How to Make a Metal Knife or Machete from Start to Finish

Last Updated on February 2021

Introduction

Have you ever thought of making your knife from scratch? Well, you can do it.

Making your own knife makes it easy for you to customize it according to your own needs and preferences. This is one of the ancient arts that you can craft with some skills and knowledge.

Metal knives can be crafted from start to finish using different types of metals for the blade and rubber, wood, and any other material that offers a comfortable grip for the handle.

It would be best to take enough time in your woodwork (when using wood for the handle) and metalwork designing for an excellent outcome. The process takes time, and sometimes it may be frustrating, which calls for keenness, attention, patience, and calmness.

Even so, do not be frustrated if your project does not come out as expected. Keep practicing, and with time you will make a metal knife from scratch to finish that you will ‘wow’ about.

What is the Ideal Metal for Making a Knife?

You can use different types of metals to make your knife, but what you intend to use the knife for will determine the metal that you will use to make the blade. For knives such as machetes that need to withstand great cutting forces, you need to use a sturdy metal that won’t break easily. For knives used for simple cutting, you need a strong metal that can endure the impact, although not as sturdy.

Carbon content determines the sturdiness, toughness, and solidity of your knife. Metals with high carbon content are tougher, more robust, and easy to re-sharpen. However, excess carbon can lead to the knife becoming brittle and prone to corrosion and rust. In that case, the knife may not withstand any impact and risks breaking.

Your ideal knife should have the right carbon content suitable for effectively performing the intended purpose without rupturing.

Tool Steels

Tool steels are a common choice in knife making due to their ability to withstand wear and impact. These are carbon steels with additional alloy properties that improve their mechanical strength and properties. The alloy properties enhance the steel’s resistance to rust and corrosion.

A common tool steel grade used in making knives is A2. Although it may not be as hard as other materials in this class, it is tough and sturdy. However, it may be prone to rust if used in an environment with high humidity.

On the other hand, D2 tool steel has better resistant to rust and rupture than A2, but not as tough. The best option in the tool steel category is the M2, which remains sharp for a longer period and retains the knife edge.

Carbon Steel

The carbon steel grades have a higher carbon percentage and are suitable for knife making because of the hardness, toughness, and strength they give a knife, making it resist impact and wear. However, you need to ensure standard heat treating on the carbon steel for excellent results.

Using a rapid quencher may cause the knife to be brittle or break, while annealing may cause it to be soft and get dull easily.

Carbon steel knives may also be exposed to rusting if not well taken care of. This is because carbon does not have enough alloy elements to make it rust-resistant completely. In that case, you need to ensure maximum care for your knife to remain in good condition.

Some of the standard carbon steel grade fit for knife making include C1045, C1090, and C1075.

Stainless Steel

Another excellent metal ideal for making knives is stainless steel. The advantage of using stainless steel metal in making your ideal knife is the addition of chromium and extra alloy elements that make it more corrosion-resistant compared to the other two metal types. Most steel knives are constructed from martensitic, while others are crafted from ferritic stainless steel. When you use any of these stainless steel grade metals with high carbon content, you will be able to attain the highest sturdiness, hardness, and toughness.

Common grades include 440 and 420.

Sourcing for the most suitable metal for making your knife is not as hard as it was years back. This is because there are many cheaper available ways to acquire raw materials for knife construction.  These are some of the places you can source scrap metals for knife making: For more information on where to find free scrap metal [Read our Full Guide]

  • From your immediate neighbors
  • Business area
  • Construction sites
  • Dumpsites
  • Source online

Step 1: Sketch the Blade

Sketching your knife’s design is the most crucial aspect of the knife making process. Given that you will be making your customized knife, you may have to spend lots of time to complete the process. So it would be best if you figured your expected outcome and put it down on paper.

The first thing you need to figure out is the shape of the blade and the handles and design it on paper. This minimizes the number of times you may have to make corrections on your knife once you start making it.

Next, decide on the handle’s material and the process you intend to use to attach it to the blade. The most common methods of attaching the handle are through-tang, partial, and full-tang.

For full tang, the blade’s length extends up to the end of the knife’s handle. Although the width may not be the same, the length is always the same. Most knives feature this design, which is also easy for beginners to make.

A partial tang is not so common and is the hardest to make among the three types. In this design, the blade does not extend to the end of the handle. Instead, part of the blade protrudes but remains hidden in the handle. However, they are less sturdy and durable compared to full tang knives. Some of the knives made using this method are the Sushi and Japanese sword.

On the other hand, a through-tang knife looks like a partial-tang, but the blade extends through the handle and is held on the other end with a rivet or nut. Common knives made using this method are the turned-handle and ka-bars knives bar.

With this knowledge, you can decide which type to go for, but a full-tang tends to be easier to make for beginners. Once you choose your ideal design, sketch it down on a scale of 1: 1 and cut it out. Trace it on the metal and cut it out.

Step 2: Design the Blade

Once you have your design, now choose the material. For beginners, we recommend using carbon steel such as C1045 because it makes a sharp blade and easy to make corrections. Stainless steel metal is also good but not ideal for beginners because it requires maximum care. It should not be tampered with, which makes it only suitable for professionals.

Additionally, you will need to have a slab of about ¼ inch. You will also need the handle material, such as wood, rubber, metal, bone, stone, meteorite, and any other material that can offer a comfortable grip. In this case, we will use wood.

You will also need to have nuts or rivets for attaching the blade to the handle.

Some of the items that you will need at this step include

  • 01 Carbon Steel sheet
  • Sketched design
  • A pair of the chosen handles material
  • Brass block (for bolster)
  • Brass bar (for peening)
  • Corby Rivets or nuts
  • File
  • Drill
  • Drill bit for brass bar
  • Drill bits for Rivets
  • Rasp
  • Epoxy
  • Hacksaw
  • Kitchen steel
  • Sharpening stone

Step 3 Shaping the Blade’s Outline

Now you have the steel, take the sketched design on the paper and cut it out. Place it on the steel and trace the design using a permanent marker, a sharp tool, or engineers blue. With the hacksaw, carefully cut the outline, but leave approximately 5mm of the steel around the outline for waste.

Leaving lesser material around the outline ensures that the material you will eliminate using the file is less, saving you time and energy. You also need to be careful when filing not to exceed the outline. Progressively, file the steel until you reach the outline you made on all sides. You will spend some time here, but be more careful when getting closer to the outline.

Step 4 Add the Bevel

The bevel is the section on the blade that slopes and thins towards the edges. Draw a line in the middle of the blade, from the tip towards the handle side, where you would want the blade’s edge. Hold the edge tightly on a table, and with the file, slowly start grinding the edge to make the chamfer contour. Some people prefer using a belt slander at this stage instead of a file, which works perfectly but takes some time.

While you are filing towards the outline, ensure you try to maintain an even angle between the steel and the file.  Continue filing on the same angle from the tip towards the blade’s end (do not file where the handle will attach).

Ensure that you do not get past the line of the edge to avoid your blade having a dip. You can always remove more material from the blade to get another shape, but you cannot correct a dip and remain with the initial profile. So your time and be careful.

Once you are done with one side, turn the blade and repeat the process on the other side. When using your hands, this process takes some time compared to when using a metal bench grinder.

Step 5: Finishing the Blade (First Time) and Drilling Holes for the Handle

After adding the bevel, the next step is to finish the blade’s design and make holes for attaching the handle. Before heat-treating, you need to drill the holes for attaching the handle. The size of the holes on the bolster should be the same as those on the brass bar. For instance, if the holes on the bolster are 4mm, the holes on the brass bar should also be 4mm.

Now choose where you want to drill the holes, and start drilling. The holes for the Corby rivets’ size should be the same as the rivets’ thin central part.  Measure the circumference of the rivet using a pair of welding tool calipers.

You will also have to finish working on the blade before heat-treating. You will need sandpaper with coarse to finer grits (example 60-220), sanding block, and enough time.

With the sandpaper, carefully sand out all the stains and scratches made by the file and create a finer finish-don’t omit this stage. This step requires a lot of time, so you need to be patient to get the work done efficiently.

Start sanding with the roughest grade you have in the same direction. After you have eliminated all the stains and scratches, move to a finer grade. Keep repeating the process until all the scratches and stains are removed and move to the next grade. Repeat the process up to the finest grade of sandpaper you have. At this point, you should have a fine flat blade.

Ensure you sand the whole blade, from the tip to the end of the handle. It is vital for the area where the blade meets the brass to be smooth and flat. Moreover, it is better to sand the parts that will be hidden than leave out those that will be visible. This will ensure you acquire the finest results.

Step 6 Heat-Treating

The heat treating process is the most critical stage in the knife making process. It entails heating the blade at a specific temperature using a gas forge, coal forge, or any other source of heat.

The process involves two essential steps- hardening and tempering. Hardening the blade entails heating it to a specific temperature and quenching it. This makes the blade hard but brittle at the same time. You should be careful when handling the knife at this stage not to drop it. When dropped, it can break instantly.

After hardening, the next step is tempering. It involves gradually heating the knife to a certain set temperature and sustaining it at that level for about an hour. This is based on the level of hardness you want. Tempering makes it less brittle while enhancing its strength.

The next step requires you have a hardening bath.  For instance, for C1045, you will need oil. Each type of steel requires a different quenching method-they are not the same for all metals. Some of the most common quenchers are water, oil, air, and many more. Then deep the blade in the oil to quench it and make it non-magnetic.

Next, you will have to harden a magnet, which will help you decide on the steel’s hardening temperature.

To start the process, set up the fireplace, heat the blade at a medium-high temperature. While still heating, by tapping it against the magnet, if it does stay attached, it means it is now ready. Once you confirm it is non-magnetic, let it cool in the air for a number of times. This process is known as annealing, which reduces the strains due to spinning and grinding processes.

After annealing, you need to heat it at the same temperature, then deep it into a hardening bath (oil), and take it out. File the edge to test for its hardness. If the knife is hard enough, the file won’t leave any marks. You can now put off the fire.

Next, preheat the oven at the ideal temperature for your preferred hardness (400-450 degrees) for the tempering step. Consider using medium hardness. Higher temperatures result in a softer and finer blade. Let the blade heat for about an hour and remove it from the oven to cool.

Step 7 Finishing the Blade (Second Time)

At this step, the blade will have changed to black due to quenching at the hardening stage. Similar to step 5, start sanding out with coarser grit sandpaper to remove the black oil deposits.

Systematically, work moving towards the finest grit you have. This step requires maximum keenness because the results will be the final look of the blade. Ensure you get rid of all the scratches to acquire a smooth and finer blade.

Now cover the blade with a sheath to protect it from scratches while attaching the bolster and handle.

Step 8 attaching the bolsters

For this step, you will use two brass bars of the same thickness. Put the blade on the piece of the brass and trace the outline on the brass bar with a permanent marker. Do the same on the other piece of the brass bar, then indicate the words right (R) and left (L) for easy identification.

Now fix one bolster on the handle in the right position. With the same drill used to make the bolster holes, drill through the brass and the blade. Do the same for the other bolster. You will need to enlarge the bolster holes a little bit on the outside to create extra space for the brass bar to expand when it is peened.

Add some epoxy where the brass bar and the blade meet. Do not use too much epoxy because it may tamper with the glue and force it out when the brass is clamped together.

Attach the bolsters on the blade and let the brass bar pass through. Once the brass is through the two bolsters with the blade having the same distance on all the sides, put the blade by its side on a hard metal.

Now strike the metal pin with a peening hammer while supporting it with the metal surface below. Continue hitting the pin and turn the blade to hit the other side. This makes the brass bar to expand and grip the bolster. Leave it for around 24 hours for the epoxy to fully cure.

The next thing to do now is to sand down the brass bar until it is at the same level as the bolster. If all is done correctly, the brass bar will be completely invisible to your eye. If not, simply file the top of the brass bar to fit with the blade.

Step 9 Adding the Handle

Place the wooden slabs on the blade and ensure that they are in the right position. To achieve a tight fit between the brass, blade, and wood, ensure that the wooden parts that attach to the brass and the steel are flat.

Secure one of the slabs on the knife and ensure it is tightly fixed on the metal parts. With the same metal bit you used to make the Corby rivets’ holes drill through the holes on the handle and through the wooden slab. Repeat the same procedure on the other wooden slab.

With the wooden handle slabs drilled, you can now screw in the rivets and ensure they fit perfectly. Now add some epoxy on the wood and the steel handle, position the wooden slab well, and tighten the rivets.

As you tighten the rivets, the wood becomes squashed on the steel, and some of the glue squeezes itself out through the gaps. Be keen not to tighten excessively because the wooden material may get damaged, but ensure that they are tight enough so that everything stays in place. Wipe the excess glue with a damp cloth.

Leave it for around 24 hours for the epoxy to fully cure before you start shaping the handle.

Step 10 Shaping the Handle

At this step, you will want to remove the excess wood. You can use a circular saw, band saw, or belt sander.

To give the wood handle its ideal shape, you can use a wood chisel, file, or other wood carving tools that you can access. In this case, you can use the rasp because it is quicker in removing the unwanted wood material. It is also ideal for eliminating brass rivets too, making it easy to work on the brass and wood simultaneously.

Continue taking out the excess wood material to acquire your desired shape for the handle. As you approach the steel handle and the brass bolster, switch to a coarser sandpaper. This ensures that you achieve an even transition between the wood and the brass material.

To attain a smooth finish on the wood surface, start scrubbing with a coarser sandpaper working down to a finer grade. This process takes much less time than the time used in shaping the blade because working on wood material is a bit easy.

Step 11: Finishing the Handle

To get a beautiful finish, add wood finishing oil and a sealant. There are many different types of finishing oils available in the market that you can choose from. Start by adding some wood sealant using an old fabric material. Rub it into the wood and ensure it covers all the necessary areas. Let the sealant dry for approximately 30 minutes, then sand it with the finest sandpaper grade you have. Repeat the procedure three times.

To apply the finishing oil, put some amount on your index finger and smoothly rub it on the wood in a circular motion on the whole wood handle. Let it dry for around 30 minutes.

Using a clean finger, remove the excess oil and rub the wood with your palm for about 30 seconds at a quick speed to make it warm. This allows for the oil to get into the wood. Repeat the procedure three times and leave it for around 24 hours to harden.

Step 12 Sharpening the Blade

Why would you want you to have a knife? It is simple- to cut. To attain this, you have to work on the edge of the knife to make it sharp.

The first thing you need to do is to place the knife sharpening stone on the table. For double-sided sharpening stone, one side is always coarser than the other side.

With the coarser side placed upside, lubricate it with mineral oil. Place the knife at an angle of 20 degrees to the stone and rub along the stone, like you would do when cutting something without using too much force.

Continue rubbing on both sides of your knife’s blade until it starts to develop its edge. The sharpening process creates a ‘v’ shape that will form the sharp edge. Turn to the finer side of the sharpening stone and repeat the process. Do not forget to add the mineral oil. At this step, the knife should be sharp.

To test for the sharpness, cut through a piece of paper or fabric. If it cuts through the paper or the fabric, then it has achieved sharpness.

Step 13 Engraving (Optional)

This step is optional, but you can decide to engrave a message on the blade or the handle. Laser etching is recommended for the carbon steel knife.

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