Knife edge sharpness - when is enough - enough?

Some people like a convex edge for kitchen knives and other knives as well, depending on how they sharpen, not just large choppers. There are thin convex edges and thick convex edges! The grind of the knife comes in to play, as well as the steel itself, it's grain structure/carbide size and quantity, how it was heat treated/tempered, the grind style (there are convex thick behind the edge and convex thin behind the edge and everywhere in between), etc. Even the way the edge was finished (coarse edge, fine edge, mirror finished edge) has an effect. A big chopper with a thin edge that can be supported by the grind and steel, used properly (edge in line with the spine and not being torqued off) will perform MUCH better than a fat behind the edge knife with a coarser finish to it. A more highly sharpened edge may bite into the wood deeper and cleaner and be less susceptible to chipping or carbide pull out, too, versus a coarser or duller edge. Sawing rope constantly, a toothier edge may be prefered and even thinner behind the edge for edge retention, but steel choice comes into play, too. If my job was just to cut sisal rope all day, a very high wear resistant steel would be what I would want, with a knife with a comfy handle for applying pressure for long periods and a good way to touch it up quickly. S90V, Maxamet, 15V, 110V, etc come to mind.

Everyone has their own tolerance for when it should be resharpened and how they do it. There are so many variables it's hard to quantify.

I had a summer job when I was in High School where I was working in a packing and shipping department. I was cutting down cardboard, boxes, styrofoam and regular foam, zip ties, plastic pallet wrap and all sorts of stuff a lot. I saved up my money and bought a "really awesome" knife at the time and hated it within minutes of starting to use it. Hot spots all over the handle, but all of the online reviews praised it for not having hot spots! Edge retention was only so so, sharpening was OK. Was kinda thick behind the edge. That was what led me to starting to make my own knives back in the late 1990's, first with premade kits and blanks, then to doing my own blanks. Everyone has different standards they hold a knife to and what they expect out of it.

I don't bother with measuring angles. I grind the knife and then sharpen it at what I think it should be for the steel, blade thickness, angle and intended useage.
 
UR7knife said:
I'm trying to - I presented a specified approach and have gotten simplistic answers so far, for the most part. The convex edge is one that appears in what I've described for choppers, and bushcraft knives. I should think that after some use, it would have difficulty in shaving hair of your arm, while still being plenty sharp for the tasks you need it to perform. Which brings us back to my point from the other side: when would you stop and re-sharpen? I would think it would be when it falls short of performing the tasks you want it to, or when it starts needing more effort to do so. So there is a lower sharpness limit, depending on the task and knife class, and for all practical purposes, let's agree that the higher limit is 'shaving sharp". I propose the lower limit is different and depends on the task and knife class, and not on the hair of the hand.
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What you're being told is that your approach is needlessly complex. I own knives in all of the categories you initially defined, and when it is time to sharpen them they are all brought to a minimum of being able to shave arm hair and a maximum of hair whittling...this largely just depends on how much time I feel like dedicating to sharpening at the time. I am well aware in doing so that some may lose this super sharp edge faster than others depending on the tasks they are used for.

They are then sharpened again when I feel the level of sharpness has diminished to a point that increases the difficulty of the task the knife will be used for.

At the end of the day there is no right or wrong answer. Some people may stop sharpening when they feel a knife is "sharp enough"- a totally subjective and ever-changing personal metric. Others try to get every knife as sharp as they possibly can. Some match and maintain factory grind profiles for aesthetic reasons, others reprofile to maximize cutting abilities or durability.

Some things just don't need a concrete definition. Enough is enough when you decide it is enough, and my enough doesn't have to be the same as yours.
 
my choppers? machete i can food prep with them, billhooks are thicher behind edge so they cut for example string, but they are made to wack wood.
i sharpen them with scythe stones artificials rather coarse, and smoother natural ones.
 
UR7knife said:
let's agree that the higher limit is 'shaving sharp
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Hmm. 🤔

Nope.

Not bragging, but essentially all of my knives are shaving sharp. Even my axes are brought to shaving sharpness.

“Shaving sharp” is not necessarily super sharp, it just means that you created a relatively clean apex when sharpening.

If you aren’t achieving a shaving sharp edge then you may need to work on your technique.

Any of the edge angles you mentioned in your original post should easily get beyond “shaving”, and up to “hair popping” sharpness.

“Hair whittling” or “hair splitting” is typically the higher limit around here…
 
UR7knife said:
So..basically, you don't carry anything over 250 gr (8.8 Oz), and over 10cm blade (~4").
Apropos - when out & about, I carry at least one medium size food prep knife, which I don't keep as sharp as described, since its easier to gut a fish/ or clean game without piercing their gut inside them when cleaning, and this type of sharpness is a hindrance when de-boning a carcass of filleting a fish - but this is just me.., and a chopper, which I don't keep "shaving sharp" since I'm going to wail on it when chopping stumps for kindling, where this sharp's going to chip or break or bend first time I baton it into wood, especially if there's a knot in it.

I hoped for a more serious approach.
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I think you're over thinking it all a bit.

🤔 I have to disagree with anyone thinking a knife being sharper is ever a hindrance or any acutual cutting task can be performed better with even a slightly duller blade.

I've field dressed, skinned, and processed all sorts of game animals, birds, and fish of all types ... and a knife can NEVER be too sharp ... it's user error if you're cutting parts that shouldn't be cut or punctured when processing meat or fish. It's far easier to work around guts or bones with a properly sharpened knife than even a slightly dull one.

When a blade begins to drag or require more pressure to cut something ... it's time to touch up the edge. I occasionally shave my arm hair to check an edge while sharpening, but normally I use receipt paper to test my edges. If it drags or catches I'm not done. I'll add for most actual cutting a good toothy edge preforms better than a highly polished edge unless you're push cutting something. But a toothy edge should still shave hair or glide through that receipt paper, if it doesn't I've not properly apexed the edge.
 
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David Mary said:
Usually arm hair is what we mean around here when we say shaving sharp
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......top of the thigh thanks.... no awkward bald spots on the Yowie arms and a bare thigh is always available there as I sit at the sharpening bench !!!

I am no sharpening genius but my knives all cut in their roles. My NMFFBM will happily shave but also chops like a beast, it's not the best blade in the kitchen though.
 
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I usually go to receipt paper for the test, but lately I've had to graduate to newspaper since I was running out of room on the receipt paper! I usually go to the grocery store daily so the receipts aren't super long. I try to be able to make a clean cut in receipt paper twice as long as the edge is. So if it's a 3-in blade, I want to be able to slice six to seven inches at least of receipt paper. than I do push cut tests at different points of the blade, usually five points of the blade; 2 near the tip, one in the middle 2 near the heel, to make sure it's nice and sharp along the entire blade.
 
I’m not going back and quoting but did somebody say that they guy and filet fish with a dull knife so they don’t pierce the guts. I don’t know where you live but I’m off work for a couple months and I want to teach you how to gut/filet a fish. Not being obtuse I want to help you. Video or whatever. You do not filet fish with a dull knife.
 
I keep all of my knives at least shaving sharp. It has nothing to do with any philosophy or intended use. If they aren’t at least that sharp, they aren’t sharp enough for me.

That said, I have knives in all size ranges and use them for all manner of tasks. I don’t buy shit knives so I don’t have to worry about any perceived instability or fragility with the edges.

I would never keep anything intentionally dull or less than sharp - least of all a fillet knife.
 
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