What's the deal with convex blades

S

smitty1505

Joined
Oct 24, 2009
Messages
243
Ok so I've heard a lot about convex edges and iwas wondering what the pros and cons are to haveing one. Would it be in my best intrest to convex my small seb and strider sng?
 
Cnovex really shines when it comes to choppers and hard use knives. I've personally have not found much reason to put any folder (since people rarely use folders for splitting woods and other survival / camping knife qualities wich need to stand for batoning and chopping) for convex sharpening but larger knives and choppers really benefit for convex sharpening.
 
Older scandigrinds often turn convex during the sharpening process on stones. After a while you tput them to the grinding wheel to make them flat again. I dont se the point of a convex grind on a new edge as its a sign of use and put the knife close to the need of a grinding wheel. Om the other hand its a strong and good cutting edge. I think its an edge that a knife ashiwes after some usingtime.

Bosse
 
I'm no expert but the pro is the edge is very strong, and lasts a long time, there's a lot of meat of metal supporting the edge, picture the cross section of an apple seed versus a needle.

The drawback is it's hard to maintain/sharpen. Another poster mentioned it sometimes happens while sharpening on stoned, I've never heard that. People who like this style seem to use slack belt grinders. Some people in the HI Kukri sub-forum use sand paper on a mouse pad, laid against the thigh, to get a similar effect.
 
Sorry Matt but I think convex is the easiest edge to maintain. I use a mouse pad and 400 or 800 grit sandpaper and the edge magically appears. I would argue Bark River is the current leader in the convex style. They are some of the sharpest knives I own. Even after my clumsy meat hooks have sharpened them. My advice is try it ...you'll like it!
T
 
i have to agree with cleary, convex is the easiest thing to maintain. All I need is a sheet of 1500 grit sandpaper and a mousepad and in about 3 minutes my knife is wicked sharp again. Smitty, I would recommend you practice on a "lesser" knife and see how you handle with it. Sharpening is just another part of knife owning and is kinda neat to be able to take care of your own knife. Watch the videos on knivesshipfree.com they are the best. Best of luck to you
 
Does anyone have a link to images of convex, hollow ground, and micro-beveled edges?

I'd like to get these three sorted out if possible.

Pictures save a lot of typing. Thanks!
 
cziv said:
Does anyone have a link to images of convex, hollow ground, and micro-beveled edges?

I'd like to get these three sorted out if possible.

Pictures save a lot of typing. Thanks!
Click to expand...

Convexed busse ASH-1

hairsplit.jpg



I convex ALL my knives, I don't see any large advantage to doing so on my folders however, I just do it so I have one uniform method for sharpening, and maintaining a convex edge is just easier IMO. For choppers/hard use knives, convex really shines, specifically at pushcutting.
 
Thanks and wowser 230grains!

That edge looks like the edges on my BM 940 & 710 - only more polished.

Am I misssing anything in that assumption?
 
I have a convex folder a freind done for me. It cuts tough stuff better e.g. weed eater line. I am really happy with it.
 
I made up a few convexed scandi grind skinners for this years hunt and handed them out for use. So far 3 have been used to skin White tails and a moose and all of them love the way the skin parted from the flesh. A couple said it "rolled" the skin off.
On the other hand I like my small knives thinnnnn and flat for slicing.
Regards

Robin
 
All I've had to do to convex the edges of my knives is to sharpen them like normal and then finish on a strop. Over time (only about 3-5 resharpenings) the convex will appear in all its mirror-polished beauty. :)

On my larger blades (like my machetes) I just contour the convex by hand. It's really not too hard.
 
Terminology needs to be cleaned up a little bit.

Convex grinds can apply to the primary grind, the (usually) secondary edge bevel, or both. Some knives with a convex primary grind have no secondary bevel, thus terminating in more of a zero edge. A knife with a convex secondary edge bevel can have any kind of primary grind (flat, hollow, etc).

In theory, a convex primary grind allows for more lateral durability due to the blade being girthier in cross section (compared to a flat or hollow ground blade). This also applies to some extent on convex secondary edge bevels. On large chopping tools, convex edges seem to help keep the blade from excessively sticking in the material being chopped, and increasing mass, in addition to increasing durability.

Personally, I don't think they're particularly easy or difficult to maintain. I all depends on the amount of sharpening needed. A full convex grind with no secondary bevel and significant edge damage will be about as laborious to restore as can be, if the user wants to maintain the full convex grind and zero edge. On the other hand, minor touching up of the edge bevel only is about as simple as the user can make it. And need not be done with sandpaper and notepad.

There are lots of anecdotes about knives reprofiled convex becoming sharper. While I don't doubt such effort can result in a sharper edge, I think it may be misleading to conclude convex edges result in sharper knives. The reason is, such reprofiling results in an edge that is not only convexed, but more importantly, also usually thinner and more acute than it started out. An edge bevel being thinner and more acute will always enhance cutting ability whether it's convex, flat, or hollow.

There are other factors at work that help give convex grinds a certain amount of cachet. Some small scale custom knife makers use the method because it's easy to do on a one-by-one basis. No special machinery other than a belt grinder is needed. This is an instance where the benefit is perceived more by the association with a nice handmade knife than with any actual performance.
 
shecky said:
There are lots of anecdotes about knives reprofiled convex becoming sharper. While I don't doubt such effort can result in a sharper edge, I think it may be misleading to conclude convex edges result in sharper knives. The reason is, such reprofiling results in an edge that is not only convexed, but more importantly, also usually thinner and more acute than it started out. An edge bevel being thinner and more acute will always enhance cutting ability whether it's convex, flat, or hollow.
Click to expand...

Indeed! A lot of folks due tend to forget that when they convert a V secondary grind to a convex, they're removing the "shoulders" of the bevel and thus thinning the material.

Great post, Shecky. Pure gold, that. :thumbup:
 
Keep in mind that there is a huge difference in the amount of effort required to change a V edge to convex vs just touching up an already convexed blade.

I've converted several of my blades, and in my limited experiance it is tricky to get right, and very VERY time consuming without a power belt sander. But the end results are quite impressive in looks and performance.

Oh, and I must say that after touching up the fully convexed factory edge on my Fallkniven Thor, it push-cuts and slices better than any knife I've owned!
 
You must log in or register to reply here.
Back
Top