DIY Saw Blade Knife

Knifes are very valuable tools. The are used in several different occupations and for different tasks. In the construction world, they are prone to use and abuse. The need for an inexpensive yet durable knife is needed not only in construction, but several different fields. The most expensive competent is the metal. Using a saw blade to make the knife is not a new concept. It is easier than forging and heat treating a soft piece of metal. The biggest benefit of the saw blade is it is tempered metal. This removes many steps from the knife making process. In my case, I used a 14" concrete saw blade. They are about $100 new but many concrete contractors will give you their old ones. I was able to produce six, 7" knives from one blade. These are thicker than a traditional circular saw blade which makes them strong and have a good hardness factor. This process is possible using several different saw blades. I used materials that I already had in my possession. I designed everything to be easily replicated and reproduced to save time when making more.

Note: I am not a professional and my process is not perfect. I am new to the knife making industry and still have much to learn.

• Marker
• Cardboard
• Ruler
• Scissors
• Saw blade (of your choice)
• 4 1/2 Angle grinder
• 4 1/4 Cut off wheels (2)
• 4 1/4 Sanding flap discs (assortment of grits)
• Bench grinder (optional)
• Bench vise
• Clamps (2)
• Two part epoxy
• Handle material (of your choice)
• Handle pins (of your choice)
• Masking tape
• Drill press or hand drill
• Drill bits

Start by drawing your design, or designs, before starting the constructing process. This ensures the idea you have in your head will work in reality. Drawings allow you to get your ideas down and see what will work. It also helps to research to determine what blade shape will be the best for your application. You also want to make sure you do not take too much off here or grind a wrong curve there.

Creating cardboard cutouts of the sketches from the previous step is important. Since these will be used to trace the outline on the saw blade, they need to be accurately measured and drawn correctly. It is better to error on the side of being to big because it is easier to take material off than it is to add.

Use the cardboard cut outs to trace your design onto the saw blade you will be using. It is important that the overall length of the blade is not bigger than the diameter of the saw blade. I tried to waste the least amount of material possible. Putting edges together reduces the amount of cuts and the amount wasted. This is important if will be making several blades. However, when you put two edges together, if you make a mistake cutting one, it affects both. You must be careful and follow your lines exactly.

To cut the knife shapes from the saw blade, I used a 4 1/2 in angle grinder with a metal cut off wheel on it. This is not the only way though. A metal handsaw, jig saw, reciprocating saw, and several other tools may be used. I clamped the saw blade to the work bench using two clamps to keep the work piece steady. It is important to remember that the blade is very hard to cut. You have to take your time and make slow cuts to ensure the metal does not heat up and lose the heat treatment. If you start to see brown, or blue burning, slow down or stop cutting.

After cutting the knife out of the saw blade, there will be several edges that need to be cleaned up. I am calling this the rough shape phase. This involves removing all the marker lines and taking the edge off the cuts. I did this by starting with a bench grinder (1st photo). A heavy metal grinding disc for an angle grinder will work as well (2nd photo). Next, I moved to the angle grinder with a series of flap discs sanding wheels. I placed the knife in a bench vise. An alterative to this could be clamping it to a block of wood. I started with 60 grit, then 80 grit, and finished with 120 grit. I used this process on the entire edge of the knife except the handle part were you grip the knife.

To grind the full tang (metal under the handle), I used an angle grinder with the flap discs sanding wheels to remove material. I started with 60 grit and worked my way to 120 grit. I was making three knives at once and wanted them all to have the same shape, so I clamped all three in the vise and began grinding. This is a time consuming step that requires patience and a steady hand. While grinding, you want to make sure the metal does not get too warm and turn brown or blue.

The saw blade that I used was very thick. I am new to the knife creating industry and went the most simple route of creating the bevel. There are several different ways. The way I did it may not be the best, but it worked. I used a marker to color the edge of the knife where the blade was to be. I then used a pick tool to put a line down the center of the the marker line. This gave me a place to grind down to. I used a 120 grit sanding disc to slowly grind down. I did one side at a time and allowed the blade to cool down between sides. I took a little off one side and alternated until I achieved the desired look. I created a big bevel because the saw blade was thick.

This is an appearance step. It is not necessary. I did not polish where the handle was to be. I used 120 grit on the grinder to get some of the big scratched out of the knifes. I then moved to using a sander with 220, 320, 400, 600, 1000, 1500, and 2000 grit sand paper to get as many scratches out as possible. To polish after sanding, I used a buffing wheel on a drill with cutting compound to shine them. To protect it, I applied Mother's Mag Polish as a sort of wax. The final result was not perfect, but this was a saw blade that was used to cut concrete and rebar. This is not a piece of new aluminum that will shine like a mirror.

There are several options for handles on a knife. The most conventional is wood. I chose to use oak as my handle. I had a piece of 1 in thick hardwood that I split down the middle. I used these as my scales. I clamped them into place on both sides of the knife and drilled my two holes for pins through the wood and metal at the same time. I used a 1/4 in drill bit because that was the exact size of my pins.

This is another optional step. I was creating these knives to be easily reproduced. I took another block of the oak wood and traced the shape of the scales and the holes onto it. Because I also have the template for the knife shape, this handle template makes these knifes easier and faster to reproduce.

Next, I placed my pins into the handles and knife and clamped it all together. I started removing the majority of the wood using the the angle grinder and the 120 grit sanding disc. I then stepped up to using a sander with 220 grit sand paper. Next, I hand sanded using 500 grit sand paper to achieve a smooth feel. This process can be done in a number of ways including doing all sanding by hand. I chose to use the quickest way possible as I intend to use and abuse these knives and do not need them to be show knives.

Note: I do not have many photos for this step as I was in a time crunch with the epoxy I used.

To attach the scales to the knife, I used 2 part epoxy and 2 pins. The epoxy is very strong, however, I wanted the extra strength pins offer. I was used steel nails for my pins. This was my first time attempting pins and if I could redo the pins, I would use a softer metal. The epoxy I was using had 5 minute work time. I place it on the scales and the knife where the handles would go. I then put the nails through the holes to align it all. I placed a piece of steel under the knife where the nails were at. Once the nails were in, I cut them about 1/8 in to big. I then heated the end of the nails I cut with a small propane torch and hammered then to mushroom out. This made the pins fit snuggly. The steel plate under the knife allowed me to get a frim hit on the nails. This was definitely not an easy step. This could have gone much smoother with brass pins.

This step is another optional step. I did this step to ensure my pins/nails would not come lose. The nails had a large head on one end, but the other was hammered "flat". I taped the handle where I did not want epoxy to go with painters tape. I then put more epoxy on the part that was hammered flat to fill the hole to the edge. When the epoxy had set overnight, I removed the tape and sanded smooth by hand with 500 grit sand paper.

This step was used to put one more quick buff on the blade and one more quick sanding of the handle. This is where I carefully went over the knife looking for imperfections I could fix. I also added a simple stain to the handle. This is optional, but I recommend putting oil or a stain on the wood to keep the wood protected.

If the handle described in the previous steps seems to be to difficult or do not have the time for the lengthy process, I have an alternative.

Paracord handles are very popular and simple to make. There are several different video instructions and designs for this handle style. This is my favorite design using paracord. It begins finding the center of approximately 4 ft of paracord. Then take the center and wrap it around the front of where the handle begins. Tie the same knot you would when you tire your shoes on one side of the handle. It is a twist looking knot (see photos). The flip the knife over and tie the same knot. Repeat this process until you have reached the desired length. Tie the lose ends together to finish. I like to add a bit of super glue on the final knot to ensure it will not come apart.

Always sharpen last! This gives you the best chance of avoiding cuts.

My favorite way to sharpen a knife is with a stone. This is not the only process for sharpening though. I like to use a double sided stone like the one shown. It provides a rougher side and smoother side. I begin by placing a bit of oil on the edge for lubrication. Next I drag the knife towards me (edge facing me) at approximately 20 degree angle. Alternate sides and repeat process until the knife easily glides on the stone. Flip the stone to the finer side and repeat entire process. I followed this process using 1500 grit sand paper to clean the edge of the blade.

It is very satisfying to look back at what you started with. While this process may be very time consuming, there is definitely a sense of pride that you feel while once completed.