Steels Friendly & Unfriendly with Sharpmaker Ceramic

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Bolster
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Steels Friendly & Unfriendly with Sharpmaker Ceramic

#1

Post by Bolster »

Hello folks. I have a vast knowledge deficit when it comes to sharpening. In particular, from various readings, I'm getting the (perhaps wrong-headed) idea that there are steels that are ceramic "friendly" and steels that are not, that should rather be sharpened with diamond or CBN instead.

To wit:

While reading the follow-up comments at https://scienceofsharp.com/2019/11/03/c ... n-maxamet/, I noticed Todd stated: "Vanadium carbides are quite hard and brittle, and can easily be crushed into tiny bits with the “wrong” sharpening technique, for example using a ceramic honing rod or a Spyderco Sharp Maker." A reader responded: "Would agree with the tenor of most sharpeners (me included) that using ceramics or aluminum oxide on high vanadium carbide steels will give inferior initial sharpness …"

Then Todd elaborated: "Understand that a keen edge requires a dimension of around 100nm (1/10 of a micron) and the vanadium-rich carbides in Maxamet, or S110V, or even the chromium carbides in ZDP189 are 1-2 microns in size. So sharpening these knives to a keen edge with ceramic involves crushing those carbides (near the apex) into “nano-dust” and burnishing the matrix around them..." and then later, "...ceramics, like the Sharpmaker, crush the carbides into dust."

I don't have enough knowledge to evaluate that information; maybe you can edu-ma-cate me. :thinking My simple question is:

Are there high-carbide steels where it would be best to avoid ceramic and just use diamond/CBN?
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#2

Post by Sharp Guy »

Only steel that didn't seem to sharpen well on the Spyderco ceramic rods was S110V. No problems with any other steels including Maxamet and ZDP-189. I will say that I only use the Sharpmaker for touching up the edge and not reprofiling
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#3

Post by wrdwrght »

In my experience, the issue is not friendliness, but time. Spyderco’s ceramics have put decent edges on my S110V, Maxamet, and such. Reprofiling those edges with just the whites can succeed but will take forever. However, diamonds will, ahem, cut to the chase.

Put another way, all steels will respond to Spyderco’s ceramics, if you’re patient. Sometimes, I’m not.
Last edited by wrdwrght on Thu Jul 29, 2021 12:34 pm, edited 4 times in total.
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#4

Post by vivi »

Not sure how Todd measures sharpness, but I can get shaving sharp edges sharpening with 100 micron diamond plates.

I haven't found a steel that the sharpmaker won't effectively sharpen. I use it for touching up the apex though, not reprofiling. They cut maxamet, zdp189, k390, rex45 etc. effectively.
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#5

Post by Vaugith »

Ive also used my sharpmaker on all of my high vanadium steels and it hasn't had a problem applying a shaving sharp microbevel to any of them. I have no issue getting shaving sharp edges on high vanadium steels from AlOx water stones either. You just need soft stones that continuously release abrasive and expose fresh sharp grit. The king stones work well for this. Maybe it's burnishing instead of cleanly cutting, but I haven't been able to tell a difference in sharpness or edge retention vs my diamond abrasives yet. Still playing with it. The king stones produce a good amount of swarf... seems like it's cutting to me. If you were moving into grit sizes close to the carbide size of the steel you're working with it could become an issue in theory.
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#6

Post by Wandering_About »

Biggest issue is that, if I recall correctly, vanadium and niobium carbides are harder than most sharpening abrasives (except diamond and CBN). Tungsten carbide is up in that range also. If your sharpening abrasive is softer than the carbides, they don't get properly shaped. This mainly becomes an issue in steels that have a lot of these carbides as they will make up a lot of the edge. Using diamond or CBN for super carbide rich steels is the way to get the best out of them, if you're looking at really using those steels to their full potential. They can be sharpened with other abrasives but the apex just won't be as good, at least on a microscopic level.

Good article on carbides in steel by Larrin here, with a section on sharpening toward the bottom: https://knifesteelnerds.com/2019/07/15/ ... fe-steels/
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#7

Post by bearfacedkiller »

He references a keen edge being 0.1 microns. If you are achieving that or even a 1 micron edge then your knowledge of sharpening would be far from deficient. That is high level sharpening. You see this in many hobbies. A guy who needs a sub moa rifle who cannot shoot sub moa or a guy that needs an R1 with race tires to commute to work because he thinks he is Rossi. We need to be honest with our own abilities first before we can get too deep into the gear.

Many believe that the need for diamond/CBN stones really presents itself when trying to achieve very fine finishes. A vanadium carbide is 1-2 microns and the brown/medium rods are 15 micron, the white/fine rods are 6 micron and the white/ultra fine are 3 micron. Carbide content will matter as well but in general you are not really trying to sharpen the carbides themselves until you get to a very fine abrasive. The 15 micron abrasive is just abrading the entire carbide out of the matrix. As you get to finer abrasives like the UF you are burnishing the carbides and plowing them through the matrix. Again, the volume of them will effect this and S30V will tolerate ceramic abrasives better than S110V.

Do you like toothy edges or polished edges? I like toothy edges myself. I have sharpened every steel Spyderco has used by setting the bevel on a diamond stone and then microbeveled/deburred with the brown rods and can get an impressive edge that way. It I want more a strop with 1 micron emulsion will get it sharper than I ever need and it will still have some toothy bite.

Will using just premium diamond abrasives get a better edge? If you are an extremely good sharpener that likes a finer edge then it likely will. If not then you may not see the benefit. Of course you may still prefer the diamonds if you like the way they cut.
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#8

Post by Wandering_About »

Also, size of carbide vs abrasive grit matters. If the abrasive grit is larger than the carbides, going with diamond or CBN is not as important.
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#9

Post by Bolster »

Wandering_About wrote:
Thu Jul 29, 2021 1:16 pm
Biggest issue is that, if I recall correctly, vanadium and niobium carbides are harder than most sharpening abrasives (except diamond and CBN). Tungsten carbide is up in that range also. If your sharpening abrasive is softer than the carbides, they don't get properly shaped.

Thanks for the post. Out of curiosity, do we know the relative hardness of [ceramic stones] to [vanadium / niobium carbides]? Are ceramic stones harder than hard carbides? :thinking
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#10

Post by Bolster »

Highlights from Larrin's post, referenced by Wandering above:

"Carbide size and hardness is also significant when it comes to grinding and sharpening knives. If the abrasive is softer than the carbide the abrasive is not able to abrade the carbide. Notably, aluminum oxide (Alumina), the most common abrasive, is softer than VC, NbC, and WC. However, if the abrasive size is larger than the carbide size then the abrasive is able to pull out the steel and the carbides together so that the carbide hardness isn’t as important.... So grinding and sharpening with coarse grits are generally effective with vanadium-alloyed powder metallurgy steels even if the abrasive is softer. At finer grits the hardness of the carbide becomes more important and polishing vanadium-containing steels can be challenging because aluminum oxide is too soft. Silicon carbide has a similar hardness to those hard carbides but is not clearly harder, and in general silicon carbide is not as good at cutting steel as aluminum oxide. CBN and diamond are significantly harder than any of the carbides so they are generally better at least in terms of grinding and polishing high wear resistance steels with hard carbides."

Doesn't address ceramics, though.

Still, I get the impression that my final passes with the finest grits are best set with diamonds/CBN, rather than ceramics, for high carbide steels. Not that ceramics won't work, but that D/CBN is a step up in terms of being able to shape the edge.
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#11

Post by Wandering_About »

Bolster wrote:
Thu Jul 29, 2021 1:31 pm
Wandering_About wrote:
Thu Jul 29, 2021 1:16 pm
Biggest issue is that, if I recall correctly, vanadium and niobium carbides are harder than most sharpening abrasives (except diamond and CBN). Tungsten carbide is up in that range also. If your sharpening abrasive is softer than the carbides, they don't get properly shaped.

Thanks for the post. Out of curiosity, do we know the relative hardness of [ceramic stones] to [vanadium / niobium carbides]? Are ceramic stones harder than hard carbides? :thinking
This photo is from Larrin's article and shows the hardness of various carbides as well as alumina and silicon carbide.

Image
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#12

Post by jpm2 »

Concerning abrasive vs carbide size vs scratches, Here's a comment from Todd.
"It is important to understand that the “scratch depth” is rarely as deep as 5% of the abrasive size, so 1 micron film makes scratches in the range of tens of nanometers deep."

If the carbides are in the 2 micron range, then scratches from a 40 micron abrasive will be about carbide size. So just for reference using Todd's comment, a coarse DMT diamond plate will leave about 2 micron deep scratches. This also translates to around 240-280 ANSI and 280-320 JIS.
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#13

Post by S-3 ranch »

Everyone should check out knifegrinder.au , and watch some KG YouTube
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#14

Post by Bolster »

Wandering_About wrote:
Thu Jul 29, 2021 1:50 pm
This photo is from Larrin's article and shows the hardness of various carbides as well as alumina and silicon carbide.

Neat. Now where would Sharpmaker ceramic stones appear on that graphic?
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#15

Post by Wandering_About »

Per the Sharpmaker product page, "high alumina ceramic." So, second from the bottom is alumina in the graphic.
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#16

Post by Bolster »

Wandering_About wrote:
Thu Jul 29, 2021 5:54 pm
Per the Sharpmaker product page, "high alumina ceramic." So, second from the bottom is alumina in the graphic.
Ah, yes. I had missed the ceramic composition, thanks. I had ignorantly assumed that the ceramic itself was the abrasive, not the alumina in it. (Which raises the question, why not a SiC ceramic?)

So, would it be inappropriate to generalize that, at least in the finer grits, a high-alumina ceramic would 'struggle with'/'not be ideal for' steels high in niobium, titanium, vanadium, wolfram/tungsten, and chromium/vanadium* carbides? But that a high-alumina ceramic can easily handle iron and many chromium carbides, even in fine grits?

(*If I'm reading the elements correctly--not a chemist)

Follow-on question, since I don't own the sharpmaker diamond or CBN stones, but aren't they relatively low/coarse grit? Wouldn't we most want diamond and CBN in high/small grit sizes, and AlOx in low grit sizes?
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#17

Post by Bolster »

Bumping thread to see if I can get a response to the above ^ post?
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#18

Post by JD Spydo »

Vaugith wrote:
Thu Jul 29, 2021 12:50 pm
Ive also used my sharpmaker on all of my high vanadium steels and it hasn't had a problem applying a shaving sharp microbevel to any of them. I have no issue getting shaving sharp edges on high vanadium steels from AlOx water stones either. You just need soft stones that continuously release abrasive and expose fresh sharp grit. The king stones work well for this. Maybe it's burnishing instead of cleanly cutting, but I haven't been able to tell a difference in sharpness or edge retention vs my diamond abrasives yet. Still playing with it. The king stones produce a good amount of swarf... seems like it's cutting to me. If you were moving into grit sizes close to the carbide size of the steel you're working with it could become an issue in theory.
I totally agree with virtually everything you just stated. I've yet to find a blade steel that couldn't be sharpened with Spyderco's 204 Sharpmaker. Now I've told everyone who ever did a thread on the Sharpmaker that you should buy all the extra stones they have available for that kit i.e. the Ultra-Fine, CBN, diamond ect. Because for it to be a complete kit the old adage "The More The Merrier" certainly applies in this case.

I'm hoping at some point some other maker of sharpening stones will make other grits of stones that will work and fit with the Sharpmaker base. The Spyderco 204 Sharpmaker is by far the best sharpening kit available in my humble opinion.. The most difficult blade steel I ever sharpened on the 204 Sharpmaker kit was the extremely old 440V ( S60V). Yeah that steel that Spyderco used on a lot of the late 90s/early 2000s Spyderco models. That steel was so difficult to sharpen that I literally learned new curse words :hot-face trying to sharpen it.
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#19

Post by vivi »

Bolster wrote:
Sat Jul 31, 2021 6:58 pm
Bumping thread to see if I can get a response to the above ^ post?
spydercos ceramics work fine on any steel spyderco uses, period.
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Re: Steels Friendly & Unfriendly with Sharpmaker Ceramic

#20

Post by Wartstein »

Let me look at this the other way round:

A steel that is extremely friendly with the sharpmaker in my experience is BD1N.
I say this from my perspective as still not really skilled sharpener and would recommend BD1N to anyone who has a sharpmaker, is closer to a sharpening beginner, wants a decent steel and still just enjoy sharpening. Concerning both ease of it and "keenness" the edge can take with pretty little effort.
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