Making a knife from a file

G

GIBBY

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Oct 27, 2004
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Probably been answered before but I would like to know what is the heat treat oven formula to soften a file so that it can be worked and not brittle? How long at what temp and what's the best way to cool it? Water, oil, bury it in sand, etc....
Thanks, Mike
 
heat until glowing red and let it cool slowly
This will soften the steel so you can work it
I've done it a few times by having the file in the fireplace, run a fire in the evening and let it cool slowly overnight
Lay it flat at the bottom
 
Do you want to work it from a softer tempered state or from an annealed state? If you anneal it, you will have to heat treat it again after shaping the blade.
 
I anneal mine by heating them to Red orange then shoving them in a bucket of sand. Leave for a few hours then theynare soft enough to file. I heat treat them by getting them a few shades hotter than nonmagnetic the trying to keep the there for about five minutes the quench in warm canola oil. I am pretty low tech so this is not the best heat treat but it still makes a good edge. I then temper at 400 for an hour, twice. I don't sell my blades but I do use them a lot. This seems to work well for me.
 
From what I gather from Kevin Cashen and other metallurgists....high carbon steels (assuming the file is good high carbon steel and not case hardened or other non suitable material), should not get the vermiculite (or sand or anything slower than a still air quench) treatment. If they do get it, then they should be normalized and then subsequently thermal cycled (to take care of any possible grain growth during normalizing) after the machining is done. Any cooling that is slower than still air will place pro eutectoid carbides at the grain boundary...which gives a brittle steel. Of course, with forge type heat treat set ups, a spheroidized anneal is kinda hard. What I do is quench at 1475, then place into the oven at 1225°F for 2.5 hours....works wonders! But if you don't have that ability, I would cycle the blade in your heat treat set up a few times at around 1300°F. Get it to 1300°F, equalize, air cool to black. Repeat three or four times. This will soften the file well enough to grind on, without the vermiculite/sand slow cooling and bad carbide placement.
 
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Depends on whether you want to forge it or grind it to shape.

If you want to forge it, it's going to require the same annealing/normalizing/HT as any other piece of steel.

If you just want to grind bevels and an edge on a file, I say skip all that... just temper it at 350-375F in your kitchen oven a couple times to bring it down to around 58Rc or so, then grind it. Keep the blade cool as you grind, of course.

You can either use carbide bits to drill pin/bolt holes, or "spot-temper" the tang with a torch to soften it enough to drill with normal bits.

Making knives from old files isn't the very best way to go, for various reasons... but it can work. Have fun!
 
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