How to Make a Ninja Knife

Make a ninja knife out of plate steel

A ninja's knife is also known as a kunai knife or gouger. It is the traditional Japanese weapon used by ninjas throughout history. Original ninja kunai knives were shaped like a large leave and used to dig or gouge holes in castle walls to gain entrance, climb or scale walls and as a weapon when fighting enemies. They were not used for throwing like what is portrayed in modern day ninja movies. Modern ninja knives have taken on the appearance of a large arrowhead.

Things You'll Need

• Pencil
• Paper
• Scissors
• 1/8-inch plate steel
• Plumber's soapstone or chalk
• Safety goggles
• Plasma torch
• Bench vise
• Round diamond file
• Flat diamond file
• Whetstone
• Lubricant oil
• Soft cloth

Instructions

1. Draw the design of the ninja knife on a piece of paper. Shape the blade like an arrow head or the shape of a diamond with one end shorter than the other. Draw the handle as long as the blade. Place a circle with a hole in the center at the end of the handle. Draw the diameter of the doughnut shape a minimum of 1/4 inch. Cut out the paper ninja knife.

2. Lay the pattern on the plate steel. Trace around the outside edge of the paper knife with plumber's soapstone or chalk.

3. Light the plasma cutter. Cut the knife shape from the plate steel. Cut on the outer edge of the marked line to keep the integrity of the knife. Reposition the plate steel as necessary.

4. Secure the blade in the bench vise. Use the plasma torch and burn a hole through the circle on the end of the knife handle. Let the knife cool.

5. Secure the blade of the ninja knife in a bench vise on a horizontal plane. Use the flat and round file to shape the handle and the ring at the end of the handle. Reposition the knife as necessary.

6. Place the handle of the ninja knife in the bench vise and secure on a horizontal plane. Use a file and bevel the blade from the center to the outside edge at a 30 degree angle. Turn the knife to do the opposite edge. Flip the knife around in the bench vise and do the same bevel on the opposite side.

7. Use the flat file and bevel a second edge on the blade at a 40 to 45 degree angle. Begin the bevel 1/4-inch from the edge. Repeat the bevel for the other blade edges.

8. Remove the knife from the bench vise. Use a whetstone and lubricant oil to fine tune the beveled knife blade edges.

9. Wipe the ninja knife down with oil to help prevent rust.

Tips & Warnings

• Add another dimension to the ninja knife and wrap the handle with sea grass.

References

• Secrets of Shuriken: History
• Medieval2: Traditional Weapons of Japan