Convex Grind - Issues?

I'll disagree wholeheartedly. A well-executed convex grind can be thoroughly razor sharp, and maintain that through abuse that would leave a hollow grind chipped, or a flat grind seriously rolled. By putting more mass behind the edge, the edge itself can be stronger at the same edge angle.
 
Bark River is legendary for its sharp out of the box knives and it uses convex almost exclusively! Also see many well regarded makers on these forums who tend towards hard using knives: Daniel Koster, Scott Gossman, Christoff to name a few...
 
Sword and Shield said:
I'll disagree wholeheartedly. A well-executed convex grind can be thoroughly razor sharp, and maintain that through abuse that would leave a hollow grind chipped, or a flat grind seriously rolled. By putting more mass behind the edge, the edge itself can be stronger at the same edge angle.
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I think he notes that a knife like that can be sharp, but that it "cannot be made as sharp as a knife, and when sharpened, quickly becomes chisel-like. It also requires a great deal of thick metal to construct." My specific concern is with resharpening. Seems like a tricky edge to sharpen correctly.

Other than my new Fallknivens and the BRKT I have on order, I do not have other convex blades. Those are the brands I was talking about. Both are noted to be exquisitely sharp out of the box (my FKs certainly are).
 
It isn't difficult at all to sharpen convex. Sandpaper overlaying a mousepad is perfect- all of my folders save 2 have been convexed. As for becoming "chisel-like", my longevity champion is a Queen slimline trapper, convexed by Mike Stewart of BRKT. It's sharp as a razor, despite having been used hard and sharpened repeatedly over the last 3 years.
 
Well, he is entitled to his opinion, but he's wrong in mine. I convex everything I buy, from Bucks to Cases to whatever. It's super easy to get them sharp and then stropping keeps them sharp or brings them back quickly. Remember that sharpening on stone will result in a convex edge if the angle isn't held exactly right throughout the process.
 
Chewy1 said:
Well, he is entitled to his opinion, but he's wrong in mine. I convex everything I buy, from Bucks to Cases to whatever. It's super easy to get them sharp and then stropping keeps them sharp or brings them back quickly. Remember that sharpening on stone will result in a convex edge if the angle isn't held exactly right throughout the process.
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Yeah, the people at Fallkniven recommend two stones on their site and even provide a video, I think. For now, I'd feel safer with a leather strap or even sandpaper mounted on something like that. Never heard of using sandpaper over a mousepad before, but it certainly makes sense.
 
he may be the "best living knifemaker" :jerkit: but I do question his judgement on the convex grind

in fact I competely disagree

BUT

nah

i still disagree
 
Use whatever convex sharpening setup you like, and pick your favorite SAK. Start with a low grit, I think I started at 120, and go up from there, in my case 2500. You will see how easy it is and that it doesn't take much steel to convex an edge. :)
 
1.Get more than one opinion--- from the experts. 2.Think for yourself. He did not mention Beta Titanium, which is a suitable for a blade.
Very interesting info though.
 
My first convex blades were swamp rats, I didn't have any problem keeping them sharp, but I havne't used them much.

The bark rivers get used a lot more, they are very easy to maintain. I got a couple of leather strops and some compound and it's stupid easy now, plus I can stop beveled edges as well for ethereal shapness. I got more bark rivers just because I prefer a convex edge now. You might have to touch them up more frequently but it will only take a matter of seconds to swipe it on your jeans. It seems to only lose so much sharpness but maintains a usable level of sharpness for a long time, if that makes any sense. There are a couple of videos on you tube demonstrating sharpening a convex blade.

I stupidly put a bevel on my bandicoot and wish I hadn't. I wanted to be able to swipe it on my sharpmaker for some reason. I am hoping it will revert to convex again over time.

A huge leather stop loaded with compound is way cheaper than nice stones. I'll bet in an emergency situation you could maintain a blade with a sheet of emory cloth rolled up. Or your belt.
 
He's wrong.

Jay seems big on making hollow ground knives. Why would he extol the virtues of the opposite of what he's selling?
 
His definition of a convex grind is extreme. He assumes sort of a half-elliptical blade profile that is likely to be dull at the edge. Generally knives have relatively flat grinds and more of a taper grind at the edge. Done nice and thinnly you do get pretty good performance out of a convex grind.

Convex grinds provide great support for their edge, but at the price of greater material to remove during sharpening. A hollow ground edge is easier to maintain/sharpen since there is less material to remove. It also isn't as strong and can bind in some material. For a hunting knife I prefer a hollow ground knife. Heck, for almost any function except chopping I prefer a hollow ground knife.
 
Just for the record, given equal inclusive edge angles at the very edge, a convex edge has LESS metal behind it than either a flat ground or a hollow ground blade. A convex edge has more metal behind it than a flat ground or hollow ground edge ONLY if the edge angle is more "obtuse."

If this does not make sense, draw three "V"s, one straight, one convex, and one concave, all with the same "apex" angle, and see which one makes the fattest V.

Convex edges are considered stronger only because they are more "obtuse."
 
His laundry list of the evils of factory knives are easily neutralized if not completely destroyed. Than again, since when are knife makers/knife nuts any wiser than the general public?
 
shecky said:
His laundry list of the evils of factory knives are easily neutralized if not completely destroyed. Than again, since when are knife makers/knife nuts any wiser than the general public?
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There doesn't seem to be any clear authority or body of knowledge (like a real science of cutlery). I've seen some fledgling efforts, but no real locus of authority on these types of issues. Outside of engineering, it seems to be a largely "art and craft" approach, with experts differing sometimes on very fundamental things. Still, put ten economists in a room and you might get ten different answers.

I have quoted from some of them and heard back from other experts or people who have used something successfully that they say shouldn't work well at all. Some, for example, have said that thick blades should not cut well, whereas they simply might not cut as well as thin blades of the same material. But you can do things with blade geometry to make them cut better than you might have expected. Or, that knife blades other than stilettos are not made to pierce or penetrate.

I've found this FAQ on blade geometry helpful, but there are things in there I'm sure some here would disagree (like how difficult it is to touch up a convex blade!).

http://www.knifeart.com/bladgeomfaqb.html

Here's a sample concerning an issue I remember doing a search on here a while back. Opinions here and in other forums were all over the place, and sometimes it was the experts disagreeing with each other the most:
[FONT=arial, helvetica]
"Blade thickness or thinness is important to both strength and cutting ability of the knife. A thick blade will generally be stronger. But a thin blade will generally have a thinner edge -- and thin edges cut easier and better. So the choice of blade thickness is driven by the compromise of strength vs. cutting ability, just like the choice of point type.[/FONT][FONT=arial, helvetica] Once the blade thickness is chosen, the particular grind type (see below) can reinforce the attributes of that thickness, or try to make up for any weakness. For example, on a thick blade, a flat or hollow grind can be utilized, so that even though the spine is thick & strong, the edge is thin and cuts a bit better than expected. Or on a thin blade, a sabre grind can be used to make the edge a bit stronger than it would otherwise be. Of course, the grind can reinforce rather than counteract the blade thickness.[/FONT][FONT=arial, helvetica]"[/FONT]
 
Wow, after a half hour or so of reading, this "Jay Fisher" fellow sounds like the Lynn Thompson of the custom knife world.
I don't doubt that he makes good knives, but his writing about manufacturing companies is so generalized that it reminds me of a pre-election smear campaign.
 
Joshua J. said:
Wow, after a half hour or so of reading, this "Jay Fisher" fellow sounds like the Lynn Thompson of the custom knife world.
I don't doubt that he makes good knives, but his writing about manufacturing companies is so generalized that it reminds me of a pre-election smear campaign.
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You're right, Joshua J.!:thumbup:

Jay Fisher doesn't just make good knives, he makes freaking outstanding knives! I know, my dad's got one. Heck, the knife stand alone, which Jay also made, is a work of freaking art! That said, I think Jay ought to stick to making awesome knives and stop bashing "factories." That's a pretty broad brush he's swinging around. Though he didn't come right out and say it, I think his "ATS-55" rant was a dig at Spyderco, and to me, it just goes to show he doesn't know squat about Spyderco!

Regards,
3G
 
Just wanted to pipe in to say that I convex mine on the mousepad and wet/dry sandpaper. It's super easy. And I strop on the back of a legal pad...:)
 
Halbie said:
I think he notes that a knife like that can be sharp, but that it "cannot be made as sharp as a knife, and when sharpened, quickly becomes chisel-like. It also requires a great deal of thick metal to construct." My specific concern is with resharpening. Seems like a tricky edge to sharpen correctly.

Other than my new Fallknivens and the BRKT I have on order, I do not have other convex blades. Those are the brands I was talking about. Both are noted to be exquisitely sharp out of the box (my FKs certainly are).
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http://www.knifeforums.com/forums/showtopic.php?tid/751826/
 
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