why are full convex grinds so popular???

[new]

simple enough question.....i see a lot of people putting convex grinds on their blades, and i was wondering why this blade/edge profile was so popular???

i have heard that convex grinds improve edge durability, but that doesn't make sense to me....to reprofile a busse's edge to convex would require metal removal, and the more metal is removed, the less durable and edge would become....no???


i just see the best modders like ban, randucci, justabuyer always putting convex grinds on their blades, and i thought there had to be a good reason why they all prefer the convex edge....

and what is a "zero convex" edge???


thanks for reading....

 

[Heavy]

A convex edge pushes the material being cut away from itself.

Less drag.

Cuts better.

Lots of steel still behind the edge to make it strong.

Looks cool.

I'm drunker than Skunk



.

 

[thombrogan]

Heavy,

At any given angle, a convex edge has less metal behind the edge than a flat edge. Resharpen most knives with 15° per side and the flat edge won't creep up the blade anywhere near as high as the convexed edge.

Most of the time, the loss of force needed when cutting is much greater than the loss of strength needed to resist damage and that's just good magic in my book (except when hacking steel bedframes like a doofus ).

 

[Heavy]

Heavy,

At any given angle, a convex edge has less metal behind the edge than a flat edge. Resharpen most knives with 15° per side and the flat edge won't creep up the blade anywhere near as high as the convexed edge.

Most of the time, the loss of force needed when cutting is much greater than the loss of strength needed to resist damage and that's just good magic in my book (except when hacking steel bedframes like a doofus ).

Right right....That's what I meant....:thumbup:






Just my luck that Thom shows up...smarter than Plato this one is....





Heavy is just funnin....


.

 

[idahoskunk]

because their belts are slack :thumbup:

.

 

[MORIMOTOM]

Heavy,

At any given angle, a convex edge has less metal behind the edge than a flat edge. Resharpen most knives with 15° per side and the flat edge won't creep up the blade anywhere near as high as the convexed edge.

Most of the time, the loss of force needed when cutting is much greater than the loss of strength needed to resist damage and that's just good magic in my book (except when hacking steel bedframes like a doofus ).

 

[silverdragon33]

Heavy,

At any given angle, a convex edge has less metal behind the edge than a flat edge. Resharpen most knives with 15° per side and the flat edge won't creep up the blade anywhere near as high as the convexed edge.

Most of the time, the loss of force needed when cutting is much greater than the loss of strength needed to resist damage and that's just good magic in my book (except when hacking steel bedframes like a doofus ).

i thought the convex edge had more behind it but for an equal sharpness. thus it's stronger. correct me if i'm wrong.

not the best drawing, but this should illustrate my thought process

 

[Boar-gen]

Good info:

http://home.nycap.rr.com/sosak/convex.htm

Boar-gen

 

[new]

Good info:

http://home.nycap.rr.com/sosak/convex.htm

Boar-gen

thanks for the link....

 

[pbubsy]

Zero convex is the $#^& I wouldn't have sent my 1/300 user in to Ban for one if it woudn't be STUPID sharp and chop soo well it would leave me doo doo dumb. Though it may seem to the contrary, it's a remarkably sharp edge and the cutting edge seems to hold up better that before

 

[rbmcmjr]

i thought the convex edge had more behind it but for an equal sharpness. thus it's stronger. correct me if i'm wrong.

not the best drawing, but this should illustrate my thought process

I agree. This is the diagram I always use to explain this:

 

[Lycosa]

They cut like the BAHJEEZUS!!!

 

[hollowdweller]

Most people when they are changing a flat grind to a convex are grinding off the shoulders of the flat grind.

So while a flat grind edge that started at the same point on the blade as a convex would probably cut deeper because of the points mentioned previously, a convex made from a flat grind- or any convex where the bevel starts farther back on the blade than a flat grind will give you a lower angle and less resistance when cutting.

A blade with a full convex grind from spine to edge with the fattest part of the grind coming in the middle of the blade is really sharp and cuts deep.

I've used a few of Dan Kosters where he has put a full flat grind from the spine to the edge and they will out most convex or scandi grinds because the edge comes down so fine.

I think most people really like convex edges because most of them DO start back on the blade farther than a flat grind (esp a flat ground secondary bevel)and also convex is a bit easier for most people to get really sharp cause if you use a strop or mouse pad you don't have to be as precise with the angle.

However just to be as confusing as possible if you had a blade that was 1/16" thick with a fairly steep secondary bevel on it it would potentially cut as deep and as efficiently as a much thicker blade with a covex or scandi.

I don't think the popularity has to do with the toughness. If that were the case leave the blade full thickness all the way and then put a very steep bevel on it and you'd have a tough edge. I think the popularity has to do with the cutting efficiency of a fine low angle.

 

[mymindisamob]

Most people when they are changing a flat grind to a convex are grinding off the shoulders of the flat grind.

So while a flat grind edge that started at the same point on the blade as a convex would probably cut deeper because of the points mentioned previously, a convex made from a flat grind- or any convex where the bevel starts farther back on the blade than a flat grind will give you a lower angle and less resistance when cutting.

A blade with a full convex grind from spine to edge with the fattest part of the grind coming in the middle of the blade is really sharp and cuts deep.

I've used a few of Dan Kosters where he has put a full flat grind from the spine to the edge and they will out most convex or scandi grinds because the edge comes down so fine.

I think most people really like convex edges because most of them DO start back on the blade farther than a flat grind (esp a flat ground secondary bevel)and also convex is a bit easier for most people to get really sharp cause if you use a strop or mouse pad you don't have to be as precise with the angle.

However just to be as confusing as possible if you had a blade that was 1/16" thick with a fairly steep secondary bevel on it it would potentially cut as deep and as efficiently as a much thicker blade with a covex or scandi.

I don't think the popularity has to do with the toughness. If that were the case leave the blade full thickness all the way and then put a very steep bevel on it and you'd have a tough edge. I think the popularity has to do with the cutting efficiency of a fine low angle.

There you go, makin' sense again.:thumbup:

 

[thombrogan]

i thought the convex edge had more behind it but for an equal sharpness. thus it's stronger. correct me if i'm wrong.

not the best drawing, but this should illustrate my thought process

If you look at your drawing, the convexed edge is coming in at a wider angle on its way to the edge. Were you to measure from side to side to point to get an approximate angle, it would be higher than the flat ground's angle. To keep that same, approximate angle, the convexed edge would need to be narrower than its flat counterpart. Rick's drawing shows the same thing; a 12 degree back-bevel is thicker than a 10 degree back-bevel; but that can be done or outdone with a flat grind as well (i.e. the original configuration in Rick's pic).

 

[Hogwash]

On some knives, like an AK47, a full flat grind would remove too much metal, a full convex will get rid of the CBT and Infi dimples without removing too much, leaving a stronger sword.

On a chopper like an FFBM, a full convex grind leaves a lot of mass in the blade making it a very effective chopper before you get tired.

On a flat ground knife like an FBM LE or any of the ergos, Ban does a convex edge because he can polish it up very very sharp and it looks cool. A v-edge just doesn't look as nice.

When chopping or slicing, there is no comparison between a polished convex edge and a Busse factory v-edge but the Competition finish gets really close.

 

[kac]

So I hate to be ignorant, but, as a newbie to Busse, what kind of edge did my relatively new ASH come with? Although it didn't come particularly sharp from the factory, it did a good job cutting up the tree that fell on my Jeep in a recent storm!

 

[Bigfattyt]

Another thing about convex edges is that if you have a strop, they are very easy to maintain. Just a few licks per side after a day of use and good as new. My convexed GW made some contact with a concrete table today on the edge. I am willing to bet it take only a few minutes with the strop and polishing compound to remove all evidence of it.

I also think that doing a hand convex is much easier than trying to hand sharpen the same knife. for some reason I can't hand sharpen on stones or sticks very well (I am ok with fixed V sticks) but on my first attempt at re profiling on of my folders to a convex edge, got it right first try. Now it is super sharp and easy to maintain ( i have a lansky sharpening system, and can get hair jumping sharp blades, but it simply takes too long to clamp the knife down every time you want to touch up the blade).

 

[I'mGatMan!]

Great thread, people!

 

[MORIMOTOM]

So I hate to be ignorant, but, as a newbie to Busse, what kind of edge did my relatively new ASH come with? Although it didn't come particularly sharp from the factory, it did a good job cutting up the tree that fell on my Jeep in a recent storm!

full height flat grind, v edge.