Convex ground blade thickness.

[Quy4n8]

Why are most if not all convex ground knives made from heavy stock? The ones that I am aware of, at least in factory made knives (Fallkniven, Bark River and Marble’s) are all 3/16 to 7/32 thick. Is this a function of the grind? Could they be made from thinner (1/8-5/32) stock, but not grind full height. Other than making the knife stronger, is there any advantage in making it this thick?

 

[Esav Benyamin]

There is nothing about a convex grind that requires thick stock. Just look at an Opinel, convex and thin and very sharp.

The companies you mention are focused on big fixed blades for the field, so these would be sturdier than an EDC needs to be, for example.

Convex grinds can be very easy to sharpen, once you get used to them, which is an especial advantage in the field.

 

[Jeff Clark]

The classic example of an optimal use for a convex edge is an axe. The convex edge is strong and a thick convex blade is easier to pull out when it wedges itself into a tree. The classic sharpener for an axe is a disk sort of like a hocky puck that you use with circular strokes to maintain that convex edge. There are a lot of knife uses that don't need high strength or anti-wedging designs. For example hunting knives and kitchen knives are usually most effective with thin, sharp edges. As long as you don't make the edge too obtuse in the process you can strop a convex finish onto the edge of these types of blades and make them stronger. The trick is that you will seldom notice that additional strength in typical usage. You can also get a lot of that strength by just micro-beveling the edge at a small series of steps. I profile edges to 12 degrees per side, do most of my honing at 15 degrees, put a micro bevel on at about 17 degrees and then do just a few feather-light strokes on an ultra-fine ceramic rod at 20 degrees per side. This is piece-wise convex.

 

[Buzzbait]

My Bark River Highland, by the specs, is less than 5/32" thick, and it's a full height grind. The knife is an absolute laser. Although, when the blade gets that thin, it becomes very hard to tell whether the knife is even a full convex grind or a flat grind with a convex edge.

Thin convex grinds are out there. You just have to do a bit of homework.

 

[Gossman Knives]

I make knives out of 1/8" D2 with a convex grind. There is no requirement for blade thickness with a convex grind. It's just a type of grind as is flat and hollow.
Scott

 

[Andy_L]

The convex edge lends it self to a hard working knife which mean a lot of them are rather thick. They do tend to need a bit more thickness as you have to grind away the whole side of the knife though (according to a FAQ from BRKT section on kifeforums)

 

[george tichbourne]

Andy your information is incorrect, a convex grind removes the least amount of material from the blade. In fact that is what makes the edge so strong.

I do convex grinds on blades as thin as 1/16" and they work well.

 

[Andy_L]

could you show me some diagrams or pics of the knives that show the grind nicely

A new thing I must learn

 

[Will P.]

It's the one on the right.

Most convex knives are made thick for use as choppers. The convex edge has a lot of material near the edge itself (see here on why edge strength is important). Also, the convex edge is less likely to bind in material while chopping. Choppers tend to be thick, heavy knives, and hence yoo will see a lot of heavy choppers.

 

[george tichbourne]

Another use for the convex grind is on very thin blades like fillet knives where there is not enough material in the blade to allow a flat grind or hollow grind without significantly weakening the cutting edge. All of my 1/16" blades are convex ground because of the thin blade cut very well but also hold an edge for a long time.

Guns magazine ran an article in the February issue that featured my moose knife, a convex grind on a 1/8" blade, and it was highly praised. This knife will hold an edge long enough to dress, skin, and quarter an entire moose while having enough edge strength to be driven through a leg joint with a piece of stove wood. In fact it has been used to cut through a 3/8" steel bolt with out edge damage. Convex edges are tough customers.