File Knives

I've always loved knives. There is something primally satisfying about holding a knife in your hand. It's a feeling likely rooted in the early parts of our brain that developed for survival long ago, when holding a knife in your hand could mean the difference between eating and being eaten. Therefore it only makes sense that having the ability to make your own knife would be even more satisfying.

I embarked on my quest for a homemade knife last summer. I had seen knives made out of files online and thought they were pretty dope looking. Plus the idea of sourcing a readily available resource for the blank felt pretty survivalist. So I went out and bought a Nicholson Blackhawk handy file, bastard file, and a mini bastard file.

I annealed the files in my mini bbq by burying them under the coals and putting a hair dryer to the coals to stoke them. I got it to where it was barely starting to glow red and then I buried it in vermiculite to insulate it and slow the cooling. I realize now eyeballing the temperature is risky business but at the time I was doing the best I could. After all it worked and made the steal softer and easier to work with, which is the goal of this step.

I cut the files to size and shape with my Dremel. The blades that came with it burned out or shattered pretty quickly. I went through all twelve of them on one file before buying some reinforced blades. Once I had the general shape down it was time to grind them to shape. I didn't have access to a good grinder so I ended up dangerously half assing it with a handheld belt sander turned upside down. This means I had to hold the trigger with one hand while holding the file with the other... this resulted in a loss of precision. But I wasn't expecting much for my first knife anyway.

I drew where I wanted my bevel to end with a sharpie. With 40 grit sand paper the metal grinds away pretty fast, but the sand paper wore away pretty quickly also. I think this is because I just used whatever type of 3M paper they had at the hardware store. I don't think it specified what materials it was for but I'm fairly certain it was for wood. Using belts made for this kind of work would probably make a difference.

Once I had the knives in the shape I wanted, I tried to harden them with my home made forge. There is alot to read about hardening steal and it is very complex. But basically my goal for these files was to heat it to around 1475 F and then quench it in vegetable oil. I simply couldn't get the files hot enough in my BBQ so I ended up building this forge.

Sadly it's design is blatantly flawed and it doesn't fit the file properly, so I stuck it in at and angle for about a minute and this happened.

I ended up making it into a shorter knife, no big deal. You need to make mistakes to learn after all.
So after reading a bit about DIY forges I built this bad boy. Filled with perlite around the air pipe and packed and lined with furnace cement.

Basically without a well controlled heat source and a sensitive way to measure that heat, you can't really harden a steal that accurately. Each type of steel hardens at a different temperature, and getting that temperature wrong means underhardening the blade -which makes it softer so it won't hold an edge- or overhardening the blade -which makes it brittle and prone to cracking-. Basically I tried to use the Curie point (1414 F - the temperature at which steel loses it's magnetivity) to estimate the temperature I quenched at. I tested my blade regularly with a magnet as it was heating and once the magnet stopped sticking, I held it in the forge for about 10 more seconds before quenching it in oil. This is a highly unreliable method. It turns out that without a pyrometer the best way to accurately judge when a steel is ready to quench to attain maximum hardness is to visually assess the surface of the steel for decalescense. This is a phenomenon that occurs with all steels at their relative critical temperatures for hardening. It's seen as a shadow of black that moves in from the edges of orange glowing steel before disappearing as the steel reaches the temperature. This is caused by an endothermic change in the arrangement of the molecules in the steel. More can be found on this topic elsewhere online.

After I quenched them I immediately tempered them at 400 degrees twice for on hour, cooling in between. This reduces the hardness a little, making the knives tougher and reducing any stress built up in the knife during hardening.

As you can see I tried to fit a handguard on there too. Would have looked real nice but I messed with it too much and screwed it up beyond repair.

I also bought some Holstex and tried my hand at making sheaths. They're pretty sloppy, but not terrible!