FMAT: Knife making

[Clark Kent]

Knife making
By TaskForce3Tango - 08-15-2012 01:09 PM
Originally Posted at: FMATalk
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Okay so I've searched to see if this has been discussed before.

So how many of you make your own knives?
What kind of tools do you use? In my younger days I was a machinist. I can think of many ways to create a precision blade. However I want to dumb it down as much as possible. Do it old skool if you will. Tools I think of are grinders, files, saw, drill, stones, and blacksmithing items, anvil, hammers, fire pit, and forging.

What kind of metal do you work with?

However with todays modern tool steels do you even need to got through the tempering process? I dont see why it would hurt, but it just seems like it would almost be a waste of time.

Any input?


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[David43515]

I used to work for a proffesional custom knife shop. We generally used tool sttels in bar stock and did all our shaping with grinders. We genearlly used A-2, D-2, ATS-34, and O-1. We had some 5160 around to try out new designs because it was cheaper. Personally I prefered working with air hardening steels, Oil hardening is messy and smelly. And if the blade slightly twists or bends in the cooling process,I can tweak a dry blade while it's still warm much easier than one covered in oil. But even with modern steels you deffinately need to temper them.

Hardening the steel changes the austenite (unhardened steel crystal structures) into martzenite (hardened ones) so the steel is hard, but often very brittle. Hardening is done at very high temps (differnt temps and times are required for different steels) and cool very quickly. Tempering si done at lower temps and cools slower. this reduces some of the hardness, but also gets rid of the brittleness. That's important in a knife partly for heavy chopping, but mostly for edge retention. Often when a blade goes dull it's not worn down smoothly it's actually microscopic chipping on the edge that is making it's surface wider.

It's been 8 years since I've done any knife making, but the basic principles are still the same. That being said, if you don't know the type of steel or the temps you're working at you can still turn out good knives out of old files and lawn mower blades using a file and a few blowtorches. It's just a lot harder to do it consistantly. There are plenty of guys on youtube showing how to make bench top forges out of a blowtorch and some firebrick. And they make nice knives.