File tempering

[jcullen]

I've read you can put a Nicholson file in the kitchen oven @ 450 for 2 hrs. and it will drop the existing hardness to make the file workable. It can be ground and does not need to be re-tempered.....

 

[Doug Lester]

First of all some of the Nicholson files made these days are cases hardened and are thus unsuitable for knife making. If you have a file that is made from high carbon steel then drawing the temper in the file and then making a blade from it can work, I just don't know if I would go all the way up to 450°, I think that I would stop at 400° to keep a bit more hardness in it for the finished blade. It will be harder and slower to grind the blade and you will need to cool often to keep from drawing the temper further when grinding. It's basically the same thing as when some makers like to harden and temper thin blades before grinding the bevels.

Doug

 

[LRB]

I've read you can put a Nicholson file in the kitchen oven @ 450 for 2 hrs. and it will drop the existing hardness to make the file workable. It can be ground and does not need to be re-tempered.....

Yes, that can be done, but you will find grinding without over heating to be very slow going. You will find that any file shaping on it will be near impossible. You will find that Nicholson files make excellent blades, but better to spheroidize anneal it and reheat treat after shaping, if you have access to a HT oven. If not, temper between 400° and 450°, then grind it slow and careful cooling often.