Intro: Knife From a Car's Leaf Spring
This is my first instructable so I hope that it makes sense. I will show the basic steps for making a knife from a leaf spring off a truck. Every knife will be different so I will just explain the basic steps and alternative ways of making it if you don't have the same tools that I do.
Step 1: Materials Needed
Band saw ( or hack saw )
Drill press ( or hand drill )
Forge ( or home made forge )
1/4"x4"x 12" wood. Mine was oak.
Step 2: Design Your Knife
Draw out on a piece of paper what you want your knife to look like. Draw it to scale in the size you want your knife to be. Take into consideration the diameter and length of the steel you have to work with
Step 3: Heat Up Your Steel and Flatten It
Most spring steels from a vehicle will have an arc to it so
You need to heat it up and use a large hammer to pound it flat. This will also require a smooth flat surface.
Also , if you don't have a forge you can make one by digging a pit and lining it with fire bricks and just use a leaf blower with some ducting attached to it leading into the pit. Fill the pit with charcoal and your off to the races. You can also use an oxy acetylene torch. And I even have a friend who used a really hot Bon fire , however the heating is hard to control and keep even that way.
Step 4: Cut Out Your Design
Cut out the paper template you have drawn and tape it to you're steel. Then trace it onto the steel and cut it out with your band saw or hack saw
Step 5: Grind Your Edge
Use your belt sander and files to make your bevel and grind your edge. The more gradual the taper of the steel and the sharper angle you can get, the better you're knife will cut.
Side note .... I cleaned up the entire knife to make it shiny and pretty at this stage which proved pointless because I needed to re heat it later and you will too.
Step 6: Drill Your Holes
The previous picture shows the holes already drilled , it doesn't really matter when you drill them but they will just need to be drilled before you harden your knife.
Step 7: Heat Treat Your Blade
Here is some quick metallurgy for you. Hope this makes sense. When you originally heated your blade to take the bend out of it , it most likely wasent a super even heat , I know mine wasn't , and you let it gradually cool back to natural temperature over time. This will make the knife soft and it will bend if put under stress. Now what you need to do is evenly heat the entire blade until it reaches a cherry red color , not bright , but a medium to dark red. Another way to know it is the correct temperature is to bring it to non magnetic . This is known by taking a magnet and sticking it to the hot metal. When it reaches the propper temperature , it will no longer stick. When it has reached non magnetic you are going to dunk the entire blade in a container of oil or water. This is known as quenching. I'm sorry I don't have pictures of this process. It all happens really fast and you need to pay attention. I uses olive oil and dunked it in a disposable baking tray. You can use water but oil will give you a more flexible blade. Lots of people say to just use old motor oil but I read a lot of forums about horror stories due to impurities in it so I stayed away .
Step 8: Pretty Knife Ruined
This is why it's pointless to make your knife beautiful before you quench it lol
Step 9: Temper Your Blade
Now that you have quenched your blade you are going to want to temper it. Basically now that you dunked it. It has reached a hardened state. But the molecules are under tension from the rapid shock of the quench , so you take your blade and put it in the oven set to about 450-500• for an hour or so. Then turn off the oven and let the blade cool down gradually as the oven does . Some people do that two or three times. I only did it once and haven't had any problems. This causes the molecules to relax and the knife to be more flexible and less proned to snapping.
Side note .... One of my first blades I made , I heated way to hot ...quenched in water and didn't temper it. I threw it at a stump once and it exploded into 7 pieces. So those steps are important.
Step 10: Make a Handle
Trace your handle out and cut it out with your band saw or hacksaw
Step 11: Drill Your Handle Holes
Attach one side of the handle to the knife , then drill through the steel holes and through the wood. Then remove it , and repeat the step for the handle slab on the other side.
Step 12: Complete Your Handles
Attach your handles to the knife and sand them down until it's a comfortable grip in your hand. Then remove them and add either a few coats of oil or what I did which is just a clear coat exterior varathane.
Step 13: Attach Your Handles and Your Done!!
I'm sorry but I can't for the life of me remember what these bolts are called that I attached the handle with. They in screw in the middle and one side has a male thread and the other side a female and one end has a slot headed bit for tightening . I'm sure there are lots of different styles but that is what I used.
Anyways that is the completed project . I hope you found this informative . I also made a leather sheathe for this knife and I will do an instructable soon on how to make those.
Alex primitive made it!