Hardness testing files

C

Cappe23

Joined
Dec 6, 2015
Messages
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Hey everyone

I was looking to buy a kit of hardness testing files, but the price varies a lot.
You can find these kits for around $70-90 on ebay or amazon, but I've found similar kits for $120 or more.
What is the difference between them and is it worth the price difference?

Thank you in advance
Casper Michiels
 
I don't know the differences between brands, but I did try some a few years back and didn't have much luck. If I remember, they were precise to only 2 Rc, and using them was a nightmare. I gave up on them.
 
I know they are not very precise, but I would like to have some verification that my knives have somewhat good hardness. The hardening and tempering is really just guesswork at this at this point.
I always use O1 and right after heat treat I can skate a file on the blade but sometimes I really can't cut it anymore with a file and other times I can still file a little dent in the edge if I use the corner of the file.
And defenitely have no idea anymore what the hardness is after tempering, so it would be nice to just have a vague idea of the hardness.

This may or may not seem a stupid question, but can you somewhat check the hardness by trying to scratch the blade with another knife that you know the hardness of?
 
You can get quite good hrc estimate by scratch against hardness test blocks. Test block is better than blade with known hardness because you can control/modify contact area.

1. Ask & buy test blocks perhaps from a knife maker. 1095/W2/O1 1/8-5/32" thick, 1" W x 5" L with a couple holes for attach simple handle. Tempered HRC 59, 61, 63, 65.
2. a small 600-1000 grit diamond file
3. perm marker
4. 20-30x loupe

Let's blindly determine hrc among test blocks. gently diamond file the 90* edge of block; perm marker those scratches; rub ~1" length of marked edge against each other for all combination. Under loupe magnification - 65rc block will retained marker at trough of diamond scratches, X out 65rc tests. determine 63rc block next, so on. Square grind the test block edge (90 degrees) ready for test against your blades. Most of the time you probably don't need to square/erase marked scratches of 63 & 65rc blocks.
 
" Blindly " ? We had a group of blind workers to do regular tests for QC of bearings .It worked well.
 
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