How to Make a Knife in a Forge

Make a small campfire, and place the metal file in it until it becomes orange to red hot. Let the fire burn out before retrieving the file. Heating metal then allowing it to cool slowly makes it softer and easier to form into a knife shape. The steel used in files is of good quality and will hold an edge nicely.

Shape the file using a grinding stone (bench grinder or angle grinder) to give it the outline you would like the knife to have. This should include the handle as well as the rough edge detailing. You can save the finish sharpening for later, after the steel has been hardened.

Place the knife-shaped file into a forge or fire, and allow it to become red to yellow hot.

Remove the hot knife from the fire with a pair of tongs, and submerse it tip first and as evenly as you can into a bucket containing some used or otherwise not needed motor oil. Allow the metal to cool in the oil before removing it. Cooling steel from high temperatures to cool very quickly hardens it.

Sharpen the edge of your knife using a fine-grit file, add the desired handle from wood or any other material.