Intro: How to Make a Tiny Katana Knife
My nan's 70Th birthday is comign up soon, and me being
a poor and broke student, I decided to make her something. But one of the hardest parts of this build was deciding what to make. Everything I wanted to make was either too expensive or required tools I dont have at home. I wanted to cast a ring from aluminum, but I dont have the materials to make a proper cast or a lathe to make it not look like a toddler made it from play dough. One thing I noticed last time I was over at my grandparent's house, is that they dont have any decent knifes there. All of them are either older than earth and are so scratched they look like a cat went at them with it's claws from years of resharpening or plastic and falling apart.
I am by no means a professional knife maker, so this isn't an advanced guide on how to make a knife properly, but more of a journal of how I did it with basic power tools.
Step 1: The Plans and the Design.
Everytime I start making something, I first plan out on how it will look like, then I figure out how to actually make it, and what materials to use. In this case I wanted a simple looking knife, with a dark handle and a damascus blade. I drew most of my inspiration from japanese short swords.
In the end, I had to drop the damascus blade, since my homemade forge can't get hot enough to forge weld steel, and I couldnt find any patterns I liked online.
I started out with the handle. Since you hold the knife by the handle (obviously), it is just as important as the blade. It is just as easy to screw it up, since a handle to big or too small will be hard to hold. That's why it's important to make prototypes from cheap materials before spending money and time on real ones.
Since the inspiration form my knife were japanese swords, I did some research on tang sizes, made a 3d model of that size and then printed it on paper, to see how well it fits in your hand. In the end I had to şhrink it down to about 2/3 of the original sword's size for it to fit in the hand. I did the same thing with the blade to see if the thickness and the leinght are okay.
Step 2: Choosing Your Materials
You might be tempted to use stainless steel to make a knife's blade, but high carbon steel holds an edge better, but is also easier to sharpen and work with, even tho it's harder.
When it comes to chosing your handle material, first thing you need to consider is if you have the tools and knowledge to work with your desired material. I recomend going for hard woods, since they arent that much harder to work with than soft woods, but are harder to damage. Make sure the steel plate you buy isn't too thick, since then it would be hard to use the knife for actually cutting things. I used 6mm thick high carbon steel plate, which is on the thicker end of the scale.
Step 3: Cutting Out the Blade
Decide on a way to transfer the outline of your blade to the steel. You could print it on paper and trace it with a permanent marker, scratch it into the steel with something sharp or glue the paper outline on the steel. Don't forget tracing the tang as well! As with anything, there are many different tools to cut out the shape of the blade, but the one I had was just an angle grinder. I then used aluminum oxide sandpaper to sand down the rough edges. This kind of sandpaper will expose more sharp edges as it breaks off, making it longer lasting and better for steel.
Step 4: Making the Edge
Cutting the edge was the hardest part of actually making it. I don't have a belt gridner, so I had to cut it out with a sanding disc on my angle grinder. The largest disc I could find was 15 centimeters, so it was hard to get an even cut. I managed to get it to look decent by holding it at the same angle and moving the knife backwards and forwards. To make the ricasso I just didn't grind down the meatal where I wanted it to be, then I took a file and started squaring it off.
Step 5: Heat Treating the Blade.
The temperatures requiredn to heat treat a metal differs from steel to steel. Some steels even need to be normalized before quenching it. If you don't know if you bought pre-normalized steel, it's better to just do it anyways, it shouldn't do harm on your blade. The required heats aren't that high, so you don't need a proper forge, a simple campfire with a hair dryer pointed at it would work just fine. I used an old furnace my grandparents used for heating their house that they were going to throw away. It is a closed box so it retains heat quite nice, and the chamber where the wood burns is slightly off the bottom of the furnace, which makes blowing air into it alot easyer and more equally spread out.
Normalizing steel will give it more tensile streinght by equally redistributing the ingredients. This process is so simple, that there's no reason to skip it, even if you bought normalized steel. You just heat the steel past it's critical point temperature and let it cool in air. Don't worry, you dont need to know what that means, even I don't, but what you do need to know is, steel becomes none magnetic when heated above it's critical point. So if you're unsure if you reached the required temperature (800-900C or 1472-1652F), just put a magnet to it, and if it doesn't stick, you're almost there. Just put it back in to your heat source for a minute or two longer. Do not cool it down in water, just let it sit in the air untill it cools off enought for you to be able to touch it. Do this 2 or 3 times.
Quenching steel will make it harder, which means it will hold a sharp edge way longer. Doing it is fairly similar to normalizing it. Heat it up untill it's glowing red hot, try if it is magnetic and once the magnet doesnt stick to it anymore, and let it heat up for a little longer. Then comes the fun part. The actual quench. This is done by submerging the red hot blade into oil. You can use water, but people claimed that can cause the blade to crack from heating up too fast, but If you don't want to risk it, like me, oil. Any oil will do. Olive oil, sunflower oil even motor oil if you're rich and can afford it. Make sure you keep moving the blade once it's in oil, since air bubbles will start forming arround it, instead of the oil touching the surface of the bladem making it cool down slower. Leave your blade in the oil for 5-10 seconds, then take it out and see if it's warped. If it has, put it onto a hard surface while it's still warm enought to hammer it straight, then put it back into oil till it cools completely. If it is straight when you take it out, just put back in untill it cools down completely.
Do not drop the knife or stop here. You might think that after a hard day of roasting knives, you could go to sleep and continue tomorrow. Do not do that, simply leaving the knife out could crack it. Right now it's really hard, which would make it really sharp and stay that way for long, but it would probably break when you drop it, or just from build up of internal stresses alone if you leave it without heat treating for too long. In fact, I bet you could break it with your bare hands, but I wouldn't recommend it. We need to make it softer. This achieved by heating it up, and leavint it to cool in air.
Different temperatures will give different hardnesses. Same as before, harder means it will hold the edge better, but will be more brittle. Softer blade will become blunt sooner and will need sharpening more often, but the risk of cracking if it hits somethign hard are lower. Knife hardnesses range from 50 to 65 on the Rockwell Hardness scale. Since I have no clue how hard or soft that is, I decided to go for the middle, 58. I did some research and turns out the required temperature is 230C or 446F.
Easyest way to heat treat a blade is to just put into an oven at a required temperature and leave it there for a few hours, then take it out, let it cool down untill you can touch it and heating it up again. Same as normalizing, do not cool it down in water, but just let it cool down in air.
Whew... This was a long step!
Step 6: Sharpening the Blade
Before you put any more work into this knife, it's better to test out it will break now, than to put more work into it and having it crack later. Basically, just take it and hit harder things with it, such as wood or bricks. Don't hit other steel blocks or stone, even a soft metal might break doing that.
Once you're sure the blade won't break on you, you can proceed sharpening it. This is the part of the making process I'm least familiar with, so I recommend you read up on how to do it online. I started out by placing the knife into a vise and start grinding it down some more with a finer sanding disc on my electric sander, then move onto a grinding stone I had laying arround for sharpening scythes.
Step 7: Making the Handle and the Sheath
Since the handle and the sheath have the same profile, I carved out all the holes, glued everything together and only then cut out the shape of both of these.
I started out with the sheath, sicne it was easyer to carve it without a handle attatched to the knife. I took the blade and traced it onto the wood. First I wanted to use pine wood for a ligher toned handle and seath, but then decided it would look better if the wood was dark. Another reason I changed the material is because I often cut too deep with pine wood and had to start over, so I decided to switch to a harder material. Another plus side is that harder woods are harder to damage. I switched to walnut and started out by thinning a plank down to 7.5 milimeters on the planer (half of the total width of the sheath). I then carved out the hole in the shape of the blade using a hammer and a chizzle. I started tracing out the outline with by stabbing a chizzle into the wood and breaking the fibers. Then I placed it down as horizontaly as I could and still cut into the wood and carved out the hole. The depth was 4 milimeters, slightly over half of the width of the blade's thickness which is 3 milimeters. I then took rubber foam and lined the interior of the sheath with it. This is a squishy but a very grippy material, which will hold the knife in place once inside the sheath. I applied wood glue to the inner surfaces of the sheath and glued the two halfs together.
I did the same thing with the handle, but when gluing it together I used contact cement to glue the tang of the blade to the inner side of the handle. A day later, once the glue was completely dry with no chance of coming apart, I put the knife in the sheath and started cutting the sheath and the handle into the correct shape. First I cut it the rough shape with a saw then finished it with the sander. Cutting the bevels of both of these parts was quite hard as well, since they were not on a straight edge.
Step 8: Making the Handguard
Most of the swords I drew inspiration from had handguards between the handle and the sheath, but they all sticked out, which is not something I wanted. So I just made it flush with the rest of the knife. This part was quite simple, I just cut out the shape of the handle onto brass and cut it out, then made a hole in the shape of the blade. I coated the handle and the brass handguard with contact cement, let it dry and then put them into the place.
Step 9: Etching the Blade
This was done to make the blade look darker and more matte. It is completely unnecessary, I just felt like it would look better. This is done by mixing 1 part ferric chloride with 1 part water and leaving in there untill it reaches desired color. Be careful when cleaning off the acid, as far as I can tell it won't hurt you if you touch it (atleast it didn't burn me when I splashed myself a bit). But, depending where you live, simply washing the acid off in the sink is considered illegal, so make sure you neutralize it by washing it in baking soda mixed with water.
Step 10: Final Thoughts
Overall, this whole build took me a weekend to make, and the total ammount of work in it was arround 15-20 hours. We'll see how my grandmother likes it next weekend when I go visit her.