Production M390 - Expectation vs Reality?

Back a few posts there was a response to Mo2 that included some rebut of nearly every point he made. I can add some clarity to those as well.

False: First post was Mike insinuating that they did an hrc test on the blade edge. Of which wasn't true.
True: If you read the referenced post, you will understand that I am referring to knives that I sent to Peters previously - not those that Kurt took. My post was well before Kurt even went to Peters.

False: The 2nd to last paragraph in particular in the latest post are a bit disingenious. Saying he would have to hunt down posts. And then next calling out one comment about paint chips, which is in reference to running the test.
True: Already addressed by someone that read my statement without preconceptions; but just to verify: There were many vicious trolls on instagram that attacked anyone requesting a measured testing methodology or questioning the process used. Many of the trolls prompted responses by those on the testing team, to include Kurt, that made some statements in hindsight seem ill advised. So, it would be much easier to just remove the account than to hunt them down. But this was speculation on my part, I don't know why he removed the IG account. But in one particularly vicious attack by trolls on a customer of mine that only recommended third party verification, I copy/pasted the entire exchange and that is where I quoted Kurt's response to the care that need be taken with equipment that will be used to make commercial claims.

False: It's not hard, many knife makers get an aim's Hardness tester and read the directions. You don't need to be an expert to run an hrc test.
True: It's not hard to test for private use. But when you are going to test to call a manufacture incompetent or challenge their specifications, you probably need to do more than read a manual. For example, documents are found rather easily that say never test within 3 diameters of another test / edge / anomaly. Yet you can clearly see the shuffler has been tested at least twice within 3 diameters of another test.

False: If Mike was at Peter's, he would have known that they compared methods of running the test and calibration with Peter's and nothing is different in the methods. Not to mention they tested other knives that got the same results with on both machines. But Mike wouldn't know that, cause he wasn't there.
True: I wasn't there. But I am the one that introduced Kurt and Brad. I am the one that setup the verification with an agreement that I would be provided the results pertinent to the knives which I was invested. My conversation with Brad does not reconcile with your statement. First off, there is no way that any shop's testing / calibration methods compare with Brad's. Every morning at open they test a NIST 30, 40, 50, and 6X (don't recall if it was 61, etc.) block 3 times on each of their 3 machines. That is 36 tests just to open the shop each day. Calibration is done at any time these do not provide expected results, but never any later than the industry standard calibration dates (calibration is done by a 3rd party).
It is expected that they would match on some results. Sadly very few testing methodologies allow for "a finite number of unexplained inconsistencies".
I have had several long conversations with Brad. He is the most detailed and genuine person I have ever talked to in this expertise. For example, on their testing equipment it takes 8/10000ths of inch of to drop the hrc result by 1 point. Thus by my calculation that means a 50micron particle of dust would provide a reading up to 3 points off. When that type of precision is required, I want someone doing more that just buying themselves a tester and reading the manual (as is suggested) if they were going to challenge commercial results.

False: Yet Mike's making it seem like this anomaly makes all these tests invalid, of which does not. Then he goes and says how his work place must have all the wrong numbers...
True: No, quite the opposite. I think most of the results were probably correct. But it is a science, and especially when you are going to go after a companies livelihood with commercial claims. They had readings that any industry expert could spot as highly questionable. For example, I asked Brad how likely it was to get 4-6 different readings on 1 square inch of a blade tang. His response was that in 36 years he has never seen a variance of more than a point or two inside that amount of space. There can be false low numbers for many reasons - false high numbers are an entirely different issue. Once that shuffler received a 58 test, a big red light should have started flashing. Any testing methodology that is going to expect the respect of the industry is going to need to be easily reproducible by peer testing experts. And if you are putting out even one number that is proven patently incorrect - then the entire methodology has to be re-evaluated.

Opinion: Besides all of this, it's just two knives. Ignorant people blew it out of proportion based off of what someone like Ltk said in his video. Of which is apparently corrected and he's apologized.
Differing Opinion: To LTK is was just two knives. To me it was the total sum of EVERY knife from my modern traditional series that EVER tested outside of factory specifications. We wasted many blades testing to try and find the anomaly. But the only two we had ever seen tested low were by one person.
I think anyone that saw the videos knows it was more than a passing mention. It was the poster boys of the pitch that was being sold. LTK kept adding to his original mention with statements like he would "stand on" these results. When what I said about "headaches" was interpreted to be a legal threat, he said "bring it on". Now, he is a good guy and comments look much different in hindsight many times than they do at the point in time where you are certain that you are right. But I will point out that in his "giveaway" video, that was posted Saturday after Kurt had retested the dom himself to within specs and then taken to Peters and got four identical readings of 59.1hrc, he doubled down on the old readings but started broadening the conversation away from simple hrc readings that had been the backbone of all previous videos. Making no mention of any updates to include new readings. That was when I was compelled to make my first post since the ill advised post on the original video.

Regarding the comment about taking a blade out of the frame for testing. That was mentioned in my response to the first youtube video wherein I was discussing the knives I had sent for testing. Those knives also included a sample from the "Bolus" series which does not have nearly as much tang exposed. Brad called me to ask if he could remove it from the frame to insure a valid test. I am in no position to question him on this point.

I think Lee and Kurt are good people. I don't think they set out to have this thing blossom like it did. But there was not enough management of the situation to insure it would not turn out like it did. Lee is very "excitable" in his videos. And he drew a large crowd of folks that had no concern for what the publicity would do to the other folks involved. I did not go on a witch hunt. I kept my mouth shut for two weeks while the facts came out and only when it appeared as if those known results were not going to be offered by the testing team - I responded with a differing view on a more neutral youtube channel.

Before moving back to Oklahoma to help my parents after a terminal diagnosis for my father, I had a highly technical career. Which also included working with / for government contractors. My background and my mindset is analytical. Thus I see things differently than many. But, although I love to have conversations with the members on BF as well as other platforms - I hate controversy. Many times I play the devil's advocate and many times there are disagreements. But many times these controversy come up on social media that would never have come up with folks having a civilized conversation face to face.

There is no way for me to express how much this situation has stressed me over the last couple weeks. But to be honest, in the last week we have had personal events that leave it nearly just banter. Not that the stress has resided any, but that I never realized how much stress a person would have to endure sometimes in God's path for us. I know when you put yourself into the public eye, you open yourself up to being called a liar, a crook, etc. etc. But I would simply ask, for me, and recommend for everyone else reading - just take the time to approach a person like you would your neighbor at the picket fence on these kinds of issues. There are so many things that unite us and so few that divide us.
Thank you for the reply. That is better than the statement you originally made that implied something else.
 
If you find the time, please respond with the exact sentence/statement in which you feel something else was implied.
 
If you find the time, please respond with the exact sentence/statement in which you feel something else was implied.
I already quoted the screen shot where you implied about Kurt.Your reply with more detail that was good enough for me.
 
Good, let's squash this whole M390 hardness thing then...

Mine cuts and holds a sharp edge just fine.
 
2 Recent run Spyderco models in M390 (Delica, PM2) each hit at 62. This is not a reference to the previously hit 62hrc PM2. It’s a second, newer batch sample.
I can't message you here. Can I get you on IG or somewhere else?

Good, let's squash this whole M390 hardness thing then...

Mine cuts and holds a sharp edge just fine.
There's nothing wrong with most M390/20CV. The knives I have are good. I don't find the edge retention to be great. Maybe slightly better than S30V in some cases. It's really a matter of value rather then good vs. not good steel. I will say it's easier to sharpen than S30V, so it's got that going for it. Which is nice.
 
Banter thanks for your reply, mind reposting the link to the database?

I’d heard that the smaller knives E.g. Delica were less hard than the larger PM2 guess the data shows that is wrong.

Do you know anywhere that shows how much harder a 62 is than a say 58? I’ve read that the hrc scale is not linear, but not what the relationship is. Perhaps the steel ball bounce method would show this in that the height of bounce could reflect hardness and height could be graphed. Of course that method doesn’t sound useable for knife blades, but it could maybe answer my question.
 
Banter thanks for your reply, mind reposting the link to the database?

I’d heard that the smaller knives E.g. Delica were less hard than the larger PM2 guess the data shows that is wrong.

Do you know anywhere that shows how much harder a 62 is than a say 58? I’ve read that the hrc scale is not linear, but not what the relationship is. Perhaps the steel ball bounce method would show this in that the height of bounce could reflect hardness and height could be graphed. Of course that method doesn’t sound useable for knife blades, but it could maybe answer my question.

A poster falsely claimed above that smaller Spyderco knives in M390 tend to come in low (I believe 58 HRC was the number that thrown out). It's caused some confusion since.
 
Banter thanks for your reply, mind reposting the link to the database?

I’d heard that the smaller knives E.g. Delica were less hard than the larger PM2 guess the data shows that is wrong.

Do you know anywhere that shows how much harder a 62 is than a say 58? I’ve read that the hrc scale is not linear, but not what the relationship is. Perhaps the steel ball bounce method would show this in that the height of bounce could reflect hardness and height could be graphed. Of course that method doesn’t sound useable for knife blades, but it could maybe answer my question.
If you're referring to the Blade Banter spreadsheet, it's here.

If there's a correlation between Rockwell number and difference in hardness I haven't found it. Because it's number representing the depth of penetration you can't draw any conclusions about the amount of hardness difference without knowing the formula (or shape of the curve) of hardness to penetration depth. If this exists I haven't seen it. I would guess it's not linear and is likely closer to log scale. But this is a wild guess.
 
That shows the relationship between different hardness test values. This doesn't help me know how much harder HRC 60 is relative to HRC 58. Am I missing something that's there?

If another one of those tests has defined the hardness difference between their scale numbers youu could use those curves to figure out what it means for HRC. I haven't found another hardness test that does this. I haven't look very hard so it could be out there. I'm guessing Rockwell numbers a dimensionless for a reason.
 
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Banter thanks for your reply, mind reposting the link to the database?

I’d heard that the smaller knives E.g. Delica were less hard than the larger PM2 guess the data shows that is wrong.

Do you know anywhere that shows how much harder a 62 is than a say 58? I’ve read that the hrc scale is not linear, but not what the relationship is. Perhaps the steel ball bounce method would show this in that the height of bounce could reflect hardness and height could be graphed. Of course that method doesn’t sound useable for knife blades, but it could maybe answer my question.
Steel ball bounce would be very bad because the mass of what's being tested will effect what the hardness is, that is why portable leeb testers that use that method are not used on steel for knives because of the thin stock we use.

This is why the Rockwell test C uses a preload at 10kgf to rule out the elastic rebound before delivery of the major 140kgf for the 150kgf total, also the major load is held for a few moments to also mitigate the elastic rebound as well.

The test measures depth of permanent plastic deformation in mm

Each line on the test C dial is 0.5hrc incriminates this equals 0.001mm per 0.5hrc
0.002mm(2um) for 1 point hrc

SIZE reference 0.002mm is 2um
(0.002mm is under 0.0001" inch roughly 0.0000787")




HRC equals 100 subtracted from the mm of permanent deformation over 0.002mm increments.

So 62rc is 0.076mm of permeant deformation depth

58rc is 0.084mm of permeant deformation depth

So the difference is that 58hrc would have 0.012mm deeper deformation from the 120° conical diamond penatrator than 62hrc.

So the Rockwell will tell use how resistant to displacement the steel is and will give us an idea of how hard the matrix of the steel is but it obviously doesn't till us anything about stability or wear resistance.

There can be hundreds of different vartions to the microstructure from heat treatment so the HRC is not universal to high performance but if the microstructure is badass and the HRC is higher with the Geometry to express it for the job at hand than the higher HRC measurement can be a factor for more more resistance to plastic deformation which means less annoying rounding over of a sub micron apex with use and can increase the Stability since a harder matrix can support the Carbides better.



wEd5HOF.png
 
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That shows the relationship between different hardness test values. This doesn't help me know how much harder HRC 60 is relative to HRC 58. Am I missing something that's there?

If another one of those tests has defined the hardness difference between their scale numbers youu could use those curves to figure out what it means for HRC. I haven't found another hardness test that does this. I haven't look very hard so it could be out there. I'm guessing Rockwell numbers a dimensionless for a reason.

Some of these tables have a column for tensile strength.
I would like to hear from experts what that means.
 
That shows the relationship between different hardness test values. This doesn't help me know how much harder HRC 60 is relative to HRC 58. Am I missing something that's there?

If another one of those tests has defined the hardness difference between their scale numbers youu could use those curves to figure out what it means for HRC. I haven't found another hardness test that does this. I haven't look very hard so it could be out there. I'm guessing Rockwell numbers a dimensionless for a reason.
8 microns of depth is what sets them apart on the tester. The harder steel will resist being deformed with a fixed load.

0.5hrc =0.002mm =2um depth
2hrc =0.008mm =8um depth
Or
~three ten thousandths of an inch ~0.0003"

Most here are probably familiar with 1 thousandths of an inch 0.001" like what is found on calipers which is roughly 26um or 0.026mm. So 0.001" of depth is roughly 6.5hrc difference
 
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8 microns of depth is what sets them apart on the tester. The harder steel will resist being deformed with a fixed load.

0.5hrc =0.002mm =2um depth
2hrc =0.008mm =8um depth
Or
~three ten thousandths of an inch ~0.0003"

Most here are probably familiar with 1 thousandths of an inch 0.001" like what is found on calipers which is roughly 26um or 0.026mm. So 0.001" of depth is roughly 6.5hrc difference
Thanks BBB. I get how the testing works. What I'm not seeing is a way to say with any confidence that one HRC test number is X% harder than another HRC test number. Increasing numbers are an indication of more hardness. I haven't seen anything that lets us quantity how much more hardness it is. Is the harness scale linear? Curved? Log scale? I haven't found a reference for this yet.
 
Thanks BBB. I get how the testing works. What I'm not seeing is a way to say with any confidence that one HRC test number is X% harder than another HRC test number. Increasing numbers are an indication of more hardness. I haven't seen anything that lets us quantity how much more hardness it is. Is the harness scale linear? Curved? Log scale? I haven't found a reference for this yet.
David, we can see that the test measures depth and shows values in 0.002mm /0.5hrc increments in a linear fashion with a analog dial.
 
So is an HRC of 51 2% harder than one of 50? See this is why I’m confused. Sure the bottom line is does the edge do what you want, but I’d like to understand the relationship between the HRC number and the actual hardness. And consequently what a difference between say 59 and 62 means in the case of m390.
 

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