General Hardness of Blades

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Buzsaw said:
Been sharpening knives for 40 years, I know immediately if the said steel is at where the company said it should be, but the average joe does not, I understand everyones concern about the companies being honest or are things slipping through QC.
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So, if the company says it is 60-62 RHC, you could tell me if its actually 63 HRC?
 
Buzsaw said:
I would be pretty close
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Close on an exponentially sliding scale.
Okay.
I get it. An experienced sharpener can tell differences in hardness by feel against the stone, but no one is a human Rockwell hardness tester.
 
So, if the company says it is 60-62 RHC, you could tell me if its actually 63 HRC?

What company says their knives are 60-62 HRC? Just curious.
 
Less Than Sharpest said:
So, if the company says it is 60-62 RHC, you could tell me if its actually 63 HRC?

What company says their knives are 60-62 HRC? Just curious.
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Just a theoretical example. Would you prefer 58-60? 57-59? HRC targets typically range by 2 points.
 
It used to be pretty common for HRC values to be published by manufacturers.

I haven't kept up with the practice as I generally get the information somewhere when I've inquired.
 
Arathol said:
Of course it is, everybody has learned how to do this in one form or another. Its a learning curve, something a few of the self appointed experts-on-everything around here need to learn something about....
Can you pick up a styrofoam coffee cup without crushing it and making a mess? Of course you can, because you have learned how much force it takes to crush it and know when to stop. Can you feed yourself without jabbing the back of your mouth with the fork? Of course you can because you learned how to use the right amount of force to avoid poking holes in your mouth. Can you start a car by turning a key without breaking the key off? I would think so, because you have learned how to apply the right amount of force every time. When was the last time you forgot how to open a door and twisted the knob off? Please stop trying to prove that you can't create muscle memory to do this sort of thing.



What did everyone do before 1938 when the torque wrench didn't exist? Lots of stuff got built without them you know......
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I've known plenty of mechanics in my lifetime and I have never seen one of them put an engine together without a 'high quality' torque wrench. And they would laugh you to scorn if you tried to use a cheap torque wrench! My father-in-law, may he rest in peace, used to build racing engines. He even used a torque wrench on the lug nuts when mounting tires.
 
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Richard338 said:
If you can hone your skills and senses to such a degree through repetition, just think of Wilt Chamberlain!
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Prolific repetition doesn't carry any guarantees for quality.

Less Than Sharpest said:
I was a sharpener at BM for about four years back in the old days, and at that time (mid nineties) they had the best edges available on a production knife. But there were several strange things happening and all the old guys were being shown the door, and I left while I still had a choice to make. I write this because I wanted to say that yes, I get it, muscle memory is important, and that sharpening 450 blades a day will lead to a certain knowledge, it's not easy. It's not fun.

A few year ago Microtech advertised nationally for a sharpener and I applied, and was one of three people chosen to go to their facility in NC and work closely with Tony as he shared his experience with us. One thing that I'll share is that Tony is very hard working. Most people have no idea how hard until they're exposed to it, but I'll say that he is not only hard working, his mind is always working not only with what he's doing but with tomorrow's problems and challenges as well. MT has my deepest respect because everyone who works there works very hard, and it shows. But I digress.

I originally started this post because I wanted to point out the difference between a manufacturer and a good custom maker. Obviously there are people who can & will HRC test every blade that they grind and have heat treated, and for those individuals it is a hard science. But I can tell you through years of real world experience knife manufacturing is not a hard science. I'm currently carrying two ZT knives but I know that people have measured some blades at 58 HRC, and that happens. I am simply trying to point out the difference between a custom maker and a manufacturer. To anyone who wants to sip their coffee and tell me I don't know what I'm talking about, I can't really offer anything else. I'm not trying to prove anything. To the great individuals who will post their real world experiences I extent a heartfelt thank you.

Sharpening is very different from building an engine, but I would agree that there are great engine builders who don't actually need to use a torque wrench. They will, for a variety of reasons, but they don't have to. And unless you're the one who's stood at a grinder day after day sharpening knives or you're a mechanic who's built hundreds of engines I don't think you really understand what you're writing about. If you just want to argue about it that's fine, the forum is open to all types.

To everyone who is willing to include their real world experiences, again, I say thanks. We can all learn something new each and every day if we're willing to. Just yesterday I learned at least two things. Let's all try to help each other out.

Cheers,
dt
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You're conflating precision with whether something is a hard science or not. Metallurgy is a hard science with strong ties to both physics and chemistry. That doesn't change depending on whether you test individually or samples from large batches. Either system entails specific inputs and processes in order to obtain a predictable, objective result. A mass production heat treat operation isn't any less scientific than individually heat treating knives. In fact, the statistical sampling and testing used in mass production is also a hard science.
 
jux t said:
But, who’s going to hardness test the hardness testers?
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sherlock-holmes-glass_550.jpg

"I knew it, Watson...this Rockwell is off by at least two points!"
 
You're conflating precision with whether something is a hard science or not. Metallurgy is a hard science with strong ties to both physics and chemistry. That doesn't change depending on whether you test individually or samples from large batches. Either system entails specific inputs and processes in order to obtain a predictable, objective result. A mass production heat treat operation isn't any less scientific than individually heat treating knives. In fact, the statistical sampling and testing used in mass production is also a hard science.


I'm not trying to a smartass here. You are not getting it. I wonder if you have ever visited a mass production heat treat operation with guys working for minimum wage worrying about the typical bs that a 20 year old minimum wage worker worries about. I have. I've listened to those guys. It's not rocket science to them. It's not hard science, either. They do their job. That's it. Maybe the person operating the furnace has been on the job for a few weeks. The customer comes and picks up their blades and then when they get back to their shop they might grab an assorted handful and Rockwell test them, or, they may not. Not matter what their brochure has printed on it. So a company says that a certain blade is a certain hardness. So what? Has anyone ever gotten their ass handled to them in court because a certain number of blades weren't at their specified hardness?
I don't think so, and frankly, I'm not interested in trying the system out.

I'm certain that you're correct in your own world. But in the world of knife manufacturing, bad things happen. I've seen bad things related to heat treating happen. It happens. And I've felt the somewhat rare but none the less real examples of soft steel. All I'm suggesting is that if you really care, and can afford it, buy a custom knife. If you can tell the difference, and a lot of people can believe it or not, then that maker is most likely going to listen to you. A manufacturer might listen, or they might just give you the run around for a few months and tell jokes about you. That part is not in the brochure, but I've heard the occasional jokes. The real world is somewhat different from what is written in books.
 
Less Than Sharpest said:
You're conflating precision with whether something is a hard science or not. Metallurgy is a hard science with strong ties to both physics and chemistry. That doesn't change depending on whether you test individually or samples from large batches. Either system entails specific inputs and processes in order to obtain a predictable, objective result. A mass production heat treat operation isn't any less scientific than individually heat treating knives. In fact, the statistical sampling and testing used in mass production is also a hard science.


I'm not trying to a smartass here. You are not getting it. I wonder if you have ever visited a mass production heat treat operation with guys working for minimum wage worrying about the typical bs that a 20 year old minimum wage worker worries about. I have. I've listened to those guys. It's not rocket science to them. It's not hard science, either. They do their job. That's it. Maybe the person operating the furnace has been on the job for a few weeks. The customer comes and picks up their blades and then when they get back to their shop they might grab an assorted handful and Rockwell test them, or, they may not. Not matter what their brochure has printed on it. So a company says that a certain blade is a certain hardness. So what? Has anyone ever gotten their ass handled to them in court because a certain number of blades weren't at their specified hardness?
I don't think so, and frankly, I'm not interested in trying the system out.

I'm certain that you're correct in your own world. But in the world of knife manufacturing, bad things happen. I've seen bad things related to heat treating happen. It happens. And I've felt the somewhat rare but none the less real examples of soft steel. All I'm suggesting is that if you really care, and can afford it, buy a custom knife. If you can tell the difference, and a lot of people can believe it or not, then that maker is most likely going to listen to you. A manufacturer might listen, or they might just give you the run around for a few months and tell jokes about you. That part is not in the brochure, but I've heard the occasional jokes. The real world is somewhat different from what is written in books.
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Just because the guy loading the furnace doesn't know anything about metallurgy, it doesn't mean that the heat treat protocol was pulled out of his ass at random. Someone who actually knows their ass from their elbow creates detailed instructions on everything. While the line-level worker may not appreciate that actual thought went into what they're doing, that doesn't mean it's not the result of a hard science. One reason they use expensive computer-controlled furnaces is to make it easier to do correctly, even if you have no idea what you're doing or why you're doing it. As long as they "do their job," it'll come out right. It's the same whether you're building a skyscraper or a car: it doesn't matter if the person doing the work understands the reasoning behind why a spec is set a certain why, only that they actually do what they're supposed to.

Now, consider your example where the FNG sets the furnace at 200 instead of 2000, so none of the knives are actually hardened... Based on your assertions, the people who actually sharpen the knives should be able to tell immediately that something is wrong, so it should never be the case that an entire batch of bad product makes it out the door. If the product does ship like that, it's not a failure of hard science, it's a failure of management (a soft science).
 
Yeah, I get it. I know how things are supposed to work. But things don't always work as they're supposed to, do they? Look up how many very expensive skyscrapers in Australia are falling apart because people didn't do what the book said. Have you ever taken a shower using an electric water heating shower head?
 
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