Marking Knife From Old File

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About: Open to learn new things. every time try something new.

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.

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    6 Discussions

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    AllenL17

    2 months ago

    Good looking knife. I made some fancy turned knife with a purchased blade. However, I love the look and simplicity of your design. I am going to have to make one. Thanks for the great instructable.

    About hardening the file:
    The file should be hard enough without rehardening for marking wood. Files are typically hardened to begin with. That is if you take your time grinding with lots of quenching in water you should wind up with a pretty hard file.

    If you decide to try and harden it, you should temper it after it cools down from the hardening process. Tempering relieves the stresses introduced by hardening. Tempering is easy. You can put the hardened item in a toaster oven at 200 to 300 f for a half hour or so. Let it cool down naturally. Tempering makes the knife less brittle and thus the edge will be less likely to chip.

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    tomzi1234AllenL17

    Reply 8 weeks ago

    Thank you.

    About hardening. I am not sure if file is not only cemented or. i dont know what is called. that only outer part has enough of carbon. and the middle part could be soft.

    But even not hardened is works fine. so it looks like it is hard enoug for wood.

    i love to use it. :)

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    tomzi1234jimydog69

    Reply 5 months ago

    Thanx for advice. i know that for drilling, i did't know for bench grinder. Thank you.

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    Jake_Makes

    5 months ago

    Yeah, it's near impossible to get a blade up to critical temp with a regular torch. Nice job on the knife. Looks good.

    1 reply
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    tomzi1234Jake_Makes

    Reply 5 months ago

    i see, you are talking form experience :) thank you.