Which steel produces the finest edge?

[roughedges]

Also, what blade steels have failed you under normal use at 18 degrees inclusive?

He's not talking about failure Vivi. He is saying that (everything else being the same, I assume) an 18 degree edge is likely to dull more quickly than a 30 degree edge. Having nothing to do with the sharpness of either and particularly irregardless of the sharpness or dullness of the edge at 18 degrees.


Common sense isn't always so common.

 

[Vivi]

He's not talking about failure Vivi. He is saying that (everything else being the same, I assume) an 18 degree edge is likely to dull more quickly than a 30 degree edge.

Again, I still wonder why it's brought up, because my original words indicate nothing about angle.

I have not observed thicker edges having an edge holding advantage over thin edges. In fact my testing has shown the opposite to be more likely especially if you use a microbevel. If the edge isn't thin enough to fail there is nothing I'm aware of that would make it not hold an edge as long.

 

[akadave2]

I never said that a hair whittling edge dulled faster, Im saying that it doesnt cut some materials as well as a toothy edge. While I dont like serrated knives they do make them for a reason.

 

[JTR357]

My blades in 52100 take the finest edge. Other comparable high carbon steels are very close: 1095, W75 (Roselli) and Carbon V.

+1:thumbup:...also CPM3V works out to a fine,polished edge as well,from my experience.

 

[Vivi]

+1:thumbup:...also CPM3V works out to a fine,polished edge as well,from my experience.

I've been looking at some 3V fixed blades. How is the edge holding in your experience?

 

[The Mastiff]

I'll add MBS26
AUS8(W) 8A with added tungsten. used in kitchen knives
White steel
blue steel

 

[JTR357]

I've been looking at some 3V fixed blades. How is the edge holding in your experience?

Like nothing I've ever had before.I just acquired an L.R.Harner 6" utility knife.I chopped through a 5" maple log with it.I stabbed it as hard as I could into a 4X4 block of treated lumber(think it was fir or ash).It went in about an inch & a half.No tip damage.No edge blunting or chipping,just a little rolling .The edge is at 20 degrees & a flat grind.It wouldn't shave hair after this,but still sliced up paper very well.After a 3-5min. stropping it was shaving sharp again.
Unfortunately when I stabbed it into the block,my hand slid down onto the squared off guard & I cut my hand(not too bad though).

52100 & CPM3V are my 2 favorite steels at this time,but I think Rich Edwards' 1075 is pretty darn good too.I just haven't had time to put it through the paces.

I used to be such a stainless steel nut,until I got my first 52100 knife.Now I always prefer a carbon steel blade to stainless.Way I see it,if it's has to be stainless,it might as well be stain-proof,like H1.

Here's a pic of the Harner

 

[tsiloics]

He's not talking about failure Vivi. He is saying that (everything else being the same, I assume) an 18 degree edge is likely to dull more quickly than a 30 degree edge. Having nothing to do with the sharpness of either and particularly irregardless of the sharpness or dullness of the edge at 18 degrees.


Common sense isn't always so common.

I never said that a hair whittling edge dulled faster, Im saying that it doesnt cut some materials as well as a toothy edge. While I dont like serrated knives they do make them for a reason.

Didn't mean to steer things O/T, but two issues here.

1.) As akadave2 says, a lower edge texture (more coarse, less keen) will cut some materials better. So absolute sharpness (defined simply as fineness of edge) is not always the sole indicator of cutting performance. An example of that would be trying to cut wet webbing or cattails with a highly polished edge, vs. a more toothy edge.

2.) On the, "the sharper a knife begins, the longer it will hold an edge" thing: I think the idea here is that, all else equal, the rate of degradation is uniform, so the better you start, the better you finish. Seems reasonable in theory, but not always so in practice. The obvious example would be in using an overly acute angle to achieve the greater degree of keenness. Then the edge rolls or chips prematurely, and the blade actually dulls faster than it otherwise would have. In some steels, this might be simply a matter of the edge being too thin to adequately retain carbides, so I'm not necessarily talking about abusing an edge (as in chopping with a straight razor).

And then that brings me to a third point: Vassili, of course keenness has something to do with grind angle. Try polishing up a 90* edge and whittling hair with that. I would agree that there is relatively little difference in whittling ability between say, a 20* and a 30* polished edge. But a 15* edge definitely has an advantage over a 40* edge.

And then back to the bottom line: It is overly simplistic to think in terms of there being one definition of sharpness that translates directly into universal cutting performance. You have to consider the application, and choose a tool appropriately. BTW, that's also why the Chevy and the Ferrari aren't simply two different ways of getting from A to B.

Of course none of this has a damn thing to do with which steel will take the finest edge, lol, so sorry about that.

 

[allenC]

Of all the knife steels that I've used, I find that S30V and H-1 obtain the most keen edge.

 

[Vivi]

Of all the knife steels that I've used, I find that S30V and H-1 obtain the most keen edge.

Interesting. Is your H1 knife one that is newer or have you sharpened it many times, possibly work hardening it? I've only sharpened an H1 knife twice and both times it got sharp, but not as sharp as I'd like. I'll have to reprofile it and try again, I get better results that way.

JTR, thanks for the response. I had my eye on a ferhman. Have you found the carbon steels you use to stand up to abuse that much better than stainless? I haven't ever used stainless in a chopper, but I do have a 5 inch Brusletto with a stainless blade with a thin scandi ground edge, and I've done all the chopping abd batoning such a small knife can handle and it's served me well so far. I've seen light rolling once or twice, otherwise it's been stable.

 

[Vivi]

On the, "the sharper a knife begins, the longer it will hold an edge" thing: I think the idea here is that, all else equal, the rate of degradation is uniform, so the better you start, the better you finish. Seems reasonable in theory, but not always so in practice. The obvious example would be in using an overly acute angle to achieve the greater degree of keenness.

I don't understand why edge geometry is being brought up, though. All I am saying is,take two given knives of the same make and geometry, and sharpen one to hair scraping sharpness and the other to hair whittling sharpness (Please keep in mind I define sharpness as just sharpness, not sharpness + geometry as discussed below). Cut 100 pieces of manilla rope or cardboard with them. The one that started out sharper, following the conventions of known physics in our universe and assuming no other variables exist, ought to be sharper in the end.

And then that brings me to a third point: Vassili, of course keenness has something to do with grind angle. Try polishing up a 90* edge and whittling hair with that. I would agree that there is relatively little difference in whittling ability between say, a 20* and a 30* polished edge. But a 15* edge definitely has an advantage over a 40* edge.

If I sharpen the spine of a knife to hair whittling sharpness and post a video on youtube, can others promise to not relate razorthin edges and high degrees of sharpness to one another, exclusively?

It is overly simplistic to think in terms of there being one definition of sharpness that translates directly into universal cutting performance.

I disagree. So far we have discussed three separate "ideas," sharpness, edge finish and edge geometry. They all play a role in cutting, yet they are all separate, individually observable qualities of a blade. This is why I've always disagreed with the notion that the word "sharpness" should describe geometry and quality of the edge honing, because these are two separate characteristics that can be isolated from one another.

A highly polished edge is not ideal for every chore. But a well sharpened highly polished edge will always cut with less force than a poorly sharpened highly polished edge, just as a well sharpened coarse, toothy edge cuts better than a poorly sharpened one. Again raw sharpness does not indicate edge finish or geometry or limit the knife's application to only push cutting, it just means you, or whoever honed the knife, has good technique. Quality steels can be made to shave arm hair right off a 200 grit sanding belt or XX course DMT stone.

 

[STR]

Imagine the carbides as being held in place by the 'matrix' of the steel surrounding them. As you cut its the carbides that give you that hard slicing aggression to make the blade do what its supposed to. As is natural with cutting some carbides are going to be pulled out from the matrix in use. As this happens repeatedly it creates those areas along the edge that are no longer a nice fine 'apex' like when sharp. You know, like when it reflects no or very little light back at you looking down on the edge. Instead now you have thicker more obtuse spots that require more force to make them cut once the carbides get pulled out where it shows on the apex and in use from pressure difference requirements.

The larger carbide steels like S30V and D2 need more matrix to hold them in place better when cutting. Since the carbides are larger in size more matrix is needed to keep them in place. Do you follow?. Smaller carbide size steels like AEB-L/13C26 can simply be taken thinner (razor blade thinner to be exact) because of the fact that less matrix is needed to keep smaller carbide particles in place. If we look at it another way, when you take the larger carbide steels down as thin as a razor you lose all that matrix which gives the ability to keep an edge because no matrix strength is there to keep those larger carbides in place long enough to effectively do much more than pull out before they can cut anything for you. So, realisitically speaking you are not going to do yourself any favors taking an S30V or D2 blade past a certain thickness because of these things. I've tried best I can to describe this.

Its as good as I can get it other than just saying in one line, "SIZE DOES MATTER" but then I sound a bit like Dr. Rooth I guess.

You can polish a thick edge just like a thin one so you can make the edge fine toothed by this using a large carbide steel but the matrix surrounding the steel still has to be adequate to effectively optimize the cutting for you for both long term edge holding and strength around the apex. This is why so many put a secondary bevel on their larger carbide blades like these steels because it strengthens the edge by making it 'get thicker faster up the bevel' so to speak. Got it? Good. Now enjoy your knives.

STR

 

[Vivi]

STR, do you know what kind of magnification is required to see carbide behavior in the knife edge?

 

[STR]

STR, do you know what kind of magnification is required to see carbide behavior in the knife edge?

It doesn't really need to be seen. When it dings from chip outs minor or otherwise or is felt in needed effort to cut thats what it is basically.

Lets take talonite as an example even though technically its not steel. Its softer matrix surrounding very hard carbides. These carbides are why the stuff works to cut and is so effective on flesh and stuff like rags along with other softer materials. Use it in something harder and you soon find out how soft and weak the matrix is because the carbides pull out and the edge rolls some then needing straightened back out. You don't have to see it to feel it get dull but you can see the rolled edge, the micro chips if you look with a good magnifying glass and sometimes depending on the size with the naked eye.

As for seeing the carbides. You'd need super zoom for that I think. I'm sure there are pics of that somewhere on the web. Not sure where. Maybe here, maybe one of the sword forums.

Seems I recall some old pics of some blades (I want to say S60V/440V blades but it could be S30V I'm not sure.) But these were made too thin and it didn't just chip it out at the edge it allowed the blade to micro fracture leaving a big hair line crack in the tip third area of the blade. So thinning too much in a larger carbide steel can have another effect in that at times if that pic was any indication. I've tried to find that. I'm not having luck. Not even sure it was the BF's that I saw it.

STR

 

[tsiloics]

I don't understand why edge geometry is being brought up, though. All I am saying is,take two given knives of the same make and geometry, and sharpen one to hair scraping sharpness and the other to hair whittling sharpness (Please keep in mind I define sharpness as just sharpness, not sharpness + geometry as discussed below). Cut 100 pieces of manilla rope or cardboard with them. The one that started out sharper, following the conventions of known physics in our universe and assuming no other variables exist, ought to be sharper in the end.

You are not accounting for the structural stability of the steel. STR renders a good description of this above. Depending on the steel and absolute levels of keenness, you might be right... or you might be taking one step forward only to take three steps back.

I disagree. So far we have discussed three separate "ideas," sharpness, edge finish and edge geometry. They all play a role in cutting, yet they are all separate, individually observable qualities of a blade. This is why I've always disagreed with the notion that the word "sharpness" should describe geometry and quality of the edge honing, because these are two separate characteristics that can be isolated from one another.

A highly polished edge is not ideal for every chore. But a well sharpened highly polished edge will always cut with less force than a poorly sharpened highly polished edge, just as a well sharpened coarse, toothy edge cuts better than a poorly sharpened one. Again raw sharpness does not indicate edge finish or geometry or limit the knife's application to only push cutting, it just means you, or whoever honed the knife, has good technique. Quality steels can be made to shave arm hair right off a 200 grit sanding belt or XX course DMT stone.

Note that my statement was relating sharpness to practical cutting ability, not just sharpness vs. sharpness in the abstract, or confined only to one context. With fine-grained steel, and light duty work, you are probably right. Certainly you would be right much of the time. With coarser steel and heavier work, you might very well be wrong. You have to look at the context.

 

[Vivi]

You are not accounting for the structural stability of the steel. STR renders a good description of this above. Depending on the steel and absolute levels of keenness, you might be right... or you might be taking one step forward only to take three steps back.

I don't understand how the variable of grain structure would have any affect on the statement "the sharper the knife begins the longer it will hold an edge." If you are comparing the same steel, geometry and edge finish, just different degrees of sharpness, the two blades should behave the same, should they not? They will just start at different points of sharpness.

I asked about carbide tear out because I've never observed something that looks like this under 60x-100x magnification. I'm not sure what it would look like. But, for the sake of discussion, I took an S30V Spyderco and gave it a fresh sharpening and looked at the edge under 100x magnification. I cut cardboard with it to induce dulling, then looked at the edge again. It looked less crisp and you could see wear, but there was nothing that looked like certain pieces of the steel were coming out, or anything resembling any sort of chipping whatsoever. The edge looked a little worn and rounded, that was all. To my eye and fingernail it appeared completely normal. So how should it look if this carbide tear-out theory is true?

I'm confused and feel like we're discussing something that doesn't even warrant these posts? I don't understand how, in any given scenario, a sharper knife would become unusably dull quicker than a knife that began with a less sharp edge. Does not compute? Even if you're slicing cinder blocks with 1095 (I don't know what you mean by coarse steel so I just threw that out there) I don't see why an edge that starts out sharper would end up duller than one that starts out duller?

 

[tsiloics]

I don't understand how the variable of grain structure would have any affect on the statement "the sharper the knife begins the longer it will hold an edge."

As the (lack of) thickness of the edge approaches the size of the carbides, it provides less and less structural support for them.

If your testing routine is robust enough to remove particles rapidly, and the particles are relatively large, then it will be possible to get the edge too sharp for its own good.

IOW, you will be setting the edge up so that the activity it's being used for is removing carbides from the "matrix" rapidly, and creating voids that will dull the edge faster than one that was simply left a little thicker.

 

[Vivi]

As the (lack of) thickness of the edge approaches the size of the carbides, it provides less and less structural support for them.

If your testing routine is robust enough to remove particles rapidly, and the particles are relatively large, then it will be possible to get the edge too sharp for its own good.

IOW, you will be setting the edge up so that the activity it's being used for is removing carbides from the "matrix" rapidly, and creating voids that will dull the edge faster than one that was simply left a little thicker.

It still sounds like what you're saying is relative to edge geometry and not solely sharpness.

I've yet to observe something that sounds like what you and STR describe. I've taken fine grained steels and not so fine grained steels so thin at the edge that they failed during routine use. I didn't see any tendency for certain steels to fail worse or dramatically more easily than others, they all have their point where they're too thin for the work I was doing. Regardless at no point during my testing did a knife that start out duller than another do better, all other things being equal.

I still want to know more about this carbide tear out theory. I want to know what to look for so I can observe first hand evidence that supports it, because I've yet to see any and I've seen this theory being spoken of many times over the years.

I don't really have anything else to add to this discussion other than, as it stands, I've still never once observed a sharper edge dulling quicker than a duller edge of equal edge geometry. I still completely fail to see any logic in suggesting otherwise. *shrug*

 

[STR]

I don't have to see the money in my checking account to know that something happens to it as I write checks and I've never seen a billion dollars but I know it is there somewhere. I don't need to see the carbides to know they are in the steel either.

Carbides and the matrix holding them are integrated so effectively both can and do suffer from use. Both can ding, dent, chip, crack or deform from uses also. Its all in the elemental mix that composes the blade. We can at least agree on that can't we? If you don't want to buy my explanation because you can't see it thats fine. Mete or someone with more technical knowledge can possibly give you a more detailed view point of what is occurring and why as well as correct anything I said that is off.

Oh, and Crucible Steel has high magnification pictures of the carbides and various other particle size comparisons of steels on their web site. You can view those if you just want to see them I guess.

STR

 

[OwenM]

S30V is one of the finest stainless cutlery steels there is. Crucible even has pics on their info page showing how the carbide size is in line with the grain size-exceptionally fine.
It has been out for 6 years, now. The information is not new. Enough of this coarse BS.

edit:

Oh, and Crucible Steel has high magnification pictures of the carbides and various other particle size comparisons of steels on their web site. You can view those if you just want to see them I guess.

Now how's that for an ironic cross-post?