Nicholson Black Diamond Files

[cigardoghd]

So I was meandering around a local flea market this weekend and an old fella had a tool box full of old Nicholson Black Diamond files for super cheap so I bought all of them. Now I know a lot of people think that files aren't an ideal knife material, but for what I've got in them, I'd like to try them out. From what I understand, the run of the mill Nicholson files are 1095. However, after researching as best I can, I've seen in a couple forums that the Black Diamonds can have as much as 1.25 carbon content? If this is so, how would I go about getting the correct heat treat/hardness? Could I simply temper them down and work them as is carefully without getting them too hot and skip the heat treat? If so, what's the process for doing that? Thanks for the help guys.

 

[Jason Fry]

Yes, you can temper them down and work them at knife hardness. Around 500 degrees is a good place to start, for an hour, twice. You may have to spot heat your pin holes with a torch to get them to drill.

The other option is to anneal them, say 1200-1300 for an hour, then re-heat treat them. It would be a bit of trial and error at that point, but you could certainly figure it out.

 

[cigardoghd]

Yes, you can temper them down and work them at knife hardness. Around 500 degrees is a good place to start, for an hour, twice. You may have to spot heat your pin holes with a torch to get them to drill.

The other option is to anneal them, say 1200-1300 for an hour, then re-heat treat them. It would be a bit of trial and error at that point, but you could certainly figure it out.

What would be the best way to do that? Hold the blade edge in water and just draw hole locations out to a certain color?

 

[Jason Fry]

I put the blade end in my vise, which acts as a heat sink to protect the blade. I usually draw out the pin locations through all the colors till it goes gray. Temp is in the 650-700 range at that point, IIRC.