Why is Convex bad?

And I will concede this point. My argument was solely based on what happens at the edge- as x ==> 0, so to speak.
 
I have no problems with either convex or flat grinds, and while my freehand sharpening attempts to create a flat ground edge bevel, it invariable generates some curvature. The only thing I don't care for are the unsubstantiated claims about any particular grinds.

What I really don't get is the idea that convex edges last longer. At the same final edge angle, with the same steel, how does one last longer than the other? Really the same with friction. That is dependent on what you are cutting, and again, what kind of grind angles we are dealing with. Plus I doubt anyone has gotten accurate measures with controls of certain variables.
 
hlee said:
Unfortunately, the lines and planes that actually define a bevel have no thickness, so what is hidden in the additions that you have made to my diagram is that the v-ground blade is- in fact- still fatter at the edge.

Therefore, convex can not both be thicker behind the edge and have the same apex edge angle as a V ground edge.
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Too true, I just wanted to show that the difference in practical application is not extreme. Considering the scale of the pictures, the thickness of the lines is not a dramatic difference for a tool in hand skinning animals, breaking down cardboard boxes, or making fuzzsticks.
 
hardheart said:
I have no problems with either convex or flat grinds, and while my freehand sharpening attempts to create a flat ground edge bevel, it invariable generates some curvature. The only thing I don't care for are the unsubstantiated claims about any particular grinds.

What I really don't get is the idea that convex edges last longer. At the same final edge angle, with the same steel, how does one last longer than the other? Really the same with friction. That is dependent on what you are cutting, and again, what kind of grind angles we are dealing with. Plus I doubt anyone has gotten accurate measures with controls of certain variables.
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If anything, a convex edge should not last as long as a v ground edge- given a set edge angle. There is less metal behind the edge of a convex edge- at the edge- as the convex blade immediately falls away toward increasing acuteness. Convex edges are generally considered more robust because they are typically ground more obtusely- at the edge. This is a fact that most convex grind fanatics fail to realize or admit.

As we have come to agree, a convex edge cannot be both thicker behind the edge and have the same apex edge angle as a V-ground edge.
 
Okay, so in terms of my original question, what would you experts say is the best grind for a camping,utility, and combat knife? would convex then be the better choice if chopping WAS to be done? Or does it really just not matter.
 
Fighting knives are often saber ground; they don't need to be good carvers. For bushcraft — convex or scandi. Hands down. I don't like the way regular flat grinds or sabers perform compared to convex- or scandi grinds when it comes to carving wood.
 
Different strokes for different folks. I prefer a flat primary grind with a v bevel. I can maintain a v-ground edge well enough. I haven't gotten the hang of a convex edge yet. However, I would like to get my hands on a scandi ground blade. I just have not pulled the trigger yet.
 
I like scandi for wood carving, convex for heavy chopping, full flat grind for mid size utility, full hollow for light tasks.
 
I think the arch shape of the convex grind is what gives it a bit more robustness in chopping compared to a V grind ( I'm assuming two identical knives with the same terminating angle ). Arches distribute pressure and weight more evenly than a triangle. When shaving things, especially in making fuzz sticks a sabre grind will cause the wood to bunch at the shoulder, whereas a convex will cause it to slide over the remaining blade. A scandi and full zero bevel flat grinds can achieve this because the transition from edge to blade is less abrupt, again assuming the same knife with same terminating angle; the convex will have a bit more lateral strength along the edge, because it retains the full thickness of the blade till the very last moment.

so back to the orig question, I'd go convex for anything slicing or chopping where the material being cut/chopped will engulf the blade past where the shoulder on a V grind would normally be. Traditional kukris are convex. Traditional filipino machetes are convex. Most of the large traditional knives were.
 
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hlee said:
However, I would like to get my hands on a scandi ground blade. I just have not pulled the trigger yet.
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Do you just wanna try out a regular Mora scandi or are you lookin' for something fancier; cuz I mean, I got many entry-level ones layin' around n' I can hook ya' up with one of those for free if you like via mail. Moras are like 4-6 bucks here in Sweden and I've gotten many for free from when I was working construction. They're all hair-poppin', of course... ;)

Hit me up via PM with your digits if you're interested.
 
@ d.weglarz13

no prob man :)
You got a nice discussion started with your thread, that was kinda cool
 
yea, i enjoyed it a lot. thanks for the help, everyone. Hey, can you get just as good a convex grind if you do it with mousepad and sand paper, as opposed to a grinder or wheels? I heard someone say that convex by hand is easy to do, but is not real sharp, just the shape that works.
 
you can hand sharpen convex edges to high sharpness, but the sandpaper is going to be a little slow, and you need to take care of your angles and pressure if your backing is soft.
 
stoffi said:
Do you just wanna try out a regular Mora scandi or are you lookin' for something fancier; cuz I mean, I got many entry-level ones layin' around n' I can hook ya' up with one of those for free if you like via mail. Moras are like 4-6 bucks here in Sweden and I've gotten many for free from when I was working construction. They're all hair-poppin', of course... ;)

Hit me up via PM with your digits if you're interested.
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I appreciate the offer. I've been looking at getting a Koster bushcraft knife or one of the great looking knives by Brian Andrews. I've thought about a mora but then I think "If your gonna be a bear, be a grizzly." I think I've lusted after one of Brian Andrew's knives long enough that I should just go and place an order. Now to convince the wife I need a new knife...
 
Hahaha, alright man! Good luck with the convincing.

Hey everybody, this is a bit OT (but we had the argument on grinds a bit back so...) just out of curiosity — what would you call this type of grind:

morat.jpg


It's completely flat with a 20° bevel (40° total).
 
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stoffi said:
How about if you read up on the differences instead? This is really basic stuff and if you cared you would have looked it up by now.
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Sorry... I was trying to be polite to you by NOT posting what I found when I looked them up.

Stitchawl
 
my $0.02: either convex or bevelled blades will cut just fine so long as they're sharp. i think a lot of the angst about convex blades is from people who don't understand how to sharpen them properly or who don't realise that after sharpening them for a while you will need to re-grind the convex.


stoffi: looks like a flat grind to me.
 
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