Greetings!

This is a simple beginner level knife making project. Due to the design of the knife, it's easy to get a sharp edge and no need for making a separate handle. I wanted to make a woodworking marking knife, with one side flat (to get markings close to the marking guage).

This is not a real kiridashi (Kiridashi: A small Japanese knife having a chisel grind and a sharp point, used as a general-purpose utility knife), but the design is inspiried and the purpose of usage of the knife is really up to the owner. 😊

If you like to watch the entire project - I have made a small video here. All the details should be in this instructable.

Backstory

I found a stash of metal plates from one of the previous house owners when I was renovating. It has been in the dirt for atleast 50 years. Rusty. But I knew that the owner worked at a ship yard and he had a lot of knowledge in tools and hardware. I figured he must have saved that metal for some reason, meaning it wasn't all too bad. But I needed a small and simple project to test the quality of the metal. So I made these knives.

I hope you will enjoy this instructable - and please let me know what you think, or if you have any question, I will happily answer.

Supplies

You will need

Suitable metal plate (not mild steel).
A hacksaw (or a jigsaw with a metal cutting blade)
Marker/pen
Ruler
Utility knife
A square
A mug of water
Sanding paper (grit 240-400)
Grinding stones (grit 600 - 1000)
Buffing wheel
An owen (or a way to heat the metal around 300 degrees celsius for at least a couple of hours)
A small forge (or a way to heat the metal loose it's magnetic abilities)
Small magnet
Pliers
Vise-grip
Oil (for quenching)
Bench grinder/disc grinder (optional)
Belt sander (optional)
Palmsander (optional)
Leather strips (optional)
3 mm drillbit (optional)
Vinegar & salt (optional)
And PPE

Step 1: Cleaning the Rust

If you have new or clean metal, this step is not really applicable.

I use very old rusty metal - so I used a belt grinder and a palmsander. I will keep the struture/surface rough, because I like the way that it look. But I clean as much rust and "rotten metal" as possible by grinding it away.

Step 2: Meassure and Cut

When I'm happy, I will meassure the length. I will not use a template for this. The steel I'm using is about 2 cm wide and 4 mm thick.

I cut the angle of the blade to 45 degrees using a square. The length of each knife is 10 cm.

I use a jigsaw with metal cutting (HSS) blade. It's hard to cut, so if you have an angle grinder - use that. 😊

Also - in the video you see me holding that piece with my hands. Don't do that - use a vise or a clamp for better security!

Step 3: Grind the Shape

This is important for this type of knife. If you are right handed, the bevel of the knife shold be on the right side of the balde. So that the left side is flat. This is if you use the knife as a marking knife, you want it to register flat to the other work piece, straight edge or marking gauge. This is so that the fibers of the wood will cut away in one direction.

I use a small benchtop disc sander to grind and form the edge as you see in the picture. You can use just sanding paper for that too, but the disc sander is faster. You dont want the metal to overheat. It's not good for the knife or the sanding paper. So keep it cool with some water.

Just grind until you have the shape. The knife don't need to be sharp, just yet.

I will make a small hole with a 3 mm drill bit, so I can later fasten the leather strips/small strap. I don't have those for carrying, but for security, so you can feel without looking whats the handle part and the sharp part of the knife.

Step 4: Hardening and Annealing

If you have a forge - use that. 😊

I didn't so I made a make-shift "forge" in my portable barbecue grill.

Not shown in pictures, is that I used a air pump blowing trough a metal pipe to get the heat up faster.

I put a magnet in the end of a wooden piece and had a cup of oil next to it.

I heated the metal until glowing red (at least the edge-part). If you do this, you can harden the entire blade, but I just focused on the edge.

I quickly test the metal against the magnet to see if it has lost it's magnetic abilities. If so - the metal should be heated high enough. I then quickle quench it in (old motor) oil. This procedure will harden the blade but also make it brittle.

After that I let the metal pieces cool off, so I can hold it in my hand. I then put it back in the barbecue grill, without the extra added air flow. Just to annealing it (temper it). I let it sit in the grill, cooling slowly over night.

Step 5: Oxidizing the Metal (very Optional)

I didn't want the blade to be too shiny, so I put the metal pieces in a bath of concentraded vinegar and salt. This will remove rust, but also make the metal mat/greyish. I think it looks cool. 😊

I let the blade soak about an hour and clean it with water.

If you do this - know that the metal is very keen to rust again, so put a little oil on it as soon as possible for protection.

Step 6: Getting the Blade Sharp

Next I will grind the blade with my grinding stones to make an sharp edge. I use 600+ grit "stones". When I'm satisfied I use the buff wheel to get the extra sharpness. Remember - one side is flat with this type of knife.

I use a drillpress, but you can do this by hand.

Step 7: Marking Knife Is Done!

After putting on the leather strip/strap the knife is done. As you can see in the pictures I also marked them using a punching letters. I think they came out great. I'm very happy with the result.

If I were to make these again (and I will), I will make the handle part with a small taper, just to have a better grip.

The steel seems very good, and still keeps the sharpness of the edge. I will make more stuff from this mystery steel in the future.

Thanks for reading this instructable - hopefully it inspire someone to try it out!

If you liked it - please consider following me here and leave a comment if you want!

It will fuel me to make more and better instructables in the future. Thanks again! Here is a link to my video again, if you would like to see me making this blade in moving pictures. 😊

Also - I will enter the Metal Work Contest with this contribution. Please consider giving me a vote if you like this! Would be much appreciated! 😊