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Convex Edges; I Don't Get It
- Thread starter Lenny
- Start date
you can sharpen them on a strop or sandpaper. they have less drag since there is no shoulder like on a v edge. a convex edge is stronger too. if the edge gets too thick, you have to use a belt sander or do a lot of hand sanding to get the blade thickness down.
i plan on convexing every knife i have when i get around to it.
i plan on convexing every knife i have when i get around to it.
- Joined
- May 19, 2008
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- 1,534
I hate convex edges. I've tried to do them for years, with sandpaper, mouse pads and strops and cannot get it. When I get knives with convex edges I convert them immediately. I can get my knives shaving sharp with a Sharpmaker and I'm satisfied. Okay, that's my rant. 
- Joined
- Apr 10, 2000
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- 3,794
I would be very surprised to see someone grind perfect V edge freehand, or even using sharpmaker 
Sandpaper on the soft surface like an old mousepad or leather strop is just a simple way to get proper convex edge, and you can grind it with just 220 grit sandpaper too.
In other words, it's not the grit of the abrasive that affects the edge geometry.
Sandpaper on the soft surface like an old mousepad or leather strop is just a simple way to get proper convex edge, and you can grind it with just 220 grit sandpaper too.
In other words, it's not the grit of the abrasive that affects the edge geometry.
- Joined
- Jan 2, 2011
- Messages
- 169
I recently tried my hand at my 1st convex edge (Izula) and am pretty happy so far...
I am still learning to dial my technique, but the first thing that made immediate improvement was to ease up on the pressure. The pad was giving me a false sense of how hard I was pressing. Let the cushion to the work.
I am still learning to dial my technique, but the first thing that made immediate improvement was to ease up on the pressure. The pad was giving me a false sense of how hard I was pressing. Let the cushion to the work.
- Joined
- Feb 4, 2009
- Messages
- 1,914
I've grown found of them. They glide through material with ease and look pretty attractive as well. I haven't done any real testing so far, so I can't speak of durability, but it is generally accepted that they're stronger than a standard V. Here are a couple pics of some convexes I did a couple days ago on the belt grinder; I posted these in M,T&E.
I would be very surprised to see someone grind perfect V edge freehand, or even using sharpmaker
Sandpaper on the soft surface like an old mousepad or leather strop is just a simple way to get proper convex edge, and you can grind it with just 220 grit sandpaper too.
In other words, it's not the grit of the abrasive that affects the edge geometry.
No such thing as a perfect edge, proper ones are easy enough V- grind or convex, with a little practise.
- Joined
- Nov 17, 2008
- Messages
- 3,654
I really like them. While I normally use benchstones for sharpening, I've found that the sandpaper-and-mousepad technique is really easy, quite forgiving, and gives very good results. On the downside, I find it takes much longer to sharpen out big nicks or reprofile a knife with sandpaper than it does with DMT diasharp stones or Norton Waterstones.
- Joined
- Sep 11, 2010
- Messages
- 2,846
theres really two kinds of convex grinds i find, there are the converted ones who have a different ground primary bevel, and those that simply have a full convex grind
(ie Fallkniven A1 has a full convex grind, while my Buck Vantage Pro has a hollow grind with a convex secondary bevel)
either can be touched up or ground down with the mousepad/soft surface and sandpaper but it would definitely be a pain to do a full convex like this
Advantages:
-longer edge retention (this also has to do with steel, HT, edge geometry etc)
-blades used for large slashes (ie bushwhacking and chopping) wont bind as quickly, a lot of japanese sword smiths used old waterstones which were worn in the center which led to a convexed edge and they found that when cutting the blades wouldnt bind as quickly because there was 1. less initial resistance and 2. the shape of a convexed edge pushed the sides apart better then a V grind, which would often have the sides of the object being cut to fall back together.
(newtons 1st law i think, every action has an equal and opposite reaction)
Disadvantages:
- some say that a convex edge cant be as sharp as a V grind, as in it wont bite as deeply
-its a pain in the a$$ to do it by hand unless you have lots of practice or a system that can do it for you.
-cant be done on triple bevel chisel grinds very easily/evenly (ie even [primary bevel but secondary is just on one side), or traditional chisel grinds
im sure there are more reasons but those are the only ones that come to mind at the moment hope that helps
(ie Fallkniven A1 has a full convex grind, while my Buck Vantage Pro has a hollow grind with a convex secondary bevel)
either can be touched up or ground down with the mousepad/soft surface and sandpaper but it would definitely be a pain to do a full convex like this
Advantages:
-longer edge retention (this also has to do with steel, HT, edge geometry etc)
-blades used for large slashes (ie bushwhacking and chopping) wont bind as quickly, a lot of japanese sword smiths used old waterstones which were worn in the center which led to a convexed edge and they found that when cutting the blades wouldnt bind as quickly because there was 1. less initial resistance and 2. the shape of a convexed edge pushed the sides apart better then a V grind, which would often have the sides of the object being cut to fall back together.
(newtons 1st law i think, every action has an equal and opposite reaction)
Disadvantages:
- some say that a convex edge cant be as sharp as a V grind, as in it wont bite as deeply
-its a pain in the a$$ to do it by hand unless you have lots of practice or a system that can do it for you.
-cant be done on triple bevel chisel grinds very easily/evenly (ie even [primary bevel but secondary is just on one side), or traditional chisel grinds
im sure there are more reasons but those are the only ones that come to mind at the moment hope that helps
- Joined
- Dec 10, 2010
- Messages
- 535
I'm older than dirt and had never heard of such a thing as a convex edge until I found this forum a few months ago. I had a couple of hours to kill this evening, so I decided to give it a shot with my '60s vintage Ontario pilot knife. Not sure what steel they used in these things, but it feels similar to the 1095 in my Beckers when I sharpen it on a Sharpmaker.
Anyway, I grabbed an old mousepad and started with 320 grit wet/dry..which I quickly found was far too coarse, so I moved to 600. After about 50 passes on each side, I had a decent edge on the knife. I moved up to 800, then 1200 and the edge looked/felt fantastic. I don't have a strop, so I finished up with a few passes on some 2000 grit I had left over from another project. Not sure it's any sharper than I normally get with the Sharpmaker, but it's definitely prettier.
I have no idea if a convex edge is actually any better for my needs than the quick and dirty V-grind job I usually do with the Sharpmaker, but it was interesting and I learned something new.
Anyway, I grabbed an old mousepad and started with 320 grit wet/dry..which I quickly found was far too coarse, so I moved to 600. After about 50 passes on each side, I had a decent edge on the knife. I moved up to 800, then 1200 and the edge looked/felt fantastic. I don't have a strop, so I finished up with a few passes on some 2000 grit I had left over from another project. Not sure it's any sharper than I normally get with the Sharpmaker, but it's definitely prettier.
I have no idea if a convex edge is actually any better for my needs than the quick and dirty V-grind job I usually do with the Sharpmaker, but it was interesting and I learned something new.
i like a convex edge. the seem to hold there edge somewhat better. cut better also. might be because of the smoother transition from the cutting edge to the side of the blade, i sharped with a sharpmaker or bench diamond hone and strive to make the resulting v edge convex by stropping. ive had the best luck with my endura which is always kept super sharp and convexed by stropping. i have found its much easier to touch up and keep a sharp edge. like any edge i think the key to getting it sharp and ability to do easy touch ups is the back bevel . never tried doing one on a belt sanding rig. wish i had one to try it .
Ebbtide
Gold Member
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- Aug 20, 1999
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- 7,984
I recently tried my hand at my 1st convex edge (Izula) and am pretty happy so far...
I am still learning to dial my technique, but the first thing that made immediate improvement was to ease up on the pressure. The pad was giving me a false sense of how hard I was pressing. Let the cushion to the work.
Press hard to reshape.
Press lightly to sharpen.
I have read that if you have a full convexed edge and you manage to chip the blade the chip/crack will travel further up the blade than with a traditional V-grind due to one continuous uninterrupted blade shape. Personally I have never seen this actually happen, only what I have read.
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- Apr 10, 2000
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- 3,794
Which makes it convex, or semi convex... And that's what happens when sharpening freehand. It's just how smooth/even the convex line is.
- Joined
- Jul 20, 2006
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- 3,808
I love convex edges and I find them very easy to sharpen. I sharpen all my knives with some different grits of sandpaper and a coupe strops. Works very well and is a very cheap system to run. My knives shave hair np. If you sharpen a standard v edge using this technique, it will slowly convert to a full convex. I dont bother wasting my time converting when I get v edge blade. I just sharpen my blade when needed and let time do the rest.
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- Feb 27, 2010
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I can't sharpen V edges at all. I'm completely useless at it.
Convex edges on the other hand - all my knives are stropped using compound and it takes just five minutes to return a dull blade to hair popping sharp.
Convex edges are much more forgiving on the user when sharpening as with a V edge you are either dulling the edge or grinding the shoulder a lot. I'm not skilled enough to do this properly so with a convex you just lay it nearly flat and let the weight of the blade do all the work. Easy as pie.
I also convexed my Recon Scout by hand using (a lot) of sandpaper. Worked great but took a lot longer to achieve.
Convex edges on the other hand - all my knives are stropped using compound and it takes just five minutes to return a dull blade to hair popping sharp.
Convex edges are much more forgiving on the user when sharpening as with a V edge you are either dulling the edge or grinding the shoulder a lot. I'm not skilled enough to do this properly so with a convex you just lay it nearly flat and let the weight of the blade do all the work. Easy as pie.
I also convexed my Recon Scout by hand using (a lot) of sandpaper. Worked great but took a lot longer to achieve.
- Joined
- Apr 10, 2000
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- 3,794
Normally, you try to hold persistent angle to which you are trying to sharpen, i.e. just the edge.
Then, depending on the padding softness(or firmness) you need to get the pressure right to get the desired convex line.
With some practice and patience, you can learn to do convex edges on the stone, very simplified description would be to raise/lower the blade as you push/pull.
Then, depending on the padding softness(or firmness) you need to get the pressure right to get the desired convex line.
With some practice and patience, you can learn to do convex edges on the stone, very simplified description would be to raise/lower the blade as you push/pull.