Anyone with some time on their hands and access to a few basic shop tools can make a good-quality knife that will last a lifetime.
Gather your materials
- An old circular saw blade, ideally 3/16 inch thick - we will cut our knife from this
- A few small scrap pieces of brass rod
- Aged, dried hardwood
Tools you will need:
Tools that can save you a lot of work and aggravation:
Find some steel and mark it with the outline of a knife
The steel in a circular saw blade is hard and flexible enough to make a decent knife blade. Aside from the fact that it is carbon steel which will rust easily, it will make a very serviceable knife. However, turning an old circular saw blade into a knife blade presents a few problems. The steel is hard enough to dull or destroy normal metal-cutting tools and will quickly dull even high speed steel. Therefore, you can't simply saw out a knife blank using a hacksaw. Even a metal-cutting bandsaw would quickly become dull. Furthermore, any process such as grinding that creates excessive heat will destroy the temper of the steel, rendering the metal unsuitable for use as a knife blade without heat treatment, which we are trying to avoid.
To begin your homemade knife, draw the outline of a knife on the saw blade. A typical 8.25-inch diameter saw blade will only give you enough room for a short blade - perhaps three inches - when you take into account a minimum of five inches for the handle. If you can find a larger saw blade like the sort used in sawmills, you can make larger knives, but those blades are usually differentially tempered, and you probably can't use them without a means of heat treating steel. A carbide tipped contractor's portable circular saw blade is ideal, since the saw blade is not beveled or hollow ground. The carbide tips are generally brazed onto the saw blade and they can break off occasionally, so anyone who does construction will probably have a useless saw blade laying around. For your first knife, it's easiest to use a full-tang design. This means that the metal will extend the full length of the handle; in effect it is sandwiched by two pieces of handle material which are attached to the knife blank.
Cut out the knife blank
The best way for someone with limited tools to cut out a knife blank from a saw blade is to drill a series of holes through the saw blade following the outline of the knife blank. Drill the holes as close to the outline as possible, and as close to each other as is practical. This step will take a lot of time and effort, since we are drilling hardened steel. Lubricating the bit may help extend the life of the drill bit. Be prepared to either sharpen your drill bit several times if you know how, or to discard a handful of drill bits as they go dull. Clamp the saw blade while you drill it. When a drill bit begins to poke through the other side of the piece that it it cutting, it has a tendency to bind and fling the saw blade around like a weapon.
When you've completed a line of holes, clamp the blade in a vice, or use a c-clamp to attach it to something sturdy. Make sure that the section of steel that will end up as your knife is secured in the vice jaws or tightly clamped against something flat so that it can't bend. Then lay into the unwanted section of saw blade with your heaviest hammer. The closer your series of holes are drilled to each other, the easier it will be to break off the unwanted section. Beat it in one direction, then the other, alternating until you break off the unwanted piece.
Once you have completed this initial step, you'll have a knife blank with jagged serrated edges, like an oversized serrated edge of a tear-off postage stamp. The next step is to smooth these jagged edges and bring them to the same profile as the knife outline you initially drew on the saw blade. To cheapest way to do this is by using a file, and a lot of effort and perspiration. Clamp the blank and start removing metal using the file. This will take a lot of time, but the file will be hard enough to shape the knife blank. An easier way is to use a power grinder - either a bench grinder with an abrasive stone, an angle grinder, or a belt sander. The problem with power tools is that they will cause the steel to quickly heat up which can render it useless for our purposes. If you use power tools, grind slowly and carefully, never allowing the steel to get too hot to hold. It's imperative to wear eye protection when using power tools. A sliver of steel in your eye can blind you.
Shape the blade bevel
Once your knife blank has an acceptable profile, do your best to file the edges true. You can now begin to cut the blade bevel and give the knife its final shape. More than likely, your knife will end in a point where the top and bottom edges meet. At the end of the blade nearest the handle, it is useful to file a notch at the end of the section to be sharpened. You can do this with the edge of your file, or with a set of small needle files. This notch will provide an attractive transition between the thick, flat metal of the handle, and the sharpened metal of the blade. It will also give you some leeway when you file the blade bevel so that you don't mar the metal of the ricasso (the flat part between the blade and the handle) with a careless slip of the file. Tightly clamp the handle section of the blade blank to a flat scrap of wood, then clamp or screw the wood to some surface so that the blade sticks out in a convenient area for you to file the bevel. Begin to shape the blade with a file, removing a little metal, then flipping the blade over and removing an equal amount of metal from the other side.
For your first knife, it's easiest to give your knife a flat grind all the way from the top of the blade to the edge. Those with more experience can bevel the knife differently, depending on personal taste. The main advantage of a flat grind, other than the fact that it's easy to achieve, is that it makes it easy to give the knife a distal taper - gradually thinning the blade from the handle to the tip. Judicious use of a belt sander will make this blade shaping process go much quicker, but the usual caveats about not letting the steel heat up apply. Be especially careful near the tip, even when using a file, since the thin metal can heat up rapidly. If the metal changes color, you've almost certainly made it too hot and you'll need to file off the damaged area. There is always a temptation to make the blade wickedly sharp and pointy, but always keep in mind that the thinner the steel, the easier it will be to bend or break it. It is best to copy time-tested patterns rather than design a knife that will break at the tip or become nicked or dull.
Once your blade has its final shape and the cutting edge is very thin, you can smooth and polish it using wet/dry sandpaper. Another advantage of the flat grind is that it is easy to sand. Simply lay the sheet of sandpaper on a flat surface and rub the blade back and forth on it until the grind lines are gone. Graduate to finer grades of sandpaper until you get the finish you desire.
Attach the handle
With the blade nearly finished, it is time to attach the handle. You'll use two flat pieces of hardwood, such as some white oak from a discarded IKEA chair, or some ash cut from an old baseball bat. Use whatever you can get your hands on, as long as it's hard and stable (dry and straight grained). The most important thing is to make sure that the insides of these wood scales are perfectly flat and that when they sandwich the tang (the metal that extends the length of the handle) they lie flat with no gaps. You must take the time to plane, sand, or smooth the inside of these scales as carefully as possible before you attach them to the tang.
You can attach the scales with brass pins which will act like rivets to hold your handle together. If you can't find some thin brass rod (welding supply houses will sell it), you can easily fabricate some from a few brass hooks of the type that you'd hang keys on, or even make a pin from a brass machine screw or lag bolt. Simply use a hacksaw to cut any threads and other impedimenta away, and make sure that the rod you have is longer than your handle is wide. Using a drill bit that is the same diameter as your brass pin, carefully drill a few holes in the tang of your knife blank (either use a drill press, or be exceptionally careful to insure that you don't drill your holes crooked). Two or three pins are sufficient to hold the scales, but more can be used if desired. Once your holes are drilled, it is a good idea to lightly countersink the holes, either on the drill press or by using a round needle file. This will enable the glue to adhere to the most important parts of your knife handle and it will make it easier for the brass rod to mold itself to the hole in the tang and lock in an immovable position when the rod is peened.
Clamp one scale against the tang, making sure that the scale overhangs the tang on all edges. Using the holes you just drilled through the tang as guides, drill through the wood scale. Drill all the necessary holes in the scale without moving it. Then, clamp the other scale onto the tang and drill its holes the same way. Test fit the entire assembly together, making sure all the holes line up and the pins fit snugly through the handle. The brass pins should be longer than the width of the handle since you need extra material in order to form the rivet heads.
You can roughly carve the scales into their final shapes, making sure to leave extra wood to overhang the tang. The final carving and sanding will be done after you have attached the scales to the knife. While the handle is attached to the tang, you will be able to shape and sand every part of it except the very front, where the handle meets the ricasso. Sanding this part of the handle while it it attached to the knife will scratch the metal. Therefore, you need to finish this part of the handle before you attach the scales. Press and pin the scales together while you sand the front of the scales to bring them to their final shape.
To permanently attach the handle, your first step is to form a rivet head on one end of your brass pins. Lightly clamp a pin between two pieces of scrap wood or between two copper pennies, then peen the head over so that it is approximately 50% larger in diameter than the rod. Mix up some epoxy and liberally coat the tang and the inside of the scales. Put the scales in place on the tang and slide the brass pins all the way through the handle until the peened head stops it from sliding any further. Lightly clamp the scales to press them against the tang. Don't clamp so hard that you deform the scales, they should be flat enough to fit tightly against the tang without much pressure.
With a hacksaw, trim the unpeened end of the brass pin as close to the handle as possible without marring the wood. Press the peened end of the pin against a hard piece of metal that is covered with a thin piece of leather or cardboard or some other material that has some 'give' to it. Use the peening hammer to form a rivet head on the other end of the brass pin. The leather will insure that the rivet head sticks out a bit, which will help to avoid splitting the wood of the handle. In effect, you are squeezing the brass together, pressing it against the wood scales. The brass will expand to fill the hole in the scales and it will lock itself into the hole in the tang. Turn the knife over a few times, peening the rivet on each end until you are confident that it will hold the handle securely. Don't accidentally slip and hammer the knife handle. If there is too much brass sticking out, file some of it away until you can shape it properly with the ball-peen hammer. At this point, the brass rivet will be a lump that sticks out of each side of the handle. It will be sanded flush with the wood of the handle later, during the final finishing process.
Finish the handle
After setting the knife aside while the epoxy cures, you are ready to finish the handle. Sand the scales flush with the metal of the tang. You should end up with a perfectly smooth transition from wood to metal and back to wood. Once your wood scales are sanded even with the metal, you can use finer grades of sandpaper until you get the finish you desire. Needless to say, power tools speed up this process considerably, and since you're not working near the blade's edge, you can work a bit more quickly without risking damage to the metal. At the same time, you will need to file the lumpy heads of the brass rivets until they are flush with the wood of the handle. The sandpaper will easily smooth them out and give them a bright gold color which will darken over time. It's at this point that you'll see how well you were able to form your rivets. The more evenly you peened them, the closer to round they will be after being sanded flush with the wood.
Sharpen the knife
Now comes the moment of truth. Sharpen your knife by whatever method you prefer. Very fine wet/dry sandpaper will work, or you can use a hone if you have one. If you have cut a good bevel on your blade, and you haven't damaged the steel by allowing it to get too hot, a knife made from a circular saw blade will be as good as any mass-produced knife that you'll find for sale in a store!