CPM S110V

[tcmeyer]

When sharpening for a mirror finish, at each grit, you generally try to remove all the scratches from the previous grit.  This might be all well and good for the mirror, but doesn’t necessarily address the damage to the apex which was produced by that prior grit.  This is especially true for edge-trailing strokes, which can break off pieces at the apex which are deeper than the scratches on the bevels.  If you really want a razor-like edge, you need to remove the “serrations” left by the prior grit.  Not so easy, since the current grit is leaving “serrations” of its own.  At each stage, the apex should be slightly more refined than with the prior grit.  If you fail to remove all of that damage at any one stage, you can bet that following grits will do no better, as they remove less and less metal.  The damage will still be there when you’ve finished the job.  Maybe not as pronounced, but still there.

I’ve more or less proven this to myself by sharpening a knife with 20 strokes per side per grit (after a burr is formed), and then resharpening the same knife with 50 strokes.  The 50-stroke edge always seems sharper.

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sksharp, Organic, wickededge

[tcmeyer]

I very often use scrubbing strokes with film and have learned that the limitation is the radius of the belly of the blade.  If the belly is too pronounced, the edge will dig right in and kill your strip of film.

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Organic, wickededge

[wickededge]

RLDubbya wrote:

So what – it makes the edge look better” from me. Ultimately, I think, I will have to deal with combining the two perspectives: maybe I’ll end up using 75% less horizontal scrubbing, finding that it gives me 80% of an improvement in looks, and only negatively impacts the edge by 10%. If I instead use 90% horizontal scrubbing, I might get an 85% improvement in looks, but a negative impact to the edge of 75%.

That’s definitely an approach that could have some success. I find that I tend to compartmentalize polishing and sharpening from each other. My process starts with forming the edge geometry I want, then I work to achieve the level of polish I’m looking for, then I optimize the very edge for cutting.

-Clay

[Organic]

tcmeyer wrote:

When sharpening for a mirror finish, at each grit, you generally try to remove all the scratches from the previous grit. This might be all well and good for the mirror, but doesn’t necessarily address the damage to the apex which was produced by that prior grit. This is especially true for edge-trailing strokes, which can break off pieces at the apex which are deeper than the scratches on the bevels. If you really want a razor-like edge, you need to remove the “serrations” left by the prior grit. Not so easy, since the current grit is leaving “serrations” of its own. At each stage, the apex should be slightly more refined than with the prior grit. If you fail to remove all of that damage at any one stage, you can bet that following grits will do no better, as they remove less and less metal. The damage will still be there when you’ve finished the job. Maybe not as pronounced, but still there. I’ve more or less proven this to myself by sharpening a knife with 20 strokes per side per grit (after a burr is formed), and then resharpening the same knife with 50 strokes. The 50-stroke edge always seems sharper.

I think that this is an important point that all too often gets overlooked.

Tom, have you devised a way to monitor whether or not you have effectively removed the serrations from the previous grit, or do you have to resort to just counting the strokes? I imagine that examination with a microscope would be useful, but without measurement software and high magnification capabilities, I don’t know how one would be able to know that they have effectively replaced the previous grit serrations.

[Readheads]

My thoughts on DLP are that they are somewhat fragile and inconsistent. It is also not easy to tell when they are worn out. It would seem that rubbing them along one spot/location would wear them out more or at the least yield an inconsistent wear pattern. Is there a technique which would allow maximum use of the film surface while still going horizontal ?

 

[tcmeyer]

Organic wrote:

Tom, have you devised a way to monitor whether or not you have effectively removed the serrations from the previous grit, or do you have to resort to just counting the strokes? I imagine that examination with a microscope would be useful, but without measurement software and high magnification capabilities, I don’t know how one would be able to know that they have effectively replaced the previous grit serrations.

I’m not normally that obsessed with getting a perfect edge, so I just double or triple the number of strokes I would otherwise use if I want a really, really sharp edge.   I normally keep my USB ‘scope set to the lower magnification (about 55X), so it doesn’t give me the image I’d need to evaluate the roughness of the edge.  I proceed knowing that the increased number of strokes will have some payback.

It’s interesting to consider that a mirror-like set of bevels will not automatically give you an optimal edge, but working toward the optimal edge will produce a mirror-like bevel.  Huh!

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sksharp, Mark76, Organic, Marc H

[Readheads]

I have been looking into S110V for a chef knife and have learned that the Heat Treating is the most important aspect after having a “clean” steel from your source. The interesting thing is that most custom knifemakers hold their HT process like it is some sort of proprietary process. There are plenty of shortcuts which could be done especially in the cryo process (temps, vacuum, rates, dwells, # cycles, etc).  All of these affect the edge.  It is no surprise to me that different knifemakers will have different edge performances with the same material.

It is interesting that “we” the sharpeners are probably the best testers of the knife edge. I think that edge performance characteristics during the sharpening process would correlate to edge performance characteristics during use. There are of course many variables to each which would preclude direct correlation and consistency but I think the same trends would correlate.

Knives need professional HT which requires expensive equipment and defined/documented processes. Peters Heat Treatment in Berlin, PA is one of the best and will HT a knife with the same equip/processes as they use for Aerospace landing gear. I will not buy a knife from a custom maker unless they are transparent in their HT process. BTW, an 8 inch chef knife in S110V costs over $1200 and a maker who says trust me will not get my business.

[Rich]

Finally was able to revisit the Spyderco Manix 2 S110V blade.  After receiving the 800/1000 chosera stones, I tried to back up and see what they would do ( I finished with the 10K chosera last go round) while keeping the same 18 deg angle.  I was not successful.

From there, I went back to the 1500 diamond confirming the scratches were consistent from shoulder to apex and verifying a burr before moving on.

From here, my progression was 800/1000/2000/3000/5000/10,000 chosera. Scrubbing first then edge leading, per forum recommendation, with very light pressure until each grit had scratch uniformity.  Finally, light stropping at 16 deg with both 1 micron and 0.5 micron leather strops.

Again, this blade is sharp but not where near where I would expect it to be.  I do not believe it is my technique as I followed this with a Shun VG10 blade using both diamond and chosera to 10k and it is screaming sharp!  I know the S110V steel is supposed to be difficult to sharpen but I am at a loss…  I have ordered a set of DLF from 6 to 0.1 micron and will try them when they arrive.  I can’t imagine that the DLF will solve my issue but don’t know what else to try.

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[Marc H]

Rich,  just a dumb question first…Please clarify how your photos are oriented so I’m clear on what I’m looking at.  Are they posted “bevel down?”  If that’s the case, for less confusion you may be able to change a setting in your soft to rotated the view 180º so the bevel is up to coincide with knife clamped orientation.

To help your issue, I suggest,  just for kicks, repeat your Chosera’s 5K then 10K.  Feel the apex when doing the alternating side, bilateral, edge leading strokes to make sure your edge feels very sharp.

First, what type of strop are you using?  I assume you’re using the basic cow leather WE strops.  But we both know what assume means, LOL.

Try to lower your angle for Stropping, 3º, per side to 15º and then do your alternating, bilateral, edge trailing strops. Please let us know the results.  If this doesn’t help you might also try to lower the strop angle only 1º to 17°, after again going back to the 5K and 10K Chosera’s.  These little technique changes may help you narrow down your technique issue.

From viewing the photos your bevels look pristine.  Like they were done by a machine, they’re so straight and even and parallel.  Really good work there.

Marc
(MarcH's Rack-Its)

[Readheads]

I think you may be battling the Niobium carbides in the S110V vs the Vanadium in VG10.  Niobium carbides are much harder. The chosera stones may not be hard enough and you could be just abrading the steel matrix “around” the carbide and messing up your apex. You prob can only see it with an electron scope (on my list – LOL).

Try not using the chosera at all and see how far the diamonds will take it. Maybe use diamond emulsions on cardboard at the finest level. Zknives.com and knifeinformer.com have great info on S110V basically calling it THE HARDEST to sharpen and sometimes heat treated to 64 RC.

[Rich]

The photos are taken apex down.  Marc, I will try your suggestion of repeating the chosera 5/10k.  I believe the edge felt very sharp when finishing with them.  I will experiment with strops at 15 deg and 17 deg. The strops I am using are cow leather (not WEPS as I just replaced them with leather form Oldawan)  Yes, ASSUME (ASS out of U and ME).  Thank you for the kind words, I am really paying attention to the details!!

Readheads, your suggestion is were I was headed.  I am skeptical of the chosera stones use on S110V.  I have ordered diamond lapping films and will try when they arrive (after trying Marc’s suggestions above).  Talk to me about diamond emulsions on cardboard.  This is just another form of stropping?  Why cardboard and not a traditional strop media?

This leads me to another question. When talking sprays & emulsions, what are the differences between CBN spray/emulsion, poly diamond emulsion, boron carbide emulsion, etc.  Is one better than another or just different?  Reasons for using one over another?

Lastly, has anyone used chosera stones with S110V, CPM S90V, ZDP-189, ?  If so, what was your experience?  I really enjoy the feel these stones provide during the sharpening process.  I am trying to understand if there are applications where they should not be used.

 

[Readheads]

Rich, I have no experience in using cardboard (some others herein have talked about it though). I suppose it is just a part of the quest to find a nice stiff medium to hold the emulsions, etc while you “impact” the bevel. The various emulsions confuse me also and it would be a major science experiment to determine which works best on which medium for which steels.

Ah but the quest for knowledge can be a stimulating experience. LOL –  fun posts you all; I will be active on these posts as I hang on the Jersey shore for 2 week even though I left my WEPS home.

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[tcmeyer]

I’ve tried hardwood and brass as mediums, and they both work, using paste.  The brass seems to require a lot of effort and a lot of paste to get it fully loaded with embedded diamond particles, so I didn’t go down that path.  I haven’t tried (cereal box) cardboard, but it seems to me to be a good application.  Easy to replace, too.

[Marc H]

Rich, how many different steels or different knives have you sharpened so far with this same Wicked Edge System?  Have you been able to sharpen those knives to a sharpness of your liking?

Marc
(MarcH's Rack-Its)

[Rich]

Yes I have. Many various kitchen knives, ZT folders, Kershaw folders and spyderco folders. No others using S110V though.

[Author]

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