Khukri vs SOG

T

TomF

Joined
Apr 15, 2000
Messages
463
Howdy all! I was fooling around with various blades I have when I started remembering about the tang breaks we had a while back. I tried the tests on several other blades I have. The first major fixd blade I bought (before I really knew anything about knives) was the SOG SEAL 2000. An intersting looking but rather ungainly piece with an almost square handle profile with enough checkering in the kraton to grate your hand into hamburger under strenuous use.

Anyway, the SOG flexed considerably under stress, and i believe (but didn't try it) that it might well snap under my full weight where, of course, most HI khuks would not. The SOG is also 440A stainless steel which is not renowned for it's strength and edge-holding, and then covered in some kind of enamel powder coating. With all teh recent posts about khuk's invulnerability, I thought "What the heck..."

I took out my shop 1 22" Ang Khola and chopped down on the flat of the SOG blade near the tang-blade juncture just in front of the handle. I used mainly the weight of the AK, not much additional force.

The powder coating on the Sog was neatly parted with just a small ding in the metal. The AK's edge was badly flattened just ahead of the sweet spotwhere the belly of the chopping area begins to curve up.

So next I chopped down on the spine of the SOG, using the same amount of force.
Bad idea. The SOG's powder coat was cut and the metal dinged just like before, but the AK's edge impacted badly. 1/4 inch wide 3+ millimeters deep rectangular notch punched into the edge. The metal of the edge was rolled and crumpled out to one side.

Then I chopped down on the edge of the SOG in an edge-to-edge impact. Very bad idea. The SOG's edge got a little v-shaped notch about 1 millimeter deep and maybe half that wide. The AK edge got a notch about three times that in size and depth with metal rolling out to one side.

I took a file to the SOG and reprofiled it's edge. Took about half and hour. There is now a slight "depression" from the stright line of the edge where I ground out the metal to get rid of the notch. Then I went to work on the AK with the same file. The SOG is noticeably harder, even though it is of the "soft" 440A steel. I did some reseearch on the forums, and some people have stated that SOG does use rather hard heat treatment on their blades to increase wear resistance, etc.

Reworking the AK edge took about 45 minutes and I had to remove a lot of metal. There is still a v-notch in the edge, but it is much smaller than it was. I don't really like it there, but grinding it away completely would significantly change the profile of the belly.

While my opinions of the SOG has gone up considerably, my faith in the AK isn't really as shaken as I thought it would be. The SOG is still very difficult to get a comfortable grip on.

Some things to consider:
1. SOGs are made in Seki, Japan, where they have state of the art furnaces and heat treat methods, computer controlled milling, etc. HI khuks are made by hand with hand tools.

2. The SOG was much harder than I thought it would be, but it also flexed rather more than I thought 1/4 inch thick steel would.

3. I believe, but I'm not sure, that BirGhorka is hardening their blades to a higher Rc than Shop 1 did. I didn't try my Gelbu Special on the SOG, but I ran the file over it lightly. It feels a bit harder than the AK, but that might be my imagination.

3. The AK, and most khuks, are strictly "agrarian" utility blades, i.e. choppers, diggers, etc. The SOG is expected to perform in a variety of conditions including being used to cut wire and other things SEALs do in their missions, while not rusting in salt water.

4. The retail price of the SOG SEAL 2000 is just about the same as a mid-size HI khukri, which is also about half again the size and three time the weight.

Moral of the story: HI khukris can chop through just about anything. Nails, concrete, etc. have been mentioned in various threads on this forum. However, nails are usually completely annealed metal (i.e.soft) and concrete shatters due to it's composite nature. A really solid chunk of igneous rock, like granite, would probably be the end of a khuk, but then it would also be the end of any other knife.

So don't worry too much. Your HI khuk can destroy anything in it's path that is animal or vegetable. And most things mineral. That is, as long as it's even a bit softer than the 5160 steel of the khuk. When a khukri meets something rather harder than it is, you will get serious damage to your blade. So if possible, have some idea of what you're cutting into before you whack away at it.
You may get an unpleasant surprise.

Tom
 
What are the steps of the scientific method? I think there are five but it's been a long time since 7th grade science. Observation, Hypothesis, Testing, Law; that's all I can remember.

Observation: I have alot of blades and alot of time. And a bit of Calvin (as in "Calvin and Hobbes") in me.

Hypothesis: HI khukuris are the biggest and baddest. SOG Seal knife is for Seal wannabes.

Testing: Ouch. Unexpected results.

Law: Heat treat trumps attitude.

smile.gif


Revise hypothesis; order nuclear khuk from HI (1" thick spine, "unobtainium" edge, loaded with depleted uranium on the spine for increased mass, health insurance coverage for kamis).

Just having fun. Great and interesting post, TomF.
 
Many thanks for an interesting report, Tom. I know a lot more about the SOG than I did before.

BirGorkha has been putting a harder edge on our khukuris than I've seen come out of any shop in Nepal except a few village aruns like Nara's. I get in a village model from time to time that I know is 60+ Rc and there are probably forumites who have such a khukuri. I think Cliff got one in the too-ugly-to-sell village model I sent him awhile back. And I have tested some of the BirGorkha khukuris and I am satisfied they are 60 Rc or maybe a little more -- really more than we want. 58, 59 we think is just about ideal for the HI khukuri.

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Blessings from the computer shack in Reno.

Uncle Bill
Himalayan Imports Website
Khukuri FAQ

[This message has been edited by Bill Martino (edited 06-19-2000).]
 
Actually Tom didn't destroy either knife and he might well could have. He backed off when he thought he might snap the SOG. Cliff or I and a couple of others who do destruction testing would have kept going until something happened -- bend or break. Destruction testing tells a big story.

------------------
Blessings from the computer shack in Reno.

Uncle Bill
Himalayan Imports Website
Khukuri FAQ
 
Tom,

Try posting this in the SOG forum, the guys over there would know more about SOG knives. According to SOG the hardness of the SOG SEAL is between 56-58. I recall someone mentioning the hardness of Shop 1 khukuri's as being around 56. A harder khukuri will result in more colateral damage. Also, there is an old test around by Hilton Yam that had a 225 or 250 LB dangle off the SOG, the blade was bent as a result. The knife was still serviceable with the bent blade so it must be pretty tough.

Did you notice any chipping on the edge or was the steel rolled on either knife from the blade to blade encounter? For the amount of damage you described chipping would be inevitable. Sometimes a lot of the damage from a bad ding can be worked out with the chakma.

Do you thing there would have been a difference if the SOG moved instead of the khukuri?

Fortunately, there are few thing with a hardness over Rc 50 in the field.

Will



[This message has been edited by Will Kwan (edited 06-20-2000).]
 
I have chopped into knives with my 15" and 22" AK, uncluding one knife at 62+ RC, edge to edge the damage is usually similar, while the other blades might be harder the khukuris edges are thicker and thus this counteracts the lower RC.

There is some variation in hardness though. My 18" AK is significantly softer than my 15" and 22" AK, I have impacted and rolled its edge doing things that the other AK's are not bothered by. It is not a nail chopper.

The Villager I had was much harder than any other khukuri I have handled. It was that hard I thought it was going to break apart - but it didn't. I couldn't even roll the edge significantly. It would chop wire easily (coat hangers are a common standard I use) without edge damage. It was the perfect RC as far as I could tell and is still going strong last I heard.

How is the SOG ground, 440A stainless steel should be very strong at 1/4" stock. Low toughness and ductility though compared to the spring steel in the khukuris but high for a stainless steel.

-Cliff
 
I recall someone mentioning the hardness of Shop 1 khukuri's as being around 56.
Click to expand...

That's about right, because the GH khuks that Ron Wood tested for this month's Tacitcal Knives came in at RCs of 55 and 56. So, I'd think that "shop one" would have been making pretty consistant hardnesses (both for Bill and for me).

However, something that I think should be noted is that it's pretty difficult for the bishwakarmas to obtain "perfect regularity" in hardening. They have got it down to a science within a range of about 54 to 60 (excellent for the "tea kettle method"), but where a particular khukuri falls in that scale is usually luck of the draw.

Remember, as is the case with almost any knife (a TB khukuri, a shop 2 khukuri, or any blade) - a little edge roll on SEVERE tests shouldn't worry the normal (or even the extreme user) - especially when you have the weight of a khukuri to back up the edge.

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Craig Gottlieb
Gurkha House
Blade Forums Sponsor
 
Our specifications at shop 1 were as follows:

Only spring steel for HI khukuris
Only master kamis make HI khukuris
absolutely no child labor involved on HI projects
HI khukuris must have Rc58 or better
top quality fit and finish
top quality scabbard and frog

Any khukuri not meeting QC inspection by Kami Sherpa or his staff in Nepal would be returned as reject. Pala probably rejected 15 or 20 percent in Nepal. We offered maybe 10 or 15 percent as blems of those delivered here.

The bottom line is about 30 to 35 percent of the time we did not get what we wanted which is one of the reasons BirGorkha was started.

------------------
Blessings from the computer shack in Reno.

Uncle Bill
Himalayan Imports Website
Khukuri FAQ
 
Will, the SOG chipped, the khukri rolled. Certainly most of the damage came from the inertia of the big khuk. If the SOG had been moving, I doubt the damage would have been more than cosmetic (unless it was moving really fast). I got the distinct impression that, had I put my full weight on it, it would have either bent irrepairably or broken.

Cliff, the SOG is made from 1/4 inch stock, but not much of it is anywhere near that. it has a semi-curving flat grind from the midline and is relief beveled up to the spine. It is certainly very hard in relation to the khukri, but it is also obviously uniformly hardened, whereas the khukri is zone hardened. i think what we are seeing is something like the old "bend vs. break" debate. Tha kamis make the blade hard where it will do the work, but no harder than it has to be in order to maintain a working edge. Not neceessarily a sharp edge, but an edge that can continue to chop even with some damage. It can always be resharpend later, right? But if it chips out badly or even breaks, then there's nothing to resharpen. Also, I don't know for sure, but given teh elasticity of 5160 spring steel, if it was made really hard, it might shatter. Your villager could take it, but maybe that was the exception? As Bill has said over and over, the kamis tend to be very conservative and overbuild. Maybe they also underharden just a tad for safety's sake?
I don't know enough about the Rc scale to determine whether a 2-3 increment difference is really substantial. Is it a logarithmic scale, exponential, or linear? If it's exponential then a difference of 2 Rc would be a substantial difference in hardenss.

Craig, I think you're right. It's the blade backing up the edge that really counts. Khukris are made with a different philosophy of design and function than most other blades, and I think engineered accordingly (as I mentioned above).

Bill, how do they do a rough and ready hardness test at BirGorkha to see if they're getting good edges? What's interesting to note is that while the SOG flexed significantly (I could even see a slight permanent bend in it, so i flexed it the other way to straighten) the khukris (virtually all of 'em) don't flex much, if at all. And I'm not talking about the blade. Obviously that won't flex much unless chained to a truck. I mean the handle, which is a thin stick compared to the SOG blade, and annealed dead soft. It doesn't flex either.
How come? Dunno. In short, would I trust my bacon to a khukri? Yes. To the SOG? Ummmm, I'll get back to you.

Tom
 
On flexing.

The other day I got the blade of my 15" AK to flex considerably, perhaps 15 degrees. The task was getting pitch soaked heartwood out of old stumps. Usually I would use an axe for this task, but I decided to try the khukuri. I chopped the blade deeply in, then pried the wood out sideways as hard as I could. The knife held up extraordinary well. The steel flexed as well as a knife as it did in its previous life supporting the chassis of a car.

I too was more concerned with the tang than the blade. But the tang took no discernable bend under this heavy use.
 
Said Little Red Riding Hood:
"My, what big arms you got!"

I couldn't get my old 15" AK to bend even when hanging from it.

Tom
 
Tom: Can't say how they test for hardness at "birgorkha," but at "shop 1", TB will take the edge of one khukuri and attempt to shave off some amount of steel from the edge of the spine. He's got a pretty good eye and feel for the technique, and is able to judge edge hardness to an alarmingly good degree.

Bill has me stumped how they test for RC hardness in Nepal. At "shop 1" TB is lucky to have a buffing wheel (the only one in town, I think).

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Craig Gottlieb
Gurkha House
Blade Forums Sponsor
 
Tom,

I don't think my AK would bend if I hung from it either.

I was using my legs and abdomen, not my arms. The legs are a lot stronger. I just used my straight arms to hold on to the knife.

Craig,

I think Kami Sherpa uses a file to test hardness. I can almost guarantee he doesn't have a calibrated Rockwell hardness tester. He does ok even without the high tech equipment. Kami Sherpa has a good eye and hand. I'd take his recommendation on a good knife over a favorable laboratory analysis any day. There is no way an abstract number can incorporate all of the judgements an experienced man can make. A hardness tester will take a measurement at a single point. For a differentially tempered blade with intentional hardness variations between belly and tip, as well as from edge to spine, the file may help an experienced man form a better overall judgement than a point measurement from a tester would.
 
Tom,

A few points in Rc can make a big difference to the properties of steel. For typical tool steels Rc of 58 has a tensile strength of around 310 000 Psi. At a Rc of 56 it is 285 000 Psi. Toughness at Rc 56 is about double that of Rc58. My graph for toughness is fairly difficult to read so "double" is extremely approximate. This might explain why you see rolling instead of chipping on the Ang Khola.

A lot of toughness is lost going from Rc45- Rc50, approximately 40 ft-lb to 9 ft-lb. Rc is determined by how deep a diamond penetrator is able to depress into the sample at a set force.

Will
 
You have all heard of the calibrated eyeball. Well, you can calibrate your file, too. I have an old finishing file that I've been using for a dozen years to test hardness. There is a pix of it somewhere on one of the HI forums that I posted maybe a year back.

I used to test some khukuris for hardness at a heat treating shop in El Cajon, CA. At that time I was rehardening some blades that were too soft. I had a buddy who worked at the heat treat facility and could get the testing done free. He got me a few samples of various hardened steel and I used those to compare khukuri hardness against. My file would not cut Rc60. It would cut Rc55 pretty easily. With effort I could do some damage to Rc57-58. Dead soft I could shred to nothing. The more you use the technique the better you get and soon you don't need any samples. Your file tells you the Rc within a point or so but what it tells me and the guys who check at BirGorkha are just two things: Hard enough or not hard enough.

------------------
Blessings from the computer shack in Reno.

Uncle Bill
Himalayan Imports Website
Khukuri FAQ
 
I`m with Bill here. I check with a file. Due to the convex edge, RC 60 is not going to matter. I prefer RC 56 for ease of sharpening.

What`s wrong with child labor? During haying season, when we did it with horses,(that`s not fun), and indeed, in any farm operation in the US, kids work. No running water. No way to get the hay off of your sweaty back.And an outhouse.

I hired out as a carpenter`s apprentice at age 12. I`d been working before that. It didn`t hurt me.

I`m a bit sick of the whiners, the cryers and the do gooders.

Hard work never harmed any group. Sure; some get hurt. Life is a risk.

Realistic training kills people and bends iron. And this is just training.

I still deal with horses. I know they can hurt me; and have. I SCUBA dive and fly. Sometimes beyond the current state of my training.

Who`s going to care if I screw up and eat a hoof?

Leave Nepal alone. The US has no history in actually bettering things. They are not us. They have been who they are for centuries.
 
FNG,
Amen to hard work!Asked my MA Instructor why he didn't teach his new class the way he taught the old class!He stated it was diff. the new guys couldn't take it!He quit teaching shortly after that!I became his only Student after that!Sad comentary on today,is it not!
jim

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FNG, it's not a matter of child labor but simply of experience for quality of products, IMO. A kid cannot be a master as a ten-year-old kid cannot have fifteen years of experience.

I guess Nepali kids are not spoiled.

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Did you enjoy today?
\(^o^)/ Mizutani Satoshi \(^o^)/
 
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