Convex edge question: Blade keeps developing a wave.

[Wolfcri]

I have a fixed blade knife made by one of the popular custom knife manufacturers. I wont say who because it doesn't matter. Their customer service is awesome and they are standing behind their product. The knife is made from A2. Its my first convex and my first fixed blade knife over $100.

The blade developed a wave when I first got it after battoning through a live hardwood branch about 2" in diameter. They had me send it back and they reground the edge.

I have stopped using this knife for any kind of battoning. I have used it to carve an axe handle and some other stuff. The only other thing I used it for was to make scrapings of pine fatwood. Now the waviness is developing again. It is less severe than the forst time but still there.

Is this a convex edge thing? Is it an A2 thing?

I have beat the hell out of USMC KaBars and jammed my Emerson CQC super 7 through an above ground pool and they took it. I think I am using this knife the right way and it keeps getting wavy.

 

[Jason B.]

Its a convex ground too thin on a belt sander thing.

Sometimes they get the geometry right sometimes they don't.

Sending a knife back for sharpening is always a option but not one I would ever choose, its extremely rare that any factory sharpener has proper geometry in mind when sharpening your blade.

Convex is best done by hand but in a factory setting they don't have the time for that so its done on a slack belt sander. If the pressure or angle is not held correctly you can end up with a very thin paper like edge that literally will roll when cutting paper.

Sharpen yourself with a mouse pad and some sandpaper, you can fix the issue by using a steeper angle of around 15 degrees per side.

 

[Seals]

Could be a heat treat issue.

 

[Wolfcri]

 

[Noctis3880]

Pictures?
I'm still a little fuzzy on what "wave" means. It would be fruitful to see whether the edge rolled or was abraded away. Seems like A2 would be the steel you want to chop with rather than expect any sort of wear resistance from it.

Still, learning to sharpen and maintain your own edges(or even tweak the angle to fit your needs) is a necessary skill.

 

[Wolfcri]

Pictures?
I'm still a little fuzzy on what "wave" means. It would be fruitful to see whether the edge rolled or was abraded away. Seems like A2 would be the steel you want to chop with rather than expect any sort of wear resistance from it.

Still, learning to sharpen and maintain your own edges(or even tweak the angle to fit your needs) is a necessary skill.

Tell me about it.

I have been working on it over the last year and have come a long way. This is my first convex though. I have been doing pretty well keeping it sharp. I think I will use the BRKT stropping compounds I have and strop it at a slightly steeper angle and see if that helps. Thus far I have only lightly touched up this edge myself.

 

[Jason B.]

"Pictures are worth a thousand words"

Your edge is too thin.

 

[effer]

"Pictures are worth a thousand words"

Your edge is too thin.

+1
The edge is simply too thin.

I would sharpen it to a regular V-edge (30 deg) on a sharpmaker or using what ever else you use for your other knives and then convex it. So sharpen in to V-edge till you get rid of the "wave". Then use sandpaper to convert V-edge back to convex.

 

[Wolfcri]

I got the OK to exchange it. Thanks for the replies. I dont want to lose that much steel from an otherwise new knife.

 

[FlyingKiwi]

+1
The edge is simply too thin.

I would sharpen it to a regular V-edge (30 deg) on a sharpmaker or using what ever else you use for your other knives and then convex it. So sharpen in to V-edge till you get rid of the "wave". Then use sandpaper to convert V-edge back to convex.

Why the v-edge? Just some low grit sandpaper on a mouse pad, only contacting 1/4" of the edge with moderate pressure and a higher angle edge is formed.

 

[effer]

Why the v-edge? Just some low grit sandpaper on a mouse pad, only contacting 1/4" of the edge with moderate pressure and a higher angle edge is formed.

Because angle of V-edge is easier to control for a person who is new to convex edges and hand sharpening.

I got the OK to exchange it. Thanks for the replies. I dont want to lose that much steel from an otherwise new knife.

Exchange is always great, because you're getting a new knife in return, but you still might get one with thin edge. If you use it and see any "wave" effects again, I would strongly recommend to sharpen it to more obtuse angle instead of sending it in. You will not loose much steel, if you not over do it, and your edge will be much stronger.