Getting frustrated with stropping Barkie CPM 3V

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gadgetgeek

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May 19, 2007
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I'm doing something wrong here. Bark river mini-bushcrafter, I kept sorta thinking that I am getting it sharp, and it will reasonably cut paper. But I put some scratches in it with a ceramic stone, and an hour later, they are still there. and its certainly not getting sharper. (not getting duller which helps) I'm really not moving enough material to make a difference. I'm using Lee Valley green compound which does the job on everything else I've used it on. I've got some other compound that are a sort of no-name bunch, more the chalky variety. the white compound will darken up a bit, and the black might be leaving a different scratch pattern, but its hard to say for sure. the other colors in the kit were red, brown, blue and greenish. strops are chunks of leather.

Any thoughts on what I might be screwing up? I'd like to convex it all the way out, and not bother with a micro bevel, but if that's the best way, I guess that's what I'll do.
 
If you feel that you aren't removing enough material with the compounds you are using currently, then I would suggest purchasing and experimenting with other stropping compounds that have lower grit/s. Then you would be able to progress up through the varying grit types to your liking.

- JCH
 
With 2.75 % vanadium in CPM-3V your best bet would be to use CBN or diamond as a stropping compound.
These are the only 2 abrasives actually able to cut cleanly through the vanadium carbides.
 
Try Mother's Mag & Aluminum Polish. I personally use this as a final step by applying it to a 1x42 felt belt and using it as a power strop on my Kalamazoo.

Puts a nice mirror shine on S110V:thumbup::
IMG_1374_zpslfhnqb3x.jpg


It's technically meant to polish chrome and the like, but it's surprisingly good to strop a knife on too.
 
Thanks Noctis, thats exactly it. If I can't change the scratch pattern, then what am I doing?

I've gone back to the white strop... might be doing something. My difficulty is a lot of brands are not available here in australia, or stuff is way marked up.

a lot of the other threads I read talked about CBN, but just as many saying it was not needed. might have to find some.
 
If you want the best possible edge on CPM-3V and many other high vanadium carbide steels like S30V, S90V, S110V, etc, you need CBN and/or diamond.
Other compounds will only abrade the matrix, giving you a sub-par edge.
 
kwackster said:
If you want the best possible edge on CPM-3V and many other high vanadium carbide steels like S30V, S90V, S110V, etc, you need CBN and/or diamond.
Other compounds will only abrade the matrix, giving you a sub-par edge.
Click to expand...
What's the "best possible" edge? One characteristic I've noted with the S--V series is that you can take them to the point where you can split hairs with them yes, but after about 5 minutes of use they'll quickly blunt down to a "toothy" microsaw edge. The only reason I bother to take it further is because I only have to use one more 1x42 felt belt loaded with the Mother's Mag Polish(which I'm pretty sure is globally available). If it makes clean slices through paper, anything past that is just extra and won't last very long if you actually use the knife.
 
kwackster said:
With 2.75 % vanadium in CPM-3V your best bet would be to use CBN or diamond as a stropping compound.
These are the only 2 abrasives actually able to cut cleanly through the vanadium carbides.
Click to expand...
^^This.

gadgetgeek said:
I'm doing something wrong here. Bark river mini-bushcrafter, I kept sorta thinking that I am getting it sharp, and it will reasonably cut paper. But I put some scratches in it with a ceramic stone, and an hour later, they are still there. and its certainly not getting sharper. (not getting duller which helps) I'm really not moving enough material to make a difference. I'm using Lee Valley green compound which does the job on everything else I've used it on. I've got some other compound that are a sort of no-name bunch, more the chalky variety. the white compound will darken up a bit, and the black might be leaving a different scratch pattern, but its hard to say for sure. the other colors in the kit were red, brown, blue and greenish. strops are chunks of leather.

Any thoughts on what I might be screwing up? I'd like to convex it all the way out, and not bother with a micro bevel, but if that's the best way, I guess that's what I'll do.
Click to expand...

As you're already noticing, green compound on a leather strop is about as far from being able to cut (therefore polish or sharpen) vanadium carbides as it can be, and the other compounds in your kit won't do a lot better either. Diamond or CBN compound in 3µ or smaller, on wood like balsa, basswood, etc, will make short work of polishing that steel, and the edge itself will finish up crisper as well (assuming good technique, of course). Used on firm/hard wood, you'd start seeing a shine come up in likely a minute or less.


David
 
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The best possible edge on high vanadium carbide steels is one that has a row of actually shaped and sharpened vanadium carbides in the apex, and that is something only CBN or diamond will be able to do.
Such an edge will be sharper and also last longer than an edge finished on any other stropping compound, even though they may look more or less the same to the naked eye.

As an example, forum member Sadden did a nice write-up and video on sharpening & polishing S90V steel here:

http://www.bladeforums.com/forums/s...S90V-Down-to-0-1-Micron?highlight=Sadden+S90V
 
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Obsessed with Edges said:
... Diamond or CBN compound in 3µ or smaller, on wood like balsa, basswood, etc, will make short work of polishing that steel, and the edge itself will finish up crisper as well (assuming good technique, of course). Used on firm/hard wood, you'd start seeing a shine come up in likely a minute or less.

David
Click to expand...

I carry a Northstar EDC often and this is what I use on it as well as on my Dozier D2 blades. IIRC, it's a 1.5 micron CBN compound from Kenneth Schwartz that I use on balsa wood. Gives great edges. I'm not concerned with scratch patterns on my edges, but it sure makes them perform well.
 
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With Vanadium content that high I'd finish it off with some diamond lapping film, anything finer than 6 micron will put on a nice finish for bushcrafting. The smaller sized sheets are very inexpensive and will last a long time.
 
I will stick with my 4% rule and say that the vanadium content is not high enough to require diamond or CBN.

All CPM-3V I have sharpened, bark river included, have easily sharpened on my waterstones and stropped on a bare leather strop. I have never once felt the need for a more aggressive abrasive. I have even used a King 1k and Naniwa 2k green brick to complete an edge in a very timely manor.

Stropping is for final finishing after the use of stones or abrasive paper typical of Convex sharpening. Stropping should not be thought of as the main method to sharpen convex blades.
 
Since OP is not in US, I share similar problem getting what people usually recommend.
I'd suggest to try 1000 - 2000 grit sandpaper (wet/dry), which should be coarse enough to plow out the carbides and yet fine enough to prepare for Autosol on paper over stone/any hard surface. Autosol seems to be at 10-20 micron range, so should be able to polish the matrix enough to remove the remaining burr and polish up to hazy mirror.
 
Interesting stuff so far. My King 1k didn't even darken the slurry on this thing.

The trouble is I'm getting a lot of generalities. All I'm looking for is a working edge. I like as sharp as practically possible, at the very least the edge should be a little grabby, which it isn't so far. Its getting better with the white compound I've got which should be a diamond compound. But slowly.

Now would 1 micron CBN or Diamond on leather give me a reasonably fast cutting solution, and give a reasonable edge, should I go higher, or lower? will there be an appreciable difference between CBN and Diamond at the same size? Since this is also going to be for field maintenance I'd rather go for a fast robust edge, rather than a polished perfect one. Most of my knives get done on a 800 grit ceramic, and might see a couple swipes over the green strop. Since I'm going for no micro bevel is there a reason not to use leather and just keep going flat on the main grind? Its what I've done on a mora1 and the edge is really nice. Id rather not bother with a wooden paddle strop just for durability sake.

But without knowing much about how the 3V reacts at the edge, I'm feeling like a lot of the stuff I do might not really carry over. Its not a SAK or an ESEE.
 
What Jason B said- Can/have you gotten this sharp on stones first? Or are you trying to sharpen with a strop? Big difference. If it's sharp already, should be no problem using black or white compounds to bring it back up.
 
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