blademan 13 :
in the works and I guess I was just suffering from tunnel vision as to what my definition of a "brush blade" was.
It was a valid point, the label I used is not a overly accurate one for this knife as you pointed out. The problem is that the secondary uses of the blade, while only making up a small percentage of the actual work done, are so different in required abilities that they dominate the design aspects. Optimally you would use more than one blade.
A few years ago when I started running optimized profiles, slimming everything out until I reached the absolute limit of performance, I found though that while the knives became like lazers, the focus became more and more narrow. Eventually you reach a point where you get a blade than can only cut soft live woods, if you continue to the extremes.
This knife was intended to be mainly a brush cutter, however which could handle basically anything. Rereading the review this isn't clear, so thanks for pointing that out. I added a few paragraphs to clarify this point. Shortly I'll add some more specific info as the value of the more robust profile, with some examples of this blade compared to a truely optomized limbing and brush clearing tool.
It is obvious from your profile of the grind on this knife that a simple flat grind of the same spine thickness would be the more efficient cutter when ground to an equally fine edge.
Yes, and then the knife could then be convex ground to an even lower cross section.
I have always found that a proper geometry has as much to do with hardwood penetration as mass.
Yes, balance and mass provide the power, the geometry determines the efficiency. How much power goes into the cut, and how much is wasted pushing the wood apart is all geometry.
[Ray Kirk]
Also, the configuration chosen was standard Kirk fare, "flat ground to about .040 and then convex to about .016 on the edge. I sharpen that to about a 20 degree included angle edge".
What does "flat ground to about 0.040 and then convex to about 0.016 on the edge." mean? The primary flat grind goes to 0.040" thick and then there is convex bevel which is applied which brings it down to 0.016" at which point the final 20 degree edge angle is applied?
Ray has not experienced any wrinkling with this geometry and was still experimenting with how thin he could take it before edge damage.
Ray is fairly skilled with a knife which means in general his optimal geometry will be much lower than average. I worked with his much smaller JS bowie with a similar acute edge profile and saw it ripple on hard woods. To be quite clear this was on a sloppy cut, through the hardest of seasoned wood. It is debatable if this level of durablity is required. If you work with enough care you never need it. However when the blade starts getting longer, power goes up signifiantly and you need a thicker edge profile to handle the strain.
But again, the type of wood that causes damages for me is wood that in general is usually avoided. These are windblown trees, dead or dying, which have essentially been seasoned for years. The branches are small (fraction of an inch), and so hard they often shatter when cut. The edges are so sharp they can easily break the skin with light contact, just as bad as the thorns on a rose bush (which is really fun to cut as I found out a couple of days ago). It is horrible wood to work. When I was carrying extreme profiled blades I always used a "beater" on these trees, or reverse the knife and just smashed the limbs off (which tends to leave lots of small sharp stubs - no fun to carry).
It again is a matter of choice, do you raise the edge bevel and in so doing sacrifice the cutting ability on the softer woods to be able to cut the hardest of woods, or carry an additional blade to handle these trees (or just avoid them). For most camping and similar trips this wood is however actually the best used as it is least damaging to the enviroment (actually helps the other trees grow), plus it is the easiest to burn and use in construction as it is feather light compared to wet wood (far less than half the weight). Plus it makes the best tools as it is heavily seasoned.
[concrete block chopping]
If I remember right, your destructive tests on some of Ray's knives more than prove they are able to withstand the infamous "blockchopping" almost as well as one knife who' used this type of test as a "claim to fame". The fact that Ray's knife was also a very efficient cutter also is worth noting.
Essentially yes, it easily out cut the WB (and PAB), and was at the same time far more durable. The concrete block test, while touted as highly desctuctive is only so to the ultra-brittle high carbon stainless steels. If the steel is tough enough, all the block can do is just impact it. And this impaction stops quite quickly because past a certain point the pressure isn't great enough to squash it any more. The problem with ATS-34 and other similar materials is that they just fracture, and can then literally completely explode. You simply can't get that kind of failure on the tougher steels.
Anyway, I have no doubt that you will enjoy using that blade. By the way, Ray's website is down, did he move it?
-Cliff
