Guards for classical Japanese style takedown knives are generally formed as variations of flat discs that slide over the tang. When working with wrought iron or steel, small copper inserts called sekigane (責金) are often used to prevent contact between the blade and the tsuba.
This photo essay will attempt to portray a simple approach to creating this type of guard using basic tools and techniques, with a focus on the installation of sekigane. The tools used in this example are a charcoal forge, hammers, pliers, chisels, drill, wire cutter, hacksaw, and files.
Wrought iron is a fairly pure form of iron which was manufactured for all structural and utilitarian applications prior to the modern production of mild steel. It is usually easy to identify in the wild by the way it corrodes into a wood grain like appearance rather than the moon-textured look of corroded steel.
A simple test for wrought iron is to cut partway through a bar and then break off the rest. It will bend and then finally break, revealing stringy iron fibers rather than the homogeneous matte-gray internal structure of modern steel. The linear striations are caused by the residual slag left between layers during smelting and refining and are often appreciated as an aesthetic point in artistic works.
Forging the Tsuba
Forging wrought iron should be done at a much higher temperature than high carbon or even mild steel. At lower temperatures there is an increased risk of cracking along the slag lines whereas higher temperatures ensure that everything is in a malleable state. Punching and drifting must be done with care and at very high heat, resist the urge to keep forging into the lower range as it cools. Because wrought iron contains no carbon it can be safely heated to a bright yellow or almost white heat without burning up. In terms of planning and shaping, the grain direction of the layers must be considered, almost as if working with wood.