Why Convex?

[HoosierQ]

I am seeing more here in ESEE about convex edges than any place I've been. Why?

I am a big Mora fan and of course those are flat scandi grinds with no secondary bevel.

Why are so many interesed in convexing? Traditionally, have we not all been trying to avoid convexing an edge? By maintaining a consitant angle on the sharpening strokes?

I know that Samurai swords are convex.

I am not knocking anybody here...I don't roll that way at all. Just need to learn. I plan on buying two or 3 ESEEs with my upcoming bonus (instead of my customary firearm) and I really want the straight dope on the higher end, survival knife scene.

 

[theamazingdrew]

holds an edge longer
the edge is stronger
it can be maintained easier
can get a wicked sharp edge with minimal work
sand paper+mousepad=5$ good set of stones or sharpening system=50$+
slices better

there is not one aspect in which a V edge is superior

 

[The Government]

^the only aspect where I see a thick V-grind might be superior is in an edge chipping scenario from contacting a rock or something. I am referring to full convex ground knives rather than secondary convex bevels. Full zero convex grinds are where you really see a huge difference. A secondary convex grind would most likely have the stated benefits over a V grind.

To the OP -Buy a full zero convex ground knife and give it a try if you never have. You will see why they are desirable.

A starter would be an Opinel for around 10 bucks. Try some wood carving with it -THEN -imagine a thick survival knife with the same grind. A thick spine and a thin edge work very well at delicate and hard use jobs.

 

[Ultimate]

The one benefit V edges have over convex edges is that they're easier to maintain in the field. Unless you carry around a mouse pad and sandpaper or strop + compound.

 

[trugracie]

The one benefit V edges have over convex edges is that they're easier to maintain in the field. Unless you carry around a mouse pad and sandpaper or strop + compound.

I do!
I took a paint stick from hardware store, and glued leather on both sides, then coated one side black and the other green.
It virtually takes no room in my pack, however, I never need it since it seems to hold an edge much better, even after 5 day hikes.

 

[Todd A]

The one benefit V edges have over convex edges is that they're easier to maintain in the field. Unless you carry around a mouse pad and sandpaper or strop + compound.

Not really. For one I do keep a small square of foam pad and a couple squares of paper in my pack.

But, I have sharpened my convex edges freehand on a stone, a EZ lap diamond sharpener, and just plain sandpaper that I keep in my wallet.

If you freehand your V edge blades on a stone, after many,many, sharpenings it will convex on its own anyway.

I just don't use any V type stick sharpeners on my convex blades.

 

[knerd]

It's just a different edge style, people will argue both sides of the argument and it comes down to personal opinion. Convex doesn't necessarily cut any better than a sharp V ground knife, it doesn't hold an edge any longer unless all you do is chop with your knife. Easier to maintain? That can be said about both a convex and a v-grind.

Needless to say it's just a preference/personal opinion. If the knife is sharp and cuts then I'm happy.

 

[Mr.Blade]

Scandigrind cuts best, but ESEE 3,4,6 have v-grind with a second bevel. ESEE 5 have sabergrind with secondary bevel. It´s easier to put an convex edge on the knife, than to make it to scandigrind with no secondary bevel, (don´t know if that even is possible). That´s why I convexed my Izula. It cuts a whole lot better, like feathersticks for example. "Why are so many interesed in convexing?" That is simply because it cuts better, when compared to V-grind with secondary bevel. Not scandigrind with no secondary bevel.
But it´s more expensive to manufacture knives with convex blades.

 

[stoffi]

My suggestion is that everybody who hasn't fully understood the benefits of each grind should buy a bunch of cheap Moras and regrind them into each type of grind and start testing them. That's what I did. I reground one into a 20° (40° total) v-grind and another one into a full convex and compared them to a regular unmodified scandi. All three knives where of the same model. The scandi cut wood most aggressively, the convex created thinner slices and the v-grind just didn't compete with the two. Yes, one can argue that the convex shape may play a part (it was thinner because of stock removal) and that the v-grind wasn't on a full flat ground blade or whatever, but I feel that it says something at least, given that I used the exact same blades for this test.

So, which would I choose if I had to bring only one into the woods which I could rely upon? I'd go for the convex, because it would hold an edge better than the scandi. Scandis are awesome whittler/carvers, but they are so at a cost — edge retention. Factory grinds often roll over or chip. The convex can chip and roll also, but it is far less likely to do so.

 

[Ultimate]

*Couldn't figure out how to delete this post*

I deleted because there is no point in arguing which grind is better in the field. It comes down to personal preference. I may say V edges are easier to take care of, you may say convex edges are. In my experience, my V edges are easier to take care of in the field. Maybe it's because I don't carry sufficient methods to care for convex edges. Maybe it's luck. Who knows. All that matters is what you do works for you.

 

[stoffi]

Well, I don't agree that it comes down to personal preference. I mean, performance has nothing to do with that.
But, yes — how you choose to sharpen things and what equipment you wish to bring and learn to use is entirely up to you.

Personally, I'm at an expert level when it comes to sharpening v-grinds, but I'm only starting out with fully convex blades.
I can still confess that I have noticed that convex blades perform better than most v-grinds, but I'm only moderately good at sharpening a convex blade, so far...

 

[guns_and_labs]

My suggestion is that everybody who hasn't fully understood the benefits of each grind should buy a bunch of cheap Moras and regrind them into each type of grind and start testing them. That's what I did. I reground one into a 20° (40° total) v-grind and another one into a full convex and compared them to a regular unmodified scandi. All three knives where of the same model. The scandi cut wood most aggressively, the convex created thinner slices and the v-grind just didn't compete with the two. Yes, one can argue that the convex shape may play a part (it was thinner because of stock removal) and that the v-grind wasn't on a full flat ground blade or whatever, but I feel that it says something at least, given that I used the exact same blades for this test.

That's a great suggestion.

I happened on an alternative. I have two Dozier KS-3 Professional Guides Knives, one with the a typical Dozier grind (which looks to be 12.5-15 degrees on each side) and one with a full convex grind. I did the same thing, tried them on a variety of tasks, and found the v-grind to be superior on precise tasks -- though not by much. I'm sure the convex is quite sturdy, and might last longer (though all Doziers last a long time), but I could not slice as thin nor skin/cape as precisely. Now if I can find a KS-3 with a scandi grind, I'll have the comparison complete.

 

[stoffi]

Do you have any pics of this? I tried looking at the knives you spoke of, but the images where not very informative of the blade shape etc.

 

[theamazingdrew]

^the only aspect where I see a thick V-grind might be superior is in an edge chipping scenario from contacting a rock or something.

it has been proven many times over that a convex edge of the same angle (meaning they both bite at the same angle) has 400% more durbility than a v edges while still being thinner.
I have tested this many times, so have many professional makers (mike stewart in particular).

 

[Dannyboy Leather]

Post expired.

 

[Ultimate]

The best tool for determining your success will be good 'consistent' results.

Which is why it comes down to preference in the end. I've used V edges much much longer than I have convex and I get "good consistent results" when I need to touch them up. I'm not talking about using a blade during the day and coming home to touch it up. I'm talking about multi-day/week hikes/backpacking trips where you need to touch up the edge without your best equipment which you couldn't take with you. That's what I mean by "being in the field". For me, my V edges hold up fine in such expeditions because 1. I take care of the edge to begin with and 2. For me they are easy to maintain. My opinion might change in the future as I use convex edges more and more.

 

[Dannyboy Leather]

Post expired.

 

[Ultimate]

And nothing wrong with that. We need to use what works best for us and the cutlery we are using. Here in the ranch butcher shop, we maintain all of the shop knives with "V" edges/bevels that are slightly toothy on flat-ground blades. We have tried everything else over the years but "V" edges are just better in our experience (quicker to maintain, too) for cutting up beeves (bandsaw does much of the work these days). I also have a couple of flat-ground hunting blades in L6 that really prefer a "V" bevel over a convex. I can add an early Becker and a Swamprat to that list as these knives, geometry, metallurgy, etc., often tell the user what works best with regards to the edge and what the edge is expected to do.

Developing the basic understanding and skills in working with a variety of edges (and grinds) is a good thing in my book. We know that the convex edge is the "only" cutting edge for a durable axe head. The convex edge also does extremely well on everything from machetes to swords. In South America and Asia, the convex edge was the only type of edge that I ever saw on any of the cutlery (big and small) in the remote native villages. So, there is something to be said for its use and practicality throughout history (we all agree). There was a time, however, when I was young, that I maintained a large "V" bevel or secondary grind on my full-height convex-ground Marbles knife, not understanding the potential of extending that grind down to the very edge. A few years later, someone with more experience than I changed my mind. As an engineer, with a great deal of experience in aircraft design, I now know that angles cause drag...even in the most humble of details. How that "V" bevel drag is communicated to the users hand in terms of effort and efficiency is, another set of equations that may or may not be important to the user. Myself, I like to take the easiest route with the least amount of effort to accomplish a job (I don't always succeed). Life has enough problems within itself.

Another bevel that I use...mostly with wood. A great, superior bevel for wood working, however a lousy bevel (too thin) for chopping or heavy utility work. I often keep a larger, much more durable, convex-ground Leuku with these smaller sabre or Scandinavian-ground Puukko knives to cover all the bases. No "correct" grind for every task! "Options" are a good thing and should be expoited to their fullest potential! I just encourage folks to experiment with the options, adopt the best ones, pass that knowledge around.

A lot of good info here. Thanks.

We have tried everything else over the years but "V" edges are just better in our experience (quicker to maintain, too)

That's why I tend to prefer V edges if I know it may be a while until I can really work on the edge again.

 

[mitchshrader]

Convex edges by their nature aren't sharpest, they're sharp longest, and resharpenable fastest.. but having more support for the edge comes at a cost in pure sharpatude.

I'm a convex edge lover, and if you want a convex edge to match a beveled edge, you'll have to lengthen it until it approaches a similar angle/arc with that bevel. Short convex edges are VERY sturdy, but require touching up frequently, a good excuse for a ceramic stick. Long ones will roll, rather than chip, under heavy use, so can be 'rolled back' moreso and more often than beveled edges. That's part of the attraction of kukhris, that long convex edge with a real hard 'sweet spot' in it..

convex edges are harder to learn, balancing the two sides and achieving a perfect arc from heel to point, a single line that flows into both supporting arcs without any distortion at all.. but once you have, you've got sturdy in spades and resharpenable in moments. Show-off edges. And they make a fair excuse for two tables full of natural sharpening stones, which otherwise it's hard to come up with one.

 

[knerd]

it has been proven many times over that a convex edge of the same angle (meaning they both bite at the same angle) has 400% more durbility than a v edges while still being thinner.
I have tested this many times, so have many professional makers (mike stewart in particular).

...Eh, 400%? I find that hard to believe.

I'd think a V-grind with a microbevel (makes the edge stronger) would perform equally, if not better, than a convex grind. A convex might be stronger (wider shoulder), but you lose the function of finer cutting (thinner shoulder = less resistance into substance you're cutting) that you get in a v-grind. And for EDC blades (I doubt everyone is in the woods on a regular basis) v-grinds would definitely triumph over covex grinds. As for maintenance in the field, you can also use a strop on a v-grind and get it resharpened just like a convex it doesn't require all these sharpening systems. Again, I feel it comes to personal preference/opinion and what you're comfortable with. For every pro there is a con, no one type of grind is better than the other.