Cookware & Cutlery

How to Make a Knife Blade from Scratch

How to Make a Knife Blade from Scratch

Knives are the most basic of human tools. The first knives were made by chipping away pieces of stone until the end result was a sharpened blade. Modern ones are made with steel.

There are different methods of custom making a knife. Hand forging the steel is labor intensive and requires knowledge of how to fold and shape the metal. On the other hand you could order a pre-cut blank and add an edge and custom handle. Making a blade from scrap metal is somewhere between the two on difficulty.

Things you will need:

* Metal for blade

* Handle

* Transfer Solution

* Quenching fluid

* Heat source

* Files; Course, Medium, and Fine

* Tracing Paper, 2 sheets

* Pen compatible with Transfer solution. (the only way to be sure is to test it first)

Transfer solution:

2 tablespoons soap scrapings

1/4th cup water

1 Tablespoon turpentine

      1. Dissolve the soap in the water

      2. Mix the turpentine into soap water

Start by planning the blade. While it would be easy to jump right in and start cutting and filing the blade the end result would be unusable. Instead take some time to determine what the blade you are making is going to be used for. How long do you want it to be? How will the handle be attached, what tools and materials will you need? How will you heat or quench the blade? Having these answers enables you to begin the process of making your own blade.

Once you know what you want from the blade it’s time to start designing it. Use tracing paper since it will allow you to draw the blade and handle separately but still allow you to see how the end product will fit together. If you already have the handle copy it onto the paper and mark where the pin holes are. Having the handle already made will determine what type of tang you will be making on the blade. (The tang is the metal tab at the end of the blade that attaches it to the handle.) Carefully draw the blade using a light pencil. Make sure the lines are smooth and easy to follow.

Using the ink go back over the lines of the blade. Follow each line exactly. When it is finished it should be bold and clear lines. With little or no graphite showing.

Transfer the ink to the steel. Brush on the transfer solution. Press down lightly and smoothly. Starting at the top of the pattern press down evenly. Hold ten seconds and pull off the paper. You should be left with an exact copy of the original pattern on the surface of the steel.

Cut the pattern out using a jigsaw. Keep the blade well lubricated to avoid sparks and damaging the saw blade.

Once the pattern is cut out. It will be time to file the blade. Begin with a coarse file to remove the edge at a 30 degree angle. Go the entire length of the blade keeping the file and blade as steady as possible. The metal to be removed is proportional to the length of the blade. The formula is l(√t). Where l is the length and t is the thickness of the blade. once it is close to the right thickness and angle switch to the medium file and get it as close as possible to uniform smoothness. Use the fine file to perfect the smoothness of the blade and to get it to the desired sharpness.

Before quenching the blade also make sure that you have removed any metal burrs from the outer edges of the blade. smooth all of the blade as smoothly as you can.

When the blade is ready and you are certain there are no more improvements that can be made to it it is ready to be quenched. Heat the blade up to the critical temperature. There are several ways to tell when it is hot enough. The color will be a straw white, the metal will no longer be magnetic, and the temperature will read 1800 degrees Fahrenheit. Remove the blade from the heat. Ideally the temperature before it goes into the quench will be just above 1333. anything lower and it won’t harden. The higher above that the temperature is the more it will shock the metal which will make it more likely to crack. Any temperature between 1800 and 1333 will work for the quenching.

If you used a high carbon steel you will want to use oil to quench it. Either motor oil or olive oil will work in a pinch. For a medium carbon steel use a brine which is just a fancy way of saying salt water solution. To make a brine combine one cup of salt for each gallon of water. For maximum safety quench your blade in a metal bucket either outside or on a concrete floor.

Once the blade is hardened it is time to attach it to the handle. Using pins and glue secure the handle over the tang.

You now have a blade you can be proud of. Hopefully this is just the first of many projects to come.