- Joined
- Feb 17, 2011
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- 516
I was doing some doodling to help myself grasp these differences while trying to choose a new knife and thought they'd be worth sharing because I've seen a lot of posts on all different forums that provide some very misleading information. I thought I'd share what I noticed with you all.
I want to start off by saying that I am a big fan of convex edges and grinds. I am very impressed with Bark River knives, Fallkniven, and I love the edges on my knives that have come out convexed on their own just from sharpening by hand. There is no denying that a convex edge or full convex knife has OUTSTANDING cutting performance because it doesn't have a shoulder to wedge into the material you're cutting.
During this analyzation, I have chosen to compare convex grinds to Scandi grinds. I chose to do so because of how commonly these two grinds are compared in general. If you take a pencil and paper and draw a full flat grind with a V edge grind, you will find that drawing the curved lines to make it convex (at the edge) without changing the thickness of the blade or the edge angle will provide very similar results.
I am about to analyze the one HUGE, blatantly false myth about convexed edges and grinds: That they are more durable by their nature by providing more steel behind the edge. As you can see in the following, it is as far from the truth as you can possibly get:
Apologies for the bad drawing here. The black lines depict a Scandi ground blade. As you can see, the red lines depict roughly what you would get if you made a convex grind using the SAME thickness of blade at the SAME edge angle. As you can see, the convex grind leaves actually LESS metal behind the edge than the Scandi. Because of all of the information that states that a convex grind gives you more meat behind the edge, I also drew the blue curved lines. This depicts HOW you can achieve more steel behind the edge of the knife. The ONLY way to do so is to use a wider edge angle (or to use a thicker blade stock to begin with, but my sentence assumes we are using the same thickness).
This goes very much against the common notion held regarding a convex grind's durability. I am glad that I stumbled across this during my doodles because it opened up a lot more options to me in my purchasing decision. Initially I thought I MUST stick with a convex grind for durability. It simply isn't the case.
As a little bit extra, although it's a bit of an aside, here is what I've concluded about the differences between a Scandi and a Convex overall:
As earlier noted, I've found that the Convex ground blades I've used tend to meet less resistance for the most part. This will come down to edge geometry and blade thickness more than anything, but the lack of a shoulder does seem to provide me with a cut that meets less resistance from what I can tell. The difference isn't enormous, but is apparent.
What I have seen to be the main advantage of a Scandi grind is that you literally NEVER need to reprofile the entire blade to keep from losing cutting performance. Simply sharpen along the grind back to your zero edge and you will maintain the same geometry for the life of the blade. In this way, the Scandi is very predictable and an overall breeze to maintain. The convex, in comparison, can be maintained quite easily with a strop for a long time, but when it comes time to actually sharpen it then you must remove metal from the ENTIRE blade (thinning the blade a bit) in order to maintain the same edge angle. If you only sharpen a convex ground knife at the edge, it will come out with a wider angle when you're done.
Here's another crappy drawing to compare the sharpening so I can illustrate what I mean:
Anyway, I hope this has helped some of you. It sort of bothered me that I had been under the wrong impression for the last couple of years simply because I was taking in what other people were saying without really looking at it. The convex grind is actually my personal choice for a large fixed blade knife with a thick stock because I know that I'll never thin the blade out significantly enough in my lifetime to weaken it, but for a somewhat smaller and/or thinner knife I see more merits to the Scandi (i.e. I think that may be why it is so popular for a Bushcrafter). That's just me. And lastly, I really don't think that the convex actually having LESS metal behind the edge really matters in this comparison. If you look at how far up the blade you have to be for the convex to start to show a difference in thickness, then you know that if you have a chip that deep into your edge that it reaches the shoulders (or where they would be if you have a convex) that you have a pretty serious problem and I doubt that it has anything to do with the grind. This just illustrates that the advantage of the convex is in cutting performance, NOT in strength. Everything that goes into a knife design is a compromise, and the convex is not the "have your cake and eat it too" grind.
Note that I am not a knife expert. If there is somehow something that I failed to mention or illustrate that anybody thinks should be mentioned, please let me know. This is simply what I found out from doing some doodling.
Also, I'm sure that I'm not the only person who has figured this out. But over the last couple of years I haven't ever seen anybody pointing it out, so I wanted to make sure more people had accurate information since I know I sure didn't ever since I first started hearing about convex ground knives.
I want to start off by saying that I am a big fan of convex edges and grinds. I am very impressed with Bark River knives, Fallkniven, and I love the edges on my knives that have come out convexed on their own just from sharpening by hand. There is no denying that a convex edge or full convex knife has OUTSTANDING cutting performance because it doesn't have a shoulder to wedge into the material you're cutting.
During this analyzation, I have chosen to compare convex grinds to Scandi grinds. I chose to do so because of how commonly these two grinds are compared in general. If you take a pencil and paper and draw a full flat grind with a V edge grind, you will find that drawing the curved lines to make it convex (at the edge) without changing the thickness of the blade or the edge angle will provide very similar results.
I am about to analyze the one HUGE, blatantly false myth about convexed edges and grinds: That they are more durable by their nature by providing more steel behind the edge. As you can see in the following, it is as far from the truth as you can possibly get:
Apologies for the bad drawing here. The black lines depict a Scandi ground blade. As you can see, the red lines depict roughly what you would get if you made a convex grind using the SAME thickness of blade at the SAME edge angle. As you can see, the convex grind leaves actually LESS metal behind the edge than the Scandi. Because of all of the information that states that a convex grind gives you more meat behind the edge, I also drew the blue curved lines. This depicts HOW you can achieve more steel behind the edge of the knife. The ONLY way to do so is to use a wider edge angle (or to use a thicker blade stock to begin with, but my sentence assumes we are using the same thickness).
This goes very much against the common notion held regarding a convex grind's durability. I am glad that I stumbled across this during my doodles because it opened up a lot more options to me in my purchasing decision. Initially I thought I MUST stick with a convex grind for durability. It simply isn't the case.
As a little bit extra, although it's a bit of an aside, here is what I've concluded about the differences between a Scandi and a Convex overall:
As earlier noted, I've found that the Convex ground blades I've used tend to meet less resistance for the most part. This will come down to edge geometry and blade thickness more than anything, but the lack of a shoulder does seem to provide me with a cut that meets less resistance from what I can tell. The difference isn't enormous, but is apparent.
What I have seen to be the main advantage of a Scandi grind is that you literally NEVER need to reprofile the entire blade to keep from losing cutting performance. Simply sharpen along the grind back to your zero edge and you will maintain the same geometry for the life of the blade. In this way, the Scandi is very predictable and an overall breeze to maintain. The convex, in comparison, can be maintained quite easily with a strop for a long time, but when it comes time to actually sharpen it then you must remove metal from the ENTIRE blade (thinning the blade a bit) in order to maintain the same edge angle. If you only sharpen a convex ground knife at the edge, it will come out with a wider angle when you're done.
Here's another crappy drawing to compare the sharpening so I can illustrate what I mean:
Anyway, I hope this has helped some of you. It sort of bothered me that I had been under the wrong impression for the last couple of years simply because I was taking in what other people were saying without really looking at it. The convex grind is actually my personal choice for a large fixed blade knife with a thick stock because I know that I'll never thin the blade out significantly enough in my lifetime to weaken it, but for a somewhat smaller and/or thinner knife I see more merits to the Scandi (i.e. I think that may be why it is so popular for a Bushcrafter). That's just me. And lastly, I really don't think that the convex actually having LESS metal behind the edge really matters in this comparison. If you look at how far up the blade you have to be for the convex to start to show a difference in thickness, then you know that if you have a chip that deep into your edge that it reaches the shoulders (or where they would be if you have a convex) that you have a pretty serious problem and I doubt that it has anything to do with the grind. This just illustrates that the advantage of the convex is in cutting performance, NOT in strength. Everything that goes into a knife design is a compromise, and the convex is not the "have your cake and eat it too" grind.
Note that I am not a knife expert. If there is somehow something that I failed to mention or illustrate that anybody thinks should be mentioned, please let me know. This is simply what I found out from doing some doodling.
Also, I'm sure that I'm not the only person who has figured this out. But over the last couple of years I haven't ever seen anybody pointing it out, so I wanted to make sure more people had accurate information since I know I sure didn't ever since I first started hearing about convex ground knives.
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