When I first started forging I was working for a trucking company hauling oilfield waste water. I got a whole lot of very heavy leaf springs for free. I tried to make a couple of knives out of them which was next to impossible. I did actually get far enough with one to heat treat and when I quenched it in oil it cracked so bad that I couldn't save the knife. From that point on I decided that if I was going to put that much work into a knife I would never have that happen again. I started buying known steel and have not regretted it since.

I guess what I am trying to say is learn from my mistakes and bite the bullet. Steel is one of the cheapest things you can buy. Why not get the best. Then you will have confidence when you sell your knives. Even if they aren't as pretty as they could be. At least you will know they will hold up.

Devan, Jared has good advice. New steel is the way to go. It is not expensive and you know what you are getting. The main problem with leaf springs , used ones, is that they are used. They have been through many up and down cycles and have been put through a lot of stress. This can translate into cracks while forging, or heat treating, or in use. Also you are not quite sure what the steel is. Could be 5160, or 1075, or something else. If you can buy new spring steel from a spring shop and they know what it is, that will work. Otherwise why take a chance.

Brion

thanks very much for the advice, i am just going to save time and get new steel from the start.

Although I cant prove it I think that a lot of the large springs have some chromium added to prevent rusting. Making them more problematic when it comes to the heat treating. I would like to do more experimenting with them in the future when I have more time. For now though I wont bother with them.

Thanks Brion, and Jared for the advice! very much helpful!

I am not nearly as experienced as most of the smith's here and do not mean to step on any toes, but, in my humble opinion, I think there is something to be said for using leaf spring. I have only finished a few knives, but all those that I have finished have been made from recycled material (either old files or spring). One such knife is posted in the critiques forum. Oddly enough, the one time I used a known bar or 1084, it cracked. (I've learned a lot since then.) It is certainly true that using a known material takes a lot of unknown variables out of the equation, thus making it much easier to use with more predictable results. However, there are several good reasons I use recycled spring steel:

1. It's cheap and functional: I've heard some bladesmiths tell students to practice forging with mild steel because it's cheap. But why not use spring that is equally cheap, but also can be hardened and made into a functional knife? Recycled steel may take more time to experiment with, but, if you have the time and not the money, I think its well worth it.
2. It's a learning experience: Spring is tricky because it's unknown. However. there are ways to approximate the carbon content of a spring. For example, spark testing. Furthermore, you can learn a lot about heat treat and internal stresses in the knife. (By the way, if you use spring from the junk yard be sure to thermal cycle it, and possibly anneal to relieve the internal stresses. If you don't it will likely crack during forging.) Testing for hardness and experimenting to find the right tempering temperatures has really aided my understanding of metallurgy. Furthermore, forging the spring to the right size billet has helped my forging technique.
3. It's green: Okay, I'm not a big environmental freak, but using somebody's trash to make knives is a great way to recycle if you ask me.

   Devan, to answer your question, I use whatever spring I can find and then experiment with it. (Usually, I don't know what it came from.) Also, I have a source for free golf-cart leaf springs which are a great size (around 1/4" X 1.5-2") for knifemaking. Thick coil spring can be used for integrals. Shape is more important than alloy to me. Spark testing on a grinder can help you get an idea of the carbon content, (basically the more sparks the more carbon) but it takes a good eye to notice the subtle differences. It really helps to know someone experienced at identifying different steels.

   Ultimately, if you choose to use spring I'm sure you will come across a bad piece every once in a while. But, if you can learn to work well with a poor or unknown material, it seems logical that you will do even better when you can afford the better material. Nevertheless, if you plan on making lots of high-end knives to sell I would recommend you know the material.

   Hope this helps,

   ~Josh S.

    

josh it helps alot! i too have a source for golf cart leaf springs and i have a few of them myself as to the bringing up of this topic thanks for your insight!