There are many persons in the SCA who, for one reason or another, would like to make their own working and eating knife. The first thing they need is a piece of high carbon steel. And since most people lack any form of forging facility or experience, the second requirement is that this piece of steel is as close to the shape of a knife as possible. An old, used flat file, about 3/16 of an inch thick and seven-eight inches overall meets this requirement well, besides being period: used files and horseshoe rasps have been used as sources for knives in rural areas since time immemorial. Such a file can be picked up from a flea market for a few cents.
The second thing you will need is some tools. One way or another you will need to bring this piece of steel to a red heat to anneal: files are very hard, and will eat up stones on bench grinders. Also, if dropped to the floor, they can easily shatter. Annealing brings the metal to it's softest state, and prevents a good deal of frustration when a dropped workpiece ends up in several pieces on your floor. A wood stove will answer the purpose, as will a charcoal bbq or even a fireplace. You should have access to a bench grinder, but you don't need one-you can do all the work by hand, although it is hard on the wrist. You will need a good flat mill bastard file, the bigger the better, and a round file. You will need some metal polishing paper in various grits, up to 400 or 600, a flat, smooth piece of hardwood or smooth metal at least ten inches long, and some kind of bench vise. You will also need some kind of fireproof container at least 6 inches deep: a metallic coffee tin will work fine, and enough light oil of some sort to fill the tin. Veggie oil works fine. And lastly, some sort of magnet on a long, flameproof handle.
Now first step-annealing the file. If you know a smith you're on friendly terms with, you might get him to do it. (I accept mead and home brew-or kisses from the ladies.) If this smith is away at sea, as often I am, you'll have to do the dirty work yourself. This is where that wood stove or fireplace comes in.
You have to have a good heat in there. Next, you should be doing this in a fairly dark area so you can see the colour of the metal. Take your coffee tin-with no oil in it, and fill it with old wood ashes. Next, take your file with some sort of tongs (vise grips work fine) and stick it in the hottest part of the fire. Every now and then, pull it out and check against a dark surface. When you start getting a visible heat glow, you're getting close. Don't worry about getting the file's tang hot, as this area is already soft... just heat the blade area.
As it gets hotter and brighter, this is where your magnet comes in. Touch it to the hot steel every 20 seconds or so. When it stops sticking, take it out and stick the file in the wood ashes, and leave alone overnight. Be patient.
When annealed, clamp it in a vise and try cutting it with a file. The file should bite readily. If not, try annealing again. The next step, called profiling, you will need a permanent marker for. Outline the shape of the finished knife you desire, either single or double edged, allowing about 4 inches for the tang, which will eventually be cemented into the grip. This tang should be at least half of the blade width where it starts, and taper to the end.
Now, this is where I recommend the bench grinder. If you don't have one, expect to get sore wrists. Before you do anything, fill your container you used for the ashes with water. And put on safety goggles!
Now, your bench grinder ought to have some kind of tool rest where the stone is. Adjust it so there is no more than about a quarter inch of space between it and the running stone. This will help keep your blade from being caught and trapped between the stone and the rest. If the tool rest is non-adjustable, just be careful.
Now, get your grinder running. Clamp the end of the file in the vise grips, and using the smooth piece of metal or hardwood as a push stick in the other hand, start removing excess metal. In the words of a knifemaker of my acquaintance from the deep south," Yer jist takin' off everthing thet don't look like no knife, and thar ya go." Every couple of seconds on the stone, dip it in the water to cool it. If you have gotten it hot enough to glow, DON'T DO THIS! Let it cool off slowly, and start grinding again. Also, never force the material you are grinding into the stone. Let it grind at it's own speed. If you hear the motor slowing down, you are pushing too hard.
Once the profiling is almost done, clamp the blade in the vise and finish up to your desired lines with the heavy file. Where your tang starts, there should be a radius cut using the round file, so there is a rounded transition line from tang to blade, instead of a sharp 90 degree angle. This avoids stress cracking in use.
Now, you will start forming the edges. Taking your heavy file (If you feel confident using the grinder, go ahead and use it) start forming the edge at a 45 degree angle. Use long strokes, and work carefully, going from the blade root to the point, and back. Every few strokes, clean your file with a file card, and change sides of the blade. Do this until your edge is about 1/32 inch wide. Do not sharpen it. I find long, diagonal strokes with the file are best.
Now, you'll have a piece of black steel in the shape of a knife, with a very narrow cutting edge. Stain the edge area with a bright, permanent marker, and reclamping it in your vise, start bringing your edge back towards the back of the blade. The area dyed by the marker will show you if you are removing too much metal too close to the edge, and prevent you accidentally sharpening the knife. When you have brought your edge to the middle of the blade, it should be okay. If you are making a double edged blade, at this point start on the other side.
Now, here you can either remove all the little file teeth on your knife, or leave them on. In any case, you are ready to start draw-filing. This is done with the knife clamped solidly in the vise, the blade point facing you and the edge or edges parallel to the floor, in other words so that you are looking down at the flat of the blade.
Using your mill file, in both hands, work lengthwise back and forth along the length of your knife, until a smooth finish is obtained on both sides. Do not push in with your body, to put more weight on a stroke, as you are facing a sharp point! If your file doesn't cut, with only moderate pressure, it's too dull. If a polished surface is desired, continue this process using 120, then 220, 320 and 400 grit paper, wrapped around a hard sanding block, or the smooth piece of metal or wood you were using for a push stick. Every time you change grit, work at an angle to your last strokes. This helps to remove scratches faster, and lets you see your progress more easily. Just remember: the last strokes should be lengthwise; and make sure the blade edge is not sharpened... in fact, run over it with a file a few strokes to make sure of this. Now, we are almost ready to harden and temper the blade.
First, beg or borrow a propane torch from a friend. (Or use your own, if you have one. -ed.) With the blade tang clamped in the vise, start heating the blade. You will see colours appear in the polished surface, first a yellow, than a deep straw, than brown, than purple, than blue, and finally a grey. When you have gotten the whole blade to a grey, working back and forth with the torch, leave it alone. This is known as normalizing. Even the slight amount of heating caused by grinding the steel, and stresses caused by filing, may cause warpage in the heat treatment, and this helps relieve these stresses.
Now, get your wood stove or bbq ready, with a good layer of hot coals, and have your magnet to hand. Get your metal container (Darned handy thing, whot?) and fill it with enough oil to cover the blade section. Have ready a flat piece of metal or wood big enough to cover the container. Warm the oil slightly, either in the oven or with a torch, to anywhere from 100 to 150 degrees F.
Once your blade is cool, unclamp it and bring it into your fire. Check it periodically for colour, then with the magnet, exactly as if you were annealing it. (Hint: if your fire is sluggish, a bellows or your vacuum cleaner blower attachment works wonders. Same for annealing). Once the blade is non-magnetic, quench it in the oil, point first. If the oil flames up, cover it with the lid, but if the red area is submerged, this should not be a problem.
This is the first part of the heat treatment, the hardening or quenching step. At this point, the steel is in a crystalline structure called martensite, it's hardest state. At this point, it is extremely brittle. Once it has cooled in the oil, clean it with a paper towel. If it has properly hardened, the black scale on the blade should have popped off, leaving it a nice grey colour. If you run a file tip over it here, the tip should just skate over it. Sand it lightly with some abrasive paper. At this point, heat up your kitchen or toaster oven to 375-400 and pop the blade in. Leave alone for an hour. At the end of this time, it should be a nice straw-brown colour, possibly a purple. If not, raise the temperature about 20 degrees, and check again every 15 minutes or so. Once done, turn off the oven, and cool off the blade in water or oil. This is the tempering step, also known as drawing the temper. Many persons mistakenly think of the hardening process as tempering. What this does is break down some of the brittle crystalline structure of the steel into a softer, tougher structure, allowing the knife to be used without breaking easily.
Next, protecting the blade with some scrap leather, clamp it point down in your vise. Have some water ready for cooling. Now, polish the ricasso, or part of the blade nearest the tang. Using the propane torch, heat the tang just above it until this area starts turning a blue, and then unclamp it and cool it off quickly. This makes sure the blade is fairly soft in the ricasso/tang junction, and this is important for two reasons: first, in use this area is under the most stress and is most liable to break, and softening it helps prevent this; and, secondly, when fitting a handle, guard or bolster, you may need to file this area to get a good fit, and this makes it far easier to do so.
Your blade is now ready for mounting. Do not sharpen it until you have put the handle on and finished it. I will save this for another article. If further polishing is desired, it may be done with 400-600 grit paper, and a buffing wheel on a bench grinder. If you are unfamiliar with using a bench grinder, I would not do it, as buffing is the most potentially dangerous step in knifemaking, bar none.
Happy knifemaking!