Walter has a unique demo for this episode: a Japanese blade from a rifle barrel. Traditional Japanese swords are made with a complicated construction, which consists of an exterior skin of very hard steel and an interior made of much softer steel. The purpose for this is to make the blade more resilient, so the blade won’t break in half when it strikes things while maintaining a cutting edge that won’t have to be sharpened all the time.
Today, Walter will take an old rifle barrel and fit a soft steel inside of it, forge-welded together to make a blade that mimics the characteristics of traditional Japanese swords. This is a complicated project with a lot of different elements to it, so this is just the first part, which focuses on the forging of the blade.
The first thing he does is to find out if the steel on the barrel can even be hardened at all. He cuts a piece off and hits it with a hammer to show that it easily deforms. He heats the piece up to 1500 degrees and quenches it, which should get the steel piece to harden. He hits the piece again, and it shatters, meaning it has hardened.
He then cleans the barrel with some custom bore sandpaper and the surface of the mild steel rod. He attaches a handle of rebar, and drills a small handle at the base. He makes the rod shorter than the bore, as he has to pinch the bore shut to make sure the resulting knife’s exterior is a hundred percent hardened steel. He wrestles the rod into the bore using a rather time-consuming, complex process.