Sharpened swedge on the Umnumzaan?

T

The_Guide

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Feb 1, 2009
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Can anybody shed some light on the swedge for me? What is its purpose?

If I remember correctly, it had something to do with having an edge for firesteels, to avoid having to use and dull the main cutting edge... is there any truth to this?

(Is it actually called the swedge, or do I sound like an idiot :confused:........:p)

Thanks
The_Guide :cool:
 
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I'm not sure what the purpose is exactly, but I share your concern...
Using it on firesteels and magnesium bars is certainly feasible, and sounds like a great way to preserve the primary edge - assuming you have no other means available. (I read an article in a TK mag awhile back which observed that the glass-breaker on the Professional Soldier - and therefore on the Pacific and Green Beret - was ideal for use on magnesium and firesteels.)
Frankly though, the fact that this knife has a live edge exposed, even when closed, is my one qualm with this knife. Not that it will stop me from buying it, but I wonder how it came to happen. In keeping with the more practical-tactical design, I suppose it could be used much like a V-cutter in an emergency, but at the same time it makes me worry about using the knife as a kobutan/yawara or glass-breaker - the latter of which is supposed to be an intrinsic function of the knife. Either of those uses could potentially bring your fingers into contact with a live edge, especially under stressful circumstances.
If someone from CRK could make a more detailed explanation, I'm sure a lot of folks here would be grateful. Self included.
My own criticism aside...nice knife there, Chris.
 
Here in Texas, a sharpened second edge on a knife is unlawful, so I was concerned.
My Umnum came with an unsharpened top edge, you could run your finger over it and it would not cut.
However, because it looked sharp, I simply ran a diamond sharpener over the edge to try to alleviate any visible signs of sharpness.
I think the top edge would still make a pretty good scraper if needed. Plus it looks cool.
A great knife. I favor it over the Sebe, but then again, I have both and hope to always have a Sebenza.

Tom
 
I'm taking a guess but I would think it would add strength to the tip. Think of it this way. If the swedge wasn't there you would have a cross section of a triangle. Add the swedge and you have a diamond, which is second the area of a triangle. Therefore adding strength to the tip.
 
Xcel said:
I'm taking a guess but I would think it would add strength to the tip. Think of it this way. If the swedge wasn't there you would have a cross section of a triangle. Add the swedge and you have a diamond, which is second the area of a triangle. Therefore adding strength to the tip.
Click to expand...

I know what your thinking here...


But I highly doubt it adds strength :)
 
it is called a swedge

it does make an excellent scraper/firesteel striker

we originally left them sharp but we kept cutting ourselves so now we take them to an edge then blunt it with a ceramic rod

I've never tested tip strength so I don't know if it's stronger or not.
 
Xcel said:
I'm taking a guess but I would think it would add strength to the tip. Think of it this way. If the swedge wasn't there you would have a cross section of a triangle. Add the swedge and you have a diamond, which is second the area of a triangle. Therefore adding strength to the tip.
Click to expand...

We go through this discussion whenever the subject of fullers or grooves comes up.

The misconception comes because people think about the structural strength of I-beams and other structural elements. The mistake is that the I beam has a better strength to weight ratio than a solid beam made out of the same amount of material. Now if you took a solid beam of the same size as the I-beam, the solid beam would be stronger.

So removing material from the knife to make a swedge or a groove does not make it stronger. It can, if done properly, increase the strength to weight ratio.
 
DrFish said:
We go through this discussion whenever the subject of fullers or grooves comes up.

The misconception comes because people think about the structural strength of I-beams and other structural elements. The mistake is that the I beam has a better strength to weight ratio than a solid beam made out of the same amount of material. Now if you took a solid beam of the same size as the I-beam, the solid beam would be stronger.

So removing material from the knife to make a swedge or a groove does not make it stronger. It can, if done properly, increase the strength to weight ratio.
Click to expand...

Relative to a given rectangular cross-section, the formula for section modulus is bd^2/6. The formula for moment of inertia is bd^3/12; where b=width and d=depth. So, without going into a long song & dance, one can see that adding mass distant from the neutral axis of the cross-section is a very effective way to increase flexural strength, and an even more effective way of increasing stiffness.

An "I-beam" (a wide-flange beam) does this by concentrating mass in its horizontal components (flanges) as opposed to its vertical (web) component.

Anyway... go back and read Xcel's post again. He was talking about adding the cross-sectional shape of the swedge to the top of an otherwise swedge-less blade, not removing material in order to form the swedge. So of course this would strengthen the blade, just not in a very efficient (or even effective) manner.
 
My lefty (which arrived 2 weeks ago) wasn't sharp enough to cut, which made me happy. This knife is growing on me and is my 2nd Fave EDC right now.
 
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