Kukri making process

A

Abear

Joined
Feb 25, 2002
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Uncle Bill
Can you give us a update of your Kukri making process. Which part are hand made, which parts are machine made, and how long does it take to make one?

PS. Have you heard of something called case hardening? Your Kami's probably use that process already without knowing it. Basically, if you look at the shackle of a good pad lock, it probably has "case hardened" stamped on it. Basically, you want a tough shackle to be hammer resistant, but also a very hard shackle to be saw resistant. The solution is make the shackle out of low carbon steel, which remain ductile and tough after heat treatment. The shackel is heated inside a high carbon environment, where the carbon diffuses in the surface, changing it to high carbon steel. High carbon steel can turn very hard, but less tough when heat treated. When the shacke is quenched after heat treatment, the outer high carbon surface gets very hard, but the inner core is still very tough.
I heard some africans treat blades with animal leather and bones. That results in a hard nitrite surface. I don't know about that though.

Andrew
 
Andrew,

Case hardening is a bad idea for knives. As the blade is sharpened and worn you quickly run into the soft core, so you end up with a very short lifespan. instead the kamies zone harden the knives leaving the spine, tang, and to some extent the point relatively soft. But edge is fully hardend for a good distance (over 1/2").

n2s
 
Case hardening is a cheap solution for padlocks, that must serve it's purpose for a few bucks. As for the knives.... The spring steels that the kukris are made of is probably 5160. It's about 1% chrome and .006% carbon by weight. That makes it a medium carbon steel right about where the eutectic point is. So when cooled slowly, it forms fine pearlite, which is pretty tough stuff, and when tempered correctly, it forms martensite, which is very hard stuff. I get this knowledge from text book (but these knowledge is not all that useful in the real world where the conditions are not well quantified). So I have no idea what actually forms in the Kami's tempering process.
So in your experience, you can actually feel the hardness 1/2" inside the edge. Wow, that blade would last through lots of sharpengings. However, if the kamis heat the spring steel in charcoal which is made from carbon. more carbon can diffuse into the kukri's surfaces, turning into high carbon steel past the eutectic point. When quenched, this material can get as hard a file, but still have a strong, pearlitic core.
Anyone a material scientis or a metulurgist here? Want to volunteer polishing a cross section of a Kukri and see the structure?
 
Andrew

This is a discription of the process from the Hi FAQ


Hardness

You shouldn't make too much over the relative hardness of the edge. Bura usually has his edges at around Rc60 with a slight fade on either side of the belly, especially on the larger blades, to Rc58. Old GR's blades (from my experience of seeing only two of them) seem to run about Rc58 at B. to Rc56-57 at point and recurve. Does this make one blade better than the other?......No it does not. How the blade was forged, i.e. how often was the steel heated and how hot; how the smith beat it into shape (several techniques can and are employed here) and at what temperature it was hardened all play a more important roll here than a couple of Rockwell points on the edge.
Which brings up another point: Blade design. A blade with a thinner cross section in the area of the edge from the beginning of the bevel to the edge will be harder higher throughout up to the grind line. Real thick bevels may, in fact, have a much softer core with the outside of Rc61 and be Rc 56 in the middle. That's why when a blade or other tool that is heat treated in the manner of the Kamis reaches a certain point of wear from what ever source whether intentional (sharpening) or from use in an abrasive environment (like a snowplow blade) it seems to disappear at a faster rate. The harder outer shell is gone.
A higher hardness on a blade edge is a trade off (like almost everything else) While it will cut for longer periods without sharpening, it also takes longer to sharpen. A slightly softer edge wears faster and requires sharpening more often, but doesn't take as long.
Harder edges are more prone to chipping and softer blades tend to roll and dent. Harder edges and steel with the smoother finish resist rust better, but a softer blade cleans up easier.
 
I agree with you on the tradeoff between hardness. Especially on big knives, such as swords as opposed to small knives, such as folders. Big knife have to be very tough, perhaps toughness and resistance to chipping and impact is more important than a small knives that don't see much impact, hence harndss and wear resistance is more important than toughness. Having both is great of course.
You also get what you pay for. If you want a high quality knife with a sharp hard edge and shiny surface... You have to pay the price for shapening and rust removal. I'll go for high quality anytime.
 
The process is pretty straight foward.

They heat a spring at the length they want and use a chisel to cut off the desired length. They can guess within a couple of ounces without weighing even though scales are available.

They start the forging process, heating and pounding, forming the blade from tip to tang. When the blade is as close to final form as they want to get it they harden it -- heat to proper color and water quench by slow pour from a pitcher. The only high tech part of this process is using an electric fan to drive the forge. Then electric grinder to get rid of hammer marks.

Then they make the handle -- block of wood or piece for horn. Drill hole for tang using electric hand drill. Fit the block or horn to tang. Fashion handle to rough shape with khukuri. Bring it closer with rasp. When near final shape make bolster and buttcap. Put it all together with Himalayan Epoxy. Final finish and detail -- file, small knife and maybe a section of hacksaw blade.

Then the knife is finished and polished up by apprentice using power equipment.

Final inspection and if it passes off it goes to the sarkis for scabbard.
 
If I recall correctly 5160 has actually 0.6 % carbon. Basicly what N2S saids. There is enough carbon so that case hardening will not help.

Take a look at an old heat transfer book (pre 80's). The temperature change with time for many shapes have been modeled for heat treating applications.

Will
 
Your right, it is .6% carbon, I was thinking .006 of total weight. As for the heat transfer part, I don't think they have a Kukhri shape. Also, the heat transfer book probably makes the assumption that the boundary condition doesn't change. Meaning that if the steel is dipped into 20 degree water, the water will remain at 20 degrees. If the Kami pour water on the blade using a kettle, that water temperature probably rises by quite a bit, maybe even evaporates. In that case, the boundary conditions changed a lot.
heat transfer is a pretty tricky field, and textbook knowledge is not always applicable to the real world. a +/- 20% answer is pretty good. sometimes, you can only get it within a factor of 2. My first job after graduating was a job in fluid/heat transfer, and getting an accurate answer was pretty hard.:(

Thanks for the process update uncle Bill. I guess it's saving time on polishing that increased the production speed then.
 
Uncle Bill do the kami's sing or perhaps chant anything in particular as they work? I seem to recall reading that Japanese swordmakers follow a ritual which when someone decided to analyse, turned out to be a formula. So many whacks, cool it off, heat until the iron bubbles, so many whacks, dunk it in the powdered bone, that sort of thing. I still hope that one day you can make a video of a khukri being forged and finished. I also wish it could be possible to one day watch one of them demonstrate, perhaps at an ABANA meeting. What is daily work for them looks like pure magic out of the sheath.

Stephen
 
I bet they cuss in Nepalese while they work.

My imagination sees them talking.

"By the cho of Kali, I wish you could hit on center with the hammer!"

Perhaps Bill could provide a more accurate translation. But perhaps not, in a family forum.

;)
 
They pray and swear, too.

I think I read somewhere that in the dossier the Germans had on Patton there was a comment which said, "He swears like a stableboy and prays on his knees."

I can understand that and also the kamis.
 
I still hope that one day you can make a video of a khukri being forged and finished
Click to expand...

YES!! And to jump one step ahead: If the video was done well, and edited by someone who knows how to do that stuff, and then could be copied by a commercial lab and SOLD on the HI site. I know I would pay upwards of $19.95 for a video like that. Heck, Uncle Bill could narrate what you see on the screen in a voice over (along with background noise of hammering, swearing/praying, quenching, etc..)
I would be equally interested in the daily goings on at BirGorkha, and the Sarkis making the sheaths. Imagine the price you could charge for the Khuk or khuks that were made ON the video!!
This would be so great if its possible. Maybe if we treated it like a special khuk order? We need X number of prepaid orders to go ahead with it.

Of course this all hinges on Uncle Bill going to Nepal:D Which I doubt he's want to do just to make a video:D

What do you all think? Uncle?
 
Maybe it's time for a video cam -- I need more electronic junk I don't know how to use or maintain.
 
I think a video would be a big seller!!!! It would give people a chance to "see" the magic!:)
 
MauiRob, I will buy a video if Uncle Bill comes up with one. In fact, Uncle, a copying machine is not all that expensive, and I'll bet someone here has the expertise to edit a tape for you.

You all know about Ryan Johnson, the bladesmith. Well, he lives not far from here and has made three blades for me. Two of them I videotaped bacause they were gifts to my brothers. I can tell you this; seeing the blades actually being forged while holding the knife was an emotional experience for both brothers. They looked on their knives much differently when they knew what went into their creation. The third is my own darling and I saw it being forged. It is a treasure to me.

Yes, I will buy a tape! But can you imagine the bragging rights that'll go with the khukuri being taped? Wow!

Best wishes

Stephen
 
Uncle Bill
I'll buy a video if you make one. Some of my friends are wondering why I caught HIKV, I want to show them:D
 
Originally posted by Bill Martino
Maybe it's time for a video cam -- I need more electronic junk I don't know how to use or maintain.
Click to expand...

What you need is one of those 'live' cams, so people can see 'What's Happening at BirGorkha Right Now' ;) ;)
 
we were watching them "live", they would mount the cam near the charpi, and we would have "smellyvision".:barf:

"Wot's on the telly tonight, Love"? Ya doesn't want t'know, dearie, believe me". :rolleyes:
 
We'll see how it all plays out. Is there a way I can use 250volt 50 cycle to recharge batteries. I hear batteries don't last very long in video cams. Any video experts here?
 
Uncle,

It wouldn't be too hard to find a workable voltage adapter. The other thing to keep in mind is an adapter for the electrical sockets used at the shop.

n2s

BTW, should we edit out the cursing, or leave it all in... :)
 
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