

Jeff Clark · Apr 5, 2001

I would say the opposite about vanadium, it makes it easier to get a razor sharp edge because it forms small vanadium carbides and causes the chromium carbides to be smaller as well. The materials that I find cause trouble are chromium and molybdenum.

To really sharpen the high vanadium alloys (over .5% vanadium) it is best to use a diamond hone. This tends to compensate for difficulty cutting the vanadium carbides. My Spyderco Starmate takes a razor edge, but not as sharp as AUS-8 with more modest vanadium content.

callahwj · Apr 5, 2001

I see. I stand corrected. Thanks for your help guys.

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William Callahan

"I can picture in my mind a world without war, a world without
hate. And I can picture us attacking that world, because they'd
never expect it."
-Jack Handey

Buzzbait · Apr 5, 2001

I have a 440V blade I've been sharpening on a diamond Lansky. It takes quite a bit of work to get a razor edge, but it can be done. Technique seems to be everything.

Sharp Tools · Apr 5, 2001

I'm curious about cpm420v, is it about the same as cpm440v as far sharpening? Does it take longer to get a shaving sharp edge? (versus ats-34 for instance)
Is a diamond hone necessary to re-sharpen it? Can you re-align the angle with medium ceramic rods? (Lansky-Crock Stick) or is a diamond hone needed?

Thanks to anyone that can assist.
Kevin

Doug Mondt · Apr 5, 2001

CPM 420V is a simpler alloy than CPM 440V. The names S90V and S60V, respectively reflect the vanadium content of each, 9% and 6% rounded off to nearest whole %.

I use either diamond or other synthetic stones for sharpening these steels. Never had a problem getting a razor edge on either. CPM 440V is said to be the more aggressive cutter.

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Mondt Custom Knives
For the Word of God is...sharper than any two edged sword.

The General · Apr 5, 2001

I had a similar problem with my CPM 440V Military. I found for me the answer was quite simple.

Basicly this steel is so wear resistant, you are bending the burr or wire back and fourth and not breaking it. Thus when you come to shave, it moves and thus you get a sharp, but not amazingly sharp edge. To fix it I did three things. I use the Sharpmaker system from Spyderco, but this aught to work on any sharpener.

1. When you are using the finest grit stones on the edge and you are sure the edge is symetrical, use very very very light passes once then once on the other side and once on the other side and once on the other side etc etc. So right, left, right, left once each time. This about twenty times in total aught to help a lot.

2. In the middle of doing the above, bring the stone the other way UP the blade, in otherwords rather than the edge going towards the stone place the edge on the stone and pull it away from the stone. This is called 'stropping'. This aught to remove any wire edge.

3. hold the edge on the stone at the right angle and push the stone forwards. In this way the stone is not cutting up or down the edge, but cutting the wire edge. The wire has no where to go, it is thus cut right off!

4. Repeat step one several times(once left, once right, VERY lightly) with the finest stone you have (do ALL of this with the finest stone you have)

If that does NOT work, then the edge angle is not what you think it is and you will need to remove more steel till you are cutting the EDGE and not the side of the knife.

E-mail me if you are having any more trouble, CPM 440V is more difficult to sharpen than other simple steels, but once you have done it two or three times it only takes a couple more mins to get right.

Hope it helps

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Wayne.
"To strive to seek to find and not to yield"
Tennyson
Ranger motto

A few useful details on UK laws and some nice reviews!
http://members.aol.com/knivesuk/
Certified steel snob!

The General · Apr 15, 2001

BTTT!

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Wayne.
"To strive to seek to find and not to yield"
Tennyson
Ranger motto

A few useful details on UK laws and some nice reviews!
http://members.aol.com/knivesuk/
Certified steel snob!

JW · Apr 15, 2001

I use the spyderco sharpmaker on my custom Boguszewski 440v with excellent results much as described above but I've never tried the "back stroke" part. Never seemed to need it. I do finish with light alternating strokes. It does take a little more work to sharpen 440v but atleast I don't have to do it very often. I can't tell much difference when compared to sharpening my 420v custom Chew- or edge holding either for that matter. Both excellent steels.