Convex beveled knife (not just edge)?

C

Carl64

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Apr 3, 2005
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How possible is it to make a convex beveled production knife? Easy as anything else, or not likely with standard grinding equipment? A hollow grind seems like the natural result of a grinding wheel, but a convex grind is the opposite.

IMO, the "perfect knife" would be a slight convex grind, rather than flat, with the main bevel going down to near-zero (ie, very little edge bevel).

Lots of custom makers like convex edges, but full convex bevels are so non-existant that I sort of put them out of my head until it was mentioned in another thread. The large bevel is really the same as the bevel that makes the edge, just larger and one level up. Why not apply the same rules?

This type of blade would give you more strength towards the center of the blade (unlike full flat or hollow, which put the strength at the spine), while having minimal evvect on the angle and thickness near the edge. A partial bevel (like a delica) is OK with a wide enough blade, but still sacrificing cutting ability with the sharp hump running down the side of the blade.

It I will never be able to get such a knife, I suppose it wouldn't be hard to modify a partial flat grind.
 
As I just posted in the other thread after missing this one :foot: you might want to look at Fallkniven and Swamp Rat for convex bevels.

I think convex could confuse a lot of people not used to sharpening them. I did see a convexed Police (I think it was) over on the Spydie forums that was very pretty.

I'm almost tempted to convex one of my spydies to see how it affects performance as I've not used a convex edge much before.
 
In theory, should be a fairly easy profile to create, all it takes is a slack belt sander. But for any given blade, it would make the worst "cutter" as convex creates the "fattest" wedge. They are generally used where a very sturdy, but not particularly efficient, blade is needed. Has obvious benefit on a sword, can see it being of benefit on a machete or kukri, not sure what the "advantage" would be on a pocket knife except possibly for cutting wire. The idea that cut food "rolls away" from the outboard side of the blade is counterbalanced by the tendency of the inboard side to drift "outward" rather that cutting straight down.
 
You might want to look at Bark River knives. One of their claims to fame is a convex grind. The back of the blade is "sturdy", but the cutting edge is as sharp or sharper than anything I have (Spyderco, Benchmade, Sebenza, or customs). As another plus, they make a range that varies from pocket size to forearm size cutters.
 
A second vote for Bark River. Their knives are well made, reasonably priced, and convex ground. The steels they use are A2 and 12C27.

At this point in time, Bark River only makes fixed blades, but there's a slip joint in the works and plans for other folders.
 
I doubed that it is difficult to make, all it needs is a slack belt. My guess is more that Sal isn't all that thrilled about that kind of grind. While it maybe a very nice grind for the average knife nerd like the people on this forum, it will probably make it very difficult for the average knife user to sharpen. Not that it is really difficult but it is probably intimidating. Either you loose the full convex shape and create an "ugly" edge bevel or you have to operate with sandpaper on a mousepad or lot of experience and wrist motion on a benchstone.
 
The thinner the stock of the blade the less difference a full convex grind makes compares to a flat grind with a convex edge. If you spend a little time with a mouse matt with wet&dry paper on a flat grind knife like a calypso it becoms very much like a global kitchen knife which has a full convex grind.
 
I've got a few Bark Rivers, and they need very little sharpening, to begin with, and stropping them works as well as sharpening does for other grinds. Like, stropping on my pants leg.

However thick the stock, they make the edge about the same (very sharp) angle.
 
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