Erik :
Since you took all the mesurement your self, where does the variation in the way people measure angles come into play?
If you mean can other people measure them with more or less precision, sure they can. This is why I stated the variance I was assuming, and specifically talked about just how little a change in width and length measurement was necessary to produce such a change. Considering that I have seen specs listed measured with a simple ruler, in general you can expect a much greater variance than what I listed which was for a caliper.
which makers have I described that use thicker edges?
Simonichs specs are thicker than on both BMs I have handled, and the edges more obtuse as were the primary grinds. You have also listed no edge specifics specifics for the other makers, and those that I have read were in fact in the same class as Busse Combat in the makers own words (Rinaldi for example has described the edge on his large knives as similar to the BM). I would bet specifically that most of them grind far thicker and more obtuse than the specifics you listed as your preference. Hossom specifically has stated he would never even consider grinding a tactical knife that thin (actually even thicker). By your reasoning in the above you can apply all the labels you attached to Busse to them, and the same to their users.
... your actions and word in regards to Busse knives is inconsistent with what you have written in regrards to other makers.
Most of my comments in the above are about geometry in general, they are not simply specific to Busse knives. However yes, if you go back a few years you could probably find me making statements where I said similar to what you have done in the above, I know I did think that way a few years ago, that you could define a "right" or "wrong" geometry, same with steel, handle design etc. . I simply wasn't looking at the whole picture then. A lot of it had to do working with really different knives than my personal perference, and talking to users like Greenjacket who liked very different knives (Project handle), and and did various chores in very different ways.
When I started altering edge geometries it became crystal clear that the cutting ability gains were always accompanied with a more restricted scope of work because of the durability loss, and then I had to start carrying multiple knives to be able to handle every day work (specifics given in the above and in the reviews). From that point on I have tried to be more clear about what is gained and what is lost, and just what is needed for what kinds of work.
For example now I would view 420 as a perfectly fine blade steel, for a particular class of knives which have a particular set of performance goals [specifically high corrosion resistance, toughness and ductility with a low need for edge holding]. Whereas if you had asked me about it a few years ago I probably would have called it "junk". I have rewrote some older reviews to clarify such issues, no doubt that some older posts still exist in the archives. You would hope that this is always the case in general though, if you agreed with everything you wrote a year ago it just shows you have learned nothing in that time.
Admit that Busse uses hype ...
Hype has multiple meanings. In the most passive sense it just means strong promotion. With multiple active internet forums and ads in magazines, Busse Combat does indeed fall under that defination. However hype can also mean intentional misleading promotion, which is what it means when I use it in regards to performance claims. Considering that Busse does live public demonstrations of the blades performance and guarantess his claims, this does not fit that defination of hype.
Hoodoo :
So essentially you keep taking measurements at different places until you get the data you want to support the results you think you perceive.
That is indeed a very significant problem in general, if you use the results of a calculation to judge the merits of the data, you can't then use them to independently judge the worth of the calculated quantity as that is circular logic. This of course was not what was being done in the above. I was comparing two ways of measuring edge angles and noting the the results were not consistent.
It was about this time that I switched to measuring the angles in a different way in order to increase the precision. The second data set was generated by measuring the angles at three points along the edge, and measuring them on both sides at each point, using a fine pen to mark the point I was calling the top of the edge, and measuring from the inside of the marked line.
You are still faced with other problems though such as angles varying along the edge, which is why I have had to quote ranges in some places like 25 to 10 from base to tip. And having to deal with convex edges which need more information to be quantified, generally you can define a bevel and a shoulder, but 2-4 points along the edge in height would be better.
[medians]
statistically there is no difference between those two groups of measurements (P = 0.786).
Well yes, this is kind of obvious. The same blades were measured so yes the means or medians will agree. The topic was the precision, if you wanted to look at this with some statistics you would test variance equality. Specifically compare the results on blade A,B,D for both groups. It easily passes on a 5% level. You can't use C as it has a very different edge geometry (you can actually see it is much wider) and thus the variance it adds is actually many times the measurement uncertainty in the second group.
If dropping C makes you uncomfortable (and you could argue that it is data fudging as I have not specified how I know it has a different angle in a rigerous sense) you can easily show by propogation of errors that the two different ways of measuring will induce a vastly different spread assuming the same initial meauring tolerance. Both by simply using multiple measurement to average out the random deviations, and by eliminating certain others by using defined fixed points (the pen lines).
Jeff :
How in the hell can anyone even try to get accurate measurements on a knife edge that's been ground by hand?
By measuring it and being aware of the tolerance in what you are measuring and how this carries over to what you calculate, this is general method. Note according to Hoodoos quoted statistics, the two independent measurements are equal (being really picky there is not strong evidence they are unequal), and thus they are consistent showing that it is quite obvious that it can be done.
[edge angle measurements]
... as far as information on the manufacturer since the next knife may or may not be close to the first
That was the point. When you see edge specifics quoted from users you have to consider that what you can expect can vary quite a bit as the users number could be shifted significantly from what it actually is, and what that is could be significantly different than the next blade the maker grinds. The numbers were used to clarify how specific sized small errors in measuring and hand grinding can produce a rather large reported spread.
-Cliff
