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This instructable will show you how to, from scratch, make a folding knife with cast aluminium handles. The making of this knife does not require many power tools and can be done mostly by hand. Have fun and be careful.
Step 1: Templates
I found a set of templates that were created by John Heisz. The templates are found for free on his website www.ibuildit.ca or can be found directly at this link: http://www.ibuildit.ca/other%20projects/Images/Pocket%20Knife/folder.pdf
Step 2: Cutting Out Knife
The first part of this process is to find a piece of flat steel. It is better if you can use old saw blades or tool steel but for this project I simply used a piece that I found in a junk pile near my house. It is 3 millimeters thick, perfect for a knife blade. Before you cut it out, glue on the template onto the steel, and let it dry. I used a jig saw with a metal cutting blade on it but you could alternatively just use a hacksaw. I followed the lines as best I could, and after that, I used a metal file to fine-tune the edges.
Step 3: Sharpening
Next, I clamped the knife in the vise and slowly used a metal file to grind the steel to a point. I could have done it faster with an angle grinder but I didn't want to risk messing up the whole blade. It is a good idea to mark the center of the steel with a marker before so that the edge of the blade is centered once it is finished. After all of the rough filing was complete, I smoothed the blade with my bench grinder. You don't want to sharpen the knife all the way just yet. Keep is dull for now.
Step 4: Quenching and Tempering
To make this steel harder and able to hold an edge, we have to go through a process called quenching and tempering. To do this, I used a propane torch (I actually used MAP gas) to heat up the blade until it is glowing orange and is no longer magnetic. Then I quickly plunged it into some new motor oil until it cooled. This rapid change in temperature makes the blade extremely hard, yet also very brittle. To make the blade a little bit more flexible, we have to temper it. I put the blade on a cookie sheet and set it in the oven a 375 degrees for 2 hours and let it cool down with the oven. When you pull it out, it will have lots of grease and scale on it, but that can be easily removed with some sand paper.
Step 5: Casting Aluminium Handle
I wanted to make the knife handle out of aluminium partly because I had never seen it before and also because I am always looking for an excuse to melt more pop cans in my forge. I made the molds out of polystyrene foam. You can use other foam such as roofing foam but I get the best results with this kind. I traced the pattern onto the foam and cut it out with a jigsaw. After that, I smoothed it with some sanding sponges. To cast it, I had to sift out some really fine dirt from my mom's garden. It is better to use sand but I didn't have any that was readily available. I buried the foam in a small bread pan and used two corks as chimneys for the molten aluminium to flow into. Then I started to light my forge. I used a large fan that was used in a water heater. The fan is the most important part of my forge. For aluminium to melt, it has to reach 1,221 degrees Fahrenheit. Wood burns very quickly at that temperature so make sure to have lots of it on hand. Once I had filled about half my crucible, (about one cup of liquid) I carefully poured it into the molds. I let them cool, pulled them out, and washed them off.
Melting aluminium is very dangerous and should not be treated lightly. I made sure to have a hose nearby, and wore welding gloves, pants, and safety goggles at all times.
Step 6: Smoothing and Polishing Aluminium
After I pulled the aluminium out of the mold, I could tell that the sides were very rough and needed a lot of work to be done on them. I sanded and filed both these handles for a total of over 4 hours. Since aluminium is quite soft, you cannot use grinding wheels to smooth as the wheels get very clogged up very quickly. Also, metal files get clogged as well but you can clean them with a simple wire brush. I didn't use a power sander or anything for this but if I had one, it would go pretty fast. My method for polishing was to start with assorted flat and half round metal files, then use a 80 grit sanding sponge, then move onto a 240 grit sponge. This process seemed to work well and was the most efficient. Although I didn't get many pictures of the sanding process, I did catch a few of the final effect.
Step 7: Drilling Holes
After both sides of the handle were sanded up, I began drilling holes. I simply lined up the template and marked exactly where the holes need to go and drilled them with a cordless drill. I often used a clamp to hold the piece down while I drilled to prevent it from moving.
Step 8: Locking Mechanism
The first step in making the locking mechanism is to cut out the lever from the template onto a piece of 3 mm. thick steel. I tried to use an angle grinder to cut it out but ended up using the jigsaw again. Make sure the fit to the knife blade is close to perfect. Once it was cut out, I used the appropriate sized bit and drilled a hole near the center of the lever. The next piece in the mechanism is the spring holder. I cut it out again with the 3 mm. steel and with the jigsaw. Once it was cut out, I glued it onto one side of the handle, and let it dry. For the spring, I used an old scroll saw blade that had broken. One piece fit into the holder but I decided to shove two in for extra strength.
Step 9: Adjustments and Modifications
As I cast the handle out of aluminium instead of cut it out of wood, as John Heisz intended, there were lots of adjustments that were needed to be made. I fitted the knife together numerous times to make sure that everything lined up properly. I needed to grind down the center of a bolt to allow the knife to slide by. I also had to file down the inside edge of the aluminium scale as it was very rough and uneven.
Step 10: Cut Pins and Glue
Once you are sure that everything is fit together correctly, you can trim down the pins and glue the knife together. I used aluminium rivets as the pins, except for the bolt. For the glue, I used a glue known as Duco Cement, which is a fast setting cement.
Step 11: Finished!
Done! Just sharpen it. From some scrap steel and lots of old pop cans, I made a beautiful (in my opinion) pocket knife that can be used everyday. Again, please vote and favorite for my 'ible!
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