s90v.. any sharpening tips?

[miracleboi123]

Hello Blade Forum! My name is Gia. I just started an account and I am looking for some info.
I have some experience in sharpening knives. I have 4 benchmades, all folders, and various steels.
Right now I use a Dans Whetstone Trihone, which has worked perfectly for me(on 154 steel) for a while...
I recently bought a Benchmade 484-1 Nakamura, with s90v steel.
I did some research after noticing it would not really work well on whetstone to sharpen, I sharpened it forever! Then to realize s90v works well with diamond stones but why?

What equipment do you guys use for s90v?
Should I go purchase a cheap smiths diamond hone at walmart?
Will that sharpen it up well?

I have not heard much about this steel and usually I will go to youtube for video tips, but I can't seem to find one on this steel.
Please help!

 

[Obsessed with Edges]

S90V has a huge amount of vanadium carbides in it, which are very, very hard; MUCH harder than than the novaculite abrasive in natural stones (Arkansas), and also harder than any aluminum oxide or silicon carbide abrasives. Think of the carbides as the harder and more wear-resistant 'cobbles' of rocks in a concrete aggregate (such as in a sidewalk or driveway), which make it a lot harder to grind or wear down. For S90V, diamond would definitely work the best for it, especially when going to finer grit and higher polish, when it becomes necessary to thin/reduce/polish the carbides themselves. Less-hard abrasives in aluminum oxide or silicon carbide can work at the coarser end, by essentially 'scooping' the carbides out of the steel matrix, without having to abrade the carbides themselves; but, a diamond hone would still work more efficiently for that.

For just maintaining S90V at the factory's edge grind, a Fine or EF diamond would likely suit most needs. If more heavier grinding is needed, such as for thinning the edge/rebevelling, a Coarse or XC diamond would handle that faster.


David

 

[hank_rearden]

i've a question: why can't they make vanadium carbide sharpening stones?

 

[miracleboi123]

S90V has a huge amount of vanadium carbides in it, which are very, very hard; MUCH harder than than the novaculite abrasive in natural stones (Arkansas), and also harder than any aluminum oxide or silicon carbide abrasives. Think of the carbides as the harder and more wear-resistant 'cobbles' of rocks in a concrete aggregate (such as in a sidewalk or driveway), which make it a lot harder to grind or wear down. For S90V, diamond would definitely work the best for it, especially when going to finer grit and higher polish, when it becomes necessary to thin/reduce/polish the carbides themselves. Less-hard abrasives in aluminum oxide or silicon carbide can work at the coarser end, by essentially 'scooping' the carbides out of the steel matrix, without having to abrade the carbides themselves; but, a diamond hone would still work more efficiently for that.

For just maintaining S90V at the factory's edge grind, a Fine or EF diamond would likely suit most needs. If more heavier grinding is needed, such as for thinning the edge/rebevelling, a Coarse or XC diamond would handle that faster.


David

Thank you David for the clear explanation on why my stones won't work on this steel! Do you know on a steel like this if stropping it after the EF diamond stone would do much after I get it to a factory edge??

 

[miracleboi123]

i've a question: why can't they make vanadium carbide sharpening stones?

Haha I totally agree that would make my life a lot simpler. Never knew there was so much I needed to maintain edges on my knives!

 

[Obsessed with Edges]

Thank you David for the clear explanation on why my stones won't work on this steel! Do you know on a steel like this if stropping it after the EF diamond stone would do much after I get it to a factory edge??

For the same reasons, if you strop with diamond compound (or CBN, which is the only other abrasive hard enough), it can work very well. Other stropping compounds will have the same handicaps in dealing with the vanadium carbides in the steel. Diamond compound works very, very well when used on very firm or hard backing, like wood (balsa, basswood, mdf, maple work well); that's the best way to take edge bevels to a very high polish, and still keep the apex of the edge as crisp & sharp as it can be.


David

 

[Obsessed with Edges]

i've a question: why can't they make vanadium carbide sharpening stones?

At the very least, I'm guessing (purely speculating) the shape of the carbides might not lend itself to that. Abrasives need to be both hard and sharp-edged (i.e. 'crystalline') to 'cut' the steel well. They're very hard, but I've never heard or read of vanadium carbides being described as 'sharp-edged' or 'crystalline'; maybe 'blocky' at best, and otherwise probably roundish or amorphous in shape. Might be like trying to cut the steel with extremely hard bowling balls, I don't know...

Aside from that, it may be way too expensive anyway to even attempt to produce such a thing. Even diamond can be inexpensive (cheaper than CBN, too), so I'd not see much incentive to use anything else.


David

 

[miracleboi123]

For the same reasons, if you strop with diamond compound (or CBN, which is the only other abrasive hard enough), it can work very well. Other stropping compounds will have the same handicaps in dealing with the vanadium carbides in the steel. Diamond compound works very, very well when used on very firm or hard backing, like wood (balsa, basswood, mdf, maple work well); that's the best way to take edge bevels to a very high polish, and still keep the apex of the edge as crisp & sharp as it can be.


David

Very nice! Thank you for the feedback David! I probably will just go with a simple diamond stone for now most likely a smiths** since I already unloaded a lot of money on the Nakamura. I'll upgrade to the DMT stones then strop them! Its interesting I've never heard people use wood as the backing for strops. I always thought it was just leather! Thanks again David!!

 

[Obsessed with Edges]

Very nice! Thank you for the feedback David! I probably will just go with a simple diamond stone for now most likely a smiths** since I already unloaded a lot of money on the Nakamura. I'll upgrade to the DMT stones then strop them! Its interesting I've never heard people use wood as the backing for strops. I always thought it was just leather! Thanks again David!!

If you look into DMT's 'Dia-Paste' diamond compounds, they actually recommend using wood (either mdf or balsa, if I recall) with the compound. Other high-end sharpening gear suppliers even offer 'strops' of balsa or other woods, to be used with diamond or CBN compounds. When you really look into it and start trying many things out, you'll discover the backing/substrate under the compound is as important to results as the compound itself; really changes how a specific compound behaves, when used on different substrates.


David

 

[miracleboi123]

If you look into DMT's 'Dia-Paste' diamond compounds, they actually recommend using wood (either mdf or balsa, if I recall) with the compound. Other high-end sharpening gear suppliers even offer 'strops' of balsa or other woods, to be used with diamond or CBN compounds. When you really look into it and start trying many things out, you'll discover the backing/substrate under the compound is as important to results as the compound itself; really changes how a specific compound behaves, when used on different substrates.


David

This is a neat new concept to me but I am willing to try it out. Balsa is very affordable so I think I will go that route! Also David do you know what diamond stone grit I should stop at before stropping s90v?

 

[Sadden]

This is a neat new concept to me but I am willing to try it out. Balsa is very affordable so I think I will go that route! Also David do you know what diamond stone grit I should stop at before stropping s90v?

That would depend as to what grit your diamond stone ends up being.

Finish on a 1k stone and a 160k compound wont do much for you. Double or triple the grit of your final stone is a safe bet.

 

[Obsessed with Edges]

This is a neat new concept to me but I am willing to try it out. Balsa is very affordable so I think I will go that route! Also David do you know what diamond stone grit I should stop at before stropping s90v?

In my own uses, I know that finishing thru DMT's Fine (25µ) and EF (9µ), followed by stropping on wood (I use basswood for this) with 3µ Dia-Paste works very impressively, and brings up a high polish very fast. If you do want to improve the chances for the stropping compounds, it's more important to make sure you finish on a tight sequence of high-grit hones before attempting stropping, so there won't be any too-coarse scratches left before stropping.

If you look at DMT's grit scale for their stones and compounds, you'll see their steps go from 'Coarse' at 45µ, to 'Fine' at 25µ, to 'Extra-Fine' at 9µ, to Extra-Extra-Fine at 3µ, after which you could utilize the stropping pastes at 6/3/1µ (could get by with just the 3/1µ, for that matter). That illustrates what Sadden mentioned, in that the steps between grits stay within 2X-3X of each other, which works very well for refinement and polishing. If the gaps get much wider, it gets harder for successive smaller grits to remove scratches left by coarser grits.


David

 

[bodog]

I've used and still use cheap sharpening stones from China on S110V. I can't believe they'd be anything more than aluminum oxide based. It takes forever to reprofile the edge on a steel like S110V, literally an all day effort, but it's doable. I'm sure you know already that S110V and S90V are comparable at the same hardness.

If I just kept the factory edge angles it doesn't take long at all, maybe 10 minutes per side working from 800 grit to 1200 grit to 2000 grit. You should be able to just plow the steel off, carbides and all, because the aluminum oxide/ CBN are harder than the steel itself. The only time diamonds come into play is shaping the carbides themselves. So you should be good with basically any sharpening stone until you're down to where the grit of the stone is the same size as the carbides. That's where you need diamond sharpening mediums. I don't wait that long to use diamonds only at that point. After I get done with my 2000 grit stone I make a small jump to 3000 grit diamond paste then a bigger jump to 8000 grit paste then 14000 grit paste and finishing off with simichrome metal polish. I get hair whittling edges i can (roughly) shave my face with that last a good while and are still aggressive enough to cut materials like wet rubber, nylon belts, and tomatoes. A pretty good balance for my uses.

Diamonds will cut any steel faster. CBN will cut any steel, just a little slower, and AlOx will cut any steel, but even slower. It depends on the actual steel hardness up to a point, then once that point is reached, the hardness of the cutting medium matters.

Think about jello with chunks of rocks mixed in. As long as you have something hard enough to cut the jello portion, you should be alright forming a basic shape. Any decent knife will cut and shape that jello mix into the basic shape you need because it's primarily cutting jello at that point.. Now if you want to finely shape that jello without destroying the basic shape, you'll need something that can shape the rocks at the surface of the jello mix. the rocks will do one of two things, destroy your cutting tool if the tool is too soft or fall out of the jello leaving a nasty hole if the cutting tool is too dull. That's where having something sharper and harder than vanadium is needed, but not before, unless you simply want to speed up the process. But a butter knife will cut the jello pretty much the same as a finely sharpened razor blade at the beginning. When you're talking about coarse diamonds you're basically introducing a serrated knife into the equation. A serrated knife will give you very fast cutting ability and you can plow through the jello with a quickness, but it will be ragged cuts that you have to spend time repairing later on.

 

[Sadden]

Yes and no.

Theres 3 main types of Diamonds. Two of which are commonly used by us. Monocrystalline Diamond (Mono), Polycrystalline Diamond (Poly), and Natural Diamond.

Mono has a very blocky shape with few cutting edges , it is also by far the cheapest to produce , but the low number of cutting edges makes it slower than other varieties. This is the type used in all DMT products , Atoma Plates , most diamond sprays and compounds.

Poly Diamond has many many cutting edges , making it much faster than mono diamond. It is only available to us through Ken Schwartz, every other diamond product that is marketed to sharpeners is mono crystalline without fail. Poly is much more expensive to produce.

Cubic Boron Nitride (CBN) is crystalline in structure , meaning it like poly diamond has many cutting edges, making it faster than Mono diamond, It is more expensive to produce than Mono Diamond , but cheaper than Poly Diamond , making it a high value for its performance and a good middle ground for us. It is the second hardest substance known to man , so it can tackle even the most Vanadium rich steels

Aluminum Oxide (AlOx) , is too soft to tackle Vanadium Carbides, so high Vanadium steels will be difficult to handle with the lower grits , and impossible with the higher grits (once the carbides equal or surpass the size of the abrasive) This largely depends on the steel and heat treat. Finer grained steels such as S110V will be much easier for AlOX to handle than something like D2. But AlOx is super cheap.

 

[David Martin]

I've used and still use cheap sharpening stones from China on S110V. I can't believe they'd be anything more than aluminum oxide based. It takes forever to reprofile the edge on a steel like S110V, literally an all day effort, but it's doable. I'm sure you know already that S110V and S90V are comparable at the same hardness.

If I just kept the factory edge angles it doesn't take long at all, maybe 10 minutes per side working from 800 grit to 1200 grit to 2000 grit. You should be able to just plow the steel off, carbides and all, because the aluminum oxide/ CBN are harder than the steel itself. The only time diamonds come into play is shaping the carbides themselves. So you should be good with basically any sharpening stone until you're down to where the grit of the stone is the same size as the carbides.

This is exactly true. But your not supposed to mention this in this forum as some just love diamonds. This is SOOO refreshing to see this understanding posted here.
Which with these steels with vanadium carbides (mattering not the percent) one would have to take the stone's grit to XX FINE (1800 grit) before the sharpening of the carbides comes into play. Many folks don't sharpen near that fine grit. DM

 

[mycough]

I am pretty sure that ankerson uses silicon carbide stone on ALL steels with pretty good success. My old Norton stone works just fine on my 10V and K390 blades which are about at vanadium filled as you can get. Russ

 

[David Martin]

mycough, Good insight. Yes, he does and his are Norton stones. He is quite known for sharpening ALL his high vanadium carbide steels on the SiC stones. Taking them mostly up to about 400-450 grit. Producing hair shaving edges with no difficulties. I mostly use a Norton India and have no problems producing a arm shaving edge. Yet, I'm only sharpening S30V not the very high vanadium steels. Still, I have in my arsenal 3 SiC stones of good quality going up to 4-500 grit. Which would allow me to do what Jim A. does if I desired. I have reprofiled S30V using a Norton coarse SiC stone. As bodog stated so well, diamond stones only come into play IF you desire to cut the vanadium carbides. Then you'll need a XX Fine diamond stone. DM

 

[Obsessed with Edges]

Nobody's saying SiC or AlOx don't work at all on these steels. For those not bothering to read (with context) what's already been said, I already pointed it out earlier:

For S90V, diamond would definitely work the best for it, especially when going to finer grit and higher polish, when it becomes necessary to thin/reduce/polish the carbides themselves. Less-hard abrasives in aluminum oxide or silicon carbide can work at the coarser end, by essentially 'scooping' the carbides out of the steel matrix, without having to abrade the carbides themselves; but, a diamond hone would still work more efficiently for that.

The SiC and AlOx stones, such as Norton's Crystolon and India, are all in the lower end of the grit range, below or well below 1000, depending on the stone; Crystolon SiC stones top out at about ~320, and the EF India tops out at ~600-800 (if you're stopping there, you should be plenty happy with them). They'll work to cut the matrix steel (still not the carbides, though; they just get plowed away, and not abraded) in that range, but will still be slower. The recommendation for diamond is given just because it'll be a LOT MORE efficient, and at a much lighter touch. Difference is night & day in ease of sharpening, especially when grit gets above ~1000 or so, when SiC/AlOx don't refine it nearly as cleanly, nor leave edges as crisp.

Some of us really DO love diamonds, and for good reason; they make things EASY with steels such as mentioned in the OP. It's simply the better tool for some tasks. I also really like my SiC stones, but I reserve those for steels better suited to them. As for some AlOx stones, I have two Lansky hones in it that are ruined (both dished and glazed), done essentially in one job rebevelling an S30V blade with less than half the vanadium carbides of S90V. Both of those were well below 1000 grit (Lansky XC and C) and still didn't get the edge apexed, before I finally switched to a well-worn medium diamond hone to finish it. That was all the convincing I needed, in seeing a tired diamond hone in finer grit still work faster than the much coarser AlOx stones, which were essentially in as-new condition before I started that job, and ruined when I finally gave up on them. Touch-up sharpening on high-wear steels can still work OK with such stones, but the heavy grinding jobs will bring out their weaknesses with some steels, very quickly.

Bottom line, look at the hardness of each material involved in sharpening or grinding these steels, and it's not hard to see why some abrasives will do a better job than others (chart is from one of Norton's catalogs):



David

 

[bodog]

Nobody's saying SiC or AlOx don't work at all on these steels. For those not bothering to read (with context) what's already been said, I already pointed it out earlier:



The SiC and AlOx stones, such as Norton's Crystolon and India, are all in the lower end of the grit range, below or well below 1000, depending on the stone; Crystolon SiC stones top out at about ~320, and the EF India tops out at ~600-800 (if you're stopping there, you should be plenty happy with them). They'll work to cut the matrix steel (still not the carbides, though; they just get plowed away, and not abraded) in that range, but will still be slower. The recommendation for diamond is given just because it'll be a LOT MORE efficient, and at a much lighter touch. Difference is night & day in ease of sharpening, especially when grit gets above ~1000 or so, when SiC/AlOx don't refine it nearly as cleanly, nor leave edges as crisp.

Some of us really DO love diamonds, and for good reason; they make things EASY with steels such as mentioned in the OP. It's simply the better tool for some tasks. I also really like my SiC stones, but I reserve those for steels better suited to them. As for some AlOx stones, I have two Lansky hones in it that are ruined (both dished and glazed), done essentially in one job rebevelling an S30V blade with less than half the vanadium carbides of S90V. Both of those were well below 1000 grit (Lansky XC and C) and still didn't get the edge apexed, before I finally switched to a well-worn medium diamond hone to finish it. That was all the convincing I needed, in seeing a tired diamond hone in finer grit still work faster than the much coarser AlOx stones, which were essentially in as-new condition before I started that job, and ruined when I finally gave up on them. Touch-up sharpening on high-wear steels can still work OK with such stones, but the heavy grinding jobs will bring out their weaknesses with some steels, very quickly.


David

I think it may depend on the stone. I ruined a lanksy diamond hone in one trip because of an S440V Kershaw boa. I currently use my cheap stones on every kind of steel I have or have recently had, notably S440V again, S110V, PSF27, ingot D2, S30V, Elmax, and I now have Vanadis 4 Extra just waiting on me to work on it. No significant dishing or glazing noted at all. They actually do well. The only problem I see is if I'm reprofiling from something like 22 degrees plus down to about 15 degrees on thick blades with high hard carbide volumes. That takes some work. I'm thinking, though I don't know because I don't have diamond hones now, that the diamonds would work faster. I'm hesitant because of what I saw happen very quickly to the only one I've tried and the success I've seen with multiple other kinds of stones, mainly SiC and whatever the Chinese stones are, followed by diamond paste 3,000 grit and up.

I'm looking forward to trying some CBN and quality diamond hones like mentioned earlier by another poster.

 

[Sadden]

You just have to be aware of the carbide size of the steel. Theres a big difference in carbide size between D2 and S110v. You can go a lot finer with S110v with conventional abrasives before diamonds become necessary.

Ankerson uses coarse silicone carbide stones with success because, well they are coarse. Several times the size of the carbides in many of the steels he plays with. Silicone carbide is also friable and keeps exposing fresh cutting edges to keep the stone cutting efficiently. He would have even more success using a nagura made of silicone carbide to build a little silicone carbide slurry and to refresh the stone in between blades.

David , I can relate to your experience with the lansky stones.