tempering?

[alex_111]

hey, all.
i'm about to start making my second and third blades. i'm planning on using a file as a blank (again) because i like the look of the first blade i made that way, and it holds an edge very well (especially with its convex grind).
a question, however, has arisen.
on my first blade, i somply used jb-weld to hold on some curly maple handle scales. this worked very well, but the only reason i did so was because i couldn't drill through the tool steel. i figured that i'd try to take the temper off this time, before i start grinding. can i do this with a toaster-oven? i read somewhere that it's possible, but would like more information.
thanks.
aleX.

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"i flip you... i flip you for real..."

 

[Paracelsus]

Alex, what you want to do is called Annealing. This involves heating the blade up to the critical (non-magnetic) temperature, and cooling it very slowly. This will make the file very soft and easy to grind and drill. You can't do this with an oven. You need about 1800 degrees F. After shaping, you will need to normalize, harden, and then temper the blade again. Ask in the shop talk forum for more help.

You could just try to take some of the hardness out of the file by tempering, or using relatively low heat for several hours to soften the steel. However, if you temper too much, you will make the blade too soft for use as a knife blade. Again, ask this question in the shop talk forum.

One last point, not all files are the same. Case hardened files will make lousy knives. You need to find files or rasps made from tool steels like W2 or 1095.

Good luck.

 

[Cougar Allen]

The Shop Talk forum is the place to go with all questions about making knives. This thread will probably get moved there soon....

Files are made of O1 or similar. Ideally you would begin by annealing it -- heat to a cherry red glow or even better, heat till a magnet will no longer stick to it -- then let it cool in air. Then you'll have a nice soft blank, barely harder than mild steel, so you can grind it to shape with a lot less work than grinding hardened steel.

Then after shaping it you'll have to harden it again and then temper it. Harden by heating to nonmagnetic again and this time quench it in oil. It makes little difference what kind of oil you use; used crankcase oil is fine.

Then temper by heating to 425 degrees Fahrenheit and let it cool. You can do that in an oven but most toaster ovens are not good because they don't heat uniformly. Use the big oven and check its thermostat with an oven thermometer. Ovens are always hotter than the thermostat is set to and the older they get the hotter they get. Be careful to clean all oil off the blade with solvent or you'll smoke up the kitchen and your wife will have a cow.

It sounds like you have a knife you already ground from a file without annealing or tempering it. You can temper that knife now (which will make it less brittle) but you'll have to remove the scales first. You can remove epoxy by soaking in acetone (nail polish remover) or paint stripper. It'll probably take a couple of hours of soaking.

For your next knife, if you don't have a means to heat it red hot to anneal it (you can't do that in an oven) you can at least temper it before grinding; that'll make it easier. It'll be much easier to grind if you can find a way to anneal it.

I've just outlined the basic procedure ... there are refinements such as triple-tempering and heating the oil ... heat-treating is covered in great detail in the Shop Talk forum; use the search function. Some of the best knifemakers in the world hang out in that forum and they're a tremendous resource.



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-Cougar :{)
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