Post by Soto Sensei on Sept 5, 2010 15:12:44 GMT 10
In battle, katana was typically paired with the wakizashi or tanto, a similarly made but shorter sword. Both were worn by members of the Japanese warrior class. The two weapons together were called the daisho, and represented the social power and personal honor of the samurai.
The sword smith's signature (mei) is placed on the nakago.
Some marks on the blade are purely aesthetic. Signatures and dedications written in kanji and engravings depicting gods, dragons, or other acceptable beings, called horimono.
Some are more practical. The presence of a "blood groove" or HI (also known as "fuller") does not actually allow blood to flow more freely from cuts made with the sword. There is no difference in ease of withdrawing a blade from the saya, or a reduction of the sucking sound, which many people believe was the reason for including this feature on commando knives in World War II.
Instead, the purpose is to lighten and strengthen the sword blade. The grooves are consistent in structure to an I beam, lessening the weight of the sword yet keeping structural integrity and strength. The basic design principle is that bending causes more stress in material near the edge or back of the blade than material in the middle, due to leverage. Blood grooves remove material from near this neutral axis, which is closer to the blade's spine if one edge is sharpened. This yields stiffer blades of a given weight, or lighter blades of a given stiffness.
Furthermore the grooves (always done on both sides of the blade) make a whistling sound when the sword is swung (the tachikaze). If the swordsman hears one whistle when swinging a grooved katana then that means that just one groove is making the whistle. Two whistles means that both the edge of the blade and a groove are making a whistle, and three whistles together (the blade edge and both grooves) would tell the swordsman that his blade is perfectly angled with the direction of the cut.
The sword smith's signature (mei) is placed on the nakago.
Some marks on the blade are purely aesthetic. Signatures and dedications written in kanji and engravings depicting gods, dragons, or other acceptable beings, called horimono.
Some are more practical. The presence of a "blood groove" or HI (also known as "fuller") does not actually allow blood to flow more freely from cuts made with the sword. There is no difference in ease of withdrawing a blade from the saya, or a reduction of the sucking sound, which many people believe was the reason for including this feature on commando knives in World War II.
Instead, the purpose is to lighten and strengthen the sword blade. The grooves are consistent in structure to an I beam, lessening the weight of the sword yet keeping structural integrity and strength. The basic design principle is that bending causes more stress in material near the edge or back of the blade than material in the middle, due to leverage. Blood grooves remove material from near this neutral axis, which is closer to the blade's spine if one edge is sharpened. This yields stiffer blades of a given weight, or lighter blades of a given stiffness.
Furthermore the grooves (always done on both sides of the blade) make a whistling sound when the sword is swung (the tachikaze). If the swordsman hears one whistle when swinging a grooved katana then that means that just one groove is making the whistle. Two whistles means that both the edge of the blade and a groove are making a whistle, and three whistles together (the blade edge and both grooves) would tell the swordsman that his blade is perfectly angled with the direction of the cut.