Review : X-Ray Vision from SOG

baraqyal · Jun 1, 2001

Cliff, just out of curiosity, what folding knife do you (or would you) use as an EDC, beyond the SAK?

Also, I'd like to see you beat down a BM axis lock. Perhaps the 550 griptilian, which is fairly similar in construction to the Vision. I wonder if you would have similar results.

I'd like to comment that if you're going to make claims about how much force a knife can withstand, you better be able to measure it. Given enough time, anyone could break a knife with a 2x4 or a steel pipe. 10-15 whacks or 3/4" into wood is not a good measurement, as they can vary widely (wood hardness can depend on the tree, whacks can depend on many factors). Claiming that the tests are similar to real life are nice, but that's not hard science - it's much more like anthropology, based on personal experience. You don't have the luxury of testing a thousand knives, but at least you could test in a way that others could precisely repeat and hopefully have the same results. I really like the data about cutting ability - I'd like to see more of your tests go along those lines.

Even after your review, I still like the SOG. I would never use it as a pry bar or a wedge; knives don't replace all tools. You should put together a web page of horribly mangled knives - it's definitely interesting to look at. I haven't ever broken a knife - and I hope to never do so. Keep up the good work! (and maybe layoff SOG for a while)

-- Rob

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Me fail english? That's unpossible!

Gator97 · Jun 1, 2001

Originally posted by baraqyal:

I would never use it as a pry bar or a wedge; knives don't replace all tools.
Agree, normally or in a normal use you don't do it. However in some sort of emergency (not necessary a disaster) you might have to, and at that point it'd be nice to know what your knife is able to do, in other words use it or not, like using your knife as a prybar or whatever else is ok, or gona make things worse...

You see, I cary couple knives on me, some more in my car... Somehow I never carry on me an axe, a chisel or a hammer...
Given the circumstances my knife(ves) probably will have to serve me as those tools too. Then I'd reather have something I am sure of, and I think you too, unless you prefer to carry the full assortment

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Have Fun,
Alligator

Cliff Stamp · Jun 4, 2001

Steelhed :

fashion a pendulum device out of wood, line, and weights to more easily quantify the amount of lateral force applied to each blade.

Yes, it would I did this quite some time ago using an 8lbs maul. I can as you note, adjust the impact energy very easily and to tight tolerances. I did intended to do this with the Vision, except for the fact that the lock was functionally damaged at a very low level (wrist snap). I had expected it to be able to take the splitting easily considering the extreme lock strength (~350 lbs), however the dynamic loads caused failure at a much lower level. Live and learn, I'll be more careful next time around.

an overzealous swing made to compensate for fatigue.

A fairly bad problem indeed. I have been donig some chopping lately with different techniques and seeing how it effected a few blades. The problem is that when I get tired at the low power techniques I tend to start to slip into the upper ones and this skews thar result. Median based statistics on large samples will take care of that, however for break point work, it is a much more significant problem.

I have some other ideas for taking the "human" out of the equation

Fire away.

baraqyal :

what folding knife do you (or would you) use as an EDC, beyond the SAK?

I am interested in two broad catagories of folding knives. The first is a simple high performance cutting blade. Something for example such as Steve Mullin's Pack River folder. This would both outcut the main blade on the SAK and not have to be sharpened as often, nor would it take damage as readily from impaction/deformation. This is a pure light use blade, no impaction, no prying and no twisting. The blade should be 1/8" at max, distal taper, with a full grind to a max of 0.01" thick behind the edge.

The second class of folder I am looking for is the near opposite. It should have a lock durable enough to take moderate impacts (such as the wood splitting in the above), as well as enough lateral strength to stay together under prying/twising. The cutting ability should be decent, but obviously a lot less than the first type of folder. I am hoping that the Busse Combat folder will fit this task, which is why I have bought a few folders as of late so I will have a rough benchmark when I do get to use the Busse one.

Unfortunately, most current "tactical" folders don't go into either of these classes. They do not cut nearly as well as I would want because they are ground out of too thick stock, with too obtuse primary and secondary bevels. The only advantage to this geometry is strength but they don't have the durability necessary for harder work because of low shock resistance and poor lateral strength. So basically they are too thick to cut well, but yet will take lock damage from harder work, not a great combination.

There are of course lots of folders I have not used.

I'd like to see you beat down a BM axis lock.

It is on my to buy list. Probably next month or the one after.

Given enough time, anyone could break a knife with a 2x4 or a steel pipe.

Not exactly. Unless the impacts are above a certain level fatigue doesn't even set in. You could vice a BM and beat on the back of it with a 2x4 all day long and you would never cause stress cracks because the impacts are so low the steel can easily absorb them. Same thing with locks, there is a certain impact that will cause failure with repeated application, as you go above this failure happens more quickly, but if you go below it nothing ever happens. For example, yesterday I did 1000 hits on the Buck/Strider with a chopstick. There was no result damage, nor would there be if you continued it as the impact energies were far too low. Would all locks fail with repeated impacts by a 2x4, I don't know.

10-15 whacks or 3/4" into wood is not a good measurement, as they can vary widely (wood hardness can depend on the tree, whacks can depend on many factors).

Every measurement has an uncertainty or variance associated with it, you can never excape this. The point about the wood is a good one though, Pine for example compresses readily and thus absorbs some of the impact energy, a piece of hickory would take little or no damage from hits as energetic as I applied to the Vision. I could use some kind of standard mallet, but then it starts to get more abstract. If you are actually going to split wood in some kind of emergency situation odds are not good that you are going to be carrying a mallet. What I would like to do ideally is break one in a very controlled manner as described in the above, and then just freehand it as I did with the Vision, as it is the latter that is of critical importance to me. What I should do, as was suggested in email, is to apply the forces freehand but then quantify them, which is not difficult. I will attempt some work along these lines in the next couple of days and thus estimate the impact energies the Vision saw.

I really like the data about cutting ability - I'd like to see more of your
tests go along those lines.

The reason that this dat is so refined, is because that is what I am most interested in. The breaks are only done when I have no interest in any more cutting.

Even after your review, I still like the SOG.

So do I for various things, it cut better than a lot of folders I have seen.

-Cliff

[This message has been edited by Cliff Stamp (edited 06-04-2001).]

Cliff Stamp · Jun 5, 2001

Yesterday I made some measurements so as to give an estimate of how much energy I was applying to the blade in the above. By driving 24 nails (12, 2.5" and 12, 3.5"), into a piece of 4x4 under controlled loads I was able to calculate how much energy it took to hammer them in (51 +/- 2 ft.lbs, and 101 +/- 6 ft.lbs respectively). I then used the same 2x4" mallet as in the above and pounded another 24 nails in, 12 with wrist pops and 12 with elbow driven swings. I could then estimate the impact energy of the swings and it comes out to 25 +/- 5 ft.lbs for the wrist pops and 45 +/- 8 for the elbow swings. Thus it is a rougly 2:1 ratio, which I would expect based on the chopping comparisions with other blades done with both methods. I used two different types of nails just as a stability check, both gave the same result.

Also I spent some time hammering the points of a few blades through some sticks, as well as hammering them through some small trees (1-2" in diamater). I found that it was not as difficult as I thought it would be to split the wood with the points of the blades even with knives with more obtuse points than the Vision. I could easily do this with wrist pops unless the wood was really knotty. However to chop down the trees was another thing. While I could wrist pop the knives through Pine and other soft woods (Alder), a number of harder woods did require me to swing from the elbow. I used the same 2x4" mallet as in the above.

-Cliff

Review : X-Ray Vision from SOG

baraqyal

Gator97

Cliff Stamp

Cliff Stamp