Jose :
Are fully hardened blades in this range, or are they much more difficult to bend?
Fully hardened blades can be twice as strong or more than those with soft spines. They are also stiffer than spring tempered spined blades (in the nature of 25%), but can break easier (under lower force) due to a lack of ductility. This is why in general there is little arguement against spring tempering spines. While they do slightly lower stiffness, they massively increase ductility and impact toughness. Of course it depends on the steel and the other aspects of blade geometry such as spine curvature and other stress concentrating elements. Some blades are very ductile and tough even at full hardness.
[chopping]
Would a fully hardened blade be much more likely to break under such use?
The edge is still full hard, and that is where the crack will start as that is the focus of the impacts. Now there is an argument that the spines left soft make the edge more durable because of the shock damping, and you can feel this if you smash the flat of a large fully hardened blade against a hard object compared to one with a soft spine, however I don't think the damping effect is the critical one in regards to the onset of damage. I have seen lots of cracks on blades with really soft spines. This is one of the things on my todo list to examine.
There are going to be trade offs in almost every aspect of design.
Yes, this is what I was trying to make very clear in the start. There is no real right or wrong in blade design, just does something do what you need it to do or not.
Tapering the blade may make it less suitable to pry with, but the main function of a knife is to cut, and it's that taper that makes it an efficient tool.
Yes, I have lots of knives like that. Distal taper to a very fine point on very thin stock with full flat grinds. My point here is not that tapers are a bad thing, but that on knives of that design I would prefer a different steel, harder and of a higher carbided alloy.
Would that same offer be open to any up-and-coming smith that thinks he's up to the challenge?
No idea, ask him
Ed :
[cut bone]
I never argued for its necessity, simply stated that it was a restriction, and on knives so restricted (of which I have many) I would prefer other steels.
Only a supreme clutz would find a need to cut bone in the field.
Having the ability to cut bone is a side issue, however it is endorsed by many, Ron Hood for example uses it as a common test on his survival knives, one of many in fact as hardly everyone has the skill or knowledge to avoid bones completely. Of course there is also the self-defense arguement, bone cutting tests with such knives are fairly common. Then there is the whole range of accidental high impact stresses which can produce similar effects.
[vice jaws]
Bend a knife around a smooth radius rather than a sharp vice jaw: Yes and here is why, a scratched surface can produce a stress riser when flexed.
I am not sure what you mean there, the vice jaw scratching the surface of the blade, or scratches in the vice jaws influencing the bend. In any case a vice jaw will inherently be harder to bend around because it will induce a higher curvature at the contact point at a given bend angle.
I know of no sharp edges like that in practical use of a knife.
Entry tools get subjected to very similar forces (as do knives used to pry around joint bones - by the way this was one of the promoted design constraints for CPM-S30V). In any case, my point here was not to argue against such testing, as long as bends are consistent you can learn from it, but simply to point out that most people doing vice tests bend against the vice jaws which is a much more stressful test. owever since you are arguing suitability of tests, I can't recall the last time I had a use to bend a knife to 180 degrees several times.
-Cliff
The blade will also bend before it breaks. No, I haven't tried this myself, but I've seen a few test blades. I don't have any numbers for you, but compared to the other custom blades that I've owned, it performs on the highest end of the spectrum.
