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What the h#&@ !!!

Discussion in 'Blades' started by KCwelder, May 29, 2009.

  1. KCwelder

    KCwelder Monkey+++

    I need some help. I thought I'd try making a blade, so I took a file of suitable size and started working on it (the file) very slowly. I would grind for a few seconds until it started getting hot to the touch, then let it cool, over and over and over. Finally after exibiting alot more patience than I am known for, it was close to finished.
    I held it at arms length and inspected it and was pleased, the lines were good, choil was good, good shape and weight. As I was putting the finishing touches on it the un-thinkable happened. THAT ROTTEN SOB BROKE SMOOTH IN HALF !!!!!!!!!!
    So I guess the question is did I use the wrong steel or wrong technique?
  2. Valkman

    Valkman Knifemaker Moderator Emeritus Founding Member

    I think you'd be better off to anneal it first, then heat treat it when done. Here it sounds like it was way too hard to be a blade.
  3. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    Sounds the same to me. The heating cooling cycles while you were grinding likely induced some stress cracking. If you look very closely at the broken pieces, you might be able to see the start of a crack that won't be as shiny as the rest of the piece toward the middle; it will have a dull and/or sparkly look.
  4. dragonfly

    dragonfly Monkey+++

    I have found that they are very brittle and as valkman says, it's better to anneal the file first, then re-temper/heat treat the metal later.
    I went to leaf springs, and left files alone....I broke too many trying to work with them.
  5. Valkman

    Valkman Knifemaker Moderator Emeritus Founding Member

    Some steels like O1 are cheap enough to not worry about files and how hard they are, but if you try it again I'd at least heat it in a 450 degree oven for 2 hours to temper it down some.
  6. dragonfly

    dragonfly Monkey+++

    Hows the fingers doing?
    Hope things are getting better!
    Take care and get well soon, you are sorely needed out here, in the land of Cheapo Chinese imports!
  7. Valkman

    Valkman Knifemaker Moderator Emeritus Founding Member

    sorely needed? Was that a pun? LOL

    They'll get better, but it's gonna be 6 weeks at least. :)
  8. Galactus

    Galactus Monkey+++ Founding Member

    Bad Joke, and I was nowhere to be seen.

  9. KCwelder

    KCwelder Monkey+++

    Valkman and ghrit thanx alot. Methinks spring steel would be a better choice for a beginner like myself.
  10. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    Spring alloys can't be made as brittle as file steel, a good thing. All the same, I would anneal the spring material to start. Makes working it a lot easier. If you have what it take to anneal it, you have what it takes to heat treat it after forming.

    Go to the local junk yard and get some leaf springs to play with. You can straighten them out at the same time you are annealing, just have to get them a bit hotter. The key is a seriously slow cooling in a preheated sand bed. Comes out soft enough to chew.
  11. Cephus

    Cephus Monkey+++ Founding Member

    Much better off with spring steal as has been said .
    Easier to work not as brittle and will hold an edge till the cows come home
    after ya dip it in hot lead at 600degress for about 30 mins and put it sand
    to cool over night .
    I know it's already been said .
  12. Tango3

    Tango3 Aimless wanderer

    plenty of books at the library on knife making, won't imbue you with skilll but they take some of the utter magic out of the metallurgy involved.You can find out about the different molecular states metal goes through as the temperature rises and the rate of cooling.
    If you heat a brittle piece (i.e.a file to 400 F or so and let it cool slowly it becomes softer. if you heat a blank until a magnet no longer sticks, the final structure is determined by how slowly or quickly it is cooled,stick it directly in a tub of cold water and it will be very hard but brittle, cool it more slowly and it gains toughness *(ductility), the ability to bend a bit before breaking, valkman can talk on this but his typing fingers aren't there yet. but different smiths have their own secret recipes ( cooling in oil. cooling in GOJO hand cleaner) to achieve their preferred characteristics. :D Don't know it all, Ah just reads alot.:oops:
  13. WestPointMAG

    WestPointMAG Monkey++

    Don’t forget about lawnmower blades, think of all of the abuse they can take.
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