Convex and V Grind Questions

[C Bryant]

First off, I'm not interested in debating between which is a beter edge to have, just which does what better, I guess.

I'm trying to expand my knowledge of convexed edges. Which do you all prefer and why (for what tasks)? I do understand the difference in the geometry of the two edges, I want to know if you all find one better suited for a particlar task as opposed to the other? I own both convex and v grind blades, I love them both, though I do not have much field time behind a convexed ege so I'm looking for your opinions and experience with them.
Which is leading into my next question.
I have no experience sharpening a convexed edge. Can you guys give me some hints/tips on stropping? Can I use any old piece of leather, I hear blue jeans (denim) work well, just a few strokes or a bunch???

Thanks

 

[kgd]

I've done my best to try and get the hang of convex, but I just cannot get it to work for me. I can sharpen it, but never get it as sharp as I can with a V. I've now had a few blades purchased with convex edges but I eventually turn them into a V. I'm familiar with the V and can get it super sharp. I recognize that the convex are more robust for heavy duty work and supposedly easier to sharpen - but not by my books.

I'm a dedicated V-guy. I'm even getting pretty good at freehand sharpening on the benchstones, but then like to put that final touch on the edge with the sharpmaker.

 

[hollowdweller]

Well it depends (I think) on how steep the grind is on either type.

But most of the convex edges I have are a good deal less steep then the V grinds I have. That means they cut deeper with less effort.

Also unlike KGD there a convex is much easier for me to sharpen because I am using a strop and wet dry sandpaper. With a stone I have to be a bit more precise with the overall angle.


A good polished convex seems to cut well with very little resistance. The worst for me is a V grind with a coated blade. Not only do you have the resistance from the steeper V grind but then the coating slows me down thru increased friction since most coated are crinkly.

 

[TFin04]

At the risk of sounding like I'm debating between the two, the below is an honest answer to your question.

Which do you all prefer and why (for what tasks)?

I prefer a v edge on a flat ground knife for everything. I have no found a Convex to do anything better and with the sharpening system I use (Spyderco) it is much easier for me to maintain my V grinds.

I have nothing against convex it just doesn't do anything special for me.

 

[Quirt]

Hey I try to keep my mouth shut and my eyes and mind wide open. With that being said I've done a lot of reading and consulted with an eclectic group of knowledgeable individuals regarding this. In the process of investigating this very subject I have invested a king's ranson on both V and Convex trying to determine the asset/liablities of each and to determine which side to land on.

I really like many of the virtues of the convex - easy to sharpen in the field, older design - used by frontiermen/women etc. That is why I've purchased several to try. But the V grind works better for my wildnerness tasks...I use an ax for chopping and use a knife for the processing of game and primarly whittling tasks - making wood shavings for fires, carving a notch in a fire board, making a trigger for a snare, secondary self defense etc. The convex edges (both factory new and re-sharpen) have not been as effective for these tasks. I'm not saying it isn't any good but it just hasn't perform relative to my given taskings.

With the V grind...I can use my Spyderco sharpener as well, polish the edge on a paper wheel, or use a handi dandy new pocket sharpener I just found that goes with me everywhere. With my V grind whittling requires less effort. In survivial those who can do the most with the least amount of calorie output wins! I can do the same tasks with the several convex blades I own but it just requires more effort...with the V I can do the job quicker, faster and with less work. I'm still waiting for someone to show me a convex that works as well.

 

[siguy]

it all boils down to the edge angle really.

you can have a convex ground as thick as an axe or as thin as a straight razor, both being convex. the only difference between a convex edge and a "flat" or V edge is that convex doesn't try to be consistent.

as for sharpening, do some youtube searches for "sharpen" "strop" "convex sharpening", etc. you will pull up several videos demonstrating strop use as well as the use of a sharpening stone.

before i got a belt sander, i sharpened all my convex edges with a stone, and then smoothed them out and polished them with wet dry sandpaper. now that i have a bench grinder, i still enjoy using the stone for my own knives from time to time.

i have several scandi grinds, and it is true that it is impossible to get them to be a "true" scandi, in that you have two perfectly flat planes intersecting in a single edge. those planes, through the repeated motion of sharpening, will become slightly convex, even if so slightly that it would be difficult to judge with a microscope.

i guess basically what i'm saying is that V or convex, it doesn't really matter. it all boils down to how thin the edge is and whether the burr has been raised and then removed.

by the way, i have informally tested many different grinds and edges, and found that they all perform equally. different angles and grinds require a slightly different angle of approach, but once that angle is found (often within the first several cuts in a piece of wood) the knife works just as well as any other.

 

[StretchNM]

When cutting something with equal pressure on each side (as the edge cuts through), in my experience the convex edge cuts with significantly less resistance..... a noticeable difference.

For cutting wood for any project, using the technique used to create fuzz sticks, the scandi grind is king. Again, it's noticeable.

Take leather, for example. If you have an 8oz piece of leather, 2" long by 1/2" wide, and you stand it on edge and cut downward, a properly sharpened convex edge will slice through it literally like cutting through butter. It parts and glides through the pressure coming in from both sides. A razor sharp scandi will also cut through nicely, but with noticeably more effort, and, the scandi will tend to skew to one side or the other because of the opposing pressures.

Yet, try to slice clean, even shavings from a stick, and the scandi will cut more cleanly and efficiently.

I've left out the v-grind because, in my experience, it doesn;t cut cleaner than the convex when equal opposing forces press the material against the blade and it will not cut clean, even shavings from a stick better than a scandi. What I like the v-grind for is general cutting, where neither opposing forces are involved nor are even shavings desired. It isn;t that it's dull and won;t cut, neither is true, it cuts many things well. But I can;t think of a task that it is more suited for than the other two grinds.

 

[Vivi]

A lot of what you hear about convex edges posted on here are misconceptions related to edge angle. Previous posters did well explaining that the angle of the edge will make a larger difference than convex versus V grind.

I say go with whatever you find easiest to maintain to your desired level of sharpness, just keep your edge thin whichever direction you go.

Personally I do super thin V grind edges with a microbevel then convex the top of the bevel to round it into the primary grind. This has given me the best possible cutting performance from my knives without sacrificing edge stability. This is what they look like:

 

[norcalblacktail]

Convex is hands down the best overall edge. It outperforms most in every category and is very easy to maintain. Angle of the edge is the most important though depending on what task you intend to perform.

 

[orrey45]

it all boils down to the edge angle really.

you can have a convex ground as thick as an axe or as thin as a straight razor, both being convex. the only difference between a convex edge and a "flat" or V edge is that convex doesn't try to be consistent.

as for sharpening, do some youtube searches for "sharpen" "strop" "convex sharpening", etc. you will pull up several videos demonstrating strop use as well as the use of a sharpening stone.

....

i guess basically what i'm saying is that V or convex, it doesn't really matter. it all boils down to how thin the edge is and whether the burr has been raised and then removed.

by the way, i have informally tested many different grinds and edges, and found that they all perform equally. different angles and grinds require a slightly different angle of approach, but once that angle is found (often within the first several cuts in a piece of wood) the knife works just as well as any other.

I agree with this completely except for the last paragraph. In my experience the V grind and Scandi seem to carve into wood slighty better.

 

[Garrett Schmidt]

Take leather, for example. If you have an 8oz piece of leather, 2" long by 1/2" wide, and you stand it on edge and cut downward, a properly sharpened convex edge will slice through it literally like cutting through butter. It parts and glides through the pressure coming in from both sides. A razor sharp scandi will also cut through nicely, but with noticeably more effort, and, the scandi will tend to skew to one side or the other because of the opposing pressures.

I agree. Along with that, if the edge is convex and polished to a mirror finish it will also improve slicing through leather.

 

[sodak]

it all boils down to the edge angle really.
[...]
i guess basically what i'm saying is that V or convex, it doesn't really matter. it all boils down to how thin the edge is and whether the burr has been raised and then removed.

by the way, i have informally tested many different grinds and edges, and found that they all perform equally. different angles and grinds require a slightly different angle of approach, but once that angle is found (often within the first several cuts in a piece of wood) the knife works just as well as any other.

A lot of what you hear about convex edges posted on here are misconceptions related to edge angle. Previous posters did well explaining that the angle of the edge will make a larger difference than convex versus V grind.
[...]
Personally I do super thin V grind edges with a microbevel then convex the top of the bevel to round it into the primary grind. This has given me the best possible cutting performance from my knives without sacrificing edge stability. This is what they look like:

These 2 quotes beat me to it. I have found that the thickness of the grind is 10 times more important than convex v.s. v grind. Thin is in, baby!

 

[koyote]

so, there's convex and there's convex....

if you take a scandi grind from most any production scandi knife, it won't be perfectly flat - I use an Apex sharpener to true up my scandis and they are about as flat as can be without getting into some weird ritualistic machinery. Even then, what happens when you strop in the field? you convex the edge.

Now, there are two kinds of convex edges- there's the convex final bevel- I *think* this is the more common, and it's pretty easy to keep up with a mousepad and sandpaper.

There's a convex edge I often do which I can't figure out a proper name for. It's a zero grind, like a scandi edge would be a saber zero grind. But it's also describable as a convex scandi, which I don't like to SAY because that turns off all the people who don't like convex AND who don't like scandi

What vivi has postd actually looks a lot like the same thing!

I think the final approach angle is the most important aspect of a convex edge. I vary mine for different blade purposes, and on a lot of blades vary the convex angle throughout the blade much like a traditional leuku (more obtuse at the tip, acute down the blade, then obtuse again near the handle where the power cuts are).

For sharpening, I have managed to just use a strop and get really good results unless I've way overworked the edge on something and need to hit the sandpaper. I redid a convex edge with a ceramic rod in the field once, but it wasn't pretty. worked out fine after 10 minutes of final stropping.

I honestly, seriously, no joke, get my best result from using a piece of scrap way thick (like 12 to 14 ounce) regular veg tan leather glued to a board with the rough side up. No polish, no compound, just a bit of elbow grease and time.

I think a convex will outcut a scandi over time, but I think I can get a leeeeetle bit more scary with a scandi. Not a lot, but a little bit. (and I think both will outcut a regular v final on a flat grind or saber grind anyhow)

 

[pitdog]

I'd like to hear Scott Gossman's take on all this because he is another convex master who actually gets ' out there ' and uses his knives ! He must have reasons for making so many with convex edges as I know he is quite up to doing other grinds if requested !!!

 

[Gossman Knives]

I think both types can be made very sharp. It is not necessarily the edge but the thickness above the edge. I measure 3/16" to 1/4" above the cutting edge. If is is too thick above the edge, then cutting ability will suffer. I prefer to use a very small convexed micro bevel. I've found the added strength of this micro over a zero edge is well worth it. There is also too much emphasis put on shaving sharp. Just because a knife doesn't stay shaving sharp doesn't mean it won't cut. Depending on what you are cutting will determine how long that shaving ability will last. Rough materials like cardboard, rope for example will knock that shaving ability away real quick. I've tested many knives cutting cardboard. My own, other makers and factory. Many different types of steel. Bottom line is the users ability to sharpen a knife. I know people who just can't sharpen a knife. It's a skill that takes time to learn.
Scott

 

[JK Knives]

I prefer V grind, just because that`s what I was brought up using. However, that being said, the convex is really growing on me, and that`s what the majority of the customers want. I really don`t find one easier than the other to maintain.

 

[hollowdweller]

There was a good thread here a few years ago, where Cliff Stamp essentially said what is being said here, that how fine the edge was was really the deciding factor in how deep something would cut.

Of course he said it in his very technical way and about six million people piled on him saying convex was the second coming or something

I personally like Scandi grind and convex myself. But not because they are better than V grind, but because most V grinds have steeper edges so the scandis and convex cut better. I think Convex is easiest for me to sharpen like I said though.

One of the weird things I have seen on some blades lately is a really nice full convex grind to the BLADE, ending in a steep V grind at the edge Talk about a tease!

I'm guessing the makers were concerned about the heat treating and chipping the edge if it was too fine

I've handled a few by Dan Koster where he did a full flat grind to a very fine edge, and then put a very small v bevel on there and those cut every bit as good as the finest convex or scandi.

 

[tonym]

I prefer Convex, but as stated above a thin edge in convex or vgrind will perform about the same.

 

[PB Wilson]

Most of my knives are V-ground because my Lansky sharpener works well enough for me. I had to thin out one of my Ontario RAT-3 blades in D2 because the angle was too obtuse and it took a loooooooong time, but it cuts quite nicely now. Much better than before.

When I get my 1x42 sander (soon!) I'll be convexing most of my blades. It's super quick and I'm certain that I'll get some wicked edges. I tried convexing another D2 Rat using sandpaper but I didn't get it where I wanted it to be. Obviously it'll take practice and probably works better with different steel, but with a grainder, I'll be able to do it more efficiently for sure.

My Moras and other knives with scandi edges will probably stay scandi, but I'm thinking hard about convexing one of them to compare. Nothing like an inexpensive test to sort out the info.

 

[hollowdweller]

Lansky is great for re grinding edges. Esp w the diamond stones.

I have a lot of Hubertus knives and they come with almost no edges on them:thumbdn:

Used the Lansky to put the edge on them:thumbup: