zero bevel grind - why not?

In my continuation of why not posts
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I've recently gotten into Scandinavian knives, and the thing that impresses me most is the zero (secondary) bevel grind for the edge. This geometry cuts like nobody's business, even in thick knives (my 5/32 thick Helle Eggen will cut rope, etc. just as well as any filet knife! *None* of my other knives, no matter how thin, or how expensive, even come close). So how come I only see this grind in Scandinavian knives? I don't think it's a weak geometry - I've cut wires/hardwood,etc. without damage. Maybe it's a bad chopper? Ok, but I can probably whittle a tree down as fast as you could chop it with a double bevel grind knife (within reasonable comparative sizes of course).

Are there custom/production knives that use this grind besides Finnish/Norwegian/Swedish?
If so, please tell me!! If not, why not?
 
C

Cliff Stamp

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Ed Schott does double full flat grinds, R. J. Martin does full flat chisel grinds, David Boye and Phil Wilson grind almost as close. They use a secondary bevel but it is very acute and the primary bevel is ground down to .01" or less behind it.

The only disadvantage is in the low durability which is relative of course. The medium camp knife I have on loan from Schott in CPM-3V with a double full flat grind has a more durable edge than several production and custom blades I have used with secondary edge bevels.

-Cliff
 
I've posed the same questions - why aren't more makers using this grind? I love this grind - my scandi knives are my best cutters. I guess Cliff hit on it - it is "less" durable than others. Perhaps, but's easy to resharpen and cuts very well even when "dulled." I'd like to see more makers offer this grind perhaps on fighters were edge durability is not paramount.
 
I'm also a big fan of the Scandinavian grind. It's hard to go back to secondary bevels once you've tried it.

But yeah, the disadvantage is relatively low durability. I haven't chipped the edge of a puukko, but I'm sure you could do it if you weren't careful. The big problem with the grind is that the edge blunts pretty quickly. It's not really "dull", but it does lose that almost magical razor sharpness after just a few passes through cardboard.

That's probably why you don't see the grind in production knives. Some knife companies have a lengthy warranty and they don't want to see their knives come back. It's true that the Scandinavian grind is easy to sharpen, but most people don't even try to sharpen their knives; they just send them back to the company. You'll also have guys who will use the knife to do something like chop bone, end up chipping the edge, then send it back for warranty work.

That kind of thing could add up to a lot of money for the knife company. In fact, you already see companies cutting corners to avoid getting knives returned for warranty work. The blades on Benchmade knives, for instance, are very hard and have very thick edges, probably to avoid dulling and chipping respectively. There's no other reason to put an axe edge on a folding knife with a 3" long blade.

Plus, let's face it, people like pretty knives with a nice finish. That's the main reason why the majority of production knives are made of stainless steel. Unfortunately, the Scandinavian grind frequently doesn't look pretty. Since you sharpen the whole bevel and sometimes grind down the flats, it's not possible to keep a nice finish on the blade.
 
It seems like I remember my double-edged Gerbers (Mark I, Command I, Mark II and Guardian) having no secondary bevel.

David Rock

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AKTI Member # A000846
Stop when you get to bone.
 
The zero bevel is harder to resharpen since you must remove material from the entire bevel surface. To keep it looking good you need to repolish the surface with a 4000-8000 grit water stone or other super fine medium.

I don't find it that high performance a grind since the blade just keeps getting thicker like a saber grind. If you cut hard material you get frictional drag along the entire bevel surface. There are trade-offs with a hollow grind where reduced friction behind the edge can be payed for when the material impinges on the blade further back (a win-some/lose-some situation). I often find it more of a winning situation with a hollow grind since cut material can often bend out of the way easier if it touches the blade at the far end of the curve rather than right behind the edge. For ease of cutting and ease of sharpening I prefer a hollow grind.
 
The full flat ground blades if made from a high quality steel will maintain an edge for a long time just using a smooth steel and a loaded strop or a ceramic rod. It takes quite awhile for this to wear enough metal so that a visible secondary edge has formed. Once this happens you do have to profile the primary bevel. Take some thick leather or styrofoam and use high quality sandpaper on top of it. Unless you knocked a piece out of the edge, the sharpening from start to finish is only a matter of minutes. The leather is to allow the blade to sink in and thus slightly round the edge. You can also roll the blade to increase the curvature of the edge bevel or use glass instead of leather and keep the bevel flat.

While full flat grinds will have frictional contact all along their surface, their edge is thinner than blades with secondary bevels and this is where the force is concentrated. It falls off very quickly as you go back from the edge.

Jeff, who makes high performance hollow grinds in light use blades - very deep grinds down to very thin edges?

-Cliff

[This message has been edited by Cliff Stamp (edited 07-24-2000).]
 
Thanks guys, and thanks Cliff.

One of the areas that I wonder about is the edge durability. I can't remember the last time I've dulled a knife to a non useful state mid-project. Now, I believe it is doable, just not common. Also, I've dulled a puukko to the point that it won't cut paper without some tearing, but it still cuts hard material (rope, wood, plastic, etc.) better than a newly sharpened double bevel grind. Since the only time I cut paper is right after I sharpen a knife (as a test), I don't really care. I generally use knives to cut the things I can't tear, or I use an exacto.
I think you get a longer lasting "useful" edge, as opposed to a long lasting shaver or paper cutter edge, with the zero bevel.

As for difficulty of sharpening - you'll never see a lansky or other angle holding device on a Scandinavian ground blade. You don't need it - the bevel is your guide. What could be easier? (Yes, I have scratched the flat part before, but to me, it adds character to a using knife)


The other thing that puzzles me is the thickness argument. I'll usually carry a blade in my briefcase to cut my daily (large) apple. My Helle Eggen is a fairly thick 5/32 blade, with what I call a zero bevel sabre grind. You'd think a blade this thick would be more difficult to use on an apple than a thinner blade. Not true. I find this knife cuts thru an apple as easily or more easily than much thinner double bevel knives. I don't know why this is true, it just is.

Cliff thanks for the references to makers using zero bevel - that Ed Schott little camper sure looks great!
 
my fathers butcher knives are 0 bevel and steel doesn't come any sharper, they go thru half frozen deer like an arc welder thru butter. btw he generally uses a couple swipe on a steel to kepp them in working order and rarely has to do so, usually when switching from one deer to another. actully this is where i first learned to love knives there was somthing magical in the way my father broke down the meat into various chops steaks and roasts. the coolest thing i ever saw was when he totally deboned a deer for hamburger, the meat was in all one piece and the bones were in a pile.

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a man is no fool to give up that which he cannot keep to gain what he cannever lose.
 
OccamsRazor:

I find this knife cuts thru an apple as easily or more easily than much thinner double bevel knives. I don't know why this is true, it just is.
Click to expand...

The drag that a blade experiences is proportional to the force exerted on the sides. The amount of force dies off *very* quickly (in general) as you go back from the edge and thus the edge profile is the dominate factor, it is much more critical than the spine thickness.

The ease of sharpening because you are grinding on the primary bevel is an important factor as you mention. Unlike secondary edge bevels, even people who are fairly new to sharpening can keep the angle constant on single grind.

-Cliff

 
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