Talk to me about convex edges.

[L2bravo]

I know very little about them. Please tell me the why's and about's on them. I am really interested in this. Thanks

 

[Jason B.]

Read this and make sure you understand that convex is not what most tell you it is..
http://www.bladeforums.com/forums/s...ghlight=convex+scandi&p=12539334#post12539334

 

[Nullity]

Read this and make sure you understand that convex is not what most tell you it is..
http://www.bladeforums.com/forums/s...ghlight=convex+scandi&p=12539334#post12539334

I think it is near impossible to say anything universal about convex edges since there is an infinite number of ways to make a curved line.


To the OP:
In general, since there is no sharp transition between the edge/secondary bevel and the primary bevel, a convex edge will cut through materials better.

Some say it is stronger, but that all depends on the particular edges you are comparing. Thick is stronger than thin, regardless of edge grind.

 

[HwangJino]

For me it works as a chef.

after experimenting for a few years I found that I can find a middle between stupid sharp and durable.

 

[Omega Leather Works]

I think it is near impossible to say anything universal about convex edges since there is an infinite number of ways to make a curved line.


To the OP:
In general, since there is no sharp transition between the edge/secondary bevel and the primary bevel, a convex edge will cut through materials better.

Some say it is stronger, but that all depends on the particular edges you are comparing. Thick is stronger than thin, regardless of edge grind.

Well said. I'm starting to experiment with convex edges and I'm liking what I'm seeing.

Search youtube for "gavkoo" and "convex". He has some interesting demo's on what he believes are inherent advantages to a rounded shoulder.

 

[Ben Dover]

There is room for both. I prefer a "V", because for me, it's easier to sharpen without a belt sander. OTOH, a convex is easier to refine and polish.

Some of the finest production fixed blade knives in the world are made by Fallkniven and Bark River. They are both convex. Visit Mike Stewart's Bark River Knife and Tool website and you can get a lot of good information about convex edges.

Both the V grind and convex can be sharpened to pass the HHT.

IME, given identical steel and Ht, the V is a bit easier to sharpen and the convex holds it's edge a bit better. But in practical terms, the difference isn't great enough to matter.

If I find a knife that I like, good ergonomics, good steel, good HT, etc, I'll buy it and use it regardless of the grind. I use V grinds for my hunting and camp knives, but several members of my hunting party use Fallkniven and Bark river and are happy with them. And they maintain them, razor edge, with nothing but strops.

 

[tiguy7]

I think the advantage of a convex edge is its ability to change directions while cutting. It is not so good for making uniform slices, but it is good for boning chicken.

 

[Obsessed with Edges]

I've grown to like convex for essentially two reasons:

• The technique for creating and maintaining them is exactly the same as stropping, which suits my hands perfectly, and opens up a HUGE array of simple, readily available and usually dirt-cheap sharpening solutions.
• Thinly-ground convex edges are a slicing dream. Once I figured this out, I've never looked back.

There's lots of discussion and debate of whether they're more 'durable' or 'robust'. To me, it's essentially a wash. Any edge can be both sharp and durable, if the steel behind it is suited for the geometry, be that V-bevel or convex. I don't even worry about it anymore.


David

 

[L2bravo]

After reading the thread posted, and doing some research, I am more lost now than ever. I am not even sure how they are supposed to look, and how to even maintain them. Or anything else for that matter.

 

[Obsessed with Edges]

After reading the thread posted, and doing some research, I am more lost now than ever. I am not even sure how they are supposed to look, and how to even maintain them. Or anything else for that matter.

Fret not. To me, the most relevant takeaway from that thread, for someone trying to understand the basics, is:

Too many people severely overthinking things.
(...)

That's not saying what else was 'discussed' in the thread isn't relevant or helpful to those interested. But, there's no need to let all that distract you from getting the basics down. The best way to get acquainted with convex is just to pick up a blade and make it so. That could be as simple as 'stropping' it on some medium-grit sandpaper. Start on a blade with a relatively thin grind, like a hollow grind or thin flat grind; it'll convex more easily. Then use it for a while, and draw your own conclusions. Nothing else matters.


David

 

[David Martin]

I use both, knives with a convex grind and a good hollow grind. I've noticed when I'm cutting into cheese, cutting up an apple (something firm)or skinning a fat hog. The convex edge requires more pushing to make it cut deeply into these materials than a decent hollow ground blade. When skinning something with fat the tight quarters of the cut will grab the sides of the blade and not allow it to cut deeply. Thus, one thinks it's dull as the hard push required to make it cut. Whereas, in reality it's the thickness of the blade preventing it from cutting. As for it lasting longer like an axe, this may be a valid point. Still, it could be only slight. Yet, I shy away from the convex for this reason. DM

 

[Obsessed with Edges]

I use both, knives with a convex grind and a good hollow grind. I've noticed when I'm cutting into cheese, cutting up an apple (something firm)or skinning a fat hog. The convex edge requires more pushing to make it cut deeply into these materials than a decent hollow ground blade. When skinning something with fat the tight quarters of the cut will grab the sides of the blade and not allow it to cut deeply. Thus, one thinks it's dull as the hard push required to make it cut. Whereas, in reality it's the thickness of the blade preventing it from cutting. As for it lasting longer like an axe, this may be a valid point. Still, it could be only slight. Yet, I shy away from the convex for this reason. DM

I've noticed a similar tendency for a convex to be 'grabbed' when splitting apples also. Cutting part of the way into a whole apple, the apple seems to clench down on the blade in almost vise-like fashion. First noticed it with an Opinel, which otherwise cuts like a laserbeam. It's the one thing about a convex that makes me scratch my head a little bit. I've noticed a hollow or sabre grind blade seems to handle apples better; I assume the 'void' created between the blade's hollow and the apple sort of minimizes the 'vacuum effect' that sometimes makes food cling to a blade when sliced. High hollow grinds work well on tomatoes also, apparently for the same reason. My thin, high-hollow-ground Case Sod Buster Jr. is one of the better tomato-slicers I've seen.

I think thinner is better, in general, for apple-slicing. Sharpness of the edge sometimes doesn't even matter much. My Dad actually uses a table knife (flatware) to split & quarter apples, on a ceramic tile countertop no less. Makes me cringe when I hear the edge of that blade CLACK against the tile. In that scenario, I'm glad he just uses the table knife.


David

 

[HeavyHanded]

The thing I like best about convex and Scandi for that matter, the backbevel gets thinned with the cutting edge and the whole blade maintains its geometry. Both, if ground nice and thin, will slice OK. Not as well as many a hollow grind, but well enough.

For choppers, the convex is the way to go, whether a machete, axe, hatchet. I can't say the edge lasts any longer than a V bevel, but it certainly chops better. And for smaller knives made from thick stock, converting from a V bevel sabre grind to a full convex will make a huge difference in performance.

Overall I haven't noticed any solid improvement in edge retention - type of edge grind appropriate for the intended use still makes the biggest difference IMHO (and steel type of course). Most of my V bevel edges are now flat grind or hollow grind. If I were to buy another sabre grind I'd convert it in short order.