Why the rather fast and obvious move to convex edges......?

M

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Jun 26, 2011
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First off.......this is my first post in this section and I've wondered for awhile as to the why part. Secondly, I have nothing in particular against convex edges and own several customs with such edges/grinds and they come incredibly sharp, however, such edges don't lend themselves to being sharpened very well with my brand new "Wicked Edge" sysytem........:rolleyes:. With alot of work, I can produce a 1/2 #**, usable edge, but nothing like what this system can do with a full flat, hollow ground or similar "V" edge bladed knife.

I am not complaining so much as wondering why so many makers have decided to make that move. Of course, many have stayed the course for ever, but I've noticed that many more, as of late, have "moved on over' to the convex side.

I am an avid hunter and can appreciate a hunting knife that holds it's edge well and lasts longer than the normal processing of just one deer. I hunt elk each year and know quite well the unfortunate experience of having only one knife along that fell waaaay short of my expectations when attending to a bull. I now carry and use dedicated game processing tools such as hunting knives (drop points) saw's, skinners, capers and such, rather than to try to make any of these do jobs they are not designed for. If I needed a pry bar, I'd take one of those too, but suffice it to say that I don't mistreat any tool unless I've found myself in a survival sitaution.

Having said that, I'm supposing that a majority of BF members, especially the "buyers" and opposed to the "makers", have a system like mine that easily sharpens their knives, customs or not, to a very usable sharpness. I also suspect that perhaps the #1 benefit of a convex edge is that there's less chance for chipping or breaking the edge as it is heftier/thicker than other grinds just above the edge and gradually gets even thicker on up the grind. The convex edge also likely cuts better as this "gradual thickening of the edge on up the blade" hleps to part whatever your cutting to essentially make the business end that much easier. Sounds like I'm making a push for convex edges and that's understandable........I know they're good edges. But...............

I don't process buffs nor elephants where I would either need thick reams of meat parted for me by the knife nor do I need to use any of my knives as pry bars where I would worry about damaging the edge. I've knocked down almost 30 bulls and have only once wished that I had a different knife along, which was my youth and ignorance showing through brightly (perhaps now as well, but that's why I'm here asking the questions). Again, I have dedicated tools for specific jobs. For me and IMHO and IMHE and perhaps no one else on earth (maybe that will save my behind from being flamed), I like a plain 'ole full flat, V-edge blade that I can easily sharpen and does what I need of it to do. Surely other grinds can do as well or better, but for me anyway, I have a sharpening sytsem that I can use easily and get great results, works for me very well while afield, can loan out to others in camp and they immediately know what to do with it and finally.........justifies my purchase of this damn system............just kidding. I love the "Wicked Edge" and wouldn't be without one now that I've used it.

I'm just thinking this............the average guy (me) has a sharpening sytem which is likely a system designed to accomodate the sharpening of V-edge'd blades. They've been around for years, they keep gettin' better all the time and we know what to do with them. Sure, I could go out and purchase the tools necessary to create sharp convex edges and I doubt that it would take me very long to learn how to do so (I thought that I'd get that in before somebody beat me to it............;)). If I used my hunting knives more robustly than I do and used them on chores outside of their intended use, then I could see the primary reasoning behind the more skookum convex blade, but I don't and I would have to guess that I'm not the only fellow that doesn't abuse his tools (we'll leave that alone....:eek:).

In conclusion (yep......we're almost at the end), I know that not many custom knives remain on the shelf for very long once advertised on BF. That is truly a compliment which I impart to the many wonderful knife makers we have here, but I'm wondering if even the quick and constant sales could be even quicker and more constant IF many of the convex edge'd knives were full flats or V-edge'd blades. I'm assuming that many of the purchasers of this suddenly larger % of convex bladed knives already know how to sharpen them, but I'd have to think that I'm not the only guy around who either doesn't want to learn, truly prefers the V-edged blades or doesn't know what he is getting into when he says "I'll take it" when he purchases a convex bladed knife. Many purchasers are likely deer hunters on down to varmints. I've killed a few major bucks in my life and have never come close to needing a convex edge's skookumness to finish the job. A mature bull elk............5-8 times the mass of your average deer and outside of that incident early on in my hunting career, no more than your old fashioned, out-of date, museum piece, full flat ground, V-bladed knife edge was necessary.

Give me a 3in. (+/-) drop point, full flat, V-edge blade, a 2.5-3.0in. skinner with the same edge (sharpened and angled to accomodate such duties) and a good, compact boning saw......................then I'm golden......;).

We all roll different ways for different reasons, whether real or imagined. This was just my take on this particular matter......no foul nor harm intended.

Have a great evening...........
 
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I sure love a good convex.

I am partial to full flat grind with a nice polished convex.

I am great at sharpening convex edges with a strop, sandpaper etc.

Full convex grind also are great in my book, as long as they are not too thick a grind.
 
Full flat is the way to go, generally thinner is better. I haven't really warmed up to convex edges.
 
Convex is a more durable edge, but a V (thinner) edge tends to be a keener edge, but it will likely lose the fine edge before a convex edge will degrade.

I like a convex on larger knives that might be called upon to chop or perform tasks that some might call abusive.


Mastersmith Ed Fowler has studied and written extensively on the topic. He does his edge in convex. Do a search. Internet is your friend... thanks Al Gore. :D


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Convex edges are thinner with less metal than a flat ground arrangement of the same final edge angle. Any thinner edge will cut more easily than a thicker one. Convexing is the new thing, like bushcraft or tactical, that is why you see it mentioned so often. A sharp edge is a sharp edge, it doesn't matter if the tools used to sharpen it had a soft back or not. The amount of convexity at the edge apex is right around zero, so it has no effect on terminal edge shape.
 
I've wondered about the convexed edge myself, I know there great but i sometimes have trouble seeing most of the advantages, they do seem tougher though. Still my convexed edge knives all become V's in the end for the reason the Op stated, my sharpening system(s) are just built that was. Honestly while they convex might be better, I can do a good v sharpen on the go with little effort or time, so it work better for me.

A lot of custom makers will do the V instead of the convexed if you ask though, so it's not like you have to choose.
 
I don't care one way or the other... I just take the knife with whatever kind of edge it has on it. I try to keep the same type of edge that came on the knife, but most of my maintenance is touchups done with strops, so it's not hard to do. I don't feel like I have to change an edge to one type or the other.

I do agree that my V bevels seems to get "keener" than my convex edges, but I've also found that they lose that first level of sharpness quicker. If I spent a lot of time with blades that got some heavy use, I might lean more toward convex edges for strength, but my cutting requirements are 80% slicing materials that are not as wide as the blade, so a hollow ground V edge works as well for my EDC blades as a flat ground convex edge.
 
I do full convex because my grinder only allows flat grinding on one side of the blade.
 
Whenever I find really old/used knives at a garage sales or thrift shops, it seems like the old timers who owned them almost always convexed their knives to a significant degree. Im not sure if others notice this, but I rarely find them with flat sharpened edges. This makes me believe it is not all that new of a technique -maybe it is just the discussion that is new, along with the internet and bladeforums.
 
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There's a very good description as to why a convexed primary edge grind is a superior cutting edge in "Flat Grinding with Harvey Dean," which I'll try to translate into words, since he sketches out some pictures.

The analogy he uses is of an ice breaker (ship). Those generally have hulls that have a convexed shape to them, and the idea is that material is forced out and away from the hull, whereas a flatter v-hull, like on a racing boat, would break or get stuck easily in the ice. I think the geometry behind it is that when you cut material, it's generally going to be pretty straight, and a flat grind edge will have more of the material against it, and there's nothing in the way the edge is ground that will force the material out and away from the edge, which means it's going to have to work harder to cut, even though it may have a much "keener" edge. In contrast, a convex edge, with it's curve, by nature will only have a single point of contact, and since it's an edge, as you cut, it will act as a low-friction wedge to force the material you're cutting out, and away from the edge, thereby making it actually easier to cut.

You can see the effects of this in push cutting a piece of paper or cardboard or something. First try just push cutting it regularly. Then have someone put very light outward pressure on the sides of the paper as you push cut. It will cut much more easily. The convex edge just provides that splitting assistance naturally, by the way it's designed, while a straight edge won't.

That's not to say that a flat ground primary edge bevel won't cut very well. When done properly, it WILL cut very well. But a properly done convexed edge is, theoretically, a better cutting edge, particularly if you keep it nice and toothy.

I believe National Living Treasure Jerry Fisk does a convex edge, and you end up with a very sharp edge, that's not really hard to maintain with some sandpaper and stropping. Which, incidentally, is much cheaper than a Wicked Edge, or any other kind of sharpening system.

http://www.youtube.com/watch?v=T63Kv-Z2Ml4

Not to mention, many people naturally end up convexing their edges if they sharpen by hand.

That's why I convex the edges I do, and I feel that I do get better performance out of the blades with convexed edges. Hope that explanation makes sense.
 
Personally I think that it thins the material of the edge and blends the shoulders into the body of the grind. It also provides a slightly more obtuse edge for its supporting volume, so you are able to thin the material of the edge's grind whilst leaving the edge itself stable enough to hold up under use.
 
Any edge regardless how it comes, will be convexed as I do freehand. Getting the system is way too expensive in this third world country.

I use stone, sandpaper and some polishing compound on cardboard.
 
My experience is that my knives tend to eventually transition their way into a convex grind. Personally though because of my terrible sharpening skills I find this to quickly become a pain...

I think that the convex grind isn't really anything new. Its the basic grind used on most machetes and axes and provides a thicker base to keep your edge from rolling/chipping, and has been around for a long time. I think with the reivival of the axes, large survival knives, and bushcraft in general people simply began using the name more often. As for the superiority of convex grinds... their good at some things and bad at others.

Personally I like a hollow grind or flat grind on my knives simply because I find this gives me a more precise cutting edge. On anything that I might bash and smash then a convex grind is perfect because it can handle that stress extremely well and keep a better edge. As for edge holding abilities, I guarantee you that I can dull any blade no matter the grind. So I personally would rather have something that is easy to resharpen, and considering that currently I lack the ability to sharpen a convex knife... I'd rather have a flat ground one.

-MC
 
I think because they are easy for novices to sharpen.

I've found that using paper wheels or regular stones, my edges turn a slight convex anyway. As long as it is sharp, I don't spend much time worrying about what type of edge it is.
 
medcommander said:
My experience is that my knives tend to eventually transition their way into a convex grind. Personally though because of my terrible sharpening skills I find this to quickly become a pain...

I think that the convex grind isn't really anything new. Its the basic grind used on most machetes and axes and provides a thicker base to keep your edge from rolling/chipping, and has been around for a long time. I think with the reivival of the axes, large survival knives, and bushcraft in general people simply began using the name more often. As for the superiority of convex grinds... their good at some things and bad at others.

Personally I like a hollow grind or flat grind on my knives simply because I find this gives me a more precise cutting edge. On anything that I might bash and smash then a convex grind is perfect because it can handle that stress extremely well and keep a better edge. As for edge holding abilities, I guarantee you that I can dull any blade no matter the grind. So I personally would rather have something that is easy to resharpen, and considering that currently I lack the ability to sharpen a convex knife... I'd rather have a flat ground one.

-MC
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I think you're missing the question, which wasn't about the main grind, but the edge grind. You don't get a hollow ground edge. It's either flat (v or chisel), or convex. Any one can sharpen a convex knife. Just takes a piece of leather and some stropping compound. Or a rock. Or some sandpaper. It's a MUCH easier edge to maintain in the field than a flat edge grind, because a flat edge grind requires you to be very precise with the angle. A convex edge doesn't.
 
A flat edge grind is easy to maintain, they can be sharpened with the same things you listed. The two planes of a convex grind still meet at a certain slope, you have to match that to sharpen the steel in the same place. You can still round a convex edge or sharpen at too shallow an angle and miss the edge.

Tormek, Tru-hone, F. Dick, Chef's Choice, etc disc-shaped power sharpeners hollow grind edges.
 
I use convex edges, mainly for chopping. I use V Grinds, mainly for slicing. You can do either task with either edge. In my experience, convex grinds are sturdier and can handle accidental strike damage better. In a survival situation, I think they would hold a useable edge longer if made of the same steels. I free hand sharpen both.
 
hardheart said:
A flat edge grind is easy to maintain, they can be sharpened with the same things you listed. The two planes of a convex grind still meet at a certain slope, you have to match that to sharpen the steel in the same place. You can still round a convex edge or sharpen at too shallow an angle and miss the edge.

Tormek, Tru-hone, F. Dick, Chef's Choice, etc disc-shaped power sharpeners hollow grind edges.
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hardheart said:
Convex edges are thinner with less metal than a flat ground arrangement of the same final edge angle. Any thinner edge will cut more easily than a thicker one. Convexing is the new thing, like bushcraft or tactical, that is why you see it mentioned so often. A sharp edge is a sharp edge, it doesn't matter if the tools used to sharpen it had a soft back or not. The amount of convexity at the edge apex is right around zero, so it has no effect on terminal edge shape.
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Exactly correct.
 
IMO any grind type can be set up poorly for any application. The convex may have some advantages in theory, but in practice I doubt that would translate into a noticeable difference between two knives made equally well using different blade grinds.
 
I have a sneaking suspicion that the main reason most manufacturers that have taken up the convex edge with enthusiasm have done so because it is easier and faster to finish the knife.
 
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