Try this at home. New sharpening method.

[Fireman]

https://youtu.be/jPIJkXfUg5E
But please for everyone’s sake... don’t cut ham.

[spoonrobot]

[soc_monki]

Watched the videos, really surprised at the results! Kind of weird to have a coarse finish on one side and fine on the other. I've been experimenting using an extra coarse or coarse diamond stone and then refining a little with a spyderco medium. Very bitey but fine at the same time.

Don't know if I'll do coarse on one side and ultra fine on the other, but if it works? Can't fault it.

[MFlovejp]

I’m very curious about this. I’ll give it a try on the KME when I get some time. I’m thinking the ZDP Delica will be an ideal candidate.

[Wartstein]

The title of the thread is a bit misleading:
I thought I´d see a new way how to do the sharpening, like with a new tool or while hanging head down from the ceiling or whatever

/ But this actually is a lot more interesting! Has anyone here ever done it? One side of the edge very coarse, the other pretty fine? In which tasks this might be advantageous, in which not so much? And what is the theory behind it?

Good thing: I can try for myself
Wonder if, in order to produce this kind of edge, it is enough to just use the white rod on the sharpmaker on one side, the CBN on the other for finishing - it should, right?

[MFlovejp]

Wonder if, in order to produce this kind of edge, it is enough to just use the white rod on the sharpmaker on one side, the CBN on the other for finishing - it should, right?

I believe it was something like 250 grit on one side, 6000 grit on the other. I can't exactly replicate that but I'm thinking 300 for the coarse and I can go way up through my Arkansas stones for the fine.

[Wartstein]

Wonder if, in order to produce this kind of edge, it is enough to just use the white rod on the sharpmaker on one side, the CBN on the other for finishing - it should, right?

I believe it was something like 250 grit on one side, 6000 grit on the other. I can't exactly replicate that but I'm thinking 300 for the coarse and I can go way up through my Arkansas stones for the fine.

Thanks!
I don´t think that with my limited gear I can reproduce the exact same edge like in the vid, but certainly roughly so, in order to just try the general idea.
Again, really interesting! But then: I somehow think if the "coarse/fine" - approach was really advantageous in a larger variety of tasks, some of the "sharpening wizards" here on the forum would have come up with it and shared it here already?!

[TenGrainBread]

What really matters is the apex. I'd like to see a magnified image of the apex of an edge sharpened this way.

[MFlovejp]

Again, really interesting! But then: I somehow think if the "coarse/fine" - approach was really advantageous in a larger variety of tasks, some of the "sharpening wizards" here on the forum would have come up with it and shared it here already?!

Who knows, maybe we're on the verge of a great discovery, a sharpening revolution! Or maybe not haha. I'll give it a try and report back. I suppose I'll need to come up with some kind of testing criteria... and locate some cardboard.

[Holland]

very cool idea, curious to see results from more people

[sal]

Hey Fireman,

Thanx for the thread and link.

I applaud him for doing his testing. Love it. Edges have been around for a long time. The packaging has changed over the centuries and I' sure many things have been done to it over the past 40,000 years. much lost in time.

Even Damascus and how to make it was lost for centuries until Bill Moran "re-discovered" how to do it. Now, thanx to the internet, this type of information can be shared.

Mike Janich has always felt the single hollow bevel Warncliffe was "da-kine". The Japanese Kataba is single bevel and hollow on the other side to reduce friction and have the material being sliced fall to one side. Now, information can be shared and we all get to learn. We are the hive. Hopefully we'll get to keep it and share it. I encourage all of you to test, get loupes, try diifferent things......and then share.

sal

[Matus]

It is a bit of an extreme approach, but I am not all that surprised. In the world of high end kitchen knives (read: mainly simple carbon steels like white 1,2, blue, 1, 2, etc.) many users report better edge retention when knives are finished on natural stones which by nature are a mix of different grits. There are even some synthetic stones that have mix of a different grits in them - for example Gesshin Synthetic Natural stone (one that I have) has a mixture of 2 or 3 grits somewhere between 2k and 5k.

Of course, worlds of kitchen and pocket knives are worlds apart - from materials that are being cut (food is much less abrasive), level of expected sharpness (higher with kitchen knives - a knife that still slices printing paper may feel already dull when trying to cut food), over steels and how these steels abrade (during use AND during sharpening) - so this needs to be taken with a grain of salt.

[Cl1ff]

I saw the vid earlier and think it’s a really interesting Idea which I would like to try in the future.
The single bevel hollow grind sounds really interesting, Sal! I recall a thread where you were gauging interest in a version of the Yojimbo with the grind?
It reminds me of the Yakutian knives with are convex on one side and flat on the other, but that “flat” side is fullered. Very interesting geometry.
Asymmetry is surprisingly common in nature.
In fact, some animal teeth have serrations on serrations! Maybe one of the great members here will give this method a go on a serrated blade?

[ChrisinHove]

Whereas the use of the coarse grit both sides might diminish the edge microserrations, I wonder whether these are retained more fully if one side is sharpened coarse, the other fine?

My kitchen knives are due for a sharpen shortly, which creates some blind testing with the Mrs. I’ll give this a go.

[Matus]

Just a few words on the single bevel - I have a few blades that have a 'true' single bevel grind (that is with an urasuki - or the hollow grind on left side - since I am right handed) - like kiridashi. These are quite specialized tools for fine precise work, cutting carboard with a single bevel knife will lead to an experience, that the knife just does not want to cut straight. On top of that, the edge of a single bevel tools is usually thinner and thus more fragile.

Now, would it be cool if Spyderco would make a folding kiridashi with a compression lock? Absolutely! But for the sake of our stones wrists and fingers, please not mono-steel, but ni-mai .... and please don't forget the lefties.

[Wartstein]

I find both very interesting:
- Hollow single bevel grind
- V grind with one side coarse, one side polished

But I think in discussing those: They might share some similarities in there properties, but still are very different things / approaches...

[kobold]

What really matters is the apex. I'd like to see a magnified image of the apex of an edge sharpened this way.

You would be able to see the nano serrations I guess.

[pantagana23]

That's a micro-serrated edge

[kobold]

Another one

https://www.youtube.com/watch?v=ChiFWYb7_VM

[Wartstein]

Another one

https://www.youtube.com/watch?v=ChiFWYb7_VM

Really, really interesting once more!

Especially, as said at the beginning of the vid, the guy that came up with the "250 / 6000 grit" -edge thinks it would be (quoting [edit] Pete): "Truly versatile and form fitting for most purposes"

Also interesting what the "physics" / "mechanics" behind this findings may be. Paraphrasing Pete: Is it more like that the coarse edge "leads" and when it breaks down the polished edge takes over? Or vice versa? Or something else?