I came up with this design few months ago, when I was in the middle of school exams. Now it´s the summer break so I finally found time to transform thought into thing.
Materials: 5mm (little less than 1/4 inch) mild steel, saw blade, nails, spring.
Tools: angle grinder with cut-off and grinding wheel, drill press, files, belt sander with bevel jig, shop torch, hammer.
Step 1: Handles
First I cut the rough shape from mild steel with angle grinder and cut off wheel. Then i smotthed the cuts to final shape and surface with file.
Next I drilled the holes for pins on drill press. I drilled both handles at once which lead to perfectly matching holes. Lastly I chamfered the edges with belt grinder and file.
Step 2: Blade
I cut the rough shape from old miter saw blade using angle grinder with cut off wheel. The final shape was done by filing with first coarse than fine file.
For beveling I used small belt sander attached vertically to my table and simple beveling jig. This jig consist of just one bigger piece of wood to attach the blade with small strip of wood on the bottom to secure constant angle. Later I drilled the hole for pin.
Finally I quenched the blade using propande torch and cup of sunflower oil (it smells nicer than motor oil :-))
Step 3: Guts
For inner parts of knife I used the same saw blade as for the knife blade due to need of same thickness of theese parts.
I rough-cut al the pieces and then by trial and error I slowly adjusted them with file to fit together perfectly.
The locking mechanism on this knife is spring loaded. I used some scrap spring that I had laying in my drawer for long time, but I first made sure it´s narrower than the blade so it can move freely.
Step 4: Assembly
I started the assembly by simply sticking whole nails into the holes. Then I slided the iner parts on the nails and lastly I put on the second handle.
Next I cut off the nails leaving just a little bit sticking out. Then I punched on the nailsto flatten their heads. Before I secured the pin that goes through the blade a slided a washer just a little bit thicker than the blade itself between the handles to prevent squeezing the blade between the handles which would make opening of the blade impossible.
Step 5: Final Touches
As last step I filed and sanded the hammered nails flush and applied clear lacquer for protection.