Great stuff. Thanx much for sharing. It's really valuable for us on this forum to have an educated Academic perspective. I don't know to how many forums you present your information, but this forum as a group is appreciative. We also appreciate your "style" of humility and willingness to adapt to new information is very impressive.
Now to "Talkin' Story",
Since the beginning of our company, Gail and I have always pursued perfornance as our "thing". We've been testing for decades using CATRA as well as other Lab testing. I also highly value what I call "RWT" or Real World Testing. I have been supplying various restaurants, sub shops all over the world with our Blue handled serrated 6" Utility kitchen knife, (K04SBL) which I consider, in my opinion, the most effective general kitchen utility knife available. I have been going back to check on these knives regularly. I bring them to "home" to "scope" ( I use 10X, 22X and 50X to study edges ). Then I sharpen them or replace them. They usually last several years of daily commercial use. The results learned are very valuable.
I have had the good fortune to have Mr. Ed Schempp as a friend and business associate. We have been going to the Eugene knife show since the 80's. We always watched the "Rope cutting contest, which Ed usually won. Cutting free hanging rope. 1" then 2 1" then 3 1" etc. I have seen Ed cut 10 1" manila ropes with one strike with one of his knives. One year, I asked him If I can inspect his edge with a loupe before and after the contest. He agreed and I followed through. There was no visible damage to the edge after all of the cuts. then Ed resharpened the knife for me and let me take it to Golden for a CATRA test. The CATRA results were not very impressive, even though the knife was ???
While I was in Japan visiting the Kitchen knife factory that makes many of our kitchen knives, I asked the P resident why the MBS-26 that they use punches way above it's numbers. MBS-26 is a proprietary steel made by Daido for this company. He said that he, "Meticulously follows the heat treating instructions from the foundry". They heat treat in Lead pots. Something I hope to get into in the future with Mike Blue and Ed Schempp.
I have learned that Blades/edges will often defy the numbers one way or another, which is why we are still using RWT, and why we make the Mule Team. You afficianados are also very valuable in our search for the best performance in all areas of the "Edge/Ghost".
Just some thoughts to share.
sal
Nothing beats RWT in my opinion
Being a butcher for many years it was also eye opening when 3 butchers bought a new knife Brand/Steel and there was always 3 different reviews. We always used to chase the sharpest edge and there was always comparable results when one person sharpened all three knives.
I know it’s hard to fathom for some but we used to wear out a boning knife in less than a year
As has been mentioned by Larrin before a CATRA test is a baseline but edge geometry can affect numbers.
The one thing that keeps me waving the Spyderco flag is the spoilt for choice that we have with steels.
Im a vegetarian as technically cows are made of grass and water.
Being a butcher for many years it was also eye opening when 3 butchers bought a new knife Brand/Steel and there was always 3 different reviews. We always used to chase the sharpest edge and there was always comparable results when one person sharpened all three knives.
I know it’s hard to fathom for some but we used to wear out a boning knife in less than a year
As has been mentioned by Larrin before a CATRA test is a baseline but edge geometry can affect numbers.
This has been my takeaway from all the excellent data new testing has given us during this era of knife metallurgy enlightenment.
I'm paying far more attention to geometry when buying knives (and buying fewer knives) and working harder to sharpen an edge I actually like to use.
Different steels sharpen differently and hold that edge differently, so there's still plenty to be gleaned from testing and metallurgy, but I no longer feel compelled to buy the flavour of the month (unless it happens to come in the form of my favourite Spyderco...)
Just went back to the brutal BBB video on YouTube comparing the edge toughness of those rex 45 and m4 para 3's against that brass rod. Was the only thing that saved the rex 45 hardness? The m4 rolled over like crazy. I guess that supports a toughness argument for the m4 but in such a crazy test I would have expected a harder, less tough steel to chip out much worse than it did. Admittedly I don't know crap compared to many of you but am I missing something? https://youtu.be/WOpu13O_OFE
Larrin and BBB are informing and teaching everyone something about knife steels. From metallurgists, to steel manufacturers, knife makers, and end buyers.
Dr Larrin Thomas has done an excellent job of bringing his corner of the world to the layman. I am able to understand most of what he writes on the first pass and with a little bit of research I can understand all of it.
Thanks again Larrin for this addition to the outstanding body of work you’ve developed.
It would be good to see a micrograph of REX45 added to your micrograph article, when you have time. I’m guessing you already have it pencilled in on your list of things to do.
Also, it might be instructive to see a micrograph of the REX121 which was used for this round of tests in comparison to the image from the previous HT which resulted in excessive retained austenite.
Sal, thanks for the thoughts. MBS26 has been an outstanding steel for me, in the carving knife I luckily received from your ‘office box treasures’.
To those people who have been asking about more AEB-L, I really recommend trying one of the kitchen knives in MBS-26. It seems to have all the things people often like about AEB-L, with a bit better edge retention.
Also, it might be instructive to see a micrograph of the REX121 which was used for this round of tests in comparison to the image from the previous HT which resulted in excessive retained austenite.
Retained austenite typically doesn’t show up on conventional etching techniques. That why x-Ray diffraction, magnetic saturation, or electron backscattered diffraction is typically used instead.
Just went back to the brutal BBB video on YouTube comparing the edge toughness of those rex 45 and m4 para 3's against that brass rod. Was the only thing that saved the rex 45 hardness? The m4 rolled over like crazy. I guess that supports a toughness argument for the m4 but in such a crazy test I would have expected a harder, less tough steel to chip out much worse than it did. Admittedly I don't know crap compared to many of you but am I missing something? https://youtu.be/WOpu13O_OFE
In BBB’s test, Rex 45 was tough enough not to chip. Generally, if you can avoid bending or side loading, you will not get much chipping. As long as the edge is loaded in compression (no tension), it would require a lot of stress to damage the edge.
In constraint to BBB’s test, I experienced some chipping, when cutting rubber with REX45.
Also, it might be instructive to see a micrograph of the REX121 which was used for this round of tests in comparison to the image from the previous HT which resulted in excessive retained austenite.
Retained austenite typically doesn’t show up on conventional etching techniques. That why x-Ray diffraction, magnetic saturation, or electron backscattered diffraction is typically used instead.
Second, sorry of this counts as a resurrection, the question below seems most appropriate here instead of starting a new thread.
Unless I'm reading things incorrectly, the data sheets would seem to indicate s30v is about equal to Rex 45. They have roughly the same toughness and edge retention, with Rex 45 normally being slightly harder. But it appears based on other live tests and real world use Rex 45 is "better". Does the toughness, hardness, and carbide mix for Rex 45 make for a knife with superior "edge stability"? At least compared to S30V?
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