bh49 wrote:
Yes, IMHO CATRA testing, if it is done right will allow to compare steels in edge retention.
For machines, but not for people, it is an invalid test for that.
This is known quite well in the industry and Buck was even open about it many years ago due to the work they did.
Buck found CATRA results did not correlate well to user feedback in the IonFusion line. They then had a bunch of people at work do a bunch of cutting and measured the sharpness at intervals and those results matched user feedback quite well.
The reason for this is because CATRA uses an extremely precise cutting motion and this does not then put lateral loads on the edge which happen when a person is using the knife. These lateral loads are critical because they are what causes rolling and micro-fracture (tear out).
Thus even those CATRA is very precise, it is not very accurate and is not an unbiased estimator.On side coated blades they will self-sharpen in CATRA cutting but they do not in use by a person as the coating lip just cracks off under lateral loads.
bh49 wrote:Did I answered you question?
Yes, now as a followup, consider if valid experiments were conducted more than a 1000 years ago with none of the lab equipment today, it is obviously possible for someone today to also do valid experiments at their home. How much precision and accuracy they need depends on what conclusions they wish to form.
A normal person could easily for example perform a valid experiment to show that the speed of light is much greater than the speed of sound. They could also show for example that it is not significantly changed in that regard by relative motion.
What is critical are the conclusions they reach.
In regards to S35VN. If John concluded that because of what he saw with the Sebenza that all Sebenzas or all S35VN were defective that would be an unfounded conclusion and in invalid experiment. However if he concluded that one was defective it would be well supported by the data and it is a perfectly valid experiment.
If you look at the fact that John considers :
-material properties
-rope cutting
-EDC use
-misc stock cutting
and then does peer review (the critical part) by talking with other people who do such work and uses all of this to generate a conclusion, then it would be expected that in general he gains knowledge from the work.
Now is he right all of the time, no of course not. I have discussed with John about how at times I don't think his conclusions are supported by his data (recent work on S110V and carpet and carbides/cutting). However science in general is never right all of the time no matter how rigorous you are in method.
In the words of Richard Feynman :
"I have approximate answers and possible beliefs and different degrees of uncertainty about different things, but I am not absolutely sure of anything ..."
Another way to look at it is as simple as this :
Has John learned from his experiments - has he gained knowledge from his observations, deductions and conclusions? If he has, it is very difficult to say he is doing invalid experiments because that is foundational to the definition of science.
Moving beyond John, if you look at YT maker Mike Gavac, he has only been a knife maker for a couple of years, but the performance of his knives had improved dramatically. This is because of knowledge he has gained through basic experiments to confirm aspects of performance of knives, all done in his home, back yard and other places.
Of course such methods are not without risk, and at times conclusions can be false due to incorrect correlation and that is why people serious about knowledge (vs shilling) always utilize peer review to check and confirm their work.