Blade
- The blade in both cases with M2 & ATS-34/154CM, was shaving sharp right out of the box, however too thick and really rough. I'd expect a better sharpening job for a 100$+ knife. I like the geometry of this blade a lot, it's good for slicing, cutting, stabbing. The blade has a lot of belly and a recurve for improved cutting/slicing ability and the strong point for stabbing. I already said quite a bit about M2 steel, but those who prefer stainless steel blades, there you go, ATS-34/154CM allegedly the one of the best stainless steel available for knife blades, by now (2001) Benchmade has already switched to 154CM by Crucible as their blade material, which is practically identical to ATS-34, except that many knifemakers claim that it's a finer grained and cleaner steel and made in America, not in Japan.For the record, the edges on both 710-s and many other BM knives I've had were far from perfection. This is nothing new with Benchmade and practically every other factory knives. Their sharpening job definitely could've been better. Basically it can be broken down to 2 things, coarse edge, and the edge thickness. Yes it was sharp, but on both blades the edge grind was uneven, I could clearly see the machinery marks. It was far from what can be described as mirror polished or micro serrated :( Matter of fact, it was rather coarse. Those who know how to sharpen the knives would not care too much about that. I sharpen all of my knives to my personal taste and requirements. Still I think Benchmade could have done better work, for example every Cold Steel knife that I ever had, has much better finish. Not that it'd make AUS-8A outperform M2, just sort of frustrating, why that is such a problem to put a normal edge the knives.
Another issue with the blade is the angle it is sharpened to. Too high for a folding knife, more than 50 degrees included. Better to resharpen it to the lower, 18°-20°(36°-40° included). Kindda hard to perform this operation on the M2 blade without proper equipment, but it will pay off :) There was a very good thread on BladeForums.com addressing Axis 710 edge resharpening, where Joe Talmadge provided very detailed information how to make your Axis perform better. Click here to read.
To be fair, the edge thickness is not something specific to Benchmade. Most factory knives have the same problem to some extent, partly because of the customers too. For those who don't take care of their knives, and don't know how to sharpen them, thicker edge translates to increased edge holding ability and is harder to dent, roll, etc. The bottom line to me is that there is no excuse for poor NIB sharpening job, but it's hardly the greatest concern of mine :)
M2 Steel
- M2 high speed tool steel, that has very good characteristics such as toughness, wear resistance, edge holding (or the abrasive resistance). Click on the icon or on the following link to see the Tool Steel Comparative Chart. While M2 steel primary designation is high temperature metal cutting, which isn't really close to our everyday knife chores, it turns out to be a good blade material as well. M2 is a good one to sharpen. I like sharpening M2 blades. It's noticeably more difficult to grind than Benchmade ATS-34/154CM, but definitely it gets a keener edge. In other words, M2 can be sharpened to a finer edge & will retain sharpness much better. I wrote the above around 8 years ago, and my later experience only confirmed that. Stock M2 from Benchmade was 60-62HRC range. At later hardness measurement showed it was 60HRC exactly. Still, even at the same hardness with 154CM steel, thinner edges were possible on M2. In 2009 I've asked Phil Wilson to reharden two M2 steel blades, one came out 64HRC and the other at 64.5HRC. The details and findings related to the rehardening process is described in great details in the article - The Importance Of Knife Blade Hardness. The point is, after rehardening I was able to keep 20° total angle, which is 10° per side, on my M2 blade. On the soft materials this may not be as evident, but on something harder you'll definitely see the difference, thanks to its toughness. As you can see from the chart M2 has higher wear resistance than A2 or D2 & those are considered to be amongst the best blade materials. After some use I can definitely say that M2 performs very well, definitely better that any other stainless steel(in factory knives) I have had, that includes high end ATS-34, 154CM, let alone 440A, 425M, etc. Also, given the M2 toughness, it becomes possible to sharpen the blade thinner, thus increase its cutting ability, without compromising its lateral strength and the edge holding ability as well. BTW, speaking of toughness, you can check out Osborne 940 review, there's some more information comparing 154CM and M2 performance in a real life cutting application. The short story is that 154CM blade chipped badly on the same wire that M2 handled with flying colors, that was M2 blade with 18° edge angle and 154CM with 21°.One thing I would like to mention here in defense of M2 is the rust resistance. In general M2 is not a stainless steel, it's a carbon steel, so it will rust easier than the stainless one. Often you see people asking which 710 should I get, ATS-34/154CM or M2, and many answers sound like M2 will rust as soon as you take your eyes off of it. M2 doesn't rust that easy, in general if minimal care is taken, it won't rust at all. I have several M2 blades and no rust whatsoever on any of them, even on my BT2 stripped Nimravus, after all the edges are exposed even on coated blades right? So, IMHO unless the rust resistance is your primary concern, M2 is a better choice for a user knife, at least that's the case with the Benchmade knives.
M2 Sharpenability
- I thought I'd have to say a few words in defense of M2 steel here :) Very often people curse at M2, complaining that it's too hard to sharpen. First of all, everything is relative :) Depends what do you compare it to. I've mentioned above that M2 is harder to grind than ATS-34/154CM used by the same Benchmade. However the difference is not anything dramatic. You'll notice it, but it is not the magnitude order. Obviously grinding M2 is much worse than 440A or 425M used by many manufacturers. However everything has its price and there's no free lunch either. Simply put, increased difficulty in grinding means that during cutting, the edge will loose metal with greater difficulty as well, keeping your knife sharp 5-10 times longer than low end alloys. Of course it's not that simple, edge holding depends on many factors, but this is one of the most important.Is it worth it? Up to you to decide what do you want. Ease of sharpening plus frequent sharpening of the other way around. To me, M2, (and BG-42 and some other "hard to grind" steels) are definitely worth extra effort in grinding. The benefits definitely outweigh sharpening probs :). Once again, M2 is not any more difficult to grind than BG-42, D2 or the same ATS-34 heat treated by Paul Boss. I'm talking only about the steels I have experience with.
As always, the most depends on your skills and tools being used. If you don't know how to sharpen your knives properly, or If you try to reprofile M2 blade with a relatively high grit hone, obviously you'll be disappointed. People out there try to resharpen M2 blade with Spyderco sharpmaker, or Norton fine stones. Sure, they can't get the job done for hours and then blame M2. But those are not the right sharpening tools for serious sharpening and bevel reprofilng. Try DMT, Edge-Pro, etc, and you'll find it is not that hard. Sharpmaker and other fine stones are good closer to the end, once you get the primary bevel done, to get the fine, razor sharp edge, or for touchups, but not for profiling.