machete

[gfish]

I've been meaning to starting learning bladesmithing for a very long time. It's one of the main reasons I built a forge in the first place. I figured a machete would be a good place to start -- no one is going to complain if a machete is ugly, after all. And while I'm rarely called upon to chop my way through jungles (woe), I just like the idea of having a machete that I made myself.




I started with one of the 9/16" suspension coil springs I found at Boeing Surplus. First I straightened out a nice long section, which itself took most of a forging session. Then I flattened about two feet of it, another 2 sessions and 3 blisters.



This is the blade blank I ended up with. It doesn't show in the picture, but the regularity definitely improved as I went along. The part I did first has some very deep hammer marks in the flat of the blade. Yay learning, I guess.



Then I clamped the blade down and started filing. Why did I do it by hand? Because I don't have a belt sander. And it's a good skill to have -- you can do surprisingly precise things with just a file, if you're patient enough. I spent about 4 hours working on it, and the time passed fairly quickly. With the flat of the blade rather uneven in places, I didn't bother dressing that up any. I really like the look, anyway.



This is what I ended up with. I'm very happy with the results. The definition where the tang starts is crisp, the bevel is regular and there is only a little bit of waver to the blade.

With the blade roughly finished, I went to harden it. Which means heating it up and then quenching it all at once in water. It went well, without any deformation of the blade. I tested it with a file -- after hardening, a file should slide along the surface, unable to get a bite. Instead, the file bit in exactly like it had been for the last 5,000 strokes. Uh oh. I took one of the scraps, heated it WAY up, and quenched it. No hardening. Feeling a bit desperate, I tried quenching it in oil. Still nothing. (And now we're out of vegetable oil.) Whatever those springs are made of, it isn't basic high carbon spring steel. Too bad I didn't notice that BEFORE all the filing.



So I put a basic handle on it and called it done, leaving me with an utterly useless machete-shaped object. (One that is, I must admit, really satisfying to swing around.) But I learned a lot, and I'm pretty confident the next one I make will be much, much better. For one thing, I went to Online Metals today and picked up 9 feet of W-1 drill rod. If I can't get THAT to harden I'll need to hang up my hammer for good. We're in Spokane for the holidays, and I brought the forge over so I can get some more practice in. I figure I might as well play with really sexy heat-treating techniques while I'm at it. Should be fun.

Comments

[catsittingstill.livejournal.com]

Um. Would it be worth trying case hardening? Surround it with ground-up charcoal and heat it in a kiln or something? It sounds like Vixy has access to a kiln...

[randomdreams.livejournal.com]

Instead of charcoal, use Casenit. It's much faster.

Some car springs are made from 1040 steel, which really doesn't harden very much. That might be the case?

I was also going to suggest spring fullers, but basal_surge already covered that.

[basal-surge.livejournal.com]

I ran into an interesting method of case hardening the other day (although I can't for the life of me remember the link). A bunch of viking age re-enactors pack the blade in fat, then wrap it in a tightly wound rawhide strip, leaving part of the tang protruding. This is then encased in a thin layer of clay or similar clag to avoid excess oxidation/burning of the fat/rawhide. Then chuck it in the forge and take it up to just below welding heat and hold it there for a while (they didn't specify the duration of 'while'). In the oxygen poor environment inside the clag, the fat and rawhide carbonize, and then you get sufficient invasion of the carbon into the outer millimetre or so of the iron to case harden it. Remove, strip the clag and carbon, anneal and then quench and temper. They were using it as an experimental method to replicate the case hardening seen on some viking and other iron age files and small tools.

[gfish.livejournal.com]

I thought about it, but case-hardening a blade doesn't do a lot of good. Even the best of techniques result in such a shallow carbon penetration that it would be gone after a couple of sharpenings. I'd try it if I was really desparate, but here I'd rather just take what I've learned and make another one.

[vixyish.livejournal.com]

I don't have access to a privately-owned kiln, no. I take stuff to a pottery supply store where you pay them to fire clay pieces in their electric kilns. I do not think they would do anything involving filling their kilns with charcoal. :)