The likely reason they instruct you to start with the hardest file is so that you don't dull all of your softer files just to find out that your knife is 65 HRC.
I actually saw a Rockwell tester at an estate sale many years ago. It was $30. Thirty damn dollars. Didn’t know what it was at the time. The memory of leaving it there without buying it will forever haunt me.
You should take them and use them like files at the edge, see if they skate or bite. Make sure the teeth are going the right direction. Start with the bottom one which will skate for sure than take note when the file bites at higher hardness.
I worked as a professional material tester in a steel factory in Germany and let me tell you this: Your testing method might be MORE accurate than the rockwell testing machines, if you get a set of files which is more accurate than 5 HRc steps (given that these files really have the hardness they are supposed to have and their own hardness is NOT tested with the Rockwell method itself, lol). In the ISO norm the testing machines have +/-1.5 HRc tolerance and even when we calibrated the machine using special testing plates (with different hardness) such a plate which is supposed to be (e.g.) 55 HRc +/-0,2 was ending up with values between 54,5 and 55,5 HRc, which is totally normal, since the ISO norm (6508-2) claims that a tolerance of 0,8 Rockwell units is acceptable for a testing plate (which is used for calibrating the machine). Now we had an old rockwell hardness tester in our company and modern machines might be more accurate, but the point is - if you for instance order a custom made knife and you want 60 HRc it is totally possible that (even if nothing goes wrong with the heat treatment) you get one which has 58,5 HRc on the lower end or 61,5 HRc on the upper end and the testing machine would be totally alright, it is just an inaccurate testing method. What I recommend is measuring the hardness in Vickers and convert it to Rockwell, in my experience it is much more accurate and foolproof, because Rockwell testing might include human error when fixing the pre(paration) pressure (before the main force is applied, the method requires some tension). We were doing this all the time in the factory, because Rockwell is such an inaccurate testing method.
I have a large heavy duty Ganzo folder in 440C, it's gotta be around 61 or something because I tested it opening a can of beans, and it dulled the edge a bit but not nearly as much as I expected, and I was able to sharpen it up quickly. Shockingly good heat treat on an uber budget knife
I always wondered how hardness is tested, thanks for an instructive video. Taking the opportunity, have you tested the hardness of the much advertised Huusk knife?
Several things. First. The reason why they say to start with the hardest file is so that you don’t damage the softer files on hard surfaces. If you do it the other way, the low hardness files will rapidly become damaged. So yes, their instructions do make sense. Generally, you’re not supposed to “test” finished products. Second, the word scratch is not the best choice. Even a softer file will “scratch” a harder surface. But it’s more of a micro polish. Actually, the file should dig slightly into the surface. Don’t do what you’re doing by rapidly moving the file over the surface. That’s not the correct way to do this. Press down with moderate force, and push slightly downwards while pushing forwards. Do this a couple of times, and that’s it. If it digs in, go to the next lower number until the file skates over the surface. That’s the lower limit. But even then you may get that slight polish mark. Ignore that. And remember that these files, while marked with a RC number, can be plus or minus one RC from that number.
Very interesting video brother. I’ve heard of scratch testing but I wasn’t aware that there were kits available for doing it. I don’t know that I wanna scratch up very many of my knives but it is very tempting to get a kit and get some ballpark numbers on some of my cheaper ones(like my Ganzos, ha). Very cool and great idea. Thanks for the info. 👍
Negligible difference in the vast majority of scenarios and considering the already loose results of this testing method. It’s actually more difficult to abrade a higher grit finish than a lower one. The flatter and smoother the surface, the more resistant it is to abrasion. A lower grit finish is going to have more pronounced peaks and valleys for the file to bite into. Like microscopic jimping. 😀👍
Hello! Please, can someone explain to me? I'm about to buy product which I was told is forged under HRC28 and other part under HRC40 degrees. Is it considered as good quality or its normal one? Thanks
You can do the same thing with another knife. For example i have a morakniv classic that's right around 58 59 and moras are very consistent. When i take the tip and try to scratch a knife and it won't the said knife is 58 59 or harder if it does scratch like say a victorinox will its softer and i dont want it lol
Very interesting. Not sure D2 is supposed to be that high well if it is 60 then that would be fine. I was surprised expected to see somewhere in upper 50s. Interesting little kit. I wouldn't want to do that on too many knives. At least not before use and once it has some use marks in it then maybe. Very good review. Glad you showed it didn't know anything like that existed.
In another video, the hardness was tested out ar HRC61, which would be at the high end of 440c, so Ganzo does a pretty darn good job. I haven't seen the newer D2 blades tested yet.
Yeah, 61 would be pretty hard for 440c. I've heard that Ganzo's D2 has been testing fairly high as well. Not that I doubt their steel, but I had to test one myself. Thanks for watching Jim.
Wouldn't the test be largely dependent upon the pressure (and angle, to a degree, no pun intended...) you apply to the file? I would also think the length of stroke might effect it especially if you have a nitride coating, b/c you will have to scratch through the coating and then continue to have to scratch the metal, and every time you change direction, you are going to release the pressure a little and then have to start to scratch through a coating again. If any of the knives have a thick nitride coating, I doubt these files are going to do much to scratch through them considering most coatings start at a hardness of about 85 C IIRC. Even anodized aluminum (aluminum oxide layer) has a rockwell hardness of 60-70 C, which is pretty impressive considering how relatively soft pure aluminum is compared to steel.
There are so many variables to try and control, which is why I said this is not an accurate method. I wouldn't try this test on a coated blade of any kind. Really, it's more for fun or to get an approximate on a knife that might be counterfeit. Thanks for watching.
I ain't rubbin that thing on my cheap azz, Lightning Elite OTF EDC's !!! I love'em too much and own a Wicked Edge gen 3 pro. So I can sharpen any time I want. It's my side gig and Zen moments. I watch Clay owner of Wicked Edge, its all I need. I'm more interested in why every gawd damn knife today is D2!!!!!! IT STAINS AND RUSTS EZ. What ever happened to Stainless steels ❓❓❓❓❓❓ VG10, AUS8, OR AUS10. I'M SICK OF THE D2 PHENOMENON.
You are scratching way too much and damaging your knife. A couple of strokes is enough. You should also pay attention to the FEEL (tactile feedback) that the sliding offers - if it bites into the material, then it's harder than it, if it slides off, then it is softer than it. Depending on the purpose - you can start from the black and go direction red which will give most life to the kit itself, while going the other way around will make least damage to the material being tested.
Actually there is optimal hardness at witch certain steel is easier to resharpen.. For example s35vn at 59-60 will behave better than the one at 56 cause this soft the steels is really gummy and create nasty burr.. Steel should be at it's optimum hardness for maximizing it's properties.. What I will say is with same example I mentioned it's easier to reprofile softer steel.. Kinda a tricky thing to explain but this is my experience cause I have 2 knives in s35vn and ones of them is just 56.4 and another at 59.2 and trust me the softer one takes much longer to achieve same level of sharpness..
I don't doubt that. It's all about that very important heat treat, which unfortunately varies with these production folders. Do you scratch test your knives to obtain that HRC?
