Over sharpening your blades?

[T. Erdelyi]

Maybe I have to revaluate my opinion on reprofiling new blades, I know through regular sharpening I eventually wind up with a more acute angle but I still have a hard time believing that the factory edges on the BM, and Spyderco quality knives are that bad.
Now, my EK Bowie has been reground to a very thin edge, and slices like one of my old hollow ground folders, but I wonder if the edge could take the same amount of abuse as my Ontario Spec Plus Machete?
With so many opinions that oppose mine, I guess when my next purchase is made I'll intentionally reprofile it to a more acute angle, I'm open to suggestions as far as a final bevel angle.

 

[Bart student]

why would you have to re-evaluate your opinion?

Factory edges are not bad at all, I spent a while to learn to get edges at the same level.
I know a lot of people here want to reprofile their edges and walk around with a razor sharp single bevel edge. Ok, you can, but your average knife-user sharpens a knife and get's a more acute edge over time. When i first sharpened my spyderco endura on my profile, I was pretty pissed I couldn't get it back to razor sharp. I think that is the problem.. your general Bladeforums knifenut wants to walk around with a freshly sharpened razor sharp knife, and for that, thin edges are ideal. OK, they dull easier, but they cut extremely well, and since we sharpen our knives once a week at least, who cares ?

I once tested that very same endura in ATS-55, with a freshly sharpened convex edge ( as done on my belt grinder as I said up). After a week or two, only minor parts were capable to clean shave. But it was capable of cutting vegetables or apples or potatoes for well over 6 months after that. Then i forgot I was testing it, and before shaerpening I ran my finger over the blade and cut myself however the edge felt dull.

My point.. it's just what you are happy with. I'm still carrying my BM old AFCK with the current factory edge which was put on about three years ago. OK, it's a acute edge, but it cuts.

If you want a thin edge and beat the crap out of it with minimal damage, stay away from chrome. Really, a well HT'ed L-6 or 5160 blade can take way more abuse then we can expect because we are all used to stainless steels which are in fact a LOT weaker and less damage resistant. I don't know what your EK bowie is made of, but the less chrome and the more carbon (till about .90 %) is a good parameter on how much damage it can take.

On edges, everybody has their own preference to edge angle & type of edge. If you're good enough at sharpening you can put that on your knives. But in general if it cuts it's good enough for me.

just my opinion

Greetz and take care, bart.

 

[T. Erdelyi]

Originally posted by Bart student
why would you have to re-evaluate your opinion?

Opinions can change based on available information, that's how I learn,
My position is to convince you that I'm right based on the my knowledge, and degree of experience, if on the other hand some one has the credibility, and experience to convince me to change my mind, my opinion follows suit.

I still maintain my belief about quality factory edges, and I'm still of the opinion that thinner blades do better with steeper bevels, but I'm willing to experiment to convince myself one way or another.

 

[Cliff Stamp]

T. Erdelyi :

Now, my EK Bowie has been reground to a very thin edge, and slices like one of my old hollow ground folders, but I wonder if the edge could take the same amount of abuse as my Ontario Spec Plus Machete?

No it wouldn't. That is the critical tradeoff. There will always be a compromise between cutting ability and durability. It comes down to what you want to do, and how much damage you are willing to accept.

The engineers and designers that create these medium range folders had some sort of all around multi use angle in mind.

You are giving them too much credit, there is too much acceptance of what is "commonly known" as fact and too little R&D. Buck and Spyderco, are two standouts in this aspect, and both run their angles much lower than for example Benchmade.

... what general angle would you put to the various production tactical folders out there?

First off grind a heavy relief at about 5 -> 10 degrees per side (cutting -> chopping). The very edge only needs the steep angle, chips are usually very small. There is no advantage to having the increased angle above their depth [on folders, on larger knives prying is a use and thus edge thickness is a major concern]. This will greatly increase the cutting ability and ease of sharpening with no effective loss in durability.

Secondly, in regards to the final edge profile. Assuming you are just cutting ropes, woods, fabrices and flesh, I have gone down to under 15 degrees included even on brittle steels [ATS-34] with no problems. I run my Opinel and Twistmaster at ~10 included. The only way I have found to damage such edges in regular use is to try to cut really hard plastics, and end up twisting the edge of the knife.

I carry other knives for more "utility" work like scraping, and cutting hardened metal, very dirty materials which have inclusion etc. . Usually it is either a SAK, Leatherman, or a stout fixed blade, depending on if I am at work, or not.

To clarify though, my angles are not relevant to you. I don't have your abilities, or skill with a knife, and odds are strongly that we don't cut the same materials. You will want to experiment to see where the optimal profile exists for you. Just take them down until too much damage sets in too frequently.

Bart :

[thinner edges]

OK, they dull easier...

They will indeed get damaged easier, but if the cutting just induces edge roll and wear, the more acute the angle the longer the edge lifetime. I have tested this extensively on both high end knives and cheap Henckels and the like, and seen differences as much as 25x as much rope cut to get to the same level of bluntness (as measured by cutting light thread and poly rope) with a high relief and more acute edge. As well, because of the *much* greater level of inherent cutting ability, the reground blades will in fact cut better even when duller. MPS was the first person I saw argue this point years ago on rec.knives .

-Cliff