ABX2011 wrote:I watched a video of the rope cutting on the special stand without a base and I wonder if blade geometry/thickness comes more into play because the rope tends to squeeze the blade as the blade passes through.
If you cut over a gap with a significant amount of rope on each side you can get a pinching effect as the rope is pushed into the opening. However you can minimize this by :
-cutting over a very narrow opening so the cut is well supported on each side
-cut over the side of a block so the rope just falls away as it is cut
In general, you need to take care when using knives of vastly different geometries and even handle shapes because they will effect how you cut.
The easiest way to do this is just do a large amount of cutting and note how blades with more ergonomic handles and superior cutting blades will give you far more control. More control is less twisting and other lateral/prying loads against the edge and less high force/speed cuts due to frustration.
In general, you always want to keep in mind that you are comparing a lot more than just steels and in the end you are trying to extract from that if the steels are different. It is possible you just need to apply some basic math/statistics.
If you consider for example a very basic (reduced) problem.
Let say you have a track team of two dozen members, you want to see if a new shoe helps them so you take one guy and give him the new shoes, have him do one race and then make that decision based on his performance. It should be obvious this is a flawed approach because you could see just the effect of a variation in a race as the same guy doesn't run the same race speed all the time.
Now instead give everyone the same new shoes and look at their average performance differences over a number of practices and make a decision there. You have made a vast jump in stability of result but you could still be wrong if you were to conclude that *in general* that is a better shoe as you could be seeing effects which are :
-limited to that particular group
-effected by the weather/terrain
-caused simply because they believe it is a better shoe
Thus if you want to try to make a really stable conclusion you would look at multiple groups, over multiple factors, and attempt partial or full blinding. And then, and this is the critical part, figure out why the shoe is better and then test that hypothesis because there has to be a systematic underlying physical property :
-it is lighter
-it cushions better
-it has better traction
etc. .
The same holds for edge retention or any other property. This approach however is rarely done which is why there is so much conflict in the result reported because often conclusions which are linked to steels are not actually the steel causing the difference but other issues such as geometry, sharpening, variations in method and even just perception.
Even in actual research it isn't trivial to answer what you would think are very simple questions when people are involved because of the complexity that people add to the equation. It is therefore much easier to say if a steel would cut more/less pieces of rope in a machine than if it would if a person was using it when the environment, skill, physical strength, etc. all vary wildly.
As an example, there was a recent edge retention comparison on YT and Buck's 420HC's blade came strongly ahead in cardboard cutting over a lot of much more expensive and high wear steels. Now without seeing the knives and the data in detail there is no way to know for sure, but one simple reason that could cause this is that in general that is a very simple steel to get to a very high sharpness because it has :
-minimal retained austenite
-minimal ferrite formed in cooling
-decently high hardness
-very low carbide volume
It thus grinds easily, does not tend to form heavy burrs and is very easy to thus get a very stable edge very quickly. As initial edge sharpness and quality have a huge effect on edge holding this could be dominant over all other factors.
