METHODS OF THE CRAFT
My work begins when I receive bars of steel from various suppliers. Forging is the process of heating the bar stock to nearly 2000° and using both hand hammers and machinery to move the steel in it's plastic state into the desired knife shape.
This process builds stress within the steel however, and must be relieved through cycling the now forged blade through descending temperatures to "relax" the steel as well as soften it.
With the knife form forged, now the profile is refined by grinding off excess steel to establish the shape of the blade.
Next, any necessary holes are drilled while the steel is "soft", and pre-grinding is performed to remove the bulk of the material from the blade's edge. This saves work after heat treatment and establishes a centerline for the edge.
At this stage, the steel is normalized in preparation for heat treat. Normalizing refines the "grain structure" of the steel and prepares it for hardening by essentially making it as fine as possible.
Hardening changes the state of the steel into a new, very hard material called Martensite when quenched from a high temperature. This is the basis of a sharp knife.
To achieve this, the steel is heated to around 1500° whereby the carbon within the steel goes into solution. At this moment, the knife is quenched, basically "freezing" the carbon in its new arrangement. The knife is now extremely hard but is not yet functional.
A very hard knife will hold a great edge but will be quite brittle and prone to chipping. To help make the knife tougher without sacrificing too much hardness, the knife is tempered several times at around 400° to increase the steel's ductility.
One of the final steps to create a blade is finish grinding. This is one of the most critical steps where hardened steel is ground away, and the knife is thinned out to create what is called the "geometry" of the edge. The thinner a knife is, the less material you are trying to push out of the way as the edge cuts into food.
The grinding is done carefully with frequent water cooling to prevent the blade from overheating, which would ruin the molecular structure of the martensite that has been created.
When the blade is finished, all that's left is to build a handle to make the knife functional. All sorts of different materials can be used for this; I personally prefer stabilized woods or composite materials like Micarta or Carbon Fiber to build up a sandwich bonded with epoxy and mechanically secured with bolts. Once the glue is cured, the handle is shaped, sanded, and finished with wax.
For any cutting tool, sharpening needs to be done regularly. For the initial sharpening on a freshly minted knife, the bevel on the edge must be "set" which means removing a very small amount of material from the edge at an angle prescribed by the work intended to taper the edge of the knife basically to infinity.
This creates a small secondary bevel on the knife which is where all future sharpening work is typically done.