- 710 Axis
- Paramilitary
- ZT 0561
This review consists of :
Knives :
This review consists of : |
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Maker Webpage : Benchmade Knife Company, and their description of the 710 :
This is the CPM-M4 version which is spec'ed at 62-64 HRC. A few specifications on this one :
A very early, but still one of the better commentaries on this knife :
How to Make the Benchmade Axis Perform
I've had my Axis for quite a while now, courtesy of Les. I've made this my everyday carry 4"-blade folder, and have learned a bit about what makes this knife perform so well. Most strikingly, I've found that it takes a little work to really bring out the best in the Axis lock. The incredible ergonomics, solid lock, and recurved geometry you get for free from Benchmade -- a real high-performance edge you'll have to do for yourself.
*** Are You Leaving Some Performance On The Table?
I've been testing my Axis versus other people's Axisii over the past few months. Nothing too rigorous, just a quick test of slicing rope or whittling, and see how the two knives perform. Usually this is a test of the other guy's Axis with factory edge versus my Axis with my edge. A typical test with (say) 1.25" 3-strand rope, might yield the following: other guy's axis makes it through 1/8-1/4 of 1 strand with one swipe, my axis makes it completely through 2 strands and partly through a 3rd strand with one swipe. That's a performance difference of 700%.
*** Anatomy of the High Performance Recurved Blade
Let's stop here for a second and talk about what makes a recurved blade work. First let's get our terms straight, starting from the tip. Underneath the tip, the edge curves downward -- this is the traditional "belly". The belly reaches bottom and starts curving upwards again, in what I call the "front recurve". Then about .5" from the handle the edge peaks and starts curving downwards again, and this part I call the "back recurve".
When other people try to cut rope with their Axis, I often see them laying the Axis between the front and back recurves and trying to saw through with little bitty sawing motions, and wondering where the promised performance gains are. The performance secret of the recurve is the FRONT recurve -- the trick is to have the front recurve hit the thing-to-be-cut with speed and power. I typically lay the back recurve on the t-t-b-c, then add weight onto the handle and add speed as I draw the knife towards me, timing it to have the most power as the front recurve hits the t-t-b-c. The front recurve then bites in deeply, and I pull the knife all the way through the material, then lay it back down at the back recurve. I can cut that 1.25" rope in 2 slices this way, whereas it'd take much more time and energy to cut the rope using itty bitty sawing motions.
As you might imagine, then, getting the front recurve perfect is the main objective in my sharpening strategy. The back recurve is the least important part, as it does the least cutting -- which is good, since it's the most awkward part to sharpen due to the thumb studs. I use the belly for things like opening mail and other push/zipper cuts.
The first thing I do to Benchmade's factory bevels are thin them out. I now use the Spyderco 204 Sharpener for this. In theory any v-stick sharpener will work, but I've found the 204 has features that are a must for recurved blade sharpening.
*** The Thinning Bevels
First, I'm going to use the 204's 15-degree slots with the coarse stone, on the triangle edge. Why the edge and not the flat? Because the key to getting the back recurve sharp is to use a sharpening stick that is much smaller in diameter than the diameter of the recurve. This is the thinning bevel phase, and I do this phase in sections. First I thin the back recurve (the thumb studs get in the way a bit at 15-degrees. Then I switch to the flat part of the stones for the front recurve and belly. I use a magic marker extensively in this process. I magic marker up the edge, and the objective is to bring the 15-degree thinning bevel to within say 1/32" of the very edge (do not go all the way and create a burr).
*** The Cutting Edge
Once the thinning bevels are complete to my liking, I switch the coarse stones to the 20-degree slots, using the corner side for the first few swipes then switching to the flat side of the stone. Now I'm doing full smooth strokes, from the end of the back recurve all the way to the tip, drawing the knife towards me. I start with the corner of the stone because that gets the back recurve the best, then I switch to the flats because the works faster on the rest of the blade.
During the stroke, it's important to keep the edge of the blade perpendicular to the stone (or, think of it as keeping the edge horizontal). So when I start with the back recurve, I raise the handle up in the air a bit. As I pull towards me, I lower the handle so it's parallel to the ground just as I get to the beginning of the front recurve. Then lower the handle through the front recurve, and raise it again as I get to the belly. This sounds complicated but becomes very obvious if you just look at the edge and the stone. Whatever part of the edge is hitting the stone, make sure that part is completely horizontal.
I do these strokes one side only until I get a burr along the entire length of the other side of the edge, then switch sides and repeat. Once that's done, I switch sides between each stroke. Go to the fine stones and continue switching sides between each stroke, and lightening the pressure. Strop off whatever remains of the burr.
*** Getting the Right Grit for Performance
Now I have a thin, polished edge with no burr. This edge will whittle and shave like crazy, but won't slice well due to the polish. Now stick the coarse stones back in the 20-degree slot. Using very very light strokes, stroke the front and back recurve ONLY through the coarse stones (not the belly, we'll keep that polished). Don't push too hard or you'll create new burrs. This will rough up the front (most important) and back recurve, so it'll slice like crazy. I keep the front belly polished to open mail and do push cuts.
*** The Results ...
Now we have an Axis that can outperform the factory Axis by 700% at times! It's thinner and more polished than the factory Axis at the belly, so it'll out push-cut the factory Axis. It's thinner and more coarse than the factory Axis at the recurve, so it'll WAY outperform the factory Axisfor slicing. In fact, with this edge, the Axis will probably easily outperform every other non-recurved folder you have for slicing, and even the recurved blades with more polished or thicker edges.
Joe
jat@cup.hp.com
This knife was the introduction of the Axis lock which at the time was one of the first mainstream attempts and successes to utilize a lock design which did not have the weaknesses of many of the modern designs which is that the lock mating surfaces take all of the loads. As an example, the linear (and integral) lock when loaded puts all of the load in compression between the liner and the blade tang this causes :
The second is made even worse because of the tendency for locks to have very early or partial engagement to maximize life time (as they wear). But this puts very minimal surface contact and thus shear is very likely. The first problem can be minimized by using a steel insert in the lock face which is becoming more common.
What the Axis lock does is take the load from the blade and transfer it into the handle thus in order to make the lock fail the lock pin would either have to be sheared off or pushed through the handle. This is why in the "lock wars" of the early 2000's the Axis lock for a time was the highest rated lock in all the in-lbs claims. Aside from high strength it is also very secure because there are no issues with slipping which plague liners/integrals which are not precisely fitted.
The downside is the two omega springs which can break and the fact that Benchmade doesn't ship replacements with the knife which has lead people to request them just in case.
A few issues :
The moderate sharpness and high edge angle produced moderate cutting ability on on 3/8" hemp :
Which was about half that of an as-stock Paramilitary which came much sharper with a much lower edge angle.
On some wood work, compared to the #1260 Mora on some 1" dowel making 2" points with light force (10-30 lbs) :
The performance was much in favor of the Mora because of the much lower edge angle (9-11 dps) which produces a much higher cutting ability due to the greater mechanical advantage (it is a more efficient wedge). This difference was so great that the 710 tended to make more "curls" and the Mora actual slices, again not surprising as the 710 has almost double the edge angle.
However with heavy force (50-70 lbs) there is a dramatic increase in the performance of the 710 Axis. Now while both knives make deeper cuts the 710 makes a stronger relative increase because it as a primary grind and thus the blade thins out faster above the edge. This compensates strongly for the heavier edge angle and ends up equalizing the performance of both blades :
The picture at the right shows the large difference in chips removed with low and high force applied.
In extended use, making 500 slices through hard wood flooring there were a number of high contact points which while not causing significant irritation were showing signs they would be with extended used :
These are fairly minor and could be fixed with a buffer with an abrasive compound or even some fine sandpaper faster than the knife could be taken apart and put back together.
As an aside the initial sharpness was completely removed by this light work and the knife had little aggression left. There was no significant chipping just a lot of rolling/deformation and flattening. This is likely not an indication of the true ability of the steel but is mostly likely a combination of :
In general use on binding foods it is under the Temperance 2, and well under the cKc Chef, a few numbers on some apples :
Note the Temperance 2 shows an increase in force while the Axis decreases on the quarters. This is because the Temperance has a full distal taper so the quartering is done with the thinner tip and the main body is much thicker and thus increases the wedging. The cKc knife is very low in applied force as it takes 1-2 lbs just to hold the apple in place so it is using very little force on the cut.
In general the 710 does well if you compare it to the branded "heavy use"
tactical type folders. And while outperformed by such folders as the
Paramilitary from Spyderco it isn't outclassed and it can easily handle fine
dicing and mincing, though has issues working close to a cutting board as
expected.
In general it is only going to be outclassed by folders such as the :
As these have close to optimal cutting grinds and are designed and optimized for low stress cutting.
In lighter work such as grass cutting the 710-Axis does well as all that is demanded of a blade here is that it :
The main advantage or unique ability of the 710 is that it has a light recurve which keeps the edge able to cut such light vegetation even after it has dulled to the point where a straight edge would just slide off.
On woody vegetation it does well compared to the heavier "tactical" style folders however the high initial edge angle will keep it down in regards to performance compared to the higher performance Spyderco such as the Paramilitary simply because of the much lower edge angle on the Spyderco.
The difference this makes is in ease of :
On more forceful cutting the difference in performance is much reduced because the high flat grind produces a similar cross section when you average over a much deeper height. However it doesn't really have a handle which well allows more powerful chops as there is little retention for leuko-style rear grips.
For heavier work, the 710 does well even for fairly extreme (ab)use such as cutting sods for a walk way 1 . The knife has :
However there are a couple of negatives.
The first is that the screws in the handle back out quickly. Even when tightened down it only takes a few minutes of heavy cutting and they are loose again. This actually makes the lock unstable and it can collapse in the cutting. Thread lockers can of course stop that from happening.
The other issue isn't really a negative as much as it is a point which has to be carefully balanced.
Any steel doing that type of cutting will take damage from a combination of :
A decent steel can resist all well, and M4 does a decent job of it and even at 50X magnification it takes little damage. However the very low grindability means that the time to resharpen can be very low as seen on the graph on the right.
In such heavy work, lower carbide steels tend to be preferred because they can resist deformation and chipping even more, and be far easier to regrind.
The 710-Axis easily handles :
As this is all very shallow cutting it mainly is focused on sharpness and the narrow blade helps in turning cuts. However on such work the difference can be seen when using a blade with a lower edge angle which also has a high hollow grind such as the Modulator which will show increased performance.
To be specific, cutting the small strips of foam into cubes :
This difference is also high enough that the Modulator makes much cleaner cuts while the 710 Axis tends to cause minor fraying and splitting at the edges of the foam. But this difference really only standards out when compared to folders such as the Modulator which has a extreme level of cutting ability.
Ergonomics : The 710 has a number of very positive elements which increase comfort and reduce fatigue in hand :
However there are also a few not insignificant negatives :
There are many advances in clips in modern blades and this one is obviously very well dated and has a strong presence / printing in hand.
Security : the knife has :
With a strong and clean grip even hard stabs are not an issue, however with even light lubrication on the grip, the lack of a full guard gives concern for very hard thrusts.
Durability : the handle is G10 with steel liners with very large and robust standoffs. It is unlikely that the handle would be the weak point when over loaded.
Miscellaneous : With an open frame construction the 710 is very easy to clean. There is some concern however about pocket carry because objects such as coins can easily go into the open frame construction and impact the edge. Is also torx based construction (micro) so can easily be disassembled, though care needs to be taken around the omega springs.
The 710 Axis is known for strength and security as noted in the above however it isn't going to win any awards in regards to speed or smoothness of opening as it lacks :
It also has a strong secondary catch point where the axis pin rides forward and then reverses. It definitely is a lock which is designed around use and utility and not ease of flicking and dramatic speed of opening.
It is also only set for tip up carry, however is tapped for both left and right clip placement.
However there is a fairly significant issue with the lock in that it becomes unstable readily as the screws back out of the knife and this happens readily in use unless a thread locker is used. More detail is given in the video on the right.
M4 is a high carbon, high speed steel. In the knife industry there was, and still is to a reduced extent, some promotion of it as having high toughness however such claims are often problematic due to the lack of reference points.
The materials data, even in the most positive case as presented by the manufacturer show it to have lower toughness compared to tool steels such as A2 and is similar to high carbide stainless steels such as S30V, 1, 2, 3, 4, 5 . This is not surprising as it is a high carbon and thus high wear modification of M2.
As noted in the image to the right, it has a high carbide volume, but the carbide size is small (on the order of 2-3 micron) and thus given an optimized hardening it would be expected to hold a fine sharpness for an extended period of time, have little issues with carbide tear out and aside from gross impact concerns (chopping), the main issues would likely be with difficulty of grinding as the same thing which makes it strongly resist wear also make it very difficult to cut with a stone.
In regards to sharpening, high quality stones are needed to cut the steel well and some very simple stones will not cut it at all. For example the knife just slides along a Henckels 8k waterstone. There are waterstones such as the SPS-II stones which designed to cut even HSS well and of course diamond and CBN plates will cut any steel well.
For basic shaping, coarse grinding, then even simple stones can be used such as the simple oil stone on the right. However care has to be taken to avoid putting too much strain into the edge due to less than efficient abrasion and the steel being deformed / rubbed vs being cut. If the stone isn't cutting the steel well, even with a slurry (which can keep the surface of the stone with fresh abrasives exposed), then the edge should ideally not be apexed.
In regards to edge retention, stock cardboard cutting showed it to be very high performance which would be expected given the high hardness, fine austenite grain size and very small well distributed carbides 2 .
Overview :
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Most of the pictures in the above are in the PhotoBucket album.
1 : Sod cutting, various knives
2
: Edge retention cardboard, various steels
| Last updated : | |
| Originally written: | 13/04/2013 |