How to make a Katana?

Discussion in 'Weapons' started by Teryan, Jan 29, 2004.

  1. Teryan

    Teryan Valued Member

    I was instered in how a Katan was made. I heard it takes modern day Katan makers about six weeks with 9 hr days. If you could ponit me in the directino of some web sights or books, I would greatly apprecate it.

    Why is the Katan so sharp? I've heard that it is beacuse they fold the metal over and over (making the marks on the sword), that takes the oxygent out.

    Thank you for your help.
    Last edited by a moderator: Nov 9, 2004
  2. Kof_Andy

    Kof_Andy New Member

    Yes decent katana takes awhile to make. Thats why the custom sword are so expensive. Usually it cost average about 7000+ US dollar. Katana are sharp but they arent known for is sharpness. It takes awhile to forge because there many different material being forged with, the inner and outter lay are completely different. There soft in the inside and hard on the out side, proving it a much much stronger durablity, and balance. Is because the curved edge, help increased acceleration so its a perfect tool for cutting people. Also there kissaki has many different type for different style, depend on what the katana is use for. Here's a link for this wonderful site about japanese sword.
  3. Virtuous

    Virtuous New Member

    I have some book marks at work, Ill post them here tomorow.

    I can tell you a few things off the top of my head and answer a few of your questions.

    Why is the Katana so sharp? For starters the katana's edge has been a bit dramatized to nearly mythical porportions. A good portion of it's ability to cut is attributed to the edge but the majority of it technique.

    The reason why it cuts so well is it's design. Its curved, it has a LOT of cutting area in a relativly short distance. The katana is not designed to cleave like a midieval long sword. The theory is you place the blade along the surface and draw the blade towards or away from you. Think of a steak and a VERY sharp steak knife, if you place the edge on a steak and push straight down it will cleave the meat. It would take a fair amount of effort to do this . Now take the same knife, place it on the steak and pull the blade towards you so the edge is moving across, it will cut through it like butter. With a very sharp edge and all that extra cutting area from the curve you can image you can do a tremendous amount of cutting in one pull! Im talking through torsos, necks, arms, and legs with ease!

    Now why they fold the metal. The iron/steel available in japan at the time was very inferior in quality. Metal folding is a tried and true way of removing the impurities from the metal. So the more it was folded the purer the steel, so in a way yes it did make the steel stronger and more consistant throughout, but the real enginuity is the way they temper the steel.

    The problem at hand was the japanese had a relativly thin and light edged sword. How do you make the blade maintain a nice hard enduring edge but make it flexible enough so it doesnt shatter on impact.

    Metals have a really neat mechanical property that when you heat it to a certain point and cool it changes the crystaline structure allowing it to be very maluable (soft and flexible) if you cooled it relativly slowly (ie in oil) or very hard and britle if you cooled it very fast (ie water). This process is called quenching.

    So what the japanese did was paint clay along the edge of the of the unfinished blade and then heat it up. Clay has a higher thermal capacity than steel and so when they heated the sword The parts covered by clay would be hotter than the rest. When the sword was then quenched the part covered by the clay would relativly cool faster than the back making it harder and the back a little bit softer.
    The pattern you see is the change in the crystaline structure from hard metal to soft.

    Alot of people will say this is where the sori (the curve) comes from. This isnt true. If this was true the blade would curve in the opposite direction because the faster cooling edge would contract faster than the softer.
  4. Virtuous

    Virtuous New Member

    Another reason the edge is so hard and durable is the way it is shaped. There is no sharp 35-45 degree bezel on the edge. The edge is slowly tapered from the top to the botom. This process is called polishing and is another art in it's self.

    The forging and polishing of these blades can take months and costs 1000's and 10,1000s of dollars. To me each one is a beautiful piece of art with 100's of hours and a ton of the artisans blood and sweat goes into these. They are truly small treasures.

    This kind of turned into a small primer on smithing and metalergy, I get on a roll some times. Sorry for the novel :)
  5. Cudgel

    Cudgel The name says it all

    Virtuous you made a few small mistakes.
    Actually that is why the curvature forms. The crystaline structure that forms from rapidly cooling iron and iron carbide molecules is larger tahn that of the slower cooling crystalline structure of the spine.

    All swords have to have proper edge geometry or the wont cut. Be it a katana or a medieval longsword.
    And not all metals have these wonderful properties. Some will only harden from repeated pounding like copper and its alloys.
    Iron is one of the few emtal that has al of these properties and the additions of different metals and elements will change them. Some steels air harden will some will only oil harden.

  6. Virtuous

    Virtuous New Member

    Yeah I was thinking about that last night after I logged off and was going to investigate it some more today. Thank you for the correction.

    Have you heard of a process called flash quenching? They supposedly heat the metal and then nearly instanteously cool it sub zero temperatures? Its suppose to be extremly hard but also extremly resilliant to shattering.
  7. Cudgel

    Cudgel The name says it all

    No problem, that was one of the things that was bothering when I first got interested in how a katana was made.
    Yeah Ive heard about it for something like it. I few of my friends were gonna makes some swords out of 440c stainless steel and then ship them out for that, it never happened. But Im really interested in how well it works, I might save up some moent and send out a knife I made to have that done to it as I botched the heat treat I did to it.
  8. Teryan

    Teryan Valued Member

    Thanks for the help, I dont mind books Virtuous (I enjoyed reading that). What happened to those links you were talking about?

    @ Cudgel Thanks for the links.
  9. Virtuous

    Virtuous New Member

    Actually they were the same one's as Cudgel's. (well the only ones worth their weight in salt that I could find)
  10. Korean Ninja

    Korean Ninja Banned Banned

    Dumb post made by a returning troll - BOOM!" He's TOAST!
    Last edited by a moderator: Feb 1, 2004
  11. bladesmith

    bladesmith New Member

  12. chungmoomonkey

    chungmoomonkey Just a few more months...

    well in making blades if u listen to any1 listen to bladesmith lol
  13. Charbodan

    Charbodan Valued Member

    If you are looking into this seriously, talk to someone at a ceremics or pottery shop as they will be able to guide you as to what would be the best clay to use if you want to use it in your swordmaking process.

    Different clays can handle different amounts of heat within shorts amounts of time. I would suggest a white raku clay as it as it can withstand extremely high temperatures. You don't want to use any generic blend as it may litteraly explode in your hands.

    I think a bag of good raku normaly runs arround $7.50 to $12.50.

    Good luck.
  14. Cudgel

    Cudgel The name says it all

    I wouldnt suggest talking to ceramics students or instructors. They know a lot about ceramics and clay as it apllies to ceramics, if you want to know what kind of clay to use talk to people who use clay for that purpose. But if you cant find the info, doubtful as I found some resouces on that but cant remember where, you can always learn the hard way trial and error.

    How big of a bag? I can get about 25 pounds of clay for $2. You could also probably dig up clay.
  15. Charbodan

    Charbodan Valued Member

    I suppose your right, just check out your backyard. :)

    I recomended that clay because of it's tolerance for rapid rise to extreme temperatures. Good luck anyway.
    Last edited: Mar 13, 2004
  16. Chilu

    Chilu Banned Banned has info about the forging process of katanas. One thing that makes them so good is how they are quenched(how the steel is cooled in order to harden it). They apply a think amount of clay to the edge that will be sharpened and add more and more as they get toward the dull side. That makes the edge with the least clay cool quicker so it is harder and the back softer. The edge is very hard so it can be sharped and will hold an edge better, and the back is flexible to absorb the shock when you strike. Like someone said, it cuts so well because it is curved. When you strike, you pull it back in kind of a sawing motion(ahh I can't describe it with words :cry: ) to add more power. Like someone else said, the kissaki differs on them too. The kissaki is the the tip of the sword I believe, and some are smaller than others and some are long with only a very gradual slope backwards.

    Also, a common misconception about katanas is the folding process. They don't fold the katana 1,000's of times. When they are done folding, there will be like a thousand layers(that is only 10 folds to get to 1,024 layers) or whatever, but after a few folds I don't think it really matters all that much.
    Last edited: Mar 14, 2004
  17. aml01_ph

    aml01_ph Urrgggh...

    They fold the metal lots of times to achieve what is called strain hardening. Basically what it does is cause the stress lines to intersect so that it will not fracture as easily as when unfolded. The more times folded the tougher the material becomes.
  18. mig29

    mig29 New Member

    I recommend the book: KING, Winston L. Zen and the way of the sword. It has an entire chapter about the making of japanese swords, but it´s a very hard process throught
  19. Crazymonk

    Crazymonk Banned Banned

    The end result, they would bathe it in fresh human blood. In the old days, they would take prisoners to be executed and stab them in the gut, right after the samurai is finished. Human blood was the only known substance to collesce the metals to end the sword in perfection.

    Sometimes, the prisoners know exactly what was going to happen, so they would grab as many rocks as they can and eat them. When the executioner stabs then, they would hit the rocks in the gut- ruining the sword.
  20. mig29

    mig29 New Member

    Too many Rurouni Kenshin

    That´s nonsense

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