Q&A for How to Make a Knife

Start by sketching the design that you want on paper and tracing your knife for accuracy. Let the knife’s shape guide the design—curvy blades work well with flowing styles, while straight blades suit structured designs. Leather is a natural material, so look out for scars or weak spots and use the strongest areas. Fold the leather around the knife like a taco to form the basic shape, and decide if you want the handle fully covered or partially exposed. Add a snap or strap to secure the blade, especially for upside-down carry. Consider including a welt, an extra leather layer that protects the stitching from the blade, though it’s optional. Stitch the sheath by hand with strong thread or use a machine capable of handling leather. Finally, dye or condition the leather for a durable, polished finish.

For making a bevel and finishing the shape of the knife, yes. I wouldn't recommend using a belt grinder for making the rough outline of the knife.

Lawn mower blades or the string shocks of trucks will work. Really any metal with a high amount of carbon will do.

Heat treating a blade is the process of heating up the metal and then plunging the hot metal into a liquid. Peanut oil is a great choice.

Spring steel is great for knives, as it produces a long lasting sharp edge due to its higher carbon content. it must be heat treated for optimal results, though.

If the metal is tempered it will hold whatever kind of edge you can put on it. In my experience, most knives are easy to sharpen with a knife steel.

The process of forging hardens the blade with a "quench", which involves heating the blade in the forge and plunging it in oil or water. So, yes, you need to harden the blade.

You could theoretically use one, but I wouldn't suggest it.

No, brass is soft and will bend. Use a high carbon steel for better edge retention. You can use brass rods that are 2 - 6 mm thick instead of rivets, though.

Yes, but almost all oils contains carbon and the hot steal will pull more carbon into the steel. So more carbon better usable and stonger knife edge.

They would be awesome. In fact, as long as you are a careful not to overheat them when grinding them, the heat treat they already have should be sufficient. (You know you've gotten it too hot if it goes blue when grinding, this usually happens at the tip. Go slow and cool it with water periodically).

You can get a mirror finish by sanding down to a 1000 grit, and then use a buffing wheel.