General Hardness of Blades

[Natlek]

And just for the purpose of argument/disambiguation/thought experimentation I can buy into the idea of someone with calibrated elbows sharpening 100 000 knives in a row of the same design and steel and when the get to 100 001 they could say hold on this one here feels a bit soft. Doesn't seem like that would happen often in the real world.

There is a reason that any pro mechanic no matter how many engines they've built will use a torque wrench when building an engine. Human elbows are definitely not calibrated. A master of their craft has the experience to know when to use a tool instead of trusting instinct.

So far I make about maybe more then 200 knives . Maybe half are kitchen knife .Steel i use for kitchen knives is 1.2519 on 64 Hrc. Other steel i use for small knives are M2 , M35 , M42 , T1 , T15 they are 64 to 68 hrc , and sometimes i use 52100 , 80crv2 , 15N20 .
Of course I have to sharpen every knife I make . First edge ......that take some time since i use guided system and I have ONLY 800 grit DMT diamonds .
NOW ,blindfold me, choose any steel from the one I have enumerated , and fasten it to the tool .Then give to me in hand my rod with attached DMT .............if I don't guess which steel is in question, I'll eat it
Yes , I believe that just with sharpening you can gain experience to make pretty much exactly guess what kind of steel is, not just how hard it is .
PS . Many times I sharpen knives from my neighbors, cheap stainless steel......................even if I'm half dead when we do the test I'll tell you it's that ***** steel . Diamonds do not lie, they play differently on each steel
PSS. I'm a car mechanic and i use torque wrench 40 years when i need it .But I think that without torque wrench i can do more then 95 % precise .....on one ,not ten bolts ,the hand gets tired and the feeling is lost, it is not the same....

 

[danbot]

Maybe the manufacturers should just stop advertising blade hardness with the HRC and go with "Blind taste tested by our in house experts" or some such.

 

[DMG]

Yes its the same, just on a different scale. If you know that turning the bolt on a brake caliper x amount from finger tight will produce the right torque, you can do it without a torque wrench. Same thing.....


Thats not a fact, its your opinion. There is a difference......There are good mechanics and bad mechanics. You just don't know any good ones.
Lots of mechanics who have been doing this work for years can do it, and its been done for many decades this way even before the torque wrench was developed. Experience is the key.....but the torque wrench eliminates the need for experience and training. Even so, there are plenty of bad mechanics who are more into getting it done fast than getting it done right and don't bother with a torque wrench with predictable results.


Some people just don't have what it takes I guess......they either can't or don't want to learn.....Sometimes mechanical ability is like being an artist, some people can draw anything to the last detail, some can't draw a straight line to save their life....

There are some bolts that should always be torqued with a torque wrench like head bolts, bolts connecting an aluminum and iron part, the first step of torque to yield bolts, CV axle nuts that preload the wheel bearings, and a few thousand more.

No one is good enough to skip the torque wrench on certain things, if they want good, consistent results.

 

[DMG]

How do you know the properties of the bolt? Smell? Taste? Feel?
How do consistently and reliably produce the desired properties of the bolts? Some kind of soft science will do?

look at the bolt and where it will go. Fine threads or coarse? Going into iron or aluminum? Diameter? How many threads will engage?

 

[danbot]

look at the bolt and where it will go. Fine threads or coarse? Going into iron or aluminum? Diameter? How many threads will engage?

...What grade of bolt is it? Whats the tensile strength?

 

[Richard338]

If you can hone your skills and senses to such a degree through repetition, just think of Wilt Chamberlain!

 

[Less Than Sharpest]

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

 

[danbot]

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

That's the kind of clarification I was asking for.
I have worked professionally with metal for a few decades now in manufacturing components for mass manufacturing industries, and in my experience bad heat treatments are fairly rare. Usually when they do occur it is due to a mix-up in what material is being treated.
Other mistakes can always happen, and a manufacturer will have an acceptable (to them) margin of error. A custom maker can usually have a lot more control over their own work when it comes to in-house HT or in their demand of specification compliance from a contracted heat treater.

I just find it awfully hard to buy into the accusations that large knife manufacturers are deliberately misleading their customers with their claimed RHC specs, or somehow are routinely missing the mark and not caring about it.

 

[Blues]

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 visited with Tony years ago while he was still set up in South FL. Gave me a walk through of the facilities and told me about how Chris Reeve taught him about sharpening back in the day.

While I was there, he showed me a prototype that he had on a table which had no name. I named it for him, and it became the "Kestrel", for which I received a prototype and a certificate (I have somewhere)...at a significantly reduced price, but not for free.

I haven't kept up with him over the years, but last I knew he wasn't all that far from my area in western NC.

 

[Spears]

I'll toss my 2c in for the heck of it.

I kinda of think HRC testing would be analogous to High Pressure Testing or Proof Testing in rifle barrels with a load that is near the top end of what the cartridge can handle. Necessary? Not really. Peace of mind? Absolutely (well, at least for me).

While, I don't think most manufactures would blatantly lie to customers, I do think that it would be nice if certain high-end production manufactures do individually HRC test their blades. I mean, it would not only add to the data pool for their heat treatment process but could also be valuable insight for them as far as production goes in the long run. That and, as you have stated before, why HT M390 sub-60 when it really shines in the 62+ range for cutlery? I mean, unless the manufacturer selected the steel just for marketing purposes, which I suspect could be the case sometimes, it is certainly a waste to have a "super steel" not HTed to it's potential.

I honestly would like to see Spyderco do individual HRC testing for some of their sprint runs. While Spyderco doesn't heat treat their "super steels" soft by any measure, it still would be nice to know the exact hardness and have a better estimate of performance (even though that can really be highly subjective in real-world use compared to an adhoc testing environment) since a 1 point difference in hardness can have measurably and statistically significant changes in performance. I would gladly pay the (I'm guessing) 10-20 bucks extra on a sprint run Spydie if they did that.

The only issue that I could see is, given the secondary market for the sprints, people would inevitably want to charge a higher markup for blades that are higher in hardness. I don't think the dot impression made by the Rockwell tester is substantial enough to cause worry as a point for crack propagation in the blade (though weirder things have happened).

 

[Danke42]

Well seems like we've looped right back to where we were last time.

People want super high HRC knives to win measuring contests on Facebook. Nothing more embarrassing that posting your new 3V knife up that you got at the Gathering and finding out Joe Dirt has a 3V knife from another maker 2 points harder than yours. The shame of it!

 

[Danke42]

I was thinking that I shouldn't even say anything as I'm new to posting and I didn't want to upset anyone on here, being that there are a lot of collectors, but this morning I thought differently. I'm not trying to hurt anyone's feelings, but there does seem to be a problem with manufacturers posting the hardness of a steel they use on a knife and the actual hardness that a given knife can be measured at. First, I was a knife sharpener for many years and was able to handle many different types of steel and was always amazed by the rare example of a blade that was perfectly hardened. Some steels were beyond all reasoning when it came to this somewhat non-scientific approach, but just imagine that I sharpened well over 100,000 knives and I always paid attention to what I was doing.
Secondly I personally made about 60 knives myself, all in ATS-34, and every one of them was Rockwell tested by myself to make sure that they were at the stated hardness which was 61 on the C scale. Also I want to say that I'm not a scientist and my overall methods were somewhat less that scientific, but I think that applies to most of us.
I have a few knives in ZDP-189, and they are all of San Mai construction, that is there's a softer steel on either side of the cutting steel, so I don't know how a company would measure the actual hardness of the edge. But I can tell you that the person sharpening can tell you right away. Many years ago there was a particular manufactured knife that was very much in demand and I discovered that there were some that were not hardened at all! They were all about 45-50 Rockwell and I had to argue with some people to not ship those blades. When we would get a shipment of blades back from the heat treater we would pull a few off and measure them, and there was quite a variety when it came down to what we would measure. But I can tell you all that very few blades were ever cast aside because they weren't up to par hardness wise. That is manufacturing. That is the real world.
So now there's some discussion about the merits of M390 vs 20CV and what it all means in term of edge retention. I can say for certain that it means everything. An ATS-34 blade that is actually 61 Rockwell will out cut a 20CV blade that is only 58. And I own some blades that are not as hard as they should be. When I watch a video of someone performing a cutting test, that is with two knives if the same steel, first I admire them for trying, but are they really comparing an apple to another apple?
I'm not an expert, and I welcome your responses. Please let me know what you think. I have carried a couple of different blades in M390, and a couple in 204P and I have some opinions on which steel is better.
Thanks for reading.
dt

Well I missed your whole sentence where you comment on "Manufacture" vs. "Custom Maker"...

I do appreciate that there are a lot of folks on here with varied experience in life; some with literal decades in material science or bladesmithing and when the time comes to split hairs they can do so clinically.

 

[Blues]

Well seems like we've looped right back to where we were last time.

People want super high HRC knives to win measuring contests on Facebook. Nothing more embarrassing that posting your new 3V knife up that you got at the Gathering and finding out Joe Dirt has a 3V knife from another maker 2 points harder than yours. The shame of it!

Yeah, but your lower HRC 3V knife will be tougher...so you'd have that going for you...which is nice.

 

[Danke42]

Yeah, but your lower HRC 3V knife will be tougher...so you'd have that going for you...which is nice.

Guy like me; I"ll always take tough over hard. No Maxamet here. I'm subnormally clumsy and insensitive.

 

[Blues]

Guy like me; I"ll always take tough over hard. No Maxamet here. I'm subnormally clumsy and insensitive.

Well, I like Maxamet, for what it is...but...when I bought my recent Demko AD20, I chose CPM Cru-Wear because it sort of splits the difference between 3V and M4. Tough steel with more than adequate edge retention...and better corrosion resistance than either.

I call that a win. There's something to be said for moderation and balance.

 

[Less Than Sharpest]

Most people these days will buy a knife the least expensive way possible, and the majority of manufacturers are well aware of this. Besides, it would take a considerable amount of time to HRC all of the blades, even a sprint run, and if some are not up to spec they would have to be trashed. My original point here was that if you want a hard science, spend the money and order a custom knife. If you can live with a little variation buy a production knife, carry it, and don't worry about it.

 

[danbot]

Most people these days will buy a knife the least expensive way possible, and the majority of manufacturers are well aware of this. Besides, it would take a considerable amount of time to HRC all of the blades, even a sprint run, and if some are not up to spec they would have to be trashed. My original point here was that if you want a hard science, spend the money and order a custom knife. If you can live with a little variation buy a production knife, carry it, and don't worry about it.

What if the custom maker uses a forge or a torch to heat treat their knives? Do you consider that hard science?

 

[Danke42]

Well, I like Maxamet, for what it is...but...when I bought my recent Demko AD20, I chose CPM Cru-Wear because it sort of splits the difference between 3V and M4. Tough steel with more than adequate edge retention...and better corrosion resistance than either.

I call that a win. There's something to be said for moderation and balance.

Yeah I am waiting on the production Cru-Wear PM2.

As a rule I verge to tool steels like that at the expense of ultimate hardness or high corrosion resistance.

 

[Blues]

Yeah I am waiting on the production Cru-Wear PM2.

As a rule I verge to tool steels like that at the expense of ultimate hardness or high corrosion resistance.

Me too. M2 steel Benchmades from back in the day...A2, D2, 3V... love me some tool steel. Grrrr....

 

[Buzsaw]

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.