What is a good file for testing hardness with?

SkagSig40

SkagSig40

Joined
Feb 1, 2001
Messages
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I want to get one. Right know I use the tip of my Sebenza which is between 62-63 rc. I think a file would be alot better. Does it need to be a certain width and what about the "teeth" do they need to be a certain size? Thanks for the help!!
 
Chris - MOST (not all) files are slightly above 60 Rc. I use a small Corbet, very, very fine cut, so that when it does cut an edge, the damage is slight and easily touched up with a stone. Nicholson, or any quality brand will have the fine cut and hardness required.
This is a comparative test, even with the Rockwell equipment. Some good metallurgists can read an edge with a file almost as accurately as their guages. If the file bites the edge, the edge is softer than the file, if the file skips, the edge is harder than the file....the file is about 60Rc, ergo the edge is...oh, well, you get the picture:) If it really grabs you, and you "just gotta know", go dog nuts and buy one of these :D

http://www.flexbar.com/product_hard_quickcheck.htm

BTW - use the file as though it was a small hand stone, sharpening the edge, but gently. Be prepared for it to hit the "sweet spot" and skip. If you are bearing down just a little, the skip can be painful. And messy.
 
I've used an old finishing file (little teeth) for years. If fact, for so many years I probably should get a new one.

Good advice and help, Wal.
 
Originally posted by SkagSig40
I want to get one. Right know I use the tip of my Sebenza which is between 62-63 rc. I think a file would be alot better. Does it need to be a certain width and what about the "teeth" do they need to be a certain size? Thanks for the help!!
Click to expand...

Chris if you're gonna get a file for just testing the edge hardnesses I would recommend a Nicholson Smooth or Flat Bastard in the 6 inch size. If I were also planning on using it for the occasional touchup I would get the same file in an 8 inch.
The 8" file will do some serious work. For really serious work get a 10 inch. Always get a file handle for each file you have.
And get a 'File Card' to keep your files clean. The File Card is a device with hook like teeth on one side and a heavy bristled brush on the other. The steel 'teeth' cleans any dill berries out of the file's teeth and the brush keeps the files from gathering fines and such.
Keep you files clean and rust free and they will last for years.
 
Somewhere somebody sells a little file kit for testing Rc. Start with the softest of the test files and work your way up until you find the one that cuts and you peg the Rc. But, as usual, I don't know who it is selling these kits or where one might buy them.
 
Thanks Wal, Yvsa and Uncle Bill!! That just about answers my question!

About how much pressure/force do I need to use when I'm just testing for Rc. Do I just lay the file on the blade and slide it across with only it's own weight or do I want to use light, medium or heavy pressure?

Thank you for the help!!:)
 
Originally posted by Bill Martino
I'd guess I use light to medium pressure.
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Exactly!!!! Just as though you were trying to sharpen the blade with the file, but not a true, full stroke - as soon as you feel the file begin to bite, back off. As soon as you feel the file begin to skip, when it should have started to bite, back off. In either case, you should be able to immediately feel "softer" or "harder" and that's all the filing the blade needs, and all you need to get the info you're after.
 
It's a comparative thing -- try your file on a bunch of your knives and see how it feels and sounds and looks. You already know how those knives act in use, so when you try the file on a new knife you'll have something to compare with.

Those multi-file hardness testing kits are controversial. A few knifemakers like them, but most don't. They're expensive and they still require judgement and experience and the softer files wear out very fast because you're using them on steel harder than they are -- even just one swipe wears them significantly -- so in order for the test to be at all accurate you have to keep replacing the softer files, and they're expensive, and most of us figure we can do at least as well with just an ordinary file and some experience. Experience doesn't take long to get if you have a bunch of knives around to calibrate yourself with. Try it on other things, too, springs, hardened bolts, whatever's handy.

FWIW most files are made of O1 or similar steels at full hardness, and O1 at full hardness is RC63. That doesn't mean it'll cut a knife that's also at RC63, of course. It's just comparison ... I suggest trying it with different files, too, just to see how much difference that makes (not much, usually). Then you won't have to worry about losing the only file you've ever done that test with.
 
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