Convex edge thoughts ?? I'm not a fan

[FortyTwoBlades]

Here’s a blade that shows a V edge and three different convex edges. The V edge is defined by three points: the apex and the two points of the edge shoulder.

The red line represents a convex edge using the same three points, with a tight arc. This convex edge is fat, stout and obtuse. It will be very strong, but not a good cutter, compared to the V edge.

The pencil line represents a convex edge using the same three points, but with a gentle arc. It’s still not as aggressive a cutter as the V edge, but it’s better than the red convex edge.

The green arc represents a convex edge where the shoulder was raised. This edge is almost as acute as the V edge, but also can cut deeper before the width of the blade begins to limit cutting ability.

Three convex edges, all very different. We always talk about convex edges as if they are all the same. They are not.

So, Fastriot got a convex edge profiled by someone else to standards he knew nothing about. Then he tried to resharpen it, but his own standard was most likely quite different than that used by the previous sharpener. If the original convex was like the red angle and he tried to resharpen it using the green angle, he would have to sharpen a very, very long time before he’d even approach the apex.

Convex angles can be awesome, but they can also be terrible cutters. Or anything in between. And because we talk about them without defining them, we usually end up talking past each other.

Just remember that in the diagram obviously all the shown edges have radically different effective edge angles. Using that same variable V or linear edges are just as capable of being excellent, or awful.

 

[Mikael W]

Here’s a blade that shows a V edge and three different convex edges. The V edge is defined by three points: the apex and the two points of the edge shoulder.

The red line represents a convex edge using the same three points, with a tight arc. This convex edge is fat, stout and obtuse. It will be very strong, but not a good cutter, compared to the V edge.

The pencil line represents a convex edge using the same three points, but with a gentle arc. It’s still not as aggressive a cutter as the V edge, but it’s better than the red convex edge.

The green arc represents a convex edge where the shoulder was raised. This edge is almost as acute as the V edge, but also can cut deeper before the width of the blade begins to limit cutting ability.

Three convex edges, all very different. We always talk about convex edges as if they are all the same. They are not.

So, Fastriot got a convex edge profiled by someone else to standards he knew nothing about. Then he tried to resharpen it, but his own standard was most likely quite different than that used by the previous sharpener. If the original convex was like the red angle and he tried to resharpen it using the green angle, he would have to sharpen a very, very long time before he’d even approach the apex.

Convex angles can be awesome, but they can also be terrible cutters. Or anything in between. And because we talk about them without defining them, we usually end up talking past each other.

Twindog, I like Your effort to explain the convex geometries!:thumbup:
Not many does it as clear as this, Good Work!

Now, take the redline edge.
It will hold an edge better than the greenline edge on harder materials.
The greenline will be a better slicer than the redline and will work better on softer materials.

The blackline is a compromise between both needs.
Often I end up with the blackline type of convex edge as an allround user edge, for many differrent materials.

Now, take a look at a Mora V-grind!
They are recognized as good wood cutters and I like to confirm this by my own longtime experience (+50 years) with them.
But!
Their original zerogrind edge will roll or microchip on harder materials.
So, I micro convex the very cuttingedge with a few strokes on a stone and then strop on leather.
This means I give the first 1/32" of the edge a convex profile looking like the redline edge, but very much smaller.

This cures any troubles with a too thin edge,when cutting harder materials.

The OP has troubles with a too thick edge on his 3V BR Bushcrafter.
I had the same issue with my BR Lil' Canadian when out of the box.
Thinning the shoulders/corners of the edge like the greenline, did the trick and it started to perform as a convex 3V knife should perform.

Regards
Mikael

 

[expwmbat]

Twindog, I like Your effort to explain the convex geometries!:thumbup:
Not many does it as clear as this, Good Work!

Now, take the redline edge.
It will hold an edge better than the greenline edge on harder materials.
The greenline will be a better slicer than the redline and will work better on softer materials.

The blackline is a compromise between both needs.
Often I end up with the blackline type of convex edge as an allround user edge, for many differrent materials.

Now, take a look at a Mora V-grind!
They are recognized as good wood cutters and I like to confirm this by my own longtime experience (+50 years) with them.
But!
Their original zerogrind edge will roll or microchip on harder materials.
So, I micro convex the very cuttingedge with a few strokes on a stone and then strop on leather.
This means I give the first 1/32" of the edge a convex profile looking like the redline edge, but very much smaller.

This cures any troubles with a too thin edge,when cutting harder materials.

The OP has troubles with a too thick edge on his 3V BR Bushcrafter.
I had the same issue with my BR Lil' Canadian when out of the box.
Thinning the shoulders/corners of the edge like the greenline, did the trick and it started to perform as a convex 3V knife should perform.

Regards
Mikael

This is good--now each of those will slice paper and shave, but the thinner will be much better at those tasks. Take them into the field, however, and you will quickly see a difference in how they work and hold their edge when used on harder material that is deeper than paper or hair. That's what I meant.

DJK

 

[Steely_Gunz]

I think the edge performance is based on what we are comfortable sharpening and how we learned to sharpen. My grandpa taught me how to free hand with a small stone. Years later, I got into khukuris which are almost always convexed to some degree.

I generally put a hybrid edge on my straight edge knives. I'll usually give it a thin sharp edge with a stone then give it a final convex on a loaded strop. From a thin slip joint to a 1/2" thick Nepali chopper, it'll result in a shaving edge.

I recently got into scandi grinds and I've become a big fan. I can see it as a great edge out in the wilds where one might want to just take a stone for quick repairs, plus it gets stupid sharp.

That said, my heart will always be convexed

 

[Coad]

I like convex. I put my first on a stripped bk 16. For carving I like scandi. On my mora number 1s the curved part of the blade to the tip ends up slightly convex. Not intentionally. I sharpen on sandpaper wrapped over a book. I think its the result of poor form, it doesnt hinder the knifes preformance any, so I dont mind.

 

[ridnovir]

I prefer convex. It is easy to maintain with laded strop. can be sharpened in field with portable loaded strop or even on leather belt with some compound on it. It is tough and it is durable.

 

[FTR-14c]

I often convex the shoulders off a v-grind and leave the original edge creating a hybrid. It improves performance quite a bit.
Eventually after a few sharpening I end up with a nice shallow convex that cuts great and is easy to maintain.

Edit: On the sketch, if you look at the green on the inside of the blade cutting off the corner, thats exactly what I remove on a new v- grind.

 

[mjolnir74]

I like a convex edge on my yard tools. On my folders I put a v- grind on, but maintain with a strop.

 

[Shotgun]

Based on a couple of posts here, I'm not alone in my dislike for a convex grind.

True but look at those posts. They're made by people who have trouble sharpening them. The people that can sharpen them like them. I think that says something in favor of them. If you really don't like them that's cool but at least give them a fair shake. Or don't.

 

[Shotgun]

I'm borrowing your picture.

The way that I like to picture a GOOD convex is to draw the convex INSIDE that V with the apex being at the same edge angle of the v grind. It will perform better then the v grind becuase it will have the robust edge angle(same as the V) but with a thinner profile just behind the edge.

 

[me2]

From the sound of things your Bark River is merely dull, and the convex vs. beveled edge isnt a factor yet. I'd guess you have a burr on there brought on by edge trailing strokes on the diamond that the stropping didn't remove.

As for the convex vs beveled issue, I don't have a preference where edges are concerned. I've used both interchangeably for years.

 

[Metal Made Fox]

I don't like convex edges. To me they look sloppy/ugly and most of the times reduce the functionality of the blade tip. However they perform hard cutting and chopping tasks very well. I wouldn't mind having a convex edge on a user bushcraft fixed blade. However on a folder or even a smaller fixed blade? NEVER!

 

[Shotgun]

most of the times reduce the functionality of the blade tip.

How so?

 

[Brisket]

Producing and maintaining a convex edge on a belt sander by hand with wet/dry sandpaper & strops is about as simple as it gets. Trying to do the same with rods, stones, wheels and guided systems however, it is a different story.

 

[PitchAndMoment]

Here’s a blade that shows a V edge and three different convex edges. The V edge is defined by three points: the apex and the two points of the edge shoulder.

The red line represents a convex edge using the same three points, with a tight arc. This convex edge is fat, stout and obtuse. It will be very strong, but not a good cutter, compared to the V edge.

The pencil line represents a convex edge using the same three points, but with a gentle arc. It’s still not as aggressive a cutter as the V edge, but it’s better than the red convex edge.

The green arc represents a convex edge where the shoulder was raised. This edge is almost as acute as the V edge, but also can cut deeper before the width of the blade begins to limit cutting ability.

Three convex edges, all very different. We always talk about convex edges as if they are all the same. They are not.

So, Fastriot got a convex edge profiled by someone else to standards he knew nothing about. Then he tried to resharpen it, but his own standard was most likely quite different than that used by the previous sharpener. If the original convex was like the red angle and he tried to resharpen it using the green angle, he would have to sharpen a very, very long time before he’d even approach the apex.

Convex angles can be awesome, but they can also be terrible cutters. Or anything in between. And because we talk about them without defining them, we usually end up talking past each other.

Thanks, TD! Detailed info like that feeds the ravenous inner knife nerd. I love BF becuase guys like you share knowledge like this.

 

[FortyTwoBlades]

I'm borrowing your picture.

The way that I like to picture a GOOD convex is to draw the convex INSIDE that V with the apex being at the same edge angle of the v grind. It will perform better then the v grind becuase it will have the robust edge angle(same as the V) but with a thinner profile just behind the edge.

Same.

 

[Steely_Gunz]

I don't like convex edges. To me they look sloppy/ugly and most of the times reduce the functionality of the blade tip. However they perform hard cutting and chopping tasks very well. I wouldn't mind having a convex edge on a user bushcraft fixed blade. However on a folder or even a smaller fixed blade? NEVER!

I don't get the sloppy/ugly comment Here is a picture of a Fiddleback Forge Hiking Buddy made by Andy Roy. While Andy fashions an exceptional knife, his convex edge is pretty basic. Very well done, but no marketing of being whiz-bang beyond just being made right. The hiking buddy is a pretty thin bladed knife with a 3.25"-ish blade. Basically an EDC fixed blade with a blade length around the average folder.


All I've done since I received the knife a couple of days ago is taken it across a loaded strop of leather. All of these cuts were made from mid-blade to the very tip of the knife while the paper was free hanging between my fingers.

 

[Mikael W]

I don't get the sloppy/ugly comment Here is a picture of a Fiddleback Forge Hiking Buddy made by Andy Roy. While Andy fashions an exceptional knife, his convex edge is pretty basic. Very well done, but no marketing of being whiz-bang beyond just being made right. The hiking buddy is a pretty thin bladed knife with a 3.25"-ish blade. Basically an EDC fixed blade with a blade length around the average folder.
View attachment 346786View attachment 346789

All I've done since I received the knife a couple of days ago is taken it across a loaded strop of leather. All of these cuts were made from mid-blade to the very tip of the knife while the paper was free hanging between my fingers.

Congrats!
It sure looks like a good one for EDC.
Convex Rules!

Regards
Mikael