Greenjacket :
No test should be particularly scientific.
Scientific work must meet three basic criteria; the results should be understandable, and the method must be repeatable and well simulate the conditions of interest. Measure the quantity in a recognized unit, do it in a manner that can be done again, and include all the relevant factors. In short - get a meaningful result. Not to put words in his mouth, but by the above I think that Greenjacket means "No test should be overly controlled". Control means eliminating variables, and if you eliminate the wrong ones you create a testing environment which has no similarity to the actual blade use. You can spend hours doing very detailed and repeatable work, however all the conclusions you draw based of a simple 1:1 comparison will be horribly skewed. The results are not directly meaningful and therefore not scientific because the
interpretation was flawed. When interpreting controlled work you need to be sure of the correlation to dynamic field use - this means you have do both.
R.W.Clark :
I have no interest in pounding it through steel or cutting the bottom out of a sink. I will leave that silly stuff up to those who prefer theatrics.
As someone who has done and will continue to do both of the above, I will strongly agree that there is a large amount of incentive based on the entertainment value of such work, and just idle curiosity. The results of just fooling around though can be very informative. For example digging a hole through a concrete block can be easier on some knives than digging quickly through a 2x4 piece of pine. Figuring out why leads to a greater understanding of performance in general. The immediate conclusions are not really of great direct use, as how often for example do you need to cut up a sink. The critical part is that if the test is difficult enough to effect a blade permanently then you can use it to
discriminate among knives, and thus you can draw information from such work if you repeat it with more than one blade. Beyond the pure ranking, there are also direct comparisons with field use. If you read on the HI and Busse forms you will see that large chopping class blades often encounter very hard objects (rocks, hardened metals) unintentionally. Thus knowing how a blade will fail when its edge and tip are stressed very high, is valuable for people who use such blades in a very dynamic manner.
[edges]
I don't sit and look at them under magnification.
This is not done to replace actual testing of edges, but to allow a deeper understanding of what exactly makes an edge sharp, and what makes one dull. For example check Lee's book on sharpening where he details the results of a huge grit scale used on chisels. Or as a more direct example Goddards article on sharpening in Knives 2002. He includes a photomicrograph of a burred edge to show the reader exactly what is happening to the knife edge and also describes how to test for such without using magnification. The whole picture is one that combines the two methods.
Guys who are really into that are the same guys who judge a steel based only on its charts without ever using it.
It is exactly by such methods that steels are designed. There are whole books written on the effects of elemental composition on ferrous alloys tested by standard methods for determing the various material properties. Understanding these effects allows the advancement of materials. For example Fowlers recent comments about getting a steel made with a composition based on 52100, but changed in composition slightly to promote a higher level of performance. Now if he does get such a batch of steel made will he not test it but rest on his assumptions that it is better? No. However is he willing to make predictions just on specs? Yes. Same thing for what I said about S30V recently. Based on my experience, and the rough performance specs by Crucible, I stand by what I said as a reasonable conclusion. However I have been offered a S30V blade recently, and I accepted given the interesting results posted by some. If it tests differently than what I have noted (with the work being confirmed by the maker independently), then that just means that I have to rethink the presuppositions of that conclusion.
As for the tests, nice work :
Chopped through a 2X2 four times. It will no longer shave but will still cleanly slice both typing and butcher paper.
First off, the specific description for sharpness is valuable as it is both specific and understandable. However as for the work done, it is difficult to interpret because the manner in which the chopping was done, the composition of the wood and the number of the chops will all effect the results. I have recently done the above chopping with veyr cheap blades (~30$) with similar results. Can the work be directly compared? No. For the reasons just stated. To complete the work you need a baseline blade to compare to, you can make one or better yet use a well known production piece.
I held the blade level with the cutting surface (hardwood) and cut by only applying weight straight down on the blade. I used the same small section of blade for the entire cutting test. I used 3/8" Manilla rope for the test.
The first 400 cuts were really easy. At 500 the edge started to show some damage. At 600 it was getting a little harder to push through and I was just plain tired. So it made a total of 600 clean cuts.
That is interesting and seems decently high. Personally I don't do push cuts for edge retention, I use a slicing movement for two main reasons. First off, a blade will push cut *far* longer than it will slice, thus you need more time and rope to test for essentially the same thing (there are some complications). Secondly, when I cut thick rope in general I don't have a cutting board handy and thus it is usually sliced, slicing therfore more closely represents actual use. Again same as for the 2x2, method is critical. Jerry Busse for example has done 2000 cuts at live demonstrations with a Basic #9, and the blade still shaved. Can this be directly compared to the above? No, because if Jerry did the cuts in a more controlled manner he would get better edge retention than you would on the same knife. The solution is the same as for the 2x2 chopping.
Well, I just returned from digging a hole in a piece of wood with only the tip of the knife. Hole is 2" long about 1" wide and about 1.5" deep. There is no sign of tip damage.
I think that is one of the more useful tests as it evaluates a blades performance over a very wide range of aspects. It is a means to test point strength, tip penetration, handle ergonomics and security, and even gross blade strength. However I have also found it one of the most difficult tests to get a stable result from. First off, the composition of wood varies tremendously from piece to piece, even if you keep to the same type. To get around this I dig through about 12 pieces (or until the blade breaks) before I draw a conclusions. I also time the digging and count the number of stabs used to keep me honest from blade to blade and to allow judgments of penetration and general leverage issues. I still have a problem with speed and force of the prying as the lighter and slower you go, obviously, the easier on the blade. For now I just go as hard and fast as possible, which isn't ideal for many reasons. It is for me an upper limit test, and one which very few blades pass.
There are better ways to do it though, for example rather than simply saying a blade breaks, you could evaluate its performance at a lower stress levels. Later on I am going to keep this to a specific torque level, and thus give a more meaningful result, specific point penetration would also be interesting. Since some blades have a higher lateral strength ability than others they can operate at higher torque levels and thus perform better. It is not a trivial conclusion though, because the strongest blades often need more force to stab them into the wood. One of my favorites for this type of work, isn't the strongest, nor the fastest I have seen, but does it with the lowest fatigue and can handle it safely at medium force (<1/2" stabs).
I want to get a little more spring in the spine.
I also want to get the temper line higher on the blade.
I was thinking the same thing. Both will give you much more than 20 degrees without a perm bend, and will greatly increase the gross blade strength - but at the same time lower the ductility so you can't get 180+ degree flexes which some use as criteria.
-Cliff
