School me on convex edges

[Evil D]

I've been thinking about convexing my S110V Military lately, but aside from the somewhat natural convexing that you inadvertently get when freehanding, I've never done a convex edge. I do plan on continuing to sharpen and maintain my edge on my Sharpmaker, but I'm going to thin the edge out one way or another, either by grinding the bevel down on my Edge Pro or by convexing. I've seen a lot of people mention mouse pad and sandpaper, but for the life of me I can't seem to find an old school mouse pad anywhere. I'd say my freehand skills are average at best, and I kind of hate doing freehand work because I'm always short on time and patience so the easier the better.

[vivi]

https://www.amazon.com/gp/aw/d/B01CNN0R ... ref=plSrch

If you search foam mouse pad on amazon you'll get a lot of results similar to this.

Back when I used convex edges I'd use this, some tape and various grits of sandpaper. I'd buy my sandpaper at wal-mart from the auto care section, buying 200-2000 grit.

I'd use a DMT XX Coarse to remove some of the blade steel first, as it cuts very fast. I'd knock off the shoulders of the bevel but I'd stop before I removed the entire bevel so that I hadn't touched the edge apex. Then I'd move to the sandpaper.

I'd setup the mousepad on the edge of a desk and secure it with some loops of tape underneath. I've also heard of people gluing their pad to an old book, heavy plank of wood etc. Then I'd lay a piece of sandpaper on top of the mousepad. I'd secure the sandpaper with another loop of tape on the side near me, and on the far end I'd clamp it down with a small bench vise.

I'd lay the knife flat on the sandpaper on the end next to the vise, then using edge trailing strokes I'd pull the knife towards me in a similar manner to using a bench stone, except I'd use a little more pressure than I use with stones. The extra pressure helps form the convex shape.

Repeat the process on the other side, then move up in grit until I have the polish I desire.

From there I'd use either a sharpmaker or traditional bench stone at a very high grit to apply a microbevel. Touch-ups would be done using UF sharpmaker stones or an UF bench stone, followed by a strop. When the microbevel wasn't so micro anymore, I'd go back to the sandpaper, usually starting around 800 grit since I didn't need to grind off too much metal as the overall shape was already ground into the blade.

Hope that helps. There's a chance I have an old video of my method somewhere on my PC, I'll look for it.


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Well, didn't find a video of that method, but I did find another setup I used on video.

I'd take an old DVD case. I found one that was pretty thin and flimsy, without much on the inside. Took out the DVD and booklet, then taped sandpaper to it using tape loops like I mentioned above. Works surprisingly well, and it was easy and convenient. Completely forgot about this until I saw my old video of it.

https://streamable.com/aggge

https://cdn-e1.streamable.com/video/mp4 ... e98c894567

[Evil D]

Awesome Vivi thank you for the tips. You said "when you used to use convex", sounds like you've changed? Any reason why?

[vivi]

I think convex edges cut better, but its quicker and more convenient to use my DMT XX Coarse. The DMT stones never wear out, cut faster, don't require any tape, clamps, mousepads or DVD cases, clean up with a single wipe with a wet rag etc. Good luck!

[zacmangray]

I have put a convex edge on my LW s110v manix, I really like the convex edge. It stays sharp for a long time and very minimal is needed to maintain a sharp working edge. The sharpness of the edge seems hidden, it doesn't look or even really feel sharp, but it pops hair off my arm. My s110v manix is one of the most used knives I own, and since the convex edge it has been even more carried.
I have the Lansky sharping system, it has four angles to choose from 17', 20', 25', 30'. I took my diamond stones and started with the 30', worked both sides a little, then 25' on both sides, then some at 20' and then 17'. It took me awhile, but it worked out well. When I was done with the lansky, the different angles could be seen on the edge, I then strobe the blade with a piece of leather on wood until the angles are blended together. It seems to have a really nice convex edge, although I am not a sharping expert by any means. I know how to get my knives sharp enough to where they stay sharp so I can use them.

[Evil D]

I have played around with a sort of cheater convex on my 20CP Para 2. At one time it had about 5 different visible bevels overlapping each other, each one steeper than the last. I don't know if it really made a difference.

[JD Spydo]

I'm glad that you all brought up the subject of "convex edges". Back in 2003 I got the awesome privlegde of talking to the late "BILL MORAN" at the 2003 Atlanta BLADE SHOW. He informed me that he had been using convex edges on all of his custom creations for decades.

Since then I've used the mousepads with the different grits and compounds and have had some very nice results. However I still feel like I've just scratched the surface in learning the art of obtaining an optimal convex edge. I'm wondering if Spyderco's upcoming GAUNTLET will have that capability?

It just stands to reason that a convex edge has more shoulder and probably obtains a slightly sharper apex. Is anyone here aware of any good books or written literature or even a good website that has the correct methods one could learn from?

[zacmangray]

I'm glad that you all brought up the subject of "convex edges". Back in 2003 I got the awesome privlegde of talking to the late "BILL MORAN" at the 2003 Atlanta BLADE SHOW. He informed me that he had been using convex edges on all of his custom creations for decades.

Since then I've used the mousepads with the different grits and compounds and have had some very nice results. However I still feel like I've just scratched the surface in learning the art of obtaining an optimal convex edge. I'm wondering if Spyderco's upcoming GAUNTLET will have that capability?

It just stands to reason that a convex edge has more shoulder and probably obtains a slightly sharper apex. Is anyone here aware of any good books or written literature or even a good website that has the correct methods one could learn from?

http://www.blackjackknives.com/?BISKIT= ... =cat&cat=5

[Brock O Lee]

This is my trial-and-error method using flat stones freehand. I do not like the mouse pad method. With a mouse pad and coarse sandpaper, it feels like I will easily round over the edge, and I don't have much control over the shape of the convex.

I use a similar trick as Zacmangray with the EP. Pick a low bevel angle on the EP, and partially cut a new secondary bevel. I normally go very low, less than 8 dps, or lower. When I say partially, I mean do not continue to remove metal all the way to the edge. Leave a few mm of steel behind the edge. Your objective with the low EP bevel is to remove the bulk of the old thick bevel shoulder, because that can take some time to do freehand, but to leave some meat behind the edge. With the EP you know your bevel angle stays constant, and it will form the base for the shape of your convex later. Multiple helper bevels work too.

To make the convex, I find the stock EP coarse stone works well freehand. The 120 grit leaves a scratch pattern that is only slightly more coarse than the factory finish on the Military/PM2, so scratches on the FFG are not a big deal. Cut off the old edge so that it reflects light. Blend both the shoulders of the helper bevel into a nice curve free-hand, so that there are no obvious transitions between the edge and the FFG. This is the nervy part, because you have to wing it until you are satisfied with the shape and finish, without removing too much metal. I try to stay away from the very edge during shaping, to not apex until the convex is established. Once the convex is done and apexed and deburred, I cut a micro bevel at 15 dps.

This was done completely freehand with DMT XC and C stones. I left it slightly thicker at the tip.


Low convex on the Sage 2, with EP 120 finish:


If you look at the edge near the plunge line, you can imagine how low that initial EP angle must be to gradually blend in with the FFG. I now prefer this EP "helper bevel" method with the EP 120 finish.

You are in for a treat! For a low convex like this Sage, you can expect cutting performance approaching that of the Nilakka, but a slightly more robust edge because of more meat behind the edge.

[Evil D]

I'm curious about the edge rounding issue. It makes more sense to use the pad on thicker blades where the curve of the convex us more pronounced. I feel like on a Military the curve will be almost invisible and it'll look more like a zero grind. I'm also really afraid of going too thin and creating an edge that chips out too easily. I just repaired some bad chips on this knife and I'm in no hurry to go through that ordeal again.

[Brock O Lee]

I suggest you practice on a cheap knife to get a feel for the process.

WRT removing too much metal, that is why I like the initial EP helper bevel. The closer the helper bevel extends to the apex, the thinner your edge will be. It creates a boundary for you near the apex. If you do not do that, and do not check *often*, it is easy to get carried away with a coarse stone and remove too much metal while free-handing near the apex.

[Evil D]

I think I may do the multi level bevel deal I mentioned before and then blend those in freehand. That seems like a good way to safely set a base line for the shape of the convex.

[JD Spydo]

Thanks for that information Zacmangray. The use of leather and/or crocus cloth actually does make a bit more sense than the use of a mousepad the more I think about it. I'm also wondering if it wouldn't be a good idea to start out with a relatively decent apex to begin with ( one that would at least slice notebook paper) and then just work on it until you achieve the degree of a convex edge you desire?

But I'm also wondering about using stones ( that are not flat) and/or ceramic files with a radii like Spyderco's 701 Profiles? Because with just a small part of the edge being abraded might give you better overall control on the contour you would desire. If and when a guy would get skillful at it then Spyderco's Ultra-Fine, 302 Benchstone would probably be the ticket?

[mb1]

I've been thinking about convexing my S110V Military lately, but aside from the somewhat natural convexing that you inadvertently get when freehanding, I've never done a convex edge. I do plan on continuing to sharpen and maintain my edge on my Sharpmaker, but I'm going to thin the edge out one way or another, either by grinding the bevel down on my Edge Pro or by convexing. I've seen a lot of people mention mouse pad and sandpaper, but for the life of me I can't seem to find an old school mouse pad anywhere. I'd say my freehand skills are average at best, and I kind of hate doing freehand work because I'm always short on time and patience so the easier the better.

Check out Gavko's videos on YouTube. Those really sold me on convex edge cutting performance. He demonstrates cutting depth into 2x4s, v-edge vs convex. I don't think that's the end-all proof, but it's interesting.

Gavko also does a dull-to-shaving 5 min (or less) sharpening process using a cordless drill and sandpaper attachment progression that's interesting. But I copied his mousepad/sandpaper method. It's basically what Vivi described, but using back and forth strokes instead of edge trailing only. I think it's just faster.

The only thing I don't like with the mousepad edges I did was the edge angle ended up more obtuse than I prefer. I assume this is due to the softness of the pad since I was trying to lay the knife as flat as possible. Maybe if I started with a steeper initial bevel like mentioned above, I could achieve a better finished edge angle. I might try that.

On my Southfork, I simply ground the shoulder thinner on a DMT Course stone. I never went back and convexed it, but it sure sliced noticeably better with thinner shoulders. I think some mousepad sanding would make it look prettier/smoother on the transition, but I haven't bothered yet.

Let us know what you end up with!

[jmh58]

Check out KME site as they have a stone carrier rod that is curved.. Claim this achieves a convex edge.. John :)

[bdblue]

I think convex edges are interesting and on the surface they sound so simple how could you resist. Look at a new Blackjack or Bark River knife and the blade grind just goes down to nothing, to a very sharp nothing.

But mention convex edges and you don't have any idea what big can of worms you've opened. I've read long threads about convex edges and they never end well. They start arguing about which cuts better, which is stronger, and which is easier to sharpen. Then there is a discussion about angles and people have trouble describing/understanding which is thinner, which has more/less material, what the edge angle really is, or even if a convex edge really has an edge angle. It is virtually impossible to discuss these things with words. People try drawing pictures to show one vs. the other and this doesn't work either. Then the threads hit rock bottom. Better to just say you like convex edges and not try to compare one with the other. Please lets not let this thread get out of control.

Like I said I like the idea of convex edges but I've tried and for me they are too hard to sharpen. I have the sandpaper and mouse pad, and I've put time into it, but my edge never got sharp. I sharpen my normal folders with diamond stones using a DMT Aligner guided system. I can get a good uniform sharp edge quickly. With sandpaper and a mousepad it seems to be very slow. I still own fixed blades with convex edges so I will continue working on this.