Couple weeks ago I was biking and I noticed some had dumped two lawn movers in the woods next to the road. That got my attention and I started thinking if the blades on the movers would make a good knife.
It did. On this project I will be making a small tanto style knife from one of those blades. I only ended up using half of the blade so I will be making at least 2 more knives from these blades.
Step 1: The Materials
The materials I used:
Lawn mover blade
Aluminum rod (4.2 mm thick)
Aluminum bar (10 mm thick)
Tools I used:
4.2 mm drill bit
dremel with carbide and diamond bits
Step 2: The Design
I had drawn multiple versions of this design a couple of moths ago. I really like the look of the (so called) tanto style grind on the knife. I don't think it's really the most practical type of blade for anything but that doesn't mean it sucks. Sometimes style and aesthetics are worth small sacrifices. This knife was never meant to be your every-day survival tool but rather something stylish yet functional.
First I drew the design I wanted on a paper and took a picture of it. The I took the picture to Photoshop and traced the design from the picture. I printed out 3 different sized version of the design to get the best fit possible to my own hand.
Step 3: The Blade
After cutting out the design and choosing which size seemed the best, I traced the design on a lawn mover blade I had found and straightened. Lawn mover blade in not hardened because then it would be more likely to crack rather than bend when hitting a stone.
I cut my design out roughly with a angle grinder and a cutting wheel. Then I changed the cutting wheel to a rock grinding wheel, which I have found to be very good for fast and rough stock removal. I ground the design as close as I possibly could with the angle grinder and finished grinding the shape with belt sander and a dremel tool in tight spots. In the end I flattened the sides of my blank but I left some of the rough spots on the blade to remind me of what the blade used to be. It gives the knife some more character.
After I had finished the shape of my design it was time to grind the bevels of the blade. I don't have one of those fancy vertical belt sanders you see many knife makers use, so I've built a kind of riser for the belt to be ably to leave the choil while grinding. Otherwise the edge of my sander would be too round to get a nice choil on the blade. I used a permanent marker to color the edge on my blank and used a caliper to draw teh center line to help my get the edge symmetric. There is not really many tricks to grinding a blade by hand trial and error you will learn to keep a constant angle while grinding. It's always a good idea to first leave the edge a little thicker to prevent the blade from cracking during quenching. Heat treating usually leaves teh blade with some scaling anyways so you'll have to grind the edge again anyways.
At this point I drilled the holes for my pins so that I don't have to drill the steel after hardening.
I heat treated the knife by queching it in oil and then tempered in in an oven. After the tempering I put the blade in vinegar for a couple of days, you could also boil the vinegar to speed up the process. Vinegar makes the scaling to come off easier so you don't have to spend as much time grinding the blade.
Step 4: The Bolster and the Handle
My way of making the bolster and the handle is not the fastest but I think it gives me the leas gap between the bolster and the handle. I started with a bar of aluminum. Because my aluminum bar was thick enough to make both bolsters I drilled a hole through it and cut it in half I used the factory cut surfaces on the inside, instead of the very uneven surfaces I had just cut. I put some epoxy under the bolsters and attached the bolsters to the knife with a aluminum pin. Then I used clamps to hold the thing together so long that the epoxy dried.
After the epoxy had dried I cut myself the handle blanks from walnut. I made the blanks a little oversized so that I didn't have to get the angled cut between the wood and the aluminum right the first time: After I was finished with the fit I used the epoxy to glue one of the sides to the knife. After the epoxy had dried I used the pin holes on the knife to drill the holes to the wood. The I did the same thing on the other side. After both of the sides had been glued and the holes drilled I attached the pins to the wood part with more epoxy. Then I sanded roughly the handle to my wanted shape with various sanding tools.
Step 5: Finishing
Now that I had my rough unfinished knife ready I started sanding the blade and the handle from 400 grit up to 2000 grit. After this I polished the metal parts wit ha buffing wheel and buffing compound leaving me with mirror polish. The polishing wheel also did the final sharpening of the edge and it is now razor sharp. NOTE: never polish a blade so that the wheel is spinning towards your edge. The knife can get caught to the wheel which would be really dangerous.