Spyderco Forums

Sal,
Do you know how the Chalif knives were being sharpened? I've worked in the kosher certification industry before, but not in any meat processing or kosher slaughtering. If I recall, each knife has to pass a certain set of tests, but how the knives are sharpened sometimes differs from individual to individual.

Sal,
Thinking more about what Steve said, were he saw honing steels being used with pressure, do you think that could have an influence in use? What about for sharpening if that was part of the sharpening process with the MBS 30 Chalif knives? If the steel was fatigued that could explain a lot.

Hi Jason,

I've seen a variety of sharpening methods, from small stones with short motions to large sweeping motions on large stones. I was really impressed. These guys know what they're doing when it comes to sharpening. I don't think they would press too hard on their very thin edges.

The inspection on the edges was done with a loupe looking for nicks.

sal

Sal,
That's what I have heard also, that they are good sharpeners. I have seen videos of them sharpening and read about the guidelines they use for the edges they desire. So the nicks were coming from when they were sharpening the blades? I have had a similar thing happen with micro-chipping using 154CM at 7DPS and a high polish. When I took the edge back down to 10DPS the micro-chipping disappeared. Same thing happened with D2. I couldn't see the chips with the naked eye, and only discovered them while push cutting cigarette paper. I was able to see them under a loupe, and could feel the micro-chip when running my nail along the blade edge. This is also a test the kosher slaughterers use to check their knives, but they do it 8 or 10 times on each finger. I can't remember if they check with the thumbs or not. I thought the micro-chipping might have happened during use, but I am not sure as the blades were freshly sharpened, and on a part of the blade I hadn't been using.

sal wrote: ↑

Sun Dec 30, 2018 12:24 am

Supersteelsteve wrote: ↑

Sat Dec 29, 2018 9:14 pm

How were you guys able to tell that what they were experiencing was from carbide tear out and opposed
To just edge damage from honing, or the very thin edges sliding up against the chickens spine?

Hi Steve,

the Rabbi's said they were getting nicks. It was not until we examined the Magna-fluxed edge under a microscope that we could see cracks. The conclusion was from Prof Onoue. I have to trust his judgement. He is so revered in Japan that the government lets him cut core samples out of ancient Swords for research.

sal

Thanks again for the info.

Time to get flamed lol... here we go..

Being that 440c is a relatively low carbide steel, and you experienced carbide tear out during use with 440c,..

and you said these were extremely thin geometies...

Can we start to conclude that the edge geometry /steel type ratio is more the deciding factor in carbide tearout during use than carbide content?

jasonstone20 wrote: ↑

Sat Dec 29, 2018 10:13 pm

Carbide tear out during wear is a real thing, this is how medium to high carbide steels wear, by chipping. It is a completely different matter to say that you sharpened a knife and had carbide tear out due to abrasive used. This is what is in dispute, not that it cannot happen, it can, it is just rare and thereby not a common problem. Also, it is interesting that a steel like 440C/MBS 30, not a PM 'Super Steel' was victim of carbide tear out when taking to a thin edge. This is because the steel doesn't have a high edge stability as Dr. Roman Landes describes, while MBS 26 has a good level of edge stability. Also, those are chromium carbides, which can be cut with common abrasives, not the Vanadium carbides often blamed for carbide tear out. It is going to be greatly informative to see the Spyderco report on the MBS 30 carbide tear out problem.

Yes yes yes!
I love you jason