This is a detailed step by step overview of how I make a knife, in this case a field knife bowie style.
I began with the steel, a farrier’s rasp that had over time become too dull for use, which I picked up for free from a farrier. Files and rasps are generally high carbon steel, which means I can heat treat it to make a very good knife that will not break or dull easily. I broke the rasp in two, and used the bottom half which already had a tang. I began forging (forming it with the hammer and anvil), thinning and lengthening out, by beating on the rasp, edge up on the anvil. I heated it up in my forge (which I built ago with a torch, a paint can, insulator and clay) until it was orange hot, then forged until it was nearly black, at which point I would put back in the forge and repeat.
I would hammer for a while on the edge, then put the steel flat on the anvil, face up, to flatten it and keep from folding over. As I went along, I would heat up the steel until the whole thing was orange hot, then place one edge on the anvil and wait for a few seconds before forging. Steel acts as an excellent heat sink, and so the anvil sucked the heat out from the edge touching it, while the opposite edge remained almost unchanged. Once the edge touching the anvil was nearly black, I would then begin forging. Because the opposite edge was cold, it moved very little, while the hot edge would be pounded in and thickened. I’ll explain why I did this soon.
After a few heats (forging sessions) the blade was well lengthened out. Now what I needed to do, was forge the blade on its side so it would be evenly thick across the blade (my goal was a little more than a fourth of an inch thick). When I forged on the thicker area of the blade along one edge, the steel pushed out under the hammer blows, curving the blade forward.
At this point I let the blade cool, then used a miter saw with a metal cutting blade to cut a slight slant, which you can see on the left side of the photo above. Now the reason I made the blade curved as shown, was to avoid a problem I normally reach at this point. When I normally forge the bevels (the bevel is the slant from the back of the knife into the cutting edge), I’m flattening the steel at an angle into a wedge shape. The steel being pushed away from the hammer has to go somewhere, so it expands sideways, which pushes the blade into a curve backwards, too much of a curve. However if I curve it forward first, which I did here, then when I forge in the bevels both the curves cancel out, and the blade straightens out. So what looks like the opposite of the cutting edge in the photo above, actually becomes the cutting edge.
So now I begin forging in the bevels, starting at the tip, working towards the tang, and back up to the tip.
During all this time, I had been working with a 2.5 pound cross peen hammer, to get the heavy work done. At this point I switch to a lighter 1.5 pound ball peen hammer, to even everything out and do the detail work. I have to be very careful not to make any deep hammer marks, as they will be next to impossible to grind out later on. Once the bevel is about the thickness of two quarters, I begin to forge in the ricasso. The ricasso is the section of steel between where the cutting edge stops and the guard or handle begins. I don’t bother forging in too far, as it is quite easy to grind in later.
Then I forged in a decorative feature, similar to a gut-hook, just, well, without the gut-hook. I forged it in carefully and slowly, putting the blade at a 20 degree angle on the corner of the anvil, and striking with the hammer at a 20 degree angle to the blade. This pinched the back of the blade out just a little bit, which I will later refine on the grinder.
At this point forging was done. I straightened out the blade using light taps, then normalized the blade thrice. As a blade is heated, cooled, and forged, stresses form inside the steel. Heating the whole blade to the point at which it no longer sticks to a magnet (a reddish orange or so), and then letting air cool, takes out these stresses and makes the blade much less brittle. I then marked out on the blade where to grind using a sharpie. Most smiths use a sort of chalk, but I find sharpie ink works just fine.