The Khukri - Myth or Fact ?

fearn · 18th December 2012, 06:18 PM

I don't know if you can see this thread without being a member of bladeforums, but here's the blade forums link.

The analysis is also posted here on Google Docs, which requires you to have a Google account.

In reading the Google version, I'll admit that I was wrong, in that the geometry does matter somewhat. A simple semi-circular cutout reduces the stress the most, and sharp angles bring the stress levels back up, where the sharp angles occur.

Hope this helps,

F

spiral · 18th December 2012, 06:53 PM

Thanks Fearn interesting,,,A fascinating read.

As the auther says though....

"I did not use real values for the geometry. I used generic structural steel material properties and did not account for the variation in modulus from the differential heat treatment or hardening. I did not check for mesh convergence, or verify my results were in accordance with the beam equations. I did not apply realistic loading conditions. In other words, please take these results with a grain of salt!"

As many of those factors are critical in the design & forging of kukris I think his advice to take with a grain of salt is correct.

But Many good points raised especialy re. reduction in transmited shock & vibration I think. I hadnt considered that before. I am sure thats a valuable hypothisis.

Spiral

fearn · 18th December 2012, 09:07 PM

There's a master's thesis waiting to be written here, really.

A few of things that can be done:

1. Creating a proper model of a khukuri, with the three dimensional shape, bend, and differential hardening of the cutting edge.

2. Playing with the tip angles, blade size, bend angle, thickness, cho shape, etc., to see how these affect the properties of the blade.

There's such a variation in khukuri shapes and sizes that someone really could have a lot of fun. If there are simple conclusions, they could even feed these back to the kamis who make those blades, so that the kamis could play with new blade shapes suggested by the model.

Best,

F

kronckew · 19th December 2012, 08:37 AM

fearn,

i fixed the missing tacoma narrows video at bladeforums

spiral · 19th December 2012, 01:25 PM

Thanks Fearn, Kronckew.

All good stuff!

Spiral

sirupate · 21st December 2012, 04:03 PM

These three have by far the most common kaudi

But many early kukri didn't have kaudi at all, this kukri of Prithvi Narayan Shah, potentially lends itself to the blood dripping theory near the bolster;

Even the Gurkhas are unsure about its signifigance, check 13.36 in on the vid;
Gurkhas 'In the Highest tradition'

spiral · 22nd December 2012, 10:45 PM

A clearer Life size photo taken in 2005 by myself showing the slight vestige of the kaudi on the same kukri.

This is typicle on the so called "kaudi less" pieces of this era.

The older the kukri the smaller the kaudi does seem to be generaly true...

Spiral.

Heres a karda based on the same style as many of these old kukris, with the minute kaudi still visible.

{courtsy of Runjeet at Akall arms.}

There are many other examples in Kathmando national museam...

18th December 2012, 06:18 PM	#1
fearn Member Join Date: Dec 2004 Posts: 1,247	I don't know if you can see this thread without being a member of bladeforums, but here's the blade forums link. The analysis is also posted here on Google Docs, which requires you to have a Google account. In reading the Google version, I'll admit that I was wrong, in that the geometry does matter somewhat. A simple semi-circular cutout reduces the stress the most, and sharp angles bring the stress levels back up, where the sharp angles occur. Hope this helps, F

18th December 2012, 06:53 PM	#2
spiral Member Join Date: Dec 2004 Posts: 1,712	Thanks Fearn interesting,,,A fascinating read. As the auther says though.... "I did not use real values for the geometry. I used generic structural steel material properties and did not account for the variation in modulus from the differential heat treatment or hardening. I did not check for mesh convergence, or verify my results were in accordance with the beam equations. I did not apply realistic loading conditions. In other words, please take these results with a grain of salt!" As many of those factors are critical in the design & forging of kukris I think his advice to take with a grain of salt is correct. But Many good points raised especialy re. reduction in transmited shock & vibration I think. I hadnt considered that before. I am sure thats a valuable hypothisis. Spiral

18th December 2012, 09:07 PM	#3
fearn Member Join Date: Dec 2004 Posts: 1,247	There's a master's thesis waiting to be written here, really. A few of things that can be done: 1. Creating a proper model of a khukuri, with the three dimensional shape, bend, and differential hardening of the cutting edge. 2. Playing with the tip angles, blade size, bend angle, thickness, cho shape, etc., to see how these affect the properties of the blade. There's such a variation in khukuri shapes and sizes that someone really could have a lot of fun. If there are simple conclusions, they could even feed these back to the kamis who make those blades, so that the kamis could play with new blade shapes suggested by the model. Best, F

19th December 2012, 08:37 AM	#4
kronckew Member Join Date: Mar 2006 Location: Room 101, Glos. UK Posts: 4,215	fearn, i fixed the missing tacoma narrows video at bladeforums

19th December 2012, 01:25 PM	#5
spiral Member Join Date: Dec 2004 Posts: 1,712	Thanks Fearn, Kronckew. All good stuff! Spiral

21st December 2012, 04:03 PM	#6
sirupate Member Join Date: Feb 2005 Location: England Posts: 373	These three have by far the most common kaudi But many early kukri didn't have kaudi at all, this kukri of Prithvi Narayan Shah, potentially lends itself to the blood dripping theory near the bolster; Even the Gurkhas are unsure about its signifigance, check 13.36 in on the vid; Gurkhas 'In the Highest tradition'

22nd December 2012, 10:45 PM	#7
spiral Member Join Date: Dec 2004 Posts: 1,712	A clearer Life size photo taken in 2005 by myself showing the slight vestige of the kaudi on the same kukri. This is typicle on the so called "kaudi less" pieces of this era. The older the kukri the smaller the kaudi does seem to be generaly true... Spiral. Heres a karda based on the same style as many of these old kukris, with the minute kaudi still visible. {courtsy of Runjeet at Akall arms.} There are many other examples in Kathmando national museam...