Something strange in the works
Reading a story about Japanese samurai customs of testing new swords on peasants. http://www.ghandchi.com/IONA/newsword.pdf
Courtesy of David Foster.
I feel quite a bit of blade instability and harmonics when cutting through dense objects, using differentially hardened blades.
I wouldn’t be surprised that the brittle construction and steel (ancient) Japan had to use for katanas, would break or chip the blade, if an inexperienced samurai used his blade on wood or bamboo. Thus humans were much more “squishy” even with the bones.
Personally, I prefer thorough hardened blades, relying on the overall heat treatment and steel quality (Spring steel 1060 is reasonable) rather than on the back of the katana to “absorb” shock. The hamon from the differential hardening is nice, though, visually speaking.
The thorough hardened 1045 I use for practice feels much more stable when cutting, although technically it has no edge and thus isn’t “strumming the violin string”.
I’m sure technique perfection would eliminate the harmonics from any cut, using any tool. That is a bit trickier to figure out. It helps if one has supremely strong hand grips though. More on the pinky and ring finger than the index. Not so good for shooters or mouse users, since their strongest finger is the index or middle.
I’m also combining Taiji gut or dantien movements and energy concentration, in order to power horizontal sword strikes and they feel much more “smooth” that way. The energy feedback is a lot less when both of my legs are rooted to the ground, so that when the energy from the sword connects to the object, the object pushes back via one of Newton’s Laws. That energy travels back through my arms and has to go somewhere. If I route it through my stomach and to my two legs (the stomach area connects to the hips, thus can channel open a route to the legs) it hits the ground and goes back to where it came from.
I don’t think I’ve ever read about this issue, since it’s not something people generally talk/write about unless they have actually used a sword to cut targets and that sword was a differentially hardened katana. It’s like the whole sheathing movement. If you don’t use swords, it’s easy to neglect mentioning it and how it isn’t as simple as just pushing the sword back in. Japanese katanas have a bare back with no edge to it, so one normally uses the thumb or fingers to “guide it back in” via touch contact alone. Why is this better than the two edged jian or longsword’s sheathing method? Because you don’t have to get your eyes on target, you can watch around in case the threat is not over. It would be pretty stupid if someone stabbed you in the back while your eyes were looking around to see where to sheathe your sword.
So, that is just one advantage or difference between a one edged saber like sword (the katana) and a double edged longsword. Each tool has pluses and minuses depending on what job you want to do.
I will see if I can produce more testing on this subject. I need a thorough hardened 1060 to test with, since the 1045 is thorough hardened but has a different HRC rating and doesn’t have an edge to begin with (although it cuts through the same things except really light objects).