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Has anyone else convexed the edge on any of their 15V knives? I’m trying it just now and it reprofiles and sharpens like a dream, but I’d be interested to hear if anyone else has any experience with a 15V convex edge, particularly for camp/bushcraft use.

I don’t have an answer, but I am curious and following. I love convex fixed blades.

I wouldn’t expect 15V to be extremely tough, but then DBK likes K390 for Bushcraft.

kennethsime wrote: ↑

Mon Apr 17, 2023 8:34 pm

I don’t have an answer, but I am curious and following. I love convex fixed blades.

I wouldn’t expect 15V to be extremely tough, but then DBK likes K390 for Bushcraft.

I’ll update once I’ve used it in anger for a bit. I’m stuck in my office today doing logistics and paperwork

The tedium is real.

Edu-ma-cate me on the advantages of a convexed edge. Is that the same as an appleseed edge? Why do I need one? Whenever they come up in conversation, why is there a chorus of praise for them? If only there were a learned professor who could explain it to me...

Footnote: I notice that Hapstone (make of my rig) offers some weird kind of rod with a knuckle hinge in it, apparently for making a convexed edge. Most curious.

Bolster wrote: ↑

Mon Apr 17, 2023 11:10 pm

Edu-ma-cate me on the advantages of a convexed edge. Is that the same as an appleseed edge? Why do I need one? Whenever they come up in conversation, why is there a chorus of praise for them? If only there were a learned professor who could explain it to me...

Footnote: I notice that Hapstone (make of my rig) offers some weird kind of rod with a knuckle hinge in it, apparently for making a convexed edge. Most curious.

https://www.worksharptools.com/what-is-a-convex-edge/

This explains it better than I could. Hopefully the link works.
It is common in bushcrafting.

I learned something today.

Bolster wrote: ↑

Mon Apr 17, 2023 11:10 pm

Edu-ma-cate me on the advantages of a convexed edge. Is that the same as an appleseed edge? Why do I need one? Whenever they come up in conversation, why is there a chorus of praise for them? If only there were a learned professor who could explain it to me...

Footnote: I notice that Hapstone (make of my rig) offers some weird kind of rod with a knuckle hinge in it, apparently for making a convexed edge. Most curious.

I’m not quite as erudite and articulate as you Bolster, but to paint you a picture with words it is basically a slightly rounded final bevel that causes wood to sort of spool out when you shave it. In my head I imagine it like the opposite of a hollow grind. It’s particularly useful for making feather sticks for lighting fires as the shavings spool into curls, and it seems quite durable in use compared to my traditional straight KME edges.

I think most of them are convexed by now. Unless you always use a guided sharpening system then it becomes convexed. Free hand or the Sharpmaker does it for you as you can never keep the blade perfect in your hand.

If you're using a guided system and want to get a lazy version of a convex, just start with a very low angle to knock down the bevel shoulder and then slightly increase the angle a bunch of times moving down to your final apex angle. At that point it's really easy to freehand the resulting bevel into a more proper convex and then you can micro bevel whatever angle you want at the apex.


And yeah, if you fully reprofile a bevel on a Sharpmaker, the bevel is more or less convex at least technically, but in my mind a true convex blends in with the blade grind and there's no visible beginning of the edge bevel beyond maybe a difference in the grit finish.

You are not convexing the grind, just the edge bevel which is going to have limited (but potentially noticeable if the edge is on the thick side OOB) impact on cutting performance.

Convex edge is stronger for a potentially challenging tasks for the steel

Fireman wrote: ↑

Tue Apr 18, 2023 9:56 am

Convex edge is stronger for a potentially challenging tasks for the steel

That depends on the geometry you give it. It is not stronger per se.

EDIT: WIth the same angle at the very apex as a flat sharpened edge, the convex edge will be weaker by definition. because with a fixed apex angle you will be removing material behind the edge to convex it.

However if you trade some angle at the apex for an angle-decrease further away from it you may indeed gain a stronger (as in the means of more resisting to impact or static force) while optimizing penetration ability into a hard material. But since that edge now has a more obtuse angle you have lost some edge holding (because a more acute edge cuts longer). Excellent candidate for a convex edge would be an axe, or a hatchet for example.

Not 15V, but I convexed Spyderco M4, Maxamet and other steels freehand on DMT plates. It takes no time at all really.

After a couple of days use of the 15V convex edge Shaman I have found it harder to keep it hair popping sharp, but it does seem more robust when working with local hard woods (unsurprisingly as the edge is at a slightly higher angle). It spools out wood beautifully when making feather sticks, but so does a HHG which is easy to keep scalpel sharp

As a control I’ve also convex edged my Magnacut mule which is thinner behind the edge and that performs very similarly. I’m not underwhelmed per se, but I think I’ll be switching back to a 15 degree per side fixed angle edge just because it floats my boat a bit more to have an extremely sharp edge that is long lasting.

If anyone else has any contrasting experience I’m all ears.

A fully convexed blade, as EvilD said, is a different beast than a merely convex sharpening bevel. The appleseed (AKA hamaguri) grind allows a very thin primary angle for performance with a slightly less acute final edge angle, all without creating a shoulder at the inflection point. This eases passage of the blade through the media being severed, and acts to reduce stuff sticking to the blade.

Bill1170 wrote: ↑

Wed Apr 19, 2023 11:36 pm

A fully convexed blade, as EvilD said, is a different beast than a merely convex sharpening bevel. The appleseed (AKA hamaguri) grind allows a very thin primary angle for performance with a slightly less acute final edge angle, all without creating a shoulder at the inflection point. This eases passage of the blade through the media being severed, and acts to reduce stuff sticking to the blade.

Funnily enough I’ve just been reading about this. I agree - I think just a convex bevel has been misrepresentative. I’m swapping it back as I type and looking at BRK’s idly.

I'm trying to learn, on my own, how to freehand sharpen on diamond plates. Everything I sharpen seems to come out with I convex edge. Is this normal or am I doing it wrong? I thinks its just a product of me not using the exact same angle with each pass across the stone. Is this something desirable or do I need to keep working on my form? My blades seems pretty sharp but seem to lose the razor edge pretty quickly. I do know a stropping after every couple uses helps drastically.

I used my 3V Aurora 2 (Bark River) for many months in the kitchen as the only knife and it performed very well, until I cubed some beef legs recently. It took ten minutes of stropping on a freshly loaded DMT 6 micron and then three micron diamond paste leather with the final step being just on wood, to bring it up to shaving stage. No stones. Literally, it is all in the wrist! :-)
Even BRKT white coumpound would have worked, but taking two or three times as much time.

jmj3esq wrote: ↑

Thu Apr 20, 2023 3:55 am

I'm trying to learn, on my own, how to freehand sharpen on diamond plates. Everything I sharpen seems to come out with I convex edge. Is this normal or am I doing it wrong? I thinks its just a product of me not using the exact same angle with each pass across the stone. Is this something desirable or do I need to keep working on my form? My blades seems pretty sharp but seem to lose the razor edge pretty quickly. I do know a stropping after every couple uses helps drastically.

Unless you are a robot (or Michael Christy ), your free-hand sharpened edges will be sligntly convex. How much will only depend on your skill and technique. If your blades loose sharpness faster than what you are used to with fixed angle systems, then you simply have more practice ahead of you.