Tempering a file

[Pete Allan]

A good friend of mine brought in a very worn out, old, file he found in his late Grandfathers's tool box. Says he would like for me to grind it into a "canoe" knife. A canoe knife is a fur trade era item sort of like a draw knife. I think the file could be at least 50 to 75 yrs old as my friend and I are both in our 70s so I don't think there is a chance of it being case hardened. I feel I should temper it back away from the brittle state it is in now so it won't simply snap when he goes to use it. Any one know what temp I should use to bring it back to say the upper 50s RC??? THANKS

 

[tnmike]

In order to work the file into something usable you will need to anneal it.(soften it) The way to do this is to bring the file to non magnetic heat two times and cool to room temp . Bring it to nonmagnetic a third time and place it in a barrel of vermiculite or ashes and let cool. This will soften the file so that you can grind it or forge it.

When you are ready to harden it bring to non magnetic and quench in oil. After it cools to room temperature temper it in an oven at 425F for an hour. Do this twice letting it cool to room temp.

Ive had very good luck making tools with files in this manner. (chisels, knives, drawknives etc)

 

[longline charlie]

I have had good luck with file knives. Heres how I was told to do it and it seems to work.
Grind or sand the fiile to shape holding in your bare hands. Do not ever let the edge get red hot. Keep a pitcher of icewater sitting beside your grinder. Once you have the teeth all ground off and the outline of your blade design ground in be extra careful about getting the blade hot. If you are holding in in your bare hands and not allowing the edge to turn red, you are not removing too much temper. After you get it ground to shape and the edges are sharp and you have not let it get too hot, go on to the polishing wheel from the 320 grit sanding. Same again make sure you are not overheating the edges of your blade. When its shines like a new Silver Dollar you are ready to anneal it to a useable Knife temper. Put it in your wifes oven at 450 for about 30 minutes and it will turn a golden color. This should be approximately 58-60 Rockwell. When you sharpen in and remove the Gold color off the blade if you find it is still too hard you can raise the temperature by 50 degrees and do it again. If it is too soft, as you sharpen it the edge will get harder with each sharpening.

Like I said, many will disagree with this process but try it. You just might like it and its a lot cheaper than buying your own furnace or sending out to get it heat treated too.

I would advise a Mirror Polish on the blade though as it will rust very easy in a satin finish even with the best of care.