Banshu Miki Forged Blades
Banshu Miki Forged Blades
Banshu Miki forged tools and blades represent the very best in carpentry tools, which are used by the discerning professional. The saws, planes, chisels, irons and small woodworking knives, which are being produced at present, are all recognized at a national level as traditional craft products. Following below are some of the main stages in the production of a chisel.
Stage 1
Laminating: When the relatively malleable stock or base metal has been heated to a temperature of between 1,100°C and 1,200°C, a laminating agent is applied and then a harder carbon steel is laminated to the stock to form a cutting edge.
Stage 2
Forging: Having laminated the two types of steel, they must now be forged together, so that the piece of carbon steel wraps around the edge of the stock. When this has been done, a piece from which to make a chisel is cut.
Stage 3
Forming the Shaft: Making sure not to over heat the blade, the shaft is heated and hammered into shaped and a stem to fit into the handle is made.
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Stage 4
Shaping: The piece of metal is once again heated, this time to a temperature of between 950°C to 1,000°C. Because the cutting edge is thin, care must be taken not to over heat the piece of metal as this will reduce the strength of the chisel. When the metal is at the right temperature, it is removed from the furnace and fervently beaten to the right , thickness and shape.
Stage 5
Annealing: Now that the chisel has been shaped, it is heated and then annealed, in order to make the material easier to work. The annealing has always been done using rice straw, which is used to gradually reduce the temperature of the metal to between 740°C to 750°C. Up to this point, the crystal structure of the carbon steel has been poorly defined, but now it should have become uniform and much finer.
Stage 6
Filing, Smoothing: First, using a coarse file, the shaft is rounded and then the back is given an initial filing. The front is then smoothed off.
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Stage 7
Tempering: First, a solution of powdered whetstone is painted evenly over the chisel to aid the tempering. It is then heated for two to three minutes in an electric furnace at a temperature of between 780°C to 800°C. The chisel is then quickly withdrawn from the furnace and quenched by plunging it into water.
Stage 8
Hardening: When any distortion, which occurred during tempering, has been straightened, the chisel is put in oil and then it is rinsed with water. Next, using salt heated to between 150°C and 180°C the metal is toughened. This process gives the chisel a black glossy finish.
Stage 9
Finishing: The back of the chisel, end and carbon steel edge are now ground and polished to complete a chisel with a fine cutting edge.
