Spyderco and hrc

[sal]

I guess we'll see if he comes back and has the discussion? If he just posted to tell us that we are going to lose our Industry Leadership, then.............?

sal

[zhyla]

Honestly everybody knows Spyderco knows how to achieve proper heat treatments. As do most reputable knife factories with most common steels. I think there’s a lot of hand wringing about hardness because 20 years ago heat treatment was a bit less optimal in cheaper knives.

[fanglekai]

Rockwell hardness numbers are used to spot check if the heat treatment was done properly. If you aimed for 58-60 but samples tested 53 or 65, then you can infer that something went wrong. The number tells you nothing about the microstructure, though, and that's what actually matters. Publishing the numbers is pointless. I can't wait for people to start demanding micrographs of steels from different companies and having those published on dealer sites.

Callister's Material Science & Engineering is a good textbook to learn from and is the main book we used for the materials science course for my mechanical engineering degree. Larrin's Knife Engineering book is more approachable but references Callister's book quite a few times.

[Freediver]

April Fools?

[kennbr34]

Hi Clint,

Welcome to our forum.

I made the decision not to publish Rc decades ago, simply to avoid argument. There are many people that have their own opinion on Rc or limited understanding about how the hardness fits into the cutting edge puzzle. I believe much of that has been mentioned here. It's not a secret, as mentioned, any of our knives can be tested by anyone.

Hope you enjoy your time here.

sal

I'm kind of confused what argument is being avoided. LIke, what specific arguments would occur by you publishing the numbers. Not to mention, it kind of seems like it's being argued anyway.

In the meantime, the idea that anyone can measure the hardness is a little bit untrue. Anybody with a Rockwell tester, or a set of testing files, sure. But it's not like the blade length where you can pull out a tape measure to confirm yourself, or the blade thickness where even a set of calipers are fairly common.

So if on the one hand, Spyderco knows anyone can measure it, what's the advantage of not publishing the numbers you've measured yourselves? I know a lot of people are insisting that HRC values are misleading, and that people might infer the wrong thing from such figures, but I think there's plenty of perfectly valid reasons for wanting to know, and in the meantime they tend to end up being released anyway, so it just kind of ends up being more of a hassle for those who really want to find out.

Recently I did some testing of T15, K294 and 10V, for example. The T15 and K294 I had were in Mules, but the 10V was in a Kizer blade. However, the Kizer's blade had a very similar geometry in terms of the width and primary blade geometry, so it wasn't as much of an apples-to-oranges comparison as you might think. On the other hand, there were certain things like the edge angle geometry that I couldn't get exactly 1:1, and having the hardness figures would have been useful to be able to use Larrin Thomas's regression formula to plug in the HRC values and edge angle and apply an offset to see how much of the figures were affected by which factor, but unfortunately I was never able to find K294 hardness figures, so as of yet I can only assume that the Kizer 10V out-performed it because it had a more acute edge angle. Some people will say that is why you have to test with 1:1 comparisons, but there's not a 10V Mule to do that anyway, and even besides that, if I had the full amount of variables to plug in to Larrin's regression formula, it would be much easier confirm certain things like my suspicion that the Kizer 10V isn't as hard as the Spyderco K294 and what percentage difference in edge retention I could extimate between both at different edge angles. Instead, I was pretty much left assuming that since Spyderco had ran the PMA11 Mule at 62.5 HRC that they probably ran the K294 one the same, and that since Kizer is a budget brand they probably didn't run it over 60, but I think those estimates would be a lot more solid if I had at least one of the HRC figures--and I'd sure trust Spyderco's figure for it over Kizer.

But, my niche testing, and whether it merits those figures being disclosed aside, I still don't really see what harm comes from releasing them.

[weeping minora]

Hi Clint,

Welcome to our forum.

I made the decision not to publish Rc decades ago, simply to avoid argument. There are many people that have their own opinion on Rc or limited understanding about how the hardness fits into the cutting edge puzzle. I believe much of that has been mentioned here. It's not a secret, as mentioned, any of our knives can be tested by anyone.

Hope you enjoy your time here.

sal

I'm kind of confused what argument is being avoided. LIke, what specific arguments would occur by you publishing the numbers. Not to mention, it kind of seems like it's being argued anyway.

In the meantime, the idea that anyone can measure the hardness is a little bit untrue. Anybody with a Rockwell tester, or a set of testing files, sure. But it's not like the blade length where you can pull out a tape measure to confirm yourself, or the blade thickness where even a set of calipers are fairly common.

So if on the one hand, Spyderco knows anyone can measure it, what's the advantage of not publishing the numbers you've measured yourselves? I know a lot of people are insisting that HRC values are misleading, and that people might infer the wrong thing from such figures, but I think there's plenty of perfectly valid reasons for wanting to know, and in the meantime they tend to end up being released anyway, so it just kind of ends up being more of a hassle for those who really want to find out.

Recently I did some testing of T15, K294 and 10V, for example. The T15 and K294 I had were in Mules, but the 10V was in a Kizer blade. However, the Kizer's blade had a very similar geometry in terms of the width and primary blade geometry, so it wasn't as much of an apples-to-oranges comparison as you might think. On the other hand, there were certain things like the edge angle geometry that I couldn't get exactly 1:1, and having the hardness figures would have been useful to be able to use Larrin Thomas's regression formula to plug in the HRC values and edge angle and apply an offset to see how much of the figures were affected by which factor, but unfortunately I was never able to find K294 hardness figures, so as of yet I can only assume that the Kizer 10V out-performed it because it had a more acute edge angle. Some people will say that is why you have to test with 1:1 comparisons, but there's not a 10V Mule to do that anyway, and even besides that, if I had the full amount of variables to plug in to Larrin's regression formula, it would be much easier confirm certain things like my suspicion that the Kizer 10V isn't as hard as the Spyderco K294 and what percentage difference in edge retention I could extimate between both at different edge angles. Instead, I was pretty much left assuming that since Spyderco had ran the PMA11 Mule at 62.5 HRC that they probably ran the K294 one the same, and that since Kizer is a budget brand they probably didn't run it over 60, but I think those estimates would be a lot more solid if I had at least one of the HRC figures--and I'd sure trust Spyderco's figure for it over Kizer.

But, my niche testing, and whether it merits those figures being disclosed aside, I still don't really see what harm comes from releasing them.

Many folks take the number at face-value with no additional understanding that the number is merely one data point when it comes to the heat-treatment. Human nature predicts that we absolutely do and will argue about these sorts of miniscule things.

Spyderco would have to represent why they went with x hardness, because so-and-so read in an article, forum post, or from their idol that y steel performs better at z hardness. Period. Then Spyderco would have to account for any and all additional potential for future hardness changes, batch variations, changes in hardness from one factory vs another, one model vs another, hardness differences due to blade length, or specific knife usage, etc. This will all start to inflict a perceived standard within customers minds, and when one customer doesn't get the performance that they expect, Spyderco has a whole lot of 'splainin' to do to justify their "wrong doing and disrespect towards their customers!!!". It's a perpetual cycle that ultimately will lead to discontent, whether you can grasp that understanding, or not.

[horzuff]

With Spyderco I don't mind not knowing the target hardness as I'm pretty sure they went with something at least good and probably optimal for given steel's target use. With all the tests I've seen on the interwebs I don't recall any bigger mishaps with Spyderco's heat treats, when HRC is given it's usually what I'd expect or hope for.

For other brands I'm not so confident and I'm pretty apprehensive if they don't post their targets, at least for more exotic steels.

A good example for why it matters to me with more specialized alloys is the chosen heat treat for REX45 that Kizer settled on for their Mystic. A steel that stands out due to it's high attainable hardness and that has the best hardness/toughness balance at around 65RC, even the standard heat treat advised by Crucible ends up at ~65. And yet they settled for 61-62. Why? From all the graphs I've seen, there's no way to get decent performance out of that steel at 61-62. It has to be a bad HT to reach that hardness for that steel. So what's the point of using REX45 in the first place if a decent stainless would perform just as well in the same hardness range and be both stainless and cheaper...


On a another note - I'd much rather know the HT intent and type, as in primary/secondary hardness, maximized wear resistance/toughness/corrosion resistance and so on, than plain HRC. That would actually give me the tools to glean what to expect from the blade

[The Mastiff]

I guess you can't just accept that Spyderco has reasons for doing what they do. If you do enough research here going back in time you will find enough of those reasons to figure out what is going on and the probable reasons for it.

The reasons they don't are so obvious to me I don't get why everyone doesn't see them.

:)

[Paul Ardbeg]

I don't even care about the exact HRC nr, mainly because I know Spyderco is one of the best in terms of heat treatment.

[ZrowsN1s]

My link to the hrc thread gave him the info he wanted. Probably the end of the discussion.

[Ramonade]

I don't even care about the exact HRC nr, mainly because I know Spyderco is one of the best in terms of heat treatment.

Clearly, their XHP, M390 and 20CV are stunning examples of that. I haven't seen better, and rarely equally good heat treats for these steels.
And for many others, we can't see any other heat treat in the production world anyway

PS : I said "I" and "seen", which means I don't consider it an absolute truth. Just from every other examples of the steels I've had the chance to use and sharpen.

[Quantum]

I made the decision not to publish Rc decades ago, simply to avoid argument. There are many people that have their own opinion on Rc or limited understanding about how the hardness fits into the cutting edge puzzle. I believe much of that has been mentioned here. It's not a secret, as mentioned, any of our knives can be tested by anyone.

Hope you enjoy your time here.

sal

Thank you Sal

[sal]

Hi Quantum,

Welcome to our forum.

Hi Kennbr,

In addition to the comments above, there are a few things to add;

When dealing with heat treating, most, if not all Heat treating requires a range that can be 3 or 4 degrees difference in the spread. eg: Rc 58 -61, which we have learned makes a big difference in the performance with such a broad range. We require a 2 point spread in our heat treating, which is more difficult, but we feel gives our customer the best possible performance.

Another issue that is very important is the method used to attain that hardness in the process. Add sub zero quench and that too makes a difference. That means that if we give you a single number, let's say Rc 64, it could be Rc 64 or 65. In order to actually publish an Rc,it would have to be for each individual knife, which is unrealistic.

Usually when someone really needs to know, they'll ask on the forum, and I will usually have R&D pull a piece off of the shelf and Rc test it. Then I'll let the customer know what we came up with. That has happened a few times. There are also lists like the one above that would also give you a pretty good idea. So the piece off the shelf might be Rc 65, but the knife that you purchased might be Rc 64. Now what?

And I might add, that some of the argument that we get is from folks that don't know enough about heat treat to have a good understanding , so it becomes a teaching session instead of a firm answer.

I hope that helps with your understanding?

sal

[Synov]

The link in my signature may be interesting to the participants of this thread. I just updated the chart. Small differences in hardness for high edge retention steels don't matter much, but they do matter a lot for low edge retention steels. Their toughness changes drastically with hardness. Most Spyderco steels are in the former category, so I wouldn't worry about it too much.