Reasons to Convex smaller (non-chopping) knives?

El Bandit0

El Bandit0

Joined
Feb 4, 2013
Messages
1,278
I have noticed that a lot of folks here love covex edges on their choppers.... AND on their non-chopping knives. I have used the simple v-edge (FFG or Saber) for most of my life, only being a recent convert to convexing.
However, I would like to know why so many folks insist on convexing ALL their blades... even the real bitty fixed blades and folders. My War Dog came with a beautiful convex edge on it, but I would have preferred a FFG v-edge instead... simply works better for me. I notice a lot of GW's and other small Bussekin have been reprofiled to convex as well. I guess my question is; why convex a small blade that will (almost assuredly) never be used to chop? Simply curious as to the how & why. Thanks!
Bandito
 
I would bet that most people convexing smaller knives are doing so because they are used to a sharpening system that yields such edge. I personally convex anything bigger than 5” because its easier to sharpen on belt grinder than on a wicked edge.
 
BTW, I do all my sharpening, including convexing, on stones & strops freehand. Hand convex is easy enough, just takes a bit of practice.
 
Ok, here's my half brained thought on it. If you leave the final edge angle the same and just blend the rest into the blade you are decreasing the initial amount of contact and it should cut better. The trade off would be less edge strength tho because you actually have less metal behind the edge. Is this correct? I've just spent 10 minutes thinking about this and its not as simple as it seems.
 
Really depends on the arc of the convex, you can never have more metal behind the edge than you do with a v grind IF you are sharpening at the same angle.
 
I have an old James Bowen (not his sons) Dirk/dagger with a 7 inch blade and made out of .250" D2 that I bought in 1985 for $300. I wonder what that works out to in today's dollars? This has a convex edge on both sides. I have used it many times and it STILL does not need sharpening! My opinion is that convex blades, done right, are stronger simply because there is more meat left on the blade. I can't explain why this knife is still so sharp though. It still has the original Bowen applied edge.
 
Skimo said:
Really depends on the arc of the convex, you can never have more metal behind the edge than you do with a v grind IF you are sharpening at the same angle.
Click to expand...

You are correct sir:D exept it's the other way around. If it's a concave zero grind you would be correct all the way. :D
 
Pretty simple test for this, sharpen a v grind at any angle you wish and see how much metal you need to take off of the shoulder till you have a nice flowing convex edge.

Maybe there's something I'm missing.
 
This pic and this site http://zknives.com/knives/articles/knifeedgetypes.shtml is a good recourse on knife design.

knifeedgetypes_zps7caf7819.jpg
[/URL][/IMG]
 
gixxer1237 said:
Ok, here's my half brained thought on it. If you leave the final edge angle the same and just blend the rest into the blade you are decreasing the initial amount of contact and it should cut better. The trade off would be less edge strength tho because you actually have less metal behind the edge. Is this correct? I've just spent 10 minutes thinking about this and its not as simple as it seems.
Click to expand...

I agree with you all the way. On a new knife I will knock the shoulders down and blend in the edge without touching the final edge. I feel it really improves performance.
Eventually after a few touch ups I end up with a full convex edge.
 
Lennox said:
This pic and this site http://zknives.com/knives/articles/knifeedgetypes.shtml is a good recourse on knife design.

knifeedgetypes_zps7caf7819.jpg
[/URL][/IMG]
Click to expand...

That v grind proves my point. It is ground at a lesser angle. It would be weaker than the convex next to it. But if you convex that v grind it would be even weaker, tho a great slicer. In my simple mind it all comes down to edge angle and thickness just behind the edge. If the final angle is the same the one with less material behind the edge will be the better cutter all other things being the same. It will also be weaker.

Please forgive me if none of that makes any sense. Sleep has been short this week.
 
I pretty much like V edges, scandi (which is essentially a v edge), and convex. After getting the spyderco sharpmaker however, I've gotten my knives ridiculously sharp and now use v edges on almost all my knives. I have yet to figure out how to get a convex edge as razor sharp as one made by the spyderco sharpmaker.
 
You must log in or register to reply here.
Back
Top