How to Make a Knife Blade From a File

by Jane Smith; Updated September 26, 2017
Make a Knife Blade From a File

Over time, files become worn, with broken or dull teeth and cracked tips. Tools with a history, such as the ones that you may have been given by a parent or grandparent, can be difficult to throw away. You could enshrine your grandfather's old files in a velvet-lined edge-lit, welded steel shadow box, or you could give the file new life by making it into a custom knife blade. This is a good project for a beginning metalworker with some metal shop experience. It is not a project for someone with no metalworking knowledge or shop experience at all, however. This project is completed using grinding and some minimal stock removal and does not require any forging, welding or soldering. Once you have made several of these knives, you will have learned many of the techniques needed to complete other more complex knife projects.

Items you will need

  • Old, worn out file
  • Bench grinder, grinding wheel
  • Wire wheel
  • 80- and 120-grit abrasives
  • Coffee can full of water
  • Electrical tape
  • Rubber cement
  • 3 yards parachute cord
  • Kitchen stove
  • Black marker
  • Right angle grinder
  • Abrasive saw
  • Two 3-inch long pieces of yardstick or other thin wood
Step 1

Place the file in your kitchen oven at 550 degrees Fahrenheit for one hour for tempering. Allow it to cool to room temperature. Repeat the heating and cooling process three times.

Step 2

Grind the teeth from all sides of the file using a coarse grinding wheel. Give the file a semi-smooth finish, using 80-grit abrasive, so that you will be able to lay out your knife blade profile without shredding your marker tip.

Step 3

Choose a blade shape. You will be able to use most blade shapes except for the ulu, which is too wide for the file. Lay out your desired blade profile for a full-tang, parachute cord-wrapped, handled knife. See the Resources section for advice on choosing a knife blade shape.

Step 4

Use an abrasive saw to rough cut your knife profile, which is the basic shape of the blade. Rough grind the knife profile to shape, then remove burrs with your grinding wheel and your choice of bench or angle grinder. Be sure to keep the steel cool while grinding using water. Do not allow the steel to change color during the grinding process.

Step 5

Grind the bevels of your blade to an included angle between both sides of the knife blade of 22 to 25 degrees. Finish the knife with 80- and 120-grit abrasive. Give your knife a satin finish with a wire wheel.

Step 6

Cut yardstick pieces to handle length, leaving 1/2 inch of uncovered knife tang at the butt end of your knife, 1/8 inch narrower than the knife tang. The tang is the part of the blade that extends into the handle of the knife. It is the surface to which the handle attaches to the blade. Sand or grind the edges of the wood pieces until they fit your hand comfortably. Apply rubber cement to the flat sides of the wood pieces and to your knife handle area. Allow rubber cement to dry until tacky, then press wood pieces to each side of the knife handle. Wipe away excess rubber cement. Allow to dry. Wrap handle with electrical tape until all wood is covered, but 1/2 inch of exposed tang is still visible at the butt end of the knife. Coat the taped area with rubber cement and wrap with parachute cord.

Tips

  • Please refer to the article, "Poof, You're a Sword Smith," at anvilfire.com and to the metalworking lessons available at IForgeIron.com if you do not have any previous metal shop experience (see Resources).

Warnings

  • Use wrap-around eye protection and ear protection, as well as heavy leather work gloves when completing this project.

Photo Credits

  • http://www.the-knife-connection.com/knife-blade-types.html, http://www.sharpeningsupplies.com/knife_parts.aspx