Why do khukuris have that notch? What purpose does a cho have? Does it weaken the knife?

Kailash Blades

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This is one of the most common questions about khukuris and can be seen almost everywhere that people are talking about these blades. It makes sense too. Chos are a very strange looking addition to a blade from a western perspective and every tom, dick and harry has some perspective on the matter. We've covered it in smaller detail elsewhere, but this recent question by D DangerZone98 made us feel like a dedicated thread was worthwhile.

Hey Kailash Blades. Apologies if this isn’t the correct place for it, but I have a question regarding chos on kukris. Do chos significantly weaken the knife? Are there any incidents of blade failures near the notch?

This is a functional side of the cho question which is seldom asked and one that we haven't seen addressed. Before we can get to that though let's cover the basics.

What is a Cho?
A cho, also commonly called a Kaudi in Nepal or a "khukuri notch" in the west is a cutout placed just in front of the handle that's ubiquitous on almost every traditional khukuri ever made.

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It's worth noting that though this current bisected semicircle is the most commonplace (especially on modern blades) there are many variants. Older khukuris had a much wider and shallower notch with a smaller prong, chitlanges have enclosed or "hooded" cho designs and many many blades defy this design entirely, especially in india,
Here's three antique blades showing some extreme variations from VK Kunwor. What these hope to show is that there is no unified design and that explanations heavily reliant on the form are somewhat flawed.

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The purpose, function or meaning of this blade feature is currently a mystery, no matter what anyone tells you. There are hundreds and hundreds of explanations I've seen for this feature and I'll list a few notable ones in order of least sensible to most likely, with a bit of explanation.
 

Kailash Blades

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A rangefinder for throwing the blade: An extension on a myth that these blades were thrown and came back like boomerangs. So stupid and so funny that I had to start the list with it. These blades do not return when thrown, weren't commonly thrown historically and none of the cho shapes help act as a rangefinder regardless.

Cho as Bottle opener: Bottles with caps like that weren't around for the first 200 years or so that the cho was around and neither historical or modern blades can be used to open bottles with any degree of success. The only exception to this is the Scourge khukuri and a few of it's variants by kailash blades, which is specifically designed for this purpose. I have also seen a modern khukuri that used the cho as a spanner for hex nuts. Strange, impractical but at least interesting.

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To save material: Good Steel was very scarce in Nepal up until the 21st century so this has a kernel of truth. unfortunately though these shapes were made by removing material with files etc rather than through forging and deformation meaning it actually costs just as much material as just leaving the blade plain. Some chitlange had their kaudi hot punched out but these are a relatively recent pattern compared to the total history of this design feature.

Cho as a blood drip to keep hand dry: A sensible enough functional argument but sadly they just don't perform this function. A blood covered khukuri still runs blood down the spine and flats and doesn't stop your getting a slippery grip.

Cho as blood let for piercing the finger/Ritual human blood offering zone: A super popular one that's total bullshit. This feeds into a super common and damaging myth that every time a khukuri is drawn it has to taste blood, so users would cut themselves as an offering if they didn't cut an enemy. This is a stupid thing to do to yourself during wartime, let along in the survival/ daily situations where these blades are being used as woodworking/butchering tools. This is particularly damaging because it's so widely held a belief and feeds back into Nepali culture with many there even perpetuating it.

This falsehood aside no cho of any design is made sharp enough to draw blood by pricking a thumb or some similar. The suggestion that the cho is a sacred symbol and a place to offer blood to has the strongest basis so far and is something that we'll expand on, but the suggestion that it is for human blood is nonsense.

Cho as a blade catch in combat: There are many examples of cho designs that don't ahve the required shape to fit this purpose. Could a cho catch the edge of the blade enough to manipulate the trajectory of it? Maybe, yeah. If this was the intent though I tend to think an answer this simple would have been able to last through time, been evident in accounts of historical khukuri technique or be more evident in the cho design through a more specialised and effective design. The suggestion that a cho could catch and snap a blade is rubbish though. A pronged cho will break or bend long before the opponent's blade will and again there is nothing to support this claim

Cho as a finger guard to stop sliding onto the blade: Again there are many cho designs which won't do this, notably that of the chitlange. However the earliest khukuris, the hanshee had both a much smaller prong and a much larger and shallower notch that would work pretty well for this function. Could it be that it was originally intended for this function and then drifted away from being functional over time to all these new designs? Maybe but again not very likely. While many kaudi designs can help you to stop sliding forward, the handle rings seen on correctly sized and replicated traditional blades would already cover this function. They slid between the middle and ring fingers and acted as a subhilt as sorts. I think this is a case of most khukuri users disregarding and avoiding these handle rings, imposing that a fighting blade needs a frontal guard and then concluding that this strange feature must be for this purpose. The most solid thus far but still not solid enough.

Cho as a religious, auspicious or sacred symbol: Of all the explanations this explanation has the most supporting evidence and is in the opinion of many researchers the most likely.
Within Nepali culture the inclusion of religious symbols or ornamentation to imbue power or significance is commonplace be it on doorknobs, cooking equipment or the many coloured and decorated trucks you see on the streets there. Even within the west this isn't a foreign concept. A sword with engraving helps to show wealth and communicate a form of power. A pommel might incorporate traditional celtic knotwork or similar motifs for much the same reason- it makes a blade more significant.

Many direct interpretations of the shape of a cho focus strongly on the contemporary shape that's seen so commonly. These include:

A cow's hoof/udder- Cows are sacred and a sign of wealth within hinduism, so it checks out. An alternative is that it's a buffalo's hoof in reference to the sacrifice of these animals during dashain etc. While this is a valid connection, the kind of khukuris used for these sacrifices are specialised and very large. This to filter back across to military and agricultural khukuris is unlikely.

Yoni/Lingam- For those unfamiliar a yoni is a hindu symbol representing a vagina, while a lingam represents that of a penis. Within hinduism these are powerful associations to make. A yoni has the power to create life while a lingam is seen as a powerful and sacred object. These are often carved of stone and can be found throughout hindu influenced asia.

While these are sound reasons, they do not cover any of the variants or the older common designs which just don't match these shapes. One example of a variant that does have a sound representaion explanation is that of the pagoda/temple cho on a fort william MK1 and other blades. As the name would imply, this shape echoes the rooves of a nepali temple and is a shape that is also seen in the pommels of other weapons such as the Kora. IT's worth noting that nepali kora, ram dao or Tulwar do not feature a cho. Why it's seen as so important to include this ornamentation on a khukuri rather than these blades is unclear, but I think it simply comes down to tradition. Old khukuris were made like this, so new khukuris are too. Cho creep (the movement of the cho further away from the handle) is seen as a sign of a khukuri being inauthentic by many collectors nowadays as it's a sign of drifting from tradition. They seek less cho creep as a sign of quality in modern blades despite little to no functional benefit. This has arisen organically but could potentially parallel the original mindset that allowed this feature to perpetuate throughout the centuries.

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I think this is a very important point as it represents is something very particular to Nepalese society. It's an example of a tradition for traditions sake. Nepal is a very Dogmatic society and traditions, ancestors and that which has come before is valued very highly. If you were to ask a villager why the fireplace in their house has no Chimney, they would say that it's because that's how fireplaces are made. Sure it might make their room smokey, but that's how these things have always been made and respecting that offers a sense of security and Identity. I think even discarding the potential religious origins, this significance is one that rings the most true and holds the most relevancy to this day. An example of tradition that under its own steam which has been maintained by generations of blacksmiths for hundreds of years.
 

Kailash Blades

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Cho as a stress relief channel: One of the reasons that people fixate on a cho so much as needing to have a function or purpose is that it's such an extreme alteration of form for ornamentation vs engraving. It begs the question- wouldn't this weaken the blade dramatically? I was in discussions with another khukuri enthusiast who claimed that the cho acted as a stress reliever and allowed bending to occur above it so that this bending force wouldn't all be localised at the transition between the tang and the shoulder of the ricasso. He went so far as to say he'd had a friend model it under Finite Elements Analysis and found a reduction of maximum strain in that region. For the earlist cho seen on hanshee that are wider and more shallower this holds the most weight, while modern deep semicircles would seem to go too far inwards too suddenly. While I think this is an interesting potential reason for the origins of the blade, much more research and experimentation is needed before it can be given any deeper consideration.

This all begs the question- Does a cho make a blade weaker? Should I get a blade without a cho?
THis is very hard to say. We've never had a blade break at the cho but we have seen quite a few that have broken there. We have seen far more that have broken at the handle-tang transition though. Our thoughts on this are opinions and based on our experience only.
In short:
For a rat tail tang, they likely make the blade slightly weaker but not in a significant way.
For a full tang blade their ability to act as a stress raiser is increased by how rigid the handle is and thus they weaken the blade more.
We have seen more full tang blades that have broken at the cho than rat tail tangs. Is this because a fatigued rat tail tang will break at the tang shoulder first or because the more rigid handle localises bending to the top of the cho? Very hard to say or to make a judgement of how significant the effect is.
For hard use blades of either tang style that are doing prying and twisting this is a no no in my books as in side loading it greatly increases the pressure above the cho. But even for more standard chopping blades even a very mild stress raiser can undergo increased strain and fatigue over time, causing a crack. Is this going to happen after 3 years of use? probably not. But after a decade or two we're in the range of needing to consider these kind of things. It's also worth noting that the cho area is the most functional area for push cutting as you have the most leverage and it's very useful to have some nice edge there.

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Ultimately it all comes down to personal preference. Whether you value the beauty, traditional and mystery of a traditional cho over some added practicality and speculative strength benefits of having a bare blade. Until further research and understanding is reached, the cho remains a topic best navigated with the heart rather than the mind.
Take care,
Andrew and the team at Kailash
 
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Kailash Blades

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Thanks for taking the time and effort for this essay, Andrew. Really made me appreciate my khukuris all the more. I feel proud of owning and taking care of a Kailash work.

No worries at all. We still have so much to learn about these blades and are novices compared to so many in the field. The one thing we're certain of learning mroe of every day right now is how much more there is to learn.

;);)You left out, the cho as a sharpening notch.
Now this I haven't heard of! For sharpening what? Other knives on either side of the prong like a Sharpmaker?
 
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Now this I haven't heard of! For sharpening what? Other knives on either side of the prong like a Sharpmaker?

No, many knives have this feature. It just a notch near the handle making it easier to sharpen the blade all the way to the heel with out hitting your handle on the sharpening stone.
 

Kailash Blades

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No, many knives have this feature. It just a notch near the handle making it easier to sharpen the blade all the way to the heel with out hitting your handle on the sharpening stone.
I like this theory a lot! I do have a few issues with it though. A lot of these khukuris aren't sharpened all the way to the cho in the first place, with the last few mm usually being rounded or flat. Khukuris also weren't sharpened against benchstones, with files and riverstones etc being used instead as they were a lot better with the recurve. Compared to western sharpening notches, why are these so big and deep? and why are they only on khukuri and not on kora/tulwar which could also benefit from this?
 
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Kailash Blades

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I assumed that the Cho was like a makers mark. Maybe people buying one could tell who made the knife by looking at the design of the Cho?
This is a difficult one. I can say with certainty that there have always been alternative methods of signing khukuris as your own, often stampings or carvings on the buttcap, top of the spine or even into the handle material sometimes. Since the beginning of the 20th century cho designs have become increasingly standardised, with cho variants being limited to between different types of khukuri- the Fort Williams MK1 or the chitlange for example. However prior to this point in time there was a lot more variation in shape and size which could have acted a maker's mark or flourish to help identify the work of one maker over another. Here's a collection showing a great deal of variation in historical blades. It's worth noting that there are indian made khukuris in the mix here and that while this picture does show a great deal of difference, this level of variety was far from the norm at the time, as can be seen from the large amounts of antique khukuris with near identical kaudi designs.
Take care,
Andrew
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Could it have been used as a way to make it bite into the sheath for retention. As in after it is seated in the sheath, a pull on the handle to have the cho bite into the wood or leather?
 

Kailash Blades

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Could it have been used as a way to make it bite into the sheath for retention. As in after it is seated in the sheath, a pull on the handle to have the cho bite into the wood or leather?
It's an interesting suggestion though in my experience they don't snag on the sheath at all. Due to the increased with of the belly on a khukuri, the throat of a khukuri sheath needs to be wide enough to let the whole blade through and so there's usually a sizeable gap between the cho and the outside of the sheath.
 

ErikMB

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This is a brilliant thread! Thanks so much for contributing to it, all of you.

My personal hunch about that notch is that it was developed to relieve some physical stress on the blade (as discussed above) and became stylized over the years, smiths adding it because that's how it's done (also as discussed above) without a deep understanding of its purpose or optimal shape. This lead to artistic interpretation and, in some cases, a maker's mark. Just my theory, of course.
 

Kailash Blades

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I've been thinking about it more recently as well, but it's a bit of a counterintuitive thought process.
I've made a simple diagram to help explain. Very small text so please full screen.

This is a blank of one of our rat tail tangs without a cho. As you can see the transition in material thickness there is substantial, which created a focus point for stress, strain and eventual breakage.
With the addition of a cho there is a space in front of the tang that's approximately halfway between the tang thickness and full blade height. This space bends somewhat more than the blade in front and helps take some of the suddenness and stress focus away from the tang transition. You would think that putting two stress raisers in a blade would create a weaker blade- however in this arrangement it helps to share the load somewhat. Think of a blade as being only as strong as it's weakest link- in this scenario the load is shared over more weak links making for a stronger overall system. Note that our tangs are a lot sturdier than ones from other houses/some historical pieces. Also note that earlier chos are shallower and wider, helping create a less sudden arc.
The results would be more pronounced in those settings.
It also goes some way to explain why so many full tang users have had cho failures and so few rat tail tang users- a full tang is stronger without and the cho becomes the sole stress raiser in the system and snaps.

cho stress.jpg

If proven true (which right now it definitely hasn't and is just a theory) this could be an example of a practical function of a cho that so many are grasping for. However I think this in no way explains the phenomenon. It's similar to reverse engineering the human lungs and deciding they evolved for the purpose of producing speech rather than breathing. Both speech and this potential minor stress reduction are in my view unintended but interesting side effects.
It in no way explains the various shapes and varieties of cho. It doesn't explain why this structure isn't seen on other rat tail blades from that region.
If the first smith to create a cho had a level of understanding of metal fatigue and stress dispersal to create a cho for the purpose of a stronger handle transition he would be smart enough to see that it's nowhere near as effective, obvious or simple a solution as producing a broader rat tail tang with rounded shoulders. It is lighter, but the tradeoff really isn't worth it.
Take care,
Andrew
 
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I've been thinking about it more recently as well, but it's a bit of a counterintuitive thought process.
I've made a simple diagram to help explain. Very small text so please full screen.

This is a blank of one of our rat tail tangs without a cho. As you can see the transition in material thickness there is substantial, which created a focus point for stress, strain and eventual breakage.
With the addition of a cho there is a space in front of the tang that's approximately halfway between the tang thickness and full blade height. This space bends somewhat more than the blade in front and helps take some of the suddenness and stress focus away from the tang transition. You would think that putting two stress raisers in a blade would create a weaker blade- however in this arrangement it helps to share the load somewhat. Think of a blade as being only as strong as it's weakest link- in this scenario the load is shared over more weak links making for a stronger overall system. Note that our tangs are a lot sturdier than ones from other houses/some historical pieces. Also note that earlier chos are shallower and wider, helping create a less sudden arc.
The results would be more pronounced in those settings.
It also goes some way to explain why so many full tang users have had cho failures and so few rat tail tang users- a full tang is stronger without and the cho becomes the sole stress raiser in the system and snaps.

View attachment 1603902

If proven true (which right now it definitely hasn't and is just a theory) this could be an example of a practical function of a cho that so many are grasping for. However I think this in no way explains the phenomenon. It's similar to reverse engineering the human lungs and deciding they evolved for the purpose of producing speech rather than breathing. Both speech and this potential minor stress reduction are in my view unintended but interesting side effects.
It in no way explains the various shapes and varieties of cho. It doesn't explain why this structure isn't seen on other rat tail blades from that region.
If the first smith to create a cho had a level of understanding of metal fatigue and stress dispersal to create a cho for the purpose of a stronger handle transition he would be smart enough to see that it's nowhere near as effective, obvious or simple a solution as producing a broader rat tail tang with rounded shoulders. It is lighter, but the tradeoff really isn't worth it.
Take care,
Andrew
Interesting. Have you guys considered a cho “engraving” instead of a cutout? It may be especially viable for full tang knives. It still pays homage to the traditional design but eliminates the stress riser issue.
 

Kailash Blades

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Interesting. Have you guys considered a cho “engraving” instead of a cutout? It may be especially viable for full tang knives. It still pays homage to the traditional design but eliminates the stress riser issue.
We haven't, no. We've still yet to have a full tang blade of ours snap at the cho so it doesn't have us particularly worried to the degree we'd have an alternative option like that on the table.. Currently those worried about it are in the minority and can just request no cho on checkout :)
 
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