While convex grinds appear to be an exceptional choice over today’s modern grinds, there are a few downsides to be factored into the equation. First off, convex grinds are a bit of a lost art, and require more highly skilled labor to produce. The actual edge bevel of a mass-produced knife tends to be an afterthought, with very little attention paid to it. A convex grind, especially when it is a full convex grind, must be done correctly at the point of manufacture. This raises the price of the knife. Another drawback to the convex grind lies in the area of aesthetics. To properly sharpen a full convex grind, one must remove material from the entire blade. This can create scarring of the blade finish, vastly reducing the visual appeal of the knife. And typically, a full convex grind requires a thicker blade stock than other knives, so a convex grind can add extra weight to a knife. Lastly, few people know how to properly sharpen a convex grind. And if a knife is allowed to go dull, it is of little use to anybody.
Now, with the bad stuff out of the way, let’s get into the advantages of convex grinds. Full convex grinds are extraordinarily simple and inexpensive to maintain. This may not appeal to those who rejoice in today’s plethora of sharpening gadgets, and who enjoy spending hours sharpening their knives. If a fully convex ground blade is not allowed to get too dull, stropping will usually restore the edge to full sharpness. You can buy an expensive stropping system, with a ton of mysterious stropping compounds, and have a ball when stropping your knife with these exotic materials, but you are not required to. An old mouse pad and a couple pieces of wet/dry paper will do the trick nicely. Yes, you heard me correctly. You can assemble a near perfect maintenance system with stuff you have laying around the house, or for only a few dollars cost. And when you compare your convex ground knife and simpe sharpening system to your friend’s v-grind knife and expensive edge guide sharpening system, you will probably find the cost to be about equal. The difference is that you put your money into the important thing, the knife. Your friend has been forced to compromise on the quality of the knife, in order to afford to sharpen it correctly. That’s no way to run a railroad!!!
advantage of the convex ground blade is shear cutting efficiency. A
convex grind tends to act as a wedge, parting the material being cut, thus reducing
friction or drag created by the material. Convex ground knives will tend
to be much more efficient at deep cuts than knives with v-grind
secondary bevels of similar
thickness, with less binding on the substrate.
convex grinds also tend to have a longer usable life. As one sharpens a
flat grind, the thickness of the blade at the edge bevel becomes thicker
and thicker as more material is removed. This thicker edge bevel will
result in greatly reduced cutting efficiency. Because material from the
side of the blade is removed when sharpening a full convex grind, the
thickness of the edge is a constant throughout the life of the
knife. A full convex grind will cut just as well after years of use, as
it will when brand new. This factor is especially important to people
whose knives are primary tools of their jobs or survival, as their tools
require constant maintenance.
So let’s get into how a convex grind should be properly maintained. As
I stated before, the key is not to let a convex edge become too dull.
Minor touch-ups are easily accomplished through stropping. Stropping
with an abrasive compound or paper should also keep a nice satin finish
on the blade, without the scarring created by using a bench stone. The
diagram below shows a proper stropping motion on a hard abrasive
surface. I illustrate this, as we do not always have a mouse pad or soft
leather when stropping in the field. We often have to rely on our pant
leg, smooth rock or board. The key is to draw the knife toward you,
keeping constant contact with the blade as it is rotated. You want to
abrade the entire side of the knife equally, and stop rotating as you
hit the edge of the blade. You should feel a slight change in friction
as you hit the very edge of the blade, telling you to stop rotating.
This diagram can also be used when the blade becomes extremely dull, and
you are forced to sharpen your knife on a hard bench stone, although
some people prefer to reverse this motion, pushing the blade into the
you do have the convenience of a nice soft stropping surface,
maintenance is much simpler. Place a piece of abrasive paper on top of
an old mouse pad or two, and lay the side of the blade on top. By pressing
down, the pad and paper should conform to the shape of the blade,
allowing you to make smooth, straight stropping motions. This can also
be accomplished with a soft leather strop and polishing compound, in
place of the pad and paper. The key is to have a thick and soft enough
base, so that you don’t have to rotate the blade. Typically, the grit
of paper or compound you use, depends on how much blade material needs
to be removed, and how finely polished an edge you prefer. As a rule of
thumb, I normally start with a 600 grit piece of wet/dry paper, and
finish off with 2000 grit paper. This produces a nicely polished edge,
which is wonderful for push cutting. If I completely dull the edge
of the knife, I'll start with as low as 220 grit paper.
This article was shamefully stolen from our good buddy BuzzBait's original SOSAK site and I hope he doesn't mind us using it here.