Somebody help me understand wharncliffs

res1cue

res1cue

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Feb 2, 2010
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Okay so I was reading somewhere, I can't remember where, that Michael Janich had said something like, a wharn is a great fighting knife, because it penetrates well. Now I don't care about fighting knives, but I never understood wharncliffs at all. So for the first time since I got my physics degree, I'm gonna actually use what I learned to analyze this: (please excuse my crappy drawing)

wharn.jpg


So what I have drawn here is the forces that are acting on every point on the edge of the knife that has penetrated into the surface.

The blue indicates my x and y axis.

The red F is the driving force being acted on that point. The F force is broken into two components, in the x direction, and the y direction.

The green is just showing that it is in some sort of material.

The purple is the normal force.

(I left friction out, because they will be equal in both cases, if we assume same surface area, blade width, tip angle, etc)



So on the wharncliff blade, the normal force is pushing on the spine of the blade, EQUAL to the Fy vector, because the spine of the blade has no cutting potential. So the harder you are pushing into the object, the harder the object's normal force is pushing back at you at the spine.

The same forces are present in the "normal blade", but the normal force is dramatically smaller. The edge is "shearing" through the material, and the extremely thin edge has too little surface area for the normal force to act upon. So the Normal force and Fy do NOT cancel each other out, and the remaining force is used to shear the material. In fact, if the knife is very very sharp, Normal force will be almost be zero.

Whereas, with a wharncliff, the normal force on the spine will be the same whether or not the edge is very sharp.

So with equal force, the wharncliff will cancel out some of the power you put into it, and the normal force will redirect your energy DOWNWARD a bit, which is how the edge is able to shear into the material.

Whereas, a normal blade, the cumulative Force vector will be largely unchanged (assuming sharp blade).

I can get if they want a blade with zero belly, but why do people think wharncliffs are "better" for piercing?
 
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I'm not sure if a wharncliffe blade would be "better" at piercing, but I can somewhat understand why people would feel that way.

If you draw a straight line below both pictures, just ask yourself "which one will reach the line first?"

Essentially the wharncliffe is almost like having more "reach" with the tip making first contact rather than the belly. The tip will go in deeper, but I don't know if it's more efficient at it.
 
In what I've read of Janich's knife methodology, he uses the Fililpino saber grip (grip hard with middle, ring, pinky -- index finger is gripped moderately, and the entire thumb is pressed flat and hard against the spine.) This naturally orients most modern "tactical" wharncliffe knives with the point following the thumb. This means the point/tip of the wharncliffe is now more or less ideally placed for slashing cuts and the edge is generally angled TOWARDS the flesh rather than away as would happen with a typical droppoint geometry. Typically this means deeper cuts for the same length of blade.

Whether they "pierce" better or not is something else entirely. Depends mostly on the knife. I will say this, the knife designs I've seen Janich come up with are very wharncliffe-like and have VERY sharp, almost delicate, points.
 
I don't know about piercing, but Wharncliffes are good for draw cuts, especially precision draw cuts. Their shape lends itself to precise placement of the point.
This is especially true if you are starting your cut in the center of a surface instead of at the edge.
 
The wharncliffs blade shape is pretty awesome.

They are great for precision cuts and work well on insulation on cables, packaging, letters and all sorts of tasks I find at work and at home.

Many people use them for carving, making notches etc. About all I carve with them is pencils but they do the job nicely.

They are one of those classic designs (well 19th century) that works well back then as it does today.
 
They're good for slashing more than piercing, although they can pierce as well. Kind of like a more versatile hawkbill.
 
I think the sharp point helps to give a sharp point that can pierce well, while keeping a blade shape that has a straight blade and a strong spine to support it. It's kind of like a sheepsfoot, but with a sharp point so that you can still make piercing cuts. I think it's more of a utility shape for this reason, and that's what I really like it for.

Penetration isn't as good as a drop-point or something like that though, and I think it's for the reasons you pointed out. I haven't done any "tests", I was just bored one night and we were waiting for the oven to heat up so I took a couple of pokes into a ham with my Kershaw Needs Work, and it offered quite a lot more resistance than a drop point configuration.

I could see how they would make deeper slashes than a curved blade and still maintain a sharpened point for stabbing, and that could provide a tactical advantage. However I don't see them having more penetration than a spear point or drop point.

Of course that's all considering just how much stabbing knives into a ham can tell you. :P
 
I don't thin this is Janich's grip style, but I prefer a grip like this which presents the point towards the attacker at all times-
IMG_5804.jpg


I think Janich's grip style is like this-
IMG_5800.jpg


Andy
 
I always thought that wharnies were better at penetration because more 'normal' style blades like clip point, spear point, what have you... were less 'pointy'. Also, I seem to remember reading that wharncliffes were used on ships because they could NOT be used as weapons...maybe I'm thinking of plain old sheepsfoots though...
 
OzKnifeGuy said:
I always thought that wharnies were better at penetration because more 'normal' style blades like clip point, spear point, what have you... were less 'pointy'. Also, I seem to remember reading that wharncliffes were used on ships because they could NOT be used as weapons...maybe I'm thinking of plain old sheepsfoots though...
Click to expand...

That's what I remember too

KennyB said:
I took a couple of pokes into a ham with my Kershaw Needs Work, and it offered quite a lot more resistance than a drop point configuration.
Click to expand...

That's what I would have guessed..
 
I don't think wharncliffes are any better at penetrating. Mike Janich and other SD guys have said that they like a flat edged blade because it provides maximum cutting power (deeper, nastier cuts) all the way to the tip of the blade, and all the way through your wrists/arms natural arc.
 
Thanks for the discussion, guys. I really appreciate your interest in my "take" on things.

In researching the book "Contemporary Knife Targeting," Chris Grosz and I came across a medical study in which doctors empirically tested the ability of knives to penetrate human flesh. They built a calibrated device that measured the pressure applied to the knife handle, then attached various types of knives to it. The testing medium was actual human cadavers and the penetration was the initial torso penetration for an autopsy.

The basic conclusion of the test was that the ability of a knife to penetrate was directly proportional to the acuteness of its point. Knives with large bellies to the blade that presented more edge than point did very poorly.

My own testing of knife penetration was based on the use of a ballistic pendulum--basically a six-foot piece of PVC pipe hung from a pivot on a rafter in my garage. The knife is fitted into a T-connector at the end of the pipe, it is raised to a constant level, released, and allowed to hit a fresh spot on a test target--typically a solid foam mannequin torso. I cover the torso with various types and combinations of clothing to introduce those variations as well. In my testing, wharncliffes, double-edged daggers, and very narrow blades penetrate best.

My basic goal in penetration is to get the knife through the clothing and into the target that I want to cut. Wharncliffes do this really well and then cut with full power all the way to the tip. I uderstand that the wharncliffe design, by nature, produces a tip that is not as strong as other designs. My approach to knife tactics takes that into consideration and I feel the trade-off for increased cutting performance is worth it.

I hope this helps.

Stay safe,

Mike
 
OzKnifeGuy said:
I always thought that wharnies were better at penetration because more 'normal' style blades like clip point, spear point, what have you... were less 'pointy'. Also, I seem to remember reading that wharncliffes were used on ships because they could NOT be used as weapons...maybe I'm thinking of plain old sheepsfoots though...
Click to expand...

best explanation I could find on what a Warncliffe blade is.

http://faq.customtacticals.com/geometry/shape_wharncliffe.php

I think you're only associating a Warncliffe with a ronin that happens to have a pointy tip.
 
Michael Janich said:
Thanks for the discussion, guys. I really appreciate your interest in my "take" on things.

In researching the book "Contemporary Knife Targeting," Chris Grosz and I came across a medical study in which doctors empirically tested the ability of knives to penetrate human flesh. They built a calibrated device that measured the pressure applied to the knife handle, then attached various types of knives to it. The testing medium was actual human cadavers and the penetration was the initial torso penetration for an autopsy.

The basic conclusion of the test was that the ability of a knife to penetrate was directly proportional to the acuteness of its point. Knives with large bellies to the blade that presented more edge than point did very poorly.

My own testing of knife penetration was based on the use of a ballistic pendulum--basically a six-foot piece of PVC pipe hung from a pivot on a rafter in my garage. The knife is fitted into a T-connector at the end of the pipe, it is raised to a constant level, released, and allowed to hit a fresh spot on a test target--typically a solid foam mannequin torso. I cover the torso with various types and combinations of clothing to introduce those variations as well. In my testing, wharncliffes, double-edged daggers, and very narrow blades penetrate best.

My basic goal in penetration is to get the knife through the clothing and into the target that I want to cut. Wharncliffes do this really well and then cut with full power all the way to the tip. I uderstand that the wharncliffe design, by nature, produces a tip that is not as strong as other designs. My approach to knife tactics takes that into consideration and I feel the trade-off for increased cutting performance is worth it.

I hope this helps.

Stay safe,

Mike
Click to expand...

Mr. Janich, thank you for speaking up about this. Cant argue with empirical results i guess
 
OzKnifeGuy said:
I always thought that wharnies were better at penetration because more 'normal' style blades like clip point, spear point, what have you... were less 'pointy'. Also, I seem to remember reading that wharncliffes were used on ships because they could NOT be used as weapons...maybe I'm thinking of plain old sheepsfoots though...
Click to expand...

Sheepsfoot blades are used on ships because they are used to cut large diameter rope by hammering them through with a mallet. You need the entire edge to be straight for that purpose.
 
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