File test

H

hellgap

Joined
Dec 17, 2008
Messages
1,189
ok if i have hardened the blade should a file slide off the blade steel and not cut into it . please explain thanks kellyw
 
It should skate across the hardened edge. After tempering (depending on the hardness you temper to) it should slightly bite in. We're talking about using a fairly new file for this.
 
Have been using a center punch to test all my heat treating. If it leaves a mark and doesn't distort the punch, its not hard, if it flattens the punch, and leaves a slight mark its somewhat hard, if if it doesn't leave a mark... I did something right lol. This is something I have done with only the scrap spring steel I have been working with.
 
Bear in mind that the file test is not a conclusive test for hardness. It is often the best many of us can do without a Rockwell tester, but a common file will not cut any steel harder than 58 Rc, so in reality, one still cannot be sure full hardness was achieved when using just a file test.
 
john0270 said:
Have been using a center punch to test all my heat treating. If it leaves a mark and doesn't distort the punch, its not hard, if it flattens the punch, and leaves a slight mark its somewhat hard, if if it doesn't leave a mark
Click to expand...

I use a Rockwell handness tester to determine this. :D
 
Smarty pants Barkes :)

File test to me is just a quick way to tell if the HT kind of worked. Since that's all I've got, it's all I use. It's not a magic bullet, and it's not exceptionally accurate, but it's better than a guess. There's a distinct sound difference as well between a file on hardened steel and a file on soft steel. Try your blade next to a piece of scrap and you'll see and hear the difference.
 
jkf96a said:
Smarty pants Barkes :)

File test to me is just a quick way to tell if the HT kind of worked. Since that's all I've got, it's all I use. It's not a magic bullet, and it's not exceptionally accurate, but it's better than a guess. There's a distinct sound difference as well between a file on hardened steel and a file on soft steel. Try your blade next to a piece of scrap and you'll see and hear the difference.
Click to expand...

Checking the blade with a file is one way to determined if the steel became hard. I prefer the Rockwell tester, This is my steps I take here in my shop to offer the best in performance. And its not a matter of being smarty Pants, it just being sensible in my determination. But like you stated use what you have and I do. :D

1, Color Test - Gold/ Bronzes
2, File Test - Skip
3, Rockwell Test - 59 to 62.1/2
_________________________

Terry
 
A file test will tell you it the surface is harder to penetrate than the file tooth will easily cut.
you may have enough carbides at the surface to dissuade the file, on the other hand, you may have correctly hardened the blade but still have a soft layer of decarb that the file just eats right through. File testing tells you a little, but without any other testing (can a corner cut a piece of steel of known hardness for example, or an actual rockwell tester,) you're just shooting in the dark

-Page
 
Just simply skating any old file isn't enough... A dull file will start to skate around a Rockwell 50. Sharp files are better at higher hardnesses.

The amount of pressure and the size of the surface area of contact are also factors that effect the test.

You need to do some comprehensive hardness comparisons with other blades or samples of known hardness and composition. The sound that it makes and the amount of luster or lack of luster from the file should also be taken into account.

Another little trick is to lay a sheet of white paper under the pieces being compared and look for particles. If it's close to the hardness of a file, you won't see too many, if any, particles or filings coming off. With a hardness of 58 you will see a significant amount if done right.

You can't just go by feel. :)
 
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