Saturday, July 6, 2013

Brush knife

The GF and I have recently been doing some off-trail hiking. Though we've found we can get up or down slopes of 70deg and more, we get seriously fouled and stopped by thorny plans. Now, it's not my goal to ever be hacking things down in the forest, but it's just as stupid to get lost/hurt/dead because you've lead yourself into a head-high thicket of 0.5-1" thorns you just can't seem to escape. So I figured it was time to own a real knife.

In terms of requirements, I wanted it to be thick and durable enough to also double as an ice pick for climbing steep snow. I also wanted it to be stainless steel since I don't take good care of things. I wanted a hand guard, since I seem to always get thorns in my knuckles the other times I've used even a 2' machete. Finally, I want it to be small enough that I can draw it easily. (If you've ever owned a 2'+ sword and tried to draw one of those things from a back scabbard or tried to hike with one on a hip scabbard you'll see what I mean.)

Building the knife itself was pretty straightforward. I took a 1" x 3/8" flat 316 steel stock and cut it to have a 13" blade with enough room for a handle. I then took it to the bench grinder for maybe an hour to get a blade onto it. When I put my hand onto the handle and marked where my hand would be. Unlike a regular knife or sword, this one is only for me and thus it can fit my hand *perfectly*. I welded little chunks of stainless steel supporting my hand from below, above and on specifically for my thumb to hold onto. I then finished the blade with a metal file till it was sharp-ish. I'll eventually fire and quench it, but I'll have to find someone with a furnace first.

Building the scabbard was more challenging. In the end, I went with a series of 3D-printed sections all bolted onto a steel band I'd cut holes into. I'll eventually replace the bolts with rivets when my friend returns my rivet gun.

3D printing for me is still more of process than a push-button affair. At this point, makerbot stopped selling the 3mm wire mine uses so I'm buying shittier 3rd party stuff now. The machine itself also needs to be manually warmed in the control panel before printing. But it still does the job. In this case I made the sections 40mm tall with two mounting holes. Each section has knobs on the inside that hold the blade on either side and don't let the edge touch the scabbard.

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