Cheap, Easy DIY No-spin Throwing Knives

Hi, I'm a 15 year old Homeschool student, and I recently got an interest in knife throwing. I wanted high quality knives that I could use for no-spin throwing, but then I realized just how expensive good ones were. So began the quest to DIY them. There were little resources online, but there were enough to scrape some together and I got a decent result. All of the materials for a set of three cost as much as one knife of comparable quality.

These knives can be easily made from materials available at the home improvement store, with only household items, an angle grinder, 2 discs and a file. No heat treatment is needed, as throwing knives don't need to keep a good edge. They have an approximate 60-40 handle bias and a mid-taper to help with no-spin throwing, and they are very durable. (They can be used for other throwing techniques just fine)

They are 9.75 inches long, weigh roughly ten ounces, and are 3/16 of an inch thick.

1. Appropriate PPE for all steps
2. An appropriate work space
3. Bar Stock, makes 3 knives: https://www.homedepot.com/p/Everbilt-1-1-2-in-x-36-in-Plain-Steel-Flat-Bar-with-3-16-in-Thick-801877/204225721
4. A printer and paper
5. Duct tape or packing tape
6. Scissors
7. Ruler
8. Spray paint or a black permanent marker
9. Large Coarse file
10. C-clamps or a bench vise
11. Angle grinder
12. Metal cutoff disc
13. 1/4 in. grinding disc

Optional items:

1. Sandpaper. Makes smoothing edges easier and is needed for a satin finish.
2. WD-40 for finish sanding
3. Calipers

Print the above image at 300 dpi on default scale with no margins. Use a ruler to check the square to make sure it is 1 inch across at its edge. If not, check your settings; if nothing is incorrect, change the scale until it's very close to 1 inch.

Take the paper you just printed, and, using scissors, cut the paper close the the outline of the knife, but not quite up to it.

Now cut off a strip of tape the length of the outline and adhere it flat on the side opposite the outline. See image 2. There should be tape behind the entire outline.

Again using your scissors, cut out the outline. You should be cutting off the black line. See image 3. Don't worry about ink splotches.

Now that we have the pattern printed and backed, we can mark it on the steel we are going to use. There are two methods of marking it, Spray paint and marker. Spray paint is easier and more visible, but if you can't use it sharpie is fine.

The steel we are using is hot rolled, which means there is a taper on the edges. Try to avoid the taper when placing your pattern, and make sure it is close to the end.

Using Spray Paint

Either outside or under a fume hood, place your bar stock on a piece of cardboard or something else to cover the ground. Place your pattern at the end of your stock, not over the taper on the edges. Weigh it down flat with something you don't mind spray painting. Now spray it, holding the can 8-10 inches above the workpiece. Do a few light coats until all the edges of the pattern are covered, but try to avoid pooling/dripping.

Using a Sharpie

Place your pattern at the end of your bar stock, not over the taper at the edge, and weigh it down flat. Using a permanent marker, mark all the way up to the edge of the pattern.

Next, we have to cut out the profile of the knife. I used an angle grinder, but you could use a hacksaw or coping saw. That would take a while though, so I wont cover it.

Using an angle grinder

Angle grinders can be very dangerous. Use at your own risk, and always use proper PPE and do your own research on safety before using one.

In this step we are going to do some rough profiling using a metal cutoff wheel. Because the depth of cuts is limited by our stock hitting the arbor of the angle grinder, we will first cut in notches; then cut across to them to remove the material. See image 1.

First you need to have a metal cutoff wheel on you angle grinder. Securely clamp your material pattern side up to your work surface, as in image 2. Don't leave too much off the edge of the table, as that can cause it to wobble.

Do the following steps in sections on the knife, however big are needed for your knife. Start with the notches that go perpendicular to the edge of the material, and cut them about every 3/4 of an inch. Cut them as close as you think you can comfortably get to the line, but leave 1/8 of an inch. You will be using a grinding disc to get it closer later. If there is too much material at the point of the knife to make the notches, you can make a cut parallel to the pointy part. "Cut First" on the diagram.

Now that you have the notches made, you can simply cut the profile at the end of the notches. "Cut Second" on the diagram. You should have something similar to image 3

Now, We're going to grind down the edges to the exact dimensions first using a grind disc on the angle grinder.

If you don't know how to use an angle grinder for this, now would be a good time to learn. You can look up something like "How to use a grind disc angle grinder" I'm not an expert, so I'm not the person to teach you.

Install the grind disc, then re-clamp the knife to your work surface like before. Grind it as close as you think you can without going past the line. Make sure to keep it square to the surface of the material.

Next, it needs to be filed square and exactly to the line. If you have a belt sander or bench grinder, definitely use that instead.

After filing / grinding, it should have corners that feel sharp or have a burr on them, and all of the metal that has sharpie/spray paint should be removed.

This is the step where it becomes a knife. (finally)

If you have a set of calipers, they will be very useful for marking your lines.

First we need a lines drawn 0.2 inches from the edges. If you don't have calipers, from both edges on both sides of the knife, mark 2 spaced dots 0.2 inches away from the edge. Use these to draw a line for guiding your bevel. See Image 1

Next we need to mark the guide lines on the sides. Cover the sides of the knife on the edges with sharpie. Use something pokey and a ruler or calipers to mark a line 2mm away from each edge. This should make two lines near the center, with roughly 1mm between them. If you look at image 2, you will be able to see one of these lines. (the other was already filed off)

Now it's time to actually file in the bevels. Using a large metal file, file one edge at 45 degrees until it hits the first marked line on the side of the knife. See image 2. Repeat this on the adjacent edge.

The bevel is partially done, but there's one more step left. We need to make it a much more shallow angle. The bevel should be flat from the line on the top surface down the bottom of the bevel you just filed. To do this, eyeball the angle you need to start. Then as you file, adjust the angle, judging by how fast you're reaching both sides of the bevel. It should end up one straight bevel between the line on the top and where the 2mm mark was on the side.

Now do this same thing on the adjacent bevel, then do both bevels on the other side of the knife with the same whole process. After this is done, you should have about a millimeter left on the edge.

You should now have a functional throwing knife, but it won't be comfortable in your hands. There will be some rough edges that make it hard to use.

You can fix this by crowning the sides of your knife. Simply file or sand a little off of the corners until it's not sharp anymore. You should be careful not to completely round over the sides, though, as having at least a little bit flat helps with no-spin throwing.

Congratulations, you have probably just made a fully functional throwing knife!

Other than crowning the sides, you can satin finish if you want to, for a smooth matte finish. It's definitely optional, though. To satin finish, spray on some WD-40 and sand the flats of the knife flat with 120 grit wet and dry sandpaper, making sure to sand straight forward and back longways. Repeat up to 400 grit. Now fold over a piece of 600 grit and use the point of the folded part to gently sand the surface, still making sure to do it straight back and forth in the same orientation as before. Now you will hand a matte finish with consistent, subtle lines.

Well, now you have a good throwing knife that you made yourself. If you want to improve at your throwing, you should definitely consider making a full set of three, and some sort of end grain target.

If you don't already know how to throw, I would recommend Adam Celadin on YouTube. He definitely knows what he is doing, and explains techniques well.

I don't have anything else left to say besides thank you for reading and following along.

Happy throwing!