Convex edge vs V

Convex everything, including your lawnmower and mach 3 razor. Then you will achieve enlightenment. Oh and you'll be able to shave your chest with your lawnmower like a real man.
 
singularity35 said:
hehehe, I don't really know anything busse.
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Oh. Back in 2001 thru about 2006 they had exactly the edge you describe. One side was a flat bevel, the other was convex. They called it an asymetric edge. They may still use it, but the only Busse I saw close enough to notice the edge was a Basic 7, and it was sharpened in such a manner.
 
me2 said:
Oh. Back in 2001 thru about 2006 they had exactly the edge you describe. One side was a flat bevel, the other was convex. They called it an asymetric edge. They may still use it, but the only Busse I saw close enough to notice the edge was a Basic 7, and it was sharpened in such a manner.
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So I have to ask, what side was sharper? :D
 
me2 said:
Oh. Back in 2001 thru about 2006 they had exactly the edge you describe. One side was a flat bevel, the other was convex. They called it an asymetric edge. They may still use it, but the only Busse I saw close enough to notice the edge was a Basic 7, and it was sharpened in such a manner.
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Really? I was actually trying to be funny. :D
 
You know, I appreciate the attempt by some not to have such a black and white answer about which one is "sharper", but I think it's kind of removing from the fact that people do choose convex or V for one reason or the other. So what are the factual advantages behind each type of edge?

I know that I always hear the "convex edges are sharper because they push the material apart as they cut" idea, and it's usually exemplified by talking about Katanas and how sharp they are, but what's the real story behind this? Anyone care to comment?
 
KennyB said:
You know, I appreciate the attempt by some not to have such a black and white answer about which one is "sharper", but I think it's kind of removing from the fact that people do choose convex or V for one reason or the other. So what are the factual advantages behind each type of edge?

I know that I always hear the "convex edges are sharper because they push the material apart as they cut" idea, and it's usually exemplified by talking about Katanas and how sharp they are, but what's the real story behind this? Anyone care to comment?
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I would guess that you are talking about cutting performance. What is sharpness? Is it the ability to cut? Or is it just the thinness of the edge?
 
A convexed edge geometry has less resistance when cutting through materials because of its' smooth curve. A V-bevel has more resistance due to the shoulder created by the primary and secondary bevels coming together. A V-bevel can be sharper than a convexed edge but the convexed edge might actually cut better due to it having less resistance after the cut has been initiated.
 
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singularity35 said:
I would guess that you are talking about cutting performance. What is sharpness? Is it the ability to cut? Or is it just the thinness of the edge?
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Exactly.

I would say sharpness is the final dimensions of the very edge.

I don't see how a convexed edge can be sharper than a V-bevel but I do understand how a convexed edge cuts better.
 
Depends on what you're cutting, and how you're cutting it. Convex edges generally split better (as they actually serve to drive the two halves that they're cutting apart) while a flat grind slices better (less drag on the blade since the angle of the wedge becomes less pronounced behind the edge shoulder). Also have to factor in how deep the cut is (meaning does the spine end up passing through the material or not)---for example, are you cutting through a piece of leather laying flat on a table, or through the side of a cardboard box?

Again, it's relative---you can have a full flat ground blade that has a larger cross section than a convex, and vice versa.

The thinner one always slices better/more easily, and the thicker one is always stronger. With the endless possible combinations of angles for such grinds, however, you can't definitively say that one beats the other, you just can't. Convex grinds tend to dominate in axes, because they split better and wedge less. That's a thick convex bevel. Hollow grinds tend to dominate straight razors, because there's no need for lateral strength, a great need for precision, and you can sharpen up almost the entire blade height without a significant increase in thickness at the edge shoulder and thereby get a very long life out of a tool that's used continuously. That's a thin hollow grind. These are extremes, however. When you're talking about knives of similar size and intent, the advantages start becoming a lot less definite one way or the other.

People choose one or the other for exactly the same reason that they choose Nike versus Reebok...preference.
 
Both--depending what you're cutting and how deep the blade must go. :cool:

Edit to add---I mean, if you want your mind blown, I can put a heavy convex edge bevel on a deep hollow ground blade, so the cutting medium won't have the slightest idea how to react and will just explode. :D
 
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Yes, theoretically, the convex edge is a smoother transition. However. That is usually not the reason people like or use the convex edge.
First off, most people are only exposed to thick factory bevels that don't cut very well at all. Then when a nice convex edge is their first exposure to thin edge geometry, convex becomes synonymous with sharp, and V with dull.
Secondly. When told to keep sharpening at one precise angle, people get frustrated when they re-discover that they are human beings, and therefore not very good at holding a precise angle.
Methods for sharpening a convex edge, oppositely, tell them not to hold a steady angle, and affirm their humanity in a positive way.

The convex edge is all I ever use, I don't even know how to put a straight bevel on a knife by hand. Chances are it would take way more effort than I'm willing to put in, and isn't even necessary anyway.

The problem is that "convex" gets thrown around so much and is such a blanket term that people start to ignore, and sometimes even deny, the basic principles that actually determine whether or not something cuts well.
 
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