Maximizing Edge Retention – What CATRA Reveals about the Optimum Edge

Maybe we can ask @DevinT to make an AEBL knife with the edge geometry he considers to be the best for slicing, hardened to 62+hrc, and then he can send it to CATRA, to test. If everyone is willing to donate to make this happen, I’m in. I’m sure the result will be interesting. I personally don’t care about edge retention, I’m a toughness/unbreakable Knives freak (thank you, Noss...), but in AEBL both things are correlated. This way we can see if AEBL is really the king of the hill, both in toughness and edge retention, or it performs much better in only one thing (toughness).
 
Larrin,

I want to offer my sincere thanks and appreciation for your continuous efforts to elevate the knowledge base of our craft.

You and your father freely share information that you have purchased with many years of work and dollars of your own money, and continue to do so despite the sometimes adversarial nature of the internet. In many other venues such information would be as closely guarded as it was dearly bought.

My hat is off to you, sir, and I eagerly look forward to your next installment.

Michael
 
Michael.Drinkwine said:
Larrin,

I want to offer my sincere thanks and appreciation for your continuous efforts to elevate the knowledge base of our craft.

You and your father freely share information that you have purchased with many years of work and dollars of your own money, and continue to do so despite the sometimes adversarial nature of the internet. In many other venues such information would be as closely guarded as it was dearly bought.

My hat is off to you, sir, and I eagerly look forward to your next installment.

Michael
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Thanks!
 
Edit: Normally I'd leave up my older posts, incorrect or not, for chronological viewing. I keep getting responses to older posts though that have already been corrected because folks aren't reading to the end of the thread before replying. It's ok. I've done it too.

Suffice it to say I misunderstood the parameters of the test and made incorrect judgements based on that incorrect understanding. My bad. Let's move on.
 
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Larrin said:
It is a slicing test
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Because it moves at an angle? A splitting maul moves in an arc, like a scimitar, does it slice logs in half?

I mean more of a sawing motion. Where the blade slices downward through media at a non-fixed rate. If the blade is on a weighted, pivoting arm and the pivot is fixed to the moving platform then the blade will be allowed to slice freely. The cut couldn't be attributed to excess pressure from the downward motion of the mechanism. The distance of the cut into the media isn't predetermined.
 
T.L.E. Sharp said:
Because it moves at an angle? A splitting maul moves in an arc, like a scimitar, does it slice logs in half?

I mean more of a sawing motion. Where the blade slices downward through media at a non-fixed rate. If the blade is on a weighted, pivoting arm and the pivot is fixed to the moving platform then the blade will be allowed to slice freely. The cut couldn't be attributed to excess pressure from the downward motion of the mechanism. The distance of the cut into the media isn't predetermined.
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If I'm not mistaken, I think the whole point of the CATRA test is to eliminate as many variables as possible (both human and material) to gauge the slicing performance of different steels, heat treats and edge geometry on a uniform and standardized media with a predetermined pressure and cut distance.
Edit: What kind of conclusions can be determined from the test I suppose is still debatable. In that sense I suppose you could consider it useless for your own intents and purposes.
 
T.L.E. Sharp said:
Because it moves at an angle? A splitting maul moves in an arc, like a scimitar, does it slice logs in half?

I mean more of a sawing motion. Where the blade slices downward through media at a non-fixed rate. If the blade is on a weighted, pivoting arm and the pivot is fixed to the moving platform then the blade will be allowed to slice freely. The cut couldn't be attributed to excess pressure from the downward motion of the mechanism. The distance of the cut into the media isn't predetermined.
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On what basis are you claiming there is excess pressure?
 
danbot said:
Edit: What kind of conclusions can be determined from the test I suppose is still debatable. In that sense I suppose you could consider it useless for your own intents and purposes.
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Certainly if a person simply discounts test results they are useless because they are refusing to use them. On the one hand it may be said that the person/group who designs a test has the burden of proof in terms of convincing others that the test can be related to some real-world application. On the other hand just because a test wasn’t designed exactly “how I would have done it” doesn’t mean that it is not relatable to any real-world use case.
 
How can a test like this be useless or irrelevant? No one said take all your knives and sharpen them at 10 DPS, steel, use, etc should be taken into consideration. The test is enlightening though in what it showed e.g PM process vs ingot as it relates to wear resistance, smaller angels staying sharp longer, different grit of diamond finish effecting edge performance and much more. Moreover, even if the test illustrates everything you already knew, what is the problem? If you took all the articles Larrin already did and is planning on doing, you would most definitely be more educated on the subject of steels and their performance in knives, so what is the problem?
 
Larrin said:
On what basis are you claiming there is excess pressure?
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None apparently. I just reread the article and got a completely different picture of the test and its parameters.

I apologize. While my original conclusion that the the test has little practical value for my use is still correct I think, I did reach that conclusion and pass judgement with a flawed understanding of what was actually done. I never claimed to be a brilliant man. :p

50N seems perfectly reasonable for a fixed load. I do wonder though whether your results would be different if some slight rotation were introduced to the blade.
 
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T.L.E. Sharp said:
:rolleyes:

Look, I've got no real problem with this study.
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You had a problem with reading it. The length of slice, force applied, and the very simple fact that it is a slicing test had eluded you. Any and all tests should be open to criticism, mostly to look for ways to improve the methods and conclusions. But, imo, they are not open to criticism by people who do not bother to even read them. Critique of the results would be fine if the criticism followed any particular logic.

As for your wonders about the effects of variability in cuts by hand, that was already studied. Hand fatigue and potential for injury in processing meat was found to be measurably reduced by... reducing the edge angle of the blade.
 
hardheart said:
You had a problem with reading it. The length of slice, force applied, and the very simple fact that it is a slicing test had eluded you. Any and all tests should be open to criticism, mostly to look for ways to improve the methods and conclusions. But, imo, they are not open to criticism by people who do not bother to even read them. Critique of the results would be fine if the criticism followed any particular logic.

As for your wonders about the effects of variability in cuts by hand, that was already studied. Hand fatigue and potential for injury in processing meat was found to be measurably reduced by... reducing the edge angle of the blade.
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Who said anything about doing the cuts by hand? Now who's not reading?

I said I'd like to see the effects that variable cutting angles, due to human error, would have on edge retention. I didn't ever state that a human should do it by hand. Introduce some rotation into the mount.

I admitted my original misunderstanding of the article and apologized. You going on about it just makes you look like a bit of a... ;)

I'll quit muddying the waters now. Have a good one.
 
T.L.E. Sharp said:
:rolleyes:

Look, I've got no real problem with this study. It just doesn't have any practical use for most of us here.

It's like presenting a study showing that tire width was the most important factor when determining the efficiency of a bicycle riding on the beach to a tour de France team...

They don't ride on the beach. It might have been a great study, but it isn't useful.

I don't often push cut through the broad side of narrow card stock, so this test isn't useful for me. It's also not exactly mind blowing. No fault of the participants, but finding that narrow wedges are better at splitting thin stock than thick wedges are isn't surprising.

Larrin Larrin I'd love to see the same level of scrutiny and testing done with a slicing test. Maybe cardboard or something similar. Varying edge angles and blade stock thickness. A fixed, reasonable amount of force akin to what a person might use while having the blade rotate out if center line just a couple degrees. This should create a shallow wave pattern and serve to at least attempt to replicate the less than precise nature of a human hand.
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I think you're looking at this the wrong way,
The machine isn't designed to show users exactly how many cuts they are going to get in reality, that's ridiculous

The information should be used to compare steels within a set of parameters to see how they stack up against each other at the edge with raw abrasive cutting.
 
Twindog said:
I think Ankerson's tests show that, too. I have a knife made by Luong (Bluntcut) that is 0.006 inches wide at the shoulders, and it cuts through cardboard like a laser. It's almost like cutting air. None of my knives with edge widths of 0.02 inches or wider can come anywhere close to that performance.
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Yuuuuuup
and part of my problem with the Manix.
Manix ~ 0.030" behind the edge.
= dog.
 
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