Recommendation? Scandi grinds and knife steels

[Bo-dacious]

Hey guys, just two topics I've been wondering about :

1. For some reason I seem to get scandi grinds sharper than other grinds. I've done scandi grind knives on a work sharp and a stone and both ways I get the scandi grind sharper. Does anyone know the science behind this, if there even is a reason?

2. I've read about different knife steels, but I still don't know why certain steels can get sharper (or can they?), and which types of steels and their ingredients have to do with this. I don't know why I never picked this up along the way. Can someone explain this to me, please?

Thanks,

Bo

 

[Wowbagger]

For some reason I seem to get scandi grinds sharper than other grinds.

That wide bevel may be acting as a guide to help keep you at a consistent angle. And I believe it is a touch shallower than many knives which are up around 20° . . . the scandi maybe be less. Honestly I never use anything with Scandi much except a wood carving knife a little.

Actually the way some cultures use that wide bevel is AS A SHARPENING GUIDE with the bevel right on the stone until they apex the edge. I don't like that because all that steel loads up the stone unnecessarily. Meaning I would rather have the knife ground way thin and shallow angles then use a faint steeper sharpening bevel. This is way faster to sharpen and wears / loads the stones way less.

've read about different knife steels, but I still don't know why certain steels can get sharper (or can they?), and which types of steels and their ingredients have to do with this. I don't know why I never picked this up along the way. Can someone explain this to me, please?

Nah that's mostly nonsense at least the sharpness right off the stone for that first hair whittling test.
From there on out things get ugly.

For instance I can get S110V silly hair whittlingly sharp and I can get 1095 or White Paper steel just as sharp.
Now the latter is more fun to sharpen and may even seem a bit sharper but hair whittling is pretty sharp right ?

From there the S110V looses that level of sharpness in not too long a time.
Depending on the material cut the 1095 or White Paper steel may maintain that level of sharpness for a while or loose it as quick as the S110V depending on what is cut.

The S110V is going to keep cutting for a long time in material that is abrasive and otherwise more challenging far longer than the other two steels mentioned if the heat treat and the geometry is optimized for the steel and the material being cut even though the hair cutting test is long failing the test.

NOW
This knife from White Paper steel, after a year of kitchen use, very careful use only slicing fruit and opening food packages, is still hair wittingly sharp in places where the edge has been used a lot (haha not just up next to the handle).


To use S110V for this application would just be bizarre and a waste of steel, time and sharpening equipment. Did I mention I hate using diamonds and only subject myself to it for the high vanadium steels ?
On the other hand I LOVE using waterstones and enjoy sharpening the steel that works best with those stones.

How to get the 1095 or White Paper steel that sharp ?
Edge Pro Apex with water stones.
How to get the S110V steel that sharp ?
Edge Pro Apex with diamond stones up to and including diamond 8,000

Starting to see a pattern here ?
Good.

 

[Bo-dacious]

Oh okay that makes sense.
A few follow up questuons:
What is white paper steel? Is that a company that makes knives?
Why do you hate diamond stones?
Why do you use diamonds for high vanadium steel? Is there something in diamonds that goes good with the vanadium?
(dumb question but I need to know) how do I know what steels work best with a given stone? I should know this, but this is the first I'm hearing about different stones suiting different steels better. I really want to know this as I believe it will help me a lot. And I am buying an edge pro apex 4 next month.

Thanks for the help, wow,

Bo

 

[Obsessed with Edges]

Hey guys, just two topics I've been wondering about :

1. For some reason I seem to get scandi grinds sharper than other grinds. I've done scandi grind knives on a work sharp and a stone and both ways I get the scandi grind sharper. Does anyone know the science behind this, if there even is a reason?

2. I've read about different knife steels, but I still don't know why certain steels can get sharper (or can they?), and which types of steels and their ingredients have to do with this. I don't know why I never picked this up along the way. Can someone explain this to me, please?

Thanks,

Bo

Many Scandi grinds are more acute in the first place; often sub-25° inclusive. That alone makes it much easier to get them to frighteningly-sharp edges. I've got a Helle Scandi folder with an edge at roughly 18-22° inclusive, straight from the factory. Most other knives will almost always be in the 30-40° range, or even wider. That makes a huge difference.

Secondarily, and as mentioned earlier, the wide bevels simply make it easier to hold the angle while sharpening, and that will yield better results as well.

Not to mention, the Nordic/Swedish steels often used in these knives are usually of very good, fine-grained quality. Sandvik's steels are often used (Mora, some Helle knives, etc), and they're excellent.

Lots of things contributing to it.

 

[tyyreaun]

2. I've read about different knife steels, but I still don't know why certain steels can get sharper (or can they?), and which types of steels and their ingredients have to do with this. I don't know why I never picked this up along the way. Can someone explain this to me, please?

I've heard theories that the carbide size within steels will affect the ability to take on an edge when working with very acute edge angles, like scandi grinds. With larger carbides, you're likely to rip out the carbide itself when going for an acute edge, leaving you with microscopic edge damage. The edge will still appear sharp, but it won't be as hair-whittling as it could.

PM steels will tend to have medium sized carbides. Some non-PM steels, like AEB-L, are formulated for a small carbide size, and are therefore preferred for kitchen knives, razors, etc., where you need an extremely acute edge angle.

See, for example, AEB-L vs common American carbon steels here: http://www.devinthomas.com/faq.html

From my understanding, carbide size will affect the ability to take on an acute edge without damage, but doesn't affect the ability to hold that edge - AEB-L will still wear faster than good PM steels. Once you start moving to broader edge angles (like, 15 DPS and higher), carbide size becomes less important to getting the sharpest edge possible - there's more material there to hold the carbide in place, so you're less likely to rip it out.

That's my understanding, based on several articles and threads I've read, including on Cliff Stamp's site. My understanding of the theory, or the theory itself, may not be correct.

 

[tyyreaun]

What is white paper steel? Is that a company that makes knives?

White steel, or Shiroko steel, is just a "brand" (or formulation) of steel from Japan, Hitachi. It's a fairly pure high carbon steel.

Why do you use diamonds for high vanadium steel? Is there something in diamonds that goes good with the vanadium?

Vanadium in steel forms vanadium carbides, which are extremely hard compared to other carbides you can get in traditional steels. You need diamonds to cut the carbide to sharpen the steel, instead of ripping it out whole.

 

[Bo-dacious]

Obsessed: great, those all make Sense. Except I've never owned or sharpened a knife that's over 30 degrees. Is that abnormal?

Tyre: ok so smaller carbide are Better...is there any downsm side to small carbide or up side to large carbide? What are PM steels? what is DPS? I never learned that. Good info!

Thanksot guys, it's much clearer now,

Bo

 

[Blues]

DPS = Degrees Per Side

20* DPS = 40* inclusive

 

[Obsessed with Edges]

Obsessed: great, those all make Sense. Except I've never owned or sharpened a knife that's over 30 degrees. Is that abnormal?

Tyre: ok so smaller carbide are Better...is there any downsm side to small carbide or up side to large carbide? What are PM steels? what is DPS? I never learned that. Good info!

Thanksot guys, it's much clearer now,

Bo

If you've never owned anything over 30° inclusive, I'd say you've been pretty lucky. So many production knives these days come with much wider-angled factory edges.

Smaller carbide sizes are generally preferred for finer edges that are easier to make as such. Steels with large carbides can still be sharpened to fine edges; but it's more challenging to do so, and it must be done with abrasives fully capable of shaping & slimming those big, very hard carbides. If the abrasive isn't up to it, the supporting, softer matrix steel around the carbides will be abraded/eroded away, leaving the bigger, blockier carbides exposed with less support at the edge. Edge will be coarser, and likely won't be as durable due to the lack of support for the carbides at the edge, which will leave them prone to tearing out of the edge.

One advantage, maybe the only one, of larger carbides is, if properly sharpened with the right choice of abrasives, they can lend more wear-resistance to the steel than the carbide type itself might imply. An example would be the 'ingot' style of D2 steel, of which it's chromium carbides aren't as hard as vanadium carbides, but can be very large at ~ 50+ microns in size. It's a challenging steel to sharpen to higher grits, especially up in polishing range, because those chromium carbides are so large.

'PM' steels are 'Powder Metal'. It means a very fine, uniformly-graded, powdered form of the raw steel's constituent elements is used to make the steel, which helps keep the grain & carbide sizes much finer and more evenly distributed during the steel's manufacture. That is what makes PM steels easier to sharpen to very fine edges. This, compared to conventional steel manufacture (as with the 'ingot' D2), which doesn't employ the fine, evenly-graded powder metal process; so, the resulting steel will be more varied in it's grain structure, and carbides tend to 'clump' into larger masses within the alloy (this is called 'carbide segregation'). The PM-version of D2, originally called 'CPM-D2' (CPM = 'Crucible Powder Metal') has exactly the same proportions of constituent elements as the 'ingot' D2, including all the same carbide-formers. But the PM process means the carbides will end up much smaller and more evenly distributed ('desegregated') within the steel, making CPM-D2 easier to sharpen to fine edges than ingot D2, while still maintaining good wear-resistance overall.

 

[Bo-dacious]

Blues: oooh that makes sense, thank you.

Obsessed: wow, I just learned a lot there, thank you. I didn't know what cpm meant, now I know.

Thanks a lot guys,

Bo

 

[Bo-dacious]

Come to think of it... I did try this one knife on a stone and it felt like it was almost 45 degrees. It didn't get sharp. Is that because of the angle, or something else?

Bo

 

[Obsessed with Edges]

Come to think of it... I did try this one knife on a stone and it felt like it was almost 45 degrees. It didn't get sharp. Is that because of the angle, or something else?

Bo

It probably wasn't fully apexed. When you get right down to it, that's the one thing that has to be accomplished to make any edge 'sharp' in the first place; even if the edge angle is relatively wide.

The one possible downside to sharpening a Scandi, with it's very wide bevels, is that it could take a long while to apex if the edge is very dull to start with, depending on what your method and available stones are. That's assuming one isn't just adding a narrow microbevel, which will apex faster, but at an even wider edge angle. If sharpening in true 'Scandi' fashion by grinding the entire width of the bevels, all that surface area of the bevels will be very slow to grind to the necessary depth, far enough to fully apex the edge. It literally gets exponentially slower, the wider the bevels are. I noticed that with the Helle I bought; it was close to being there, but not quite. Still took a good while to get it there.

 

[Blues]

...It literally gets exponentially slower, the wider the bevels are. I noticed that with the Helle I bought; it was close to being there, but not quite. Still took a good while to get it there.

So, what you're saying, in effect, is that it took a Helle of a long time.

(Okay, okay...it was too hard to resist. Sharpening jokes, you gotta love 'em.)

 

[Obsessed with Edges]

So, what you're saying, in effect, is that it took a Helle of a long time.

(Okay, okay...it was too hard to resist. Sharpening jokes, you gotta love 'em.)

Bingo.

 

[Bo-dacious]

LOL okay thanks, that makes sense to me!

Bo

 

[Alberta Ed]

Most traditional puukkos which feature Scandi ground blades are forged from relatively simple, low carbide steels which are very easy to hone to a hair-whittling edge. My Roselli Carpenter and erapuukko are Krupp W9, and my Ivan Campos Scandi ground blade is 1070. Similar edges are easily achieved with 1095, 50100 Carbon V), 52100, 1080, etc. I use a Black Arkansas bench stone to finish the edges on these steels. The newer 'super steels' with high carbide volumes (vanadium, niobium, etc.) require diamond hones to get the best edges, in my experience.

 

[Blues]

Most traditional puukkos which feature Scandi ground blades are forged from relatively simple, low carbide steels which are very easy to hone to a hair-whittling edge. My Roselli Carpenter and erapuukko are Krupp W9, and my Ivan Campos Scandi ground blade is 1070. Similar edges are easily achieved with 1095, 50100 Carbon V), 52100, 1080, etc. I use a Black Arkansas bench stone to finish the edges on these steels. The newer 'super steels' with high carbide volumes (vanadium, niobium, etc.) require diamond hones to get the best edges, in my experience.

I've got a couple of Roselli's UHC "wootz" blades which also can benefit from diamond and finishing on ceramic or stropping with diamond paste.

Love Scandi knives. Aside from the traditional Nordic versions, some U.S. makers have done some nice ones as well.

I recently gifted an Ivan Campos blade to a friend. Hope Ivan's doing well. I've been out of touch with him for some time.

 

[Bo-dacious]

Alberta: ok thanks. But what do you mean by low or high carbide steel? Does that mean the size of the carbide, or the amount, or something different?

Blues and Alberta: how do you know a blade is sharpened better with a certain type of stone like diamond?

Thanks guys,

Bo

 

[Blues]

Bo, as you've been learning here, some steels are extremely wear resistant for a variety of reasons, which include, among other factors, their chemistry, whether they are high carbide steels, and the heat treatment the blades receive. (Some of my knife maker friends would lament just how many belts they'd wear out while building me knives made from D2 or CPM D2, by way of example.)

As you've experienced yourself, you can spend a long time with a ceramic hone or rod trying to re-profile a blade, or perform a major sharpening...whereas a diamond hone would make much shorter work of (at least) the initial process of setting the bevels and raising a burr. Diamond, CBN and Silicon Carbide are among the better choices for tackling harder, resistant steels which would sneer at Aluminum Oxide which would be perfectly suitable for other blades.

"Softer" sharpening materials which might abrade the steel, may fall short of being able to cut and shape the carbides resulting in their either being rounded / blunted, or pulled out of the steel matrix at the edge.

There are folks here much more qualified to answer any further questions in this arena, so I'll take this opportunity to pause and stay within my lane.

 

[Bo-dacious]

Okay, thanks blues, good info.

Bo