Blacksmith C.L. Matteo describes how he forges the bigger blades on our website.
About Our Knives
About Our Knives
There are three ways to make a knife blade. The blade can be heated and pounded on an anvil (forge method), its outline can be cut out and the blade can then be shaped on a belt sander (stock removal method), or a combination of the two techniques can be used. This last option is how we make our blades.
We begin with a 13” X ¼” blank of 5160 carbon alloy steel, a medium-carbon spring steel that is very tough and flexible. It resists heavy shocks and is well suited for big blades where flexibility is desired. The handle end is forged adding length while simultaneously being thinned so that it tapers gracefully. The body of the blade is then widened which also has the effect of thinning it. Care is taken to give the blade the same number of hammer blows on each side so as not to encourage warping later. An old blacksmith’s adage says that ten minutes at the forge saves two hours at the bench, and if the blade is thinned appropriately here, time will certainly be saved at the belt sander later. The blade is left to cool, and the outline of the finished knife is traced onto it from a template. The extra material is cut or ground away revealing the finished knife silhouette.
The blade is now heated in the forge to a salmon-red color. The knife has reached its ‘critical temperature’ when a magnet no longer draws to it. It is important not to exceed this temperature for two reasons; the grain structure of the steel will enlarge, thus weakening the blade, and an overheated blade tends to warp during hardening. When the critical temperature has been reached, the blade is set aside to air-cool. This process is done twice and is called ‘normalizing’. It reduces any forging stresses that may be present in the steel. On the third heat up to critical temperature, the blade is thrust into wood ashes and left to slowly cool for a period of at least 8 hours and, more often, overnight. This ‘anneals’ the blade, leaving it in its softest state, allowing for file work or tang drilling.
Next, the blade is rough-sanded to smooth the lines, tapers and blade contours. This is the most tedious part of the blade’s manufacture because it takes time and patience to be sure neither too little nor too much material is removed. We start out with a 50 grit sanding belt and follow that with 80 grit and 150 grit belts. The blade is now ready for heat treating.
The blade is put back into the forge fire and again slowly brought up to its critical temperature. The blade is lowered edge down and point first into a shallow pan of preheated motor oil and rocked back and forth so that only about one inch of the cutting edge depth is hardened. Once all the color has left the blade, the whole blade is laid flat in the oil and left there for several minutes. The blade is then removed from the oil and wiped dry. A few passes on the belt sander reveal the blade’s shiny surface, and the blade is immediately placed in a small convection oven (a toaster oven will do in a pinch). The preheated oven is set for 420 degrees, and the blade “cooks” for up to an hour and a half. The blade is removed and left to air-cool. The shined surface will have a golden color, indicating that the edge has been tempered to a Rockwell hardness of about 55-57, perfect for a big bladed chopping knife. We repeat this process three times to be sure that the blade has been tempered all the way through.
Depending on the blade finish we are using, the blade may be dipped into acid so that a uniform gray color is achieved. The blade is buffed with 1500 grit emery paper to give it the proper look. The handle slabs are now put on, the handle is given a final polish, and the blade is sharpened.
Topic: The MOUNTAIN KNIFE(another new pic) (Read 1395 times)
