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Old 03-17-2019, 09:36 PM
jimmontg jimmontg is offline
Join Date: Jan 2016
Location: Now live in Las Cruces NM.
Posts: 1,246
Talking Nicholson Black Diamond files are not mystery steel to me.

I only use old Nicholson files, hopefully Black Diamond ones. I had one analyzed by Peters Heat Treat with a laser analyser, well try 1.7% carbon, 1.2 chrome and .7 tungsten with 1.0 manganese. Basically a superior W2 tool steel, but I wouldn't quench in water. Maybe boiling brine.
I have Nicholson files from the 60s and 70s that I still use including a needle file set. I kept them clean and oiled. I have two files I tempered and I will grind them into a knife, one is 3/16 thick and 12 inches long and will be a fighter. The other is 10 inches and 1/8 thick, I'm not sure what I'll do with it, but both will have through tangs.
I don't anneal Nicholson files, I temper them at 425 for 2 hours which gives me a hardness of Rc59-60 and grind to shape watching heat build up so as not to change the heat treat. With the new lubed ceramic belts it's fairly easy to finish them without any trouble.
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