How to Sharpen a Knife
The most controversial topic in knives is making them sharp and keeping them that way. Here is how a Mastersmith did it.
Sharpening devices: what works
Over the years I have amassed a number of sharpening devices - some effective, some not so effective. Among these are the Lansky (a device that clamps onto the blade spine while guide rods set the correct sharpening angle) - an excellent device that I would highly recommend to anyone. Crock Sticks (two ceramic rods crossed): all you do is hold the knife steady and slide down the rods - very simple yet effective. Diamond hones (generally a single rod impregnated with diamond) are used like a sharpening steel, setting the angle and sliding the edge down the rod. A belt grinder is generally only used by competent knifemakers to edge a finished knife - not practical for home use. Electric wheel-type sharpeners (Chef's Choice and the like) power-sharpen with a guide setting the angle while the edge runs through moving wheels - quite effective, but they can really scratch a fine custom knife.
I use a three-stone, oil-immersed setup made by Oregon Abrasives: a rough stone for heavy stock removal, a medium stone to establish the first cutting edge, and a finer stone for final edging. The stones rotate, and there is an oil bath in the bottom of the device. I used to use the same type of setup made by Norton (the Multistone); I prefer the Oregon set-up as it is easier and lighter, and I can interchange with my Norton stones when I wish.
The main reason I use sharpening stones is that I prefer to put an edge on a knife that its owner can replicate at home - or in the field - with a minimum of effort.
Dave's current pick: the Wicked Edge
Decades after this article was written, the sharpener Dave reaches for today is the Wicked Edge precision system - guided angles, repeatable results, no guesswork. Watch him put it to work, then find it in his Amazon shop.
Understanding grinds and edges
An article on sharpening would not be complete without a basic understanding of the different types of grinds and edge finishes.
The hollow grind is one of the most basic and common. It is accomplished on the round wheel of a belt grinder; once the initial hollow is established it is quite easy to hold and deepen with continuous passes across the wheel. Hollow grinds can produce a very sharp cutting edge, and the typical hollow-ground blade is brought to a mirror finish with the aid of a buffer. The downside, in my opinion, is that there is no metal support behind the cutting edge. It is usually a bit easier to sharpen, but I prefer a hollow-ground blade only for fine skinning or caping work - put to hard use such as chopping or splitting, the cutting edge can be a bit thin.
The convex or Moran edge - also called the cannel or appleseed edge - is usually formed on the slack-belt portion of a belt grinder: a constant curve starting at the spine and ending at the cutting edge. This grind is by nature an effective chopper, with little resistance when chopping or splitting wood. Many people have a difficult time resharpening this type of edge, and for a very fine skinning-type knife some prefer a hollow or flat-ground blade.
Flat grinding is usually produced on the flat platen attachment of a belt grinder - a constant angle from the spine of the blade to the cutting edge. A flat-ground blade is ideal for a satin (hand-rubbed) finish. The edge can be made quite sharp, and it is supported by metal behind the cutting edge. Some feel the flat grind is too time-consuming and difficult to produce; I find it makes for a sharp, durable edge that can be replicated with ease.
There are many other grinds - sabre, chisel, and so on - but the grinds I typically used on my knives were the flat grind, and the flat grind with a convex edge.
From the grinder to the stones
After my knives were flat ground, heat-treated, hand-finished and etched (if Damascus), I would go to the slack belt on my variable-speed Burr King grinder and - keeping the cutting edge down and the spine almost flat to the belt - draw the blade from side to side. This removes unwanted metal from behind the cutting edge, making for a much better cutter, and done properly it puts a slight convex edge on the blade. I would then sharpen the edge on my stones and test-cut: generally through 2x4s, rope, cardboard boxes and the like. The edge was flexed for durability over a brass rod, and if all went well, the edge was removed so the blade could be finish-sanded, the guard mounted and the handle applied.
The final edge
Once a knife is finished it is ready for final edging. I use a worn 220-grit belt on the slack portion and take a couple of passes on the cutting edge. Then to a medium grind stone: at approximately a 22°-plus angle, push the cutting edge into and across the stone, alternating sides with each stroke. Then on to the fine India stone, replicating the procedure. When almost finished, lift the spine of the blade slightly and lightly finish the strokes.
All that is left is to remove the wire edge created by the stones and belt. This can be done a number of ways. I prefer an aggressive cutting edge that I like to call a "meat-cutting" edge. There are those who prefer a polished or buffed-on edge - great for that hair-popping edge that looks so impressive, but in actual hard use it does not stand up, and it does not slice rope very well as it tends to slide.
After the wire edge is produced, I use a simple, somewhat fine kitchen steel. There is a misconception that sharpening steels remove metal - in actuality they realign the cutting edge. I use the steel the same way I sharpen: run the cutting edge down the steel on each side until the wire is removed. This leaves a very aggressive meat-cutting edge that is easily kept up at home or in the field with a few swipes of the steel. You can always use a strop if you prefer that type of edge - dragging (as opposed to pushing) the edge across the strop on each side until the burr is removed.