Intro: Marking Knife From Old File
It was a very simple and quick project.
I need a new marking knife to be able to mark something flat with a surface. That's why i decided for a design without a wooden handle.
I also choose dual bevel design because i find it simpler to be able to mark on both side or it goes both way.
Step 1: Marking and Cutting a File
For marking i use a simple marking tape and draw a simple design over it.
Than i follow the lines to cut the rough shape of it.
First i cut outer straight lines.
Than i rough cut rounds. and than i grind them to shape with grinding disk.
After the shape was OK, i start to grins the edge. and also grind off file teeth on the tip. Otherwise the blade would have teeth.
Step 2: Hardenind
I have to admit, this step was more of attempt of hardening than real hardening. My torch was not even close of hot enough. Only the tip of knife got cherry red. So i hope the most important part of knife is little harder :)
The theory is to heat it up till cherry red or till metal looses magnetism (magnet don't stick to it), than quickly put it in to water. And try to put it as straight as possible. That stress in metal don't pull it one way and bend the knife.
Step 3: Shapening
Final step was grinding on bench grinder for course grind. Don't forget to cool the knife. Bench grinder produces a lot of heat.
After that it was time for water stone. I used 1000 grit and polishing on 3000 grit.
Step 4: The Knife
It turned quite nice. it has some grinding marks that could be polished away, but already tested on stairs that i was doing, and it works like a charm.
I recommend a marking knife for all of you that are playing with wood.