File testing for hardness

[Guy Thomas]

The idea, right, is to have a "glassy" feeling when you rub the file across a freshly hardened blade? Am I right in thinking the file will in fact scratch and "bite" into the steel if I actually bear down on the file? -Guy Thomas

 

[Sumo]

actually assuming the file is close to the same hardness as the blade it might scratch it up a bit, but it wont actually cut into it, but one thing you should do if that's going to be your primary way of checking hardness is to take a couple different files to someone with a hardness tester and get them to verify it's actually the right hardness.

What my heat treater did for situations where a part is too large or odd-shaped to fit into his rockwell tester was to take a couple of the same kind of file, and temper them down so he has a range of 'known' hardness files that he can guesstimate the hardness of a part to within a couple points.

As I posted in the ATS-34 post before, I recently had a problem with that where we hardened a 3V blade and the file bit into it like it was barely hard, but after getting it Rc'ed it came out at 62, so there's quite a variation in file hardness out there.

Rich

 

[Darrel Ralph]

Sumo
Just did the same on 3v . It is 61 rc and
The file will bite. The rule of thumb that I have heard is a dull file will skid. But as you can see it dosent always apply.

The 3v takes a wicked edge and performs well in most of my tests. Reminds me of D2 in a way..

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