Can you use ceramics to sharpen s30/90/110v or not?

MyLegsAreOk

MyLegsAreOk

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Aug 31, 2017
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Topic says it all. I was certain ceramics are better for the job that diamond stones (of which I have both) but here conflicting reports as to if ceramics can sharpen vanadium carbides well enough. I never let my blades get dull so maybe I'm just doing the same thing a steel would do an rubbing microscopic elements back or maybe I am sharpening after each time on the ceramics.

So: can you use ceramics to sharpen CPM's s30v, s90v, s110v and I guess all the other variants I don't have/didn't mention.
 
I've sharpened M390 on a Shapton Glass stone, it was the easiest sharpening session I've ever had with that steel and it was the sharpest I've ever gotten that knife.
 
Simple answer: No.

Long answer: Sort of. You can use silicon carbide and aluminum oxide stones for coarse work or sintered ceramics for just crisping up the apex in the final stages, but for your fine grit sharpening you'll need diamonds. Aluminum oxide and silicon carbide are softer than vanadium carbide, so you need diamond, boron carbide, or cubic boron nitride to abrade it. The aluminum oxide and silicon carbide will only abrade the steel matrix and chromium carbides, not the vanadium carbides.

It's one of the reasons I personally don't care for high-vanadium steels. If you sharpen them using standard abrasives you'll get the steel sharp, but will have torn the carbides out of the edge and so you're not getting any benefit from them and your edge won't hold any longer than a low-alloy steel would.
 
MyLegsAreOk said:
Since my ceramics are already 1000 and 2000 grit should I just get the glass in 16,000?
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The arguement comes from the fact that the Vanadium and some other carbides are harder than say the sintered ceramic aluminum oxide of Spyderco's sharpmaker rods.

That said, I haven't had any trouble touching up even heavily carbide loaded steels like s110v on my Sharpmaker rods. I suspect that the carbides are so small that even though the ceramic rods won't cut them well they just fall out of the surrounding steel matrix when the steel is sharpened past them. Then new carbides underneath take their place. As the new carbides are exposed only abit of them stick out the steel. Once sharpened enough they fall out again. That is all just my theory.

What is true though is that even though the ceramic is softer than the vanadium carbides; it is still able to cut into and wear away those carbides to some degree, if not very well. Many people think a softer material cannot cut a harder one. It is mostly true but the softer material will cause wear to those carbides over time.

Last thing; the Sharpmaker or any hard ceramic stone is best for touching up an already properly profiled edge. Use very little pressure especially when finishing by apexing the edge. Shapton glass stones are supposed to be good for reprofiling.
 
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Lapedog said:
That said, I haven't had any trouble touching up even heavily carbide loaded steels like s110v on my Sharpmaker rods. I suspect that the carbides are so small that even though the ceramic rods won't cut them well they just fall out of the surrounding steel matrix when the steel is sharpened past them. Then new carbides underneath take their place. As the new carbides are exposed only abit of them stick out the steel. Once sharpened enough they fall out again. That is all just my theory.

What is true though is that even though the ceramic is softer than the vanadium carbides; it is still able to cut into and wear away those carbides to some degree, if not very well. Many people think a softer material cannot cut a harder one. It is mostly true but the softer material will cause wear over cutting time.

Last thing; the Sharpmaker or any hard ceramic stine is best for touching up an already properly profiled edge. Use very little pressure especially when finishing by apexing the edge.
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That's what I do. Lightly over the tip no the flat side.

miso2 said:
What FortyTwoBlades said.

Just FYI.
https://www.bladeforums.com/threads/hardness-and-abrasion-capability.1478806/
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After reading that, would anyone think that getting the diamond stone for the sharpmaker would make a difference? All in all even though I may need to use it I dislike using diamond because of the grotesque gashes it leaves. Smith slabs left me with two ugly blades I sent back to benchmade for blade replacement.
 
The issue with using sintered ceramics on vanadium carbide steels is that the carbides dull the abrasive grains, which don't release due to their sintered bond, and so you end up with a stone that loses its cutting ability and only burnishes your edge. You then have to refresh your stone's surface to expose sharp grit.
 
As FortyTwoBlades said earlier, for a coarse finish up to #1,000 or 10 micron, you would not need a diamond stone. If you want a finer finish, you may want to use very fine diamond stones or strops. Since diamond stones are very efficient in abrasion and make deep scratches, a #600 diamond stone feels more like a #300 stone in my experience. So, you need something like EEF diamond stone of DMT for finer finishes.
 
You should avoid ceramic on those steel types due to their composition. You can get them sharp with ceramic but it's not idea for use.

I have s90v benchmade 940-1 and while I can sharpen it with ceramic it will have carbide tear out and cause chipping at least from what I've read and experienced. Stick with diamonds, cbn or even SiC like Norton crystalon. Also all three will be great for stropping too
 
MyLegsAreOk said:
That's what I do. Lightly over the tip no the flat side.


After reading that, would anyone think that getting the diamond stone for the sharpmaker would make a difference? All in all even though I may need to use it I dislike using diamond because of the grotesque gashes it leaves. Smith slabs left me with two ugly blades I sent back to benchmade for blade replacement.
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I have the diamond rods for the sharpmaker and would not recommend them. The SM is an excellent system for touchups and making a knife that is already edge profiled properly much sharper. It is not a good system for reprofiling and grinding.

The experience I have with their diamond rods is that they are so coarse that it feels like my blade is skipping across the peaks of the pieces of grit. This causes the knife to skip and rattle in your hand as you try to use the diamond rods, making maintaining an angle nearly impossible.

So what I do is when an edge needs reprofiling or just came from the factory jacked up (I'm lookin' at you Inkosi!) I send it to my local Japanese knife sharpener. He does the knives for many local sushi chefs and does an amazing job. He does it all free hand using those very expensive natural Japanese stones. (I forget the names but the stones themselves were super beautiful!)

Then once I have properly laid out edge grind it is very easy to touch up the edge on the Sharpmaker. I think this is where the SM excels. I just touch up my super steel (or any) with my SM and can maintain a good edge for a very long time. In this way despite common practices and beliefs one can spend LESS time resharpening super steels than even 1095.

Say I use two knivezez all day and am heading home. Time to sharpen! :)......:(......:'( So I whip out my
Aus8 knife and it is completely dull and takes some time to bring back up to sharp. On the other hand my s110v Manix 2 only dulled a tiny bit. It only takes a few passes to restore the edge to its former sharpness.
 
MyLegsAreOk said:
That's what I do. Lightly over the tip no the flat side.



After reading that, would anyone think that getting the diamond stone for the sharpmaker would make a difference? All in all even though I may need to use it I dislike using diamond because of the grotesque gashes it leaves. Smith slabs left me with two ugly blades I sent back to benchmade for blade replacement.
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Have you tried cbn instead? Cliff stamp has a video on how to properly use them and get good results. Same price as the diamond rods.
 
Could someone show me where I can see some pictures of carbide tear out?

I have sharpened almost all of the cpm steels and I never apex with diamonds and they will pop hairs off my ceramics.
My edges are not chipping either but my highest magnification is x60 so I would like to see some examples at a higher magnification if possible.
 
willc said:
Could someone show me where I can see some pictures of carbide tear out?

I have sharpened almost all of the cpm steels and I never apex with diamonds and they will pop hairs off my ceramics.
My edges are not chipping either but my highest magnification is x60 so I would like to see some examples at a higher magnification if possible.
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https://www.bladeforums.com/threads/stropping-wear-resistant-steels-s30v-s90v-cts204p-etc.1372633/

unfortunately @eKretz the images are Photobucket. They are some of the most convincing pics of the outcome I've seen, and many were HSS steel and not even VC.

I have gotten good results stropping even with SIC, but not as good as with diamond.
 
willc said:
Could someone show me where I can see some pictures of carbide tear out?

I have sharpened almost all of the cpm steels and I never apex with diamonds and they will pop hairs off my ceramics.
My edges are not chipping either but my highest magnification is x60 so I would like to see some examples at a higher magnification if possible.
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Yeah I can pop hairs too if I get a knife already really sharp because apparently all I'm doing is burnishing. That being said nothing coming out of benchmade is sharp so the only one I touch up in the sharpmaker that comes out good is the blurp PM2 because I don't use my Big Subhilt.
Update: I watched Deadboxhero's video on youtube about sharpening the blurp PM2 and did the techniques using the Smith orange diamond stone, the fine and superfine sharpmaker ceramics, and strop and it came out sharp(er) but smooth and not toothy. What a shame.
 
HeavyHanded said:
https://www.bladeforums.com/threads/stropping-wear-resistant-steels-s30v-s90v-cts204p-etc.1372633/

unfortunately @eKretz the images are Photobucket. They are some of the most convincing pics of the outcome I've seen, and many were HSS steel and not even VC.

I have gotten good results stropping even with SIC, but not as good as with diamond.
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Now using diamond lapping compound is great but I dislike grinding on diamond plates so I rarely do.

I'm sure carbide tear out does exist but I don't think it is as big of a problem that is made out to be on many threads I've read.

Maybe the few swipes on my strop keep them carbides in line.
 
It's not so much that it's not possible to get a good edge on high-vanadium steels with standard abrasives. It's just that carbide tearout will result in the edge retention being "normal" rather than "superior", which is the whole point of those steels in the first place.
 
MyLegsAreOk said:
Yeah I can pop hairs too if I get a knife already really sharp because apparently all I'm doing is burnishing. That being said nothing coming out of benchmade is sharp so the only one I touch up in the sharpmaker that comes out good is the blurp PM2 because I don't use my Big Subhilt.
Update: I watched Deadboxhero's video on youtube about sharpening the blurp PM2 and did the techniques using the Smith orange diamond stone, the fine and superfine sharpmaker ceramics, and strop and it came out sharp(er) but smooth and not toothy. What a shame.
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OP,
Sounds like you need to set up the edge bevel with coarse stones (~#240) first. For this, you can use good ceramic stones, although diamond stones are much more efficient. Also, you implied what you want is a toothy edge. Then, you can just finish with a relatively coarse stone like #400 or #600. You may still want to use a ultra fine stone or strop to deburr at the end.

What I would do is to set the bevel with a #150 diamond stone, go through #240, #320, and #400 silicon carbide stones (aluminum oxide stones would work), and then lightly strop with 1 micron diamond suspension.

I don't own Sharpmaker, but guess that this corresponds to using the diamond (or CBN) rod for bevel setting, medium to refine, and then ultra fine for further refinement and deburring.
 
Fresh (abrasive blasted) sintered ceramic surface has good abrading ability however cutting tips will dull quickly - much faster than fixed diamond abrasive surface. Effective against hardened steels - coarse ceramic excavates, fine ceramic burnishes. Steel swarfs will be jammed/hard-smeared onto ceramic surface - loaded - lead to more finer burnishing by ceramic+more&more steel swarf.

Let's imagine, complex physics of ceramic abrasive interacts with steel microstructure, as fingers claw/knead moist+dried clay plain+aggregrate with hard 2mm pellet.
  1. Moist clay (MC) plain: easy to shape very thin edge, including wispy tail (burr & wire-edge)
  2. MC 10mm spaced pellet: can't have a continous apex thinner than 2mm, due to interruption by pellet.
  3. MC 4mm spaced pellet: apex is not stable at 2mm - thinnest possible - because pellet footing actually thinned out by burnished/flowed.
  4. Dried clay (DC) plain: easy to shape very thin edge but via pull-a-pinch, will break because thin by squeezing invariably put lateral force on the apex.
  5. DC with spare spacing pellet: discontinuous thin apex with micro chips ~ 2-6mm wide = pellet interface fractured.
  6. DC with dense spacing pellet: best case is a 2.5-3mm thick jagged apex/edge.
MC is equiv to: hardened steels with good ductility/plasticity.
DC: 63+rc steels - i.e. has very narrow plasticity range.
2mm pellet: 2um PM carbide.

Production knives in OP's listed steels are mostly hardened below 63rc, microstrcture allows some small range plastic-flow in matrix spacing between carbide, so ceramic effectiveness is highly depend on this plasticity range. The biggest downside - ceramic laterally impacts thin cross section of edge. Burnished steel is work hardened, thereby burnish 'impacts' becomes mostly pure impulse, which is higher force than impact+abrade from diamond surface.
 
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