Filing guide hardness

[Crockett]

I made a file guide from O1. One of the two pieces snapped in half the first time I tried to use it. I'm making another one. The first one I left at full hardness with no temper whatsoever. Should I temper my new one? Of course I want it to be as hard as possible. I wonder if a quick tempering at a low temperature might help prevent cracking, but still leave it hard enough. Thoughts?
Thanks,
Don

[WBE]

Temper at 375? and you should be fine. Even 400? will not allow a file to cut it, if you achieved full hardness. A common file does not cut steel harder than 58/59 Rc.

[Mike Krall]

You should be able to "snap temper" the O1. That is, 300F for an hour or two. It will be as-quenched hardness without out the brittleness.

Where's 'mete' when you need him? =]

Mike

[mete]

I'm right here Mike ! I'd go 350-400 F. That way you should get full hardness without any brittleness.

[Mike Krall]

'mete',

From your point of reference, what are the problems you see with HT-ing a filing jig at snap-temper? Not disagreement... looking to learn something.

Mike

[mete]

First a comment to Don and others . Many don't appreciate that O-1 is not a simple steel as it has enough alloying elements to make a proper soak significant .That's the first step in getting full hardness.
I'd like to see a 'snap temper 'used to make cryo a bit safer .Other uses need a higher temper .After all they call it a snap temper not just a temper. In my early training 400 F was a common standard for tempering tool steels .
One source gives 62 HRc at 300 F, 61 at 350 F and 59 at 400 F.
Another point make sure it's polished - no machining marks !

[Crockett]

Thanks guys! I temepred at 375. Seems to be OK so far, except I need to make a bigger one.
Don