Anyone ever taken there F1 convex edge and put a V grind on it?

Here's my amateur 2 cents: I have a convex custom FB by Dave Farmer. it's an awesomely sharp little full convex knife that's easy to keep super sharp by stropping on leather and occasional touch ups on mouse/sandpaper. So I wanted another one and found one second-hand here on the boards. The knie arrived with a micro V edge on it but otherwise full convex grind. It will not slice as well as the other knife with the convex grind all the way to the edge. It's that shoulder bevel getting in the way and now i'm probably going to have to re-convex the edge. Try cutting an apple with the V edge/convex grind, in my case it's not easy at all.
 
I can understand why a convex edge is a trade off for a stronger edge than a v edge, at least in theory. But if a convex edge is always stronger than a V-edge why are not all blades made that way? I mean it seems with VG-10 laminated steel the last thing to worry about would be strength in the edge. I just don't understand why convex in the first place with this particular steel. Course if you believe some reviews they claim the Fallknivens need a convex edge to keep the brittle edge from fracturing. Honestly I don't know what or who to believe & I own several Fallknivens.
 
canoe2 said:
I can understand why a convex edge is a trade off for a stronger edge than a v edge, at least in theory. But if a convex edge is always stronger than a V-edge why are not all blades made that way? I mean it seems with VG-10 laminated steel the last thing to worry about would be strength in the edge. I just don't understand why convex in the first place with this particular steel. Course if you believe some reviews they claim the Fallknivens need a convex edge to keep the brittle edge from fracturing. Honestly I don't know what or who to believe & I own several Fallknivens.
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1) It isn't stronger than a vee edge for a given edge angle. Believe geometry and common sense. Draw a vee edge. Draw a convex edge that fits inside that vee and matches at the very tip. The convex is thinner and has less steel behind the edge.

convex2.jpg


2) As far as Fallknivens...they can be "chippy" when new. Sharpen them/touch up the edge a few times and they are fine. "Convex" has nothing to do with the "chippy."
 
Probably because flat grind is easier in mass production and the difference in performance is negligible for many uses.

About needing a convex edge: A convex edge doesn't necessarily have a wider edge angle than a flat ground edge.

I have a PM2 (flat grind). Had major edge chipping. After sharpening away the chips, the resulting edge was too thick. To improve performance, I removed the shoulder where the edge bevel meets the primary bevel. The result is a geometry with three bevels and two shoulders instead of one. I could continue removing these two shoulders, producing a geometry with 5 bevels and 4 shoulders. Continuing this process would yield a convex edge with the same final edge angle as the original flat grind, better cutting performance and almost equal edge strength.
 
steff27 said:
I have a PM2 (flat grind). Had major edge chipping. After sharpening away the chips, the resulting edge was too thick. To improve performance, I removed the shoulder where the edge bevel meets the primary bevel. The result is a geometry with three bevels and two shoulders instead of one. I could continue removing these two shoulders, producing a geometry with 5 bevels and 4 shoulders. Continuing this process would yield a convex edge with the same final edge angle as the original flat grind, better cutting performance and almost equal edge strength.
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Thank you! Beautifully put. :D You are 110% correct. A convex grind with the same edge angle as a flat grind is not as strong as that flat grind. It has less material behind the edge.
 
Quote Originally Posted by canoe2 View Post
I can understand why a convex edge is a trade off for a stronger edge than a v edge, at least in theory. But if a convex edge is always stronger than a V-edge why are not all blades made that way? I mean it seems with VG-10 laminated steel the last thing to worry about would be strength in the edge. I just don't understand why convex in the first place with this particular steel. Course if you believe some reviews they claim the Fallknivens need a convex edge to keep the brittle edge from fracturing. Honestly I don't know what or who to believe & I own several Fallknivens.
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marcinek said:
1) It isn't stronger than a vee edge for a given edge angle. Believe geometry and common sense. Draw a vee edge. Draw a convex edge that fits inside that vee and matches at the very tip. The convex is thinner and has less steel behind the edge.

convex2.jpg


2) As far as Fallknivens...they can be "chippy" when new. Sharpen them/touch up the edge a few times and they are fine. "Convex" has nothing to do with the "chippy."
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I agree with Marcinek on both answers.

The Frey I use as EDC for now, did microchip at first.
Not now after a few resharpenings and a reset of the edge geometry on the 1"x30" beltsander.
The edge sees light contact with metal every day, but the damage to the edge decreases from day to day.


Regards
Mikael
 
marcinek said:
Why thank you, Mikael! Nobody knows Fallkniven better than you. :thumbup:
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That's not how it is!

However,I remember a recent thread about convex edges, where I had to admit You were right.
The convex edge feels very natural to me and as I practise freehandsharpening, my knives end up convex anyway.



Regards
Mikael
 
Mikael W said:
That's not how it is!

However,I remember a recent thread about convex edges, where I had to admit You were right.
The convex edge feels very natural to me and as I practise freehandsharpening, my knives end up convex anyway.



Regards
Mikael
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Well, I consider you the expert on the subject. :thumbup:

And I, also, prefer a convex edge since it takes advantage of my sloppy freehand sharpening technique. I "knock the shoulders off" my flat vee grinds, just like steff27. And then I can use my "sloppy" technique on them!

I think they are great, but it seems like people think they have "magical" properties that defy geometry and physics, like they are "sharper" or "stronger."
 
marcinek said:
Well, I consider you the expert on the subject. :thumbup:

And I, also, prefer a convex edge since it takes advantage of my sloppy freehand sharpening technique. I "knock the shoulders off" my flat vee grinds, just like steff27. And then I can use my "sloppy" technique on them!

I think they are great, but it seems like people think they have "magical" properties that defy geometry and physics, like they are "sharper" or "stronger."
Click to expand...

Of course geometry and physics works a lot better than Wizardry and Wichcraft!
By training sharpening, my knives have become a lot better.
Even the cheap and thin kitchen knives have improved greatly!

Knocking the shoulders off a flat v-grind do improve cutting performance and ease of sharpening, without sacrificing the strength of the very cutting edge.

This doesn't mean that very hard use like chopping, will benefit from a thin edge.
It benefits from a convex geometry, just like an axe, but also from mass behind the edge.

To my experience, it doesn't matter if the steel is 1095, A2 or VG-10.
If the geometry isn't there, the steel doesn't perform as expected.

So bottom line is I always try to expand my sharpening skills to get the most out of my knives.

Regards
Mikael
 
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