Maximizing Edge Retention – What CATRA Reveals about the Optimum Edge

Matthew Gregory said:
... @Rick Marchand would like me to express my regret in not having read the ‘ScienceOfSharp’ discussion of the 8000 grit stone, and it’s explanation of the results.

I have shame. :oops:

Please continue on with the discussion now.
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I have looked for the link to the SOS thread but for some odd reason I can't find it. If someone could re-post it I'd appreciate it. Thanks in advance and please excuse me for not being able to find something that is evidently right in plain sight.
 
Larrin said:
https://scienceofsharp.wordpress.com/2015/03/01/the-diamond-plate-progression/
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LOL and since people are gonna start jumping also to the conclusion, that there's no reason to ever go above 600 grit because of that article, here's a quote, that many may have missed, from the article: "Comparing side view images, all at 5000x magnification, shows that the roughness of the bevel actually increases with grit, rather than decreases as was observed with the Shapton water stones. "


So, before everyone jumps to conclusions, these results were only observed with diamond stones. Not, all abrasives. Another illuminating article, that doesn't much surprise me.


Although it may also offer some insight when certain high abrasion exotic alloys can never get a real fine edge. Even though it's tedious, much better results may be shown by setting bevels with diamonds and refining with ceramics.

Anyway, thanks for linking that Larrin, and there's plenty of other good info there.
 
I tried to be balanced by briefly referencing that article. I don’t think we know for sure what the optimum sharpening is for the catra test but when it comes to dmt it is approximately 600 grit.
 
what is interesting is looking at the last data table. compare the blades where the only difference is edge angle and see the improvement in wear as you go from 20dps to 13dps. or look where the only difference is the steel and the changes are almost small enough to be test error.
i think everyone will agree that CATRA is not perfect, but it is the only standardized test we have for blade performance.
 
Great article Larrin! love it!

Another thing that should be pointed out for anyone that may jump to any conclusions based upon this, (I may have missed it) is that this study is primarily about wear resistance, whereas in hunting knives, kitchen knives, and edc knives we encounter things that will require toughness and strength. An edge that can withstand pure wear resistance from abrasive cards at 10 dps may suffer denting/rolling/chipping if encountering wood, bone, or plastic. So the I think that may have been one of the balancing points that javand javand may have been referring to (although I just glanced at his post quick), so a 10 dps may be optimal for certain tasks, but a microbevel (or even the secondary bevel itself) at 15 or 20 dps may be needed for others to resist the denting/rolling/chipping.
 
razor-edge-knives said:
Great article Larrin! love it!

Another thing that should be pointed out for anyone that may jump to any conclusions based upon this, (I may have missed it) is that this study is primarily about wear resistance, whereas in hunting knives, kitchen knives, and edc knives we encounter things that will require toughness and strength. An edge that can withstand pure wear resistance from abrasive cards at 10 dps may suffer denting/rolling/chipping if encountering wood, bone, or plastic. So the I think that may have been one of the balancing points that javand javand may have been referring to (although I just glanced at his post quick), so a 10 dps may be optimal for certain tasks, but a microbevel (or even the secondary bevel itself) at 15 or 20 dps may be needed for others to resist the denting/rolling/chipping.
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This was the point I was making at least. The quote that I think is at issue in the article is:

“This finding is significant because some have speculated that lower angle edges start out sharper but a more obtuse edge lasts longer [2].”

To me this is at a minimum suggesting a conclusion based on insufficient variables. I would put forth the “speculation” that a more obtuse edge lasts longer is more than speculation. Real world practice shows it to be true for certain use knives because an edge chipping or rolling impacts its remaining sharpness. That’s why I joked this test tells you what knife is good at cutting card stock. It’s perfectly logical that in a very controlled testing environment that isolates wear as the only negative impact on the blade that acute is better. I don’t think folks should jump to saying this busts a “myth” of the longevity of an obtuse angle and start sharpening everything at a crazy degree.
 
lanternnate said:
This was the point I was making at least. The quote that I think is at issue in the article is:

“This finding is significant because some have speculated that lower angle edges start out sharper but a more obtuse edge lasts longer [2].”

To me this is at a minimum suggesting a conclusion based on insufficient variables. I would put forth the “speculation” that a more obtuse edge lasts longer is more than speculation. Real world practice shows it to be true for certain use knives because an edge chipping or rolling impacts its remaining sharpness. That’s why I joked this test tells you what knife is good at cutting card stock. It’s perfectly logical that in a very controlled testing environment that isolates wear as the only negative impact on the blade that acute is better. I don’t think folks should jump to saying this busts a “myth” of the longevity of an obtuse angle and start sharpening everything at a crazy degree.
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This was an article on edge retention, not on edge chipping or rolling. One article on one subject does not encompass all scenarios. I have lengthy articles on deformation and chipping on my site, and more will be coming. It's like taking a chapter out of a book and criticizing the chapter for not containing the rest of the book inside of it.
 
Larrin said:
This was an article on edge retention, not on edge chipping or rolling. One article on one subject does not encompass all scenarios. I have lengthy articles on deformation and chipping on my site, and more will be coming. It's like taking a chapter out of a book and criticizing the chapter for not containing the rest of the book inside of it.
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Of course you are right, I was certainly not criticizing the article just throwing a word of caution out to those that may jump to conclusions.
 
Larrin said:
This was an article on edge retention, not on edge chipping or rolling.
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You see, we have a different definition of edge retention which partly underlies this difference of opinion. You state you wrote an article about edge retention NOT edge chipping or rolling. By my definition chipping and rolling are PART of edge retention. Perhaps somewhere there is some scientific definition of edge retention that stipulates it is only a factor of wear resistance, but that’s not the definition I know or go by, and I would wager I’m not alone. My layman’s definition of edge retention is how long does the blade remain at a satisfactory level of sharpness in the course of intended use of said blade. That edge retention will be a factor of a combination of wear resistance, chipping, rolling, and other deformations of the edge from its initial sharpened state. I would categorize that you wrote an article about wear resistance (and a perfectly fine one). I, and I believe others but I don’t want to speak for them, am simply pointing out that there is more than wear resistance to total edge retention so it is best not to jump to conclusions and design solely for wear resistance in exclusion of all other factors. That’s why I called out the specific quote about disproving a more obtuse angle having a greater ability to retain an edge. I find that conclusion a stretch because not enough factors are tested in this experiment.

Larrin said:
It's like taking a chapter out of a book and criticizing the chapter for not containing the rest of the book inside of it.
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Some friendly advice, if you want to put information out there, you need to be ok with the fact that at times folks will disagree with the information you put out. That’s ok. I don’t believe anyone is trying to attack you or insult your work. Some healthy conversation around it and challenging of ideas to further flesh out the information should be seen as a good thing. If you can positively embrace these interactions there is a lot of value for all sides to be gained. Nothing is gained when folks become defensive. Just some food for thought that when someone challenges a portion, it doesn’t mean they didn’t find value in and appreciate the whole.
 
I agree with the above statements. I hope my comments weren’t taken as to generalize to all applications, or steels. I noted that a softer steel simply can’t support such fine edges. For my knives, I’ll use the steel that will support these fine edges, and use the thinnest edges I can before chipping or rolling happens based on my test blades.
 
lanternnate said:
You see, we have a different definition of edge retention which partly underlies this difference of opinion. You state you wrote an article about edge retention NOT edge chipping or rolling. By my definition chipping and rolling are PART of edge retention. Perhaps somewhere there is some scientific definition of edge retention that stipulates it is only a factor of wear resistance, but that’s not the definition I know or go by, and I would wager I’m not alone. My layman’s definition of edge retention is how long does the blade remain at a satisfactory level of sharpness in the course of intended use of said blade. That edge retention will be a factor of a combination of wear resistance, chipping, rolling, and other deformations of the edge from its initial sharpened state. I would categorize that you wrote an article about wear resistance (and a perfectly fine one). I, and I believe others but I don’t want to speak for them, am simply pointing out that there is more than wear resistance to total edge retention so it is best not to jump to conclusions and design solely for wear resistance in exclusion of all other factors. That’s why I called out the specific quote about disproving a more obtuse angle having a greater ability to retain an edge. I find that conclusion a stretch because not enough factors are tested in this experiment.



Some friendly advice, if you want to put information out there, you need to be ok with the fact that at times folks will disagree with the information you put out. That’s ok. I don’t believe anyone is trying to attack you or insult your work. Some healthy conversation around it and challenging of ideas to further flesh out the information should be seen as a good thing. If you can positively embrace these interactions there is a lot of value for all sides to be gained. Nothing is gained when folks become defensive. Just some food for thought that when someone challenges a portion, it doesn’t mean they didn’t find value in and appreciate the whole.
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The information is all there, please make your own conclusions or do your own testing.

Hoss
 
Its just a data point. You can go as deep or shallow as you like. If the test doesn't contain all if the variables that one is looking for then a new test needs to be made or a interpretation could be made.

For this one it really seems like one should make the knife as hard as possible and this as possible without having damage done caused by the intended task. It's not that radical of a idea:eek:. Well that's how I am filling in the blanks.:p
 
lanternnate said:
Some friendly advice, if you want to put information out there, you need to be ok with the fact that at times folks will disagree with the information you put out. That’s ok. I don’t believe anyone is trying to attack you or insult your work. Some healthy conversation around it and challenging of ideas to further flesh out the information should be seen as a good thing. If you can positively embrace these interactions there is a lot of value for all sides to be gained. Nothing is gained when folks become defensive. Just some food for thought that when someone challenges a portion, it doesn’t mean they didn’t find value in and appreciate the whole.
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I don’t see how disagreeing with you has made the conversation unhealthy, or why the two sentences I wrote has made me “defensive.” You are interpreting a lot about my emotional state based on two sentences.
 
DevinT said:
The information is all there, please make your own conclusions or do your own testing.

Hoss
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Title of this thread is this ...............
Maximizing Edge Retention – What CATRA Reveals about the Optimum Edge
My question is does optimum edge on knife made from CPM-154 and 154CM is 10 degree per side and that maximizing edge retention ?
 
Natlek said:
Title of this thread is this ...............
Maximizing Edge Retention – What CATRA Reveals about the Optimum Edge
My question is does optimum edge on knife made from CPM-154 and 154CM is 10 degree per side and that maximizing edge retention ?
Click to expand...


The wording of that headline is pretty careful and specific. "reveals about" implies that it has some illuminating information, however, it is not a statement of absolutes. If it had instead said "Catra Reveals the Optimum Edge", it would have been a completely different story, and I'm sure, appropriately, more contentious.

You can only make conclusions (opinions) based on the specific data set in this specific test. It doesn't purport to be a definitive answer on anything else.
 
Natlek said:
Title of this thread is this ...............
Maximizing Edge Retention – What CATRA Reveals about the Optimum Edge
My question is does optimum edge on knife made from CPM-154 and 154CM is 10 degree per side and that maximizing edge retention ?
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I’m sorry I’m not exactly sure what you’re asking. Are you saying that the article is supposed to give one optimum edge angle recommendation?
 
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