How sharp is sharp enough?

L

Leon Husock

Joined
Jul 17, 2019
Messages
333
I feel like this ends up being a bit of a pissing contest between smiths, with everyone having their own standard (will it shave? will it slice a paper towel? etc) and it ends up being a real rabbit hole. My question is, at what point is sharp sharp and it doesn't matter anymore? I'm a culinary knife maker mostly, and I recognize this standard will be different for different purposes. I feel like there's a level of sharp where after a day or two of use it's not gonna stay that level of sharp anyway, no matter how perfect your heat treat and geometry are.
 
You're right, everyone will have their different opinion on this one. For me personally, about 5 micron (3,000) is where I will stop most of the time, regardless if it's a hunting knife, pocket knife, or culinary knife. I don't ever sharpen lower than 1 micron (diamond lapping film).
 
Working sharp is fine for me. I find that geometry does the heavy lifting. As long as I'm not having trouble with cardboard it's good enough.

For folding knives I want a thinned out convex with completely blended shoulders. Geometry over steel for me but combining both is always nice ;)
 
For my EDC, a clean sweep opening the top of a big plastic True Instinct dogfood bag. Cooking, various knives depending on task - the sharpest non serrated, very thin, uniform tomato slices.
 
I test my sharpening by cutting cardboard and paper, and arm hair.....etc.

There is a certain sound cut paper makes.
A sharp knife cuts paper, unlike YouTubers. Very casual hold, no purpose, changing direction the blade should just cut...smooth sweeping cuts. Slow and easy.....

For chef's knives I do all that, and in my opinion a very sharp knife should fillet a sheet of paper cutting sideways. Not edge cutting the paper. Fillet it. Like a fish......that's sharp.
 
I ran out of arm hair on my last few knives and resorted to leg hair. You know it’s sharp when you test it out, go abt the house on that Saturday and 15 or so minutes later you feel a burning sensation. Look down and blood is running down your leg from where you shaved hair and a fine layer of skin off. I was like ok, it’ll do…if the customer wants it sharper, they can take it to someone else 😂
 
If the knife is sharp, thin geometry and bte, I don't think keeness of edge matters as much. The vast majority of people have dull thick knives so they are easily impressed.

I am starting to appreciate a 600 grit diamond edge for many tasks.

From a BESS standpoint if the edge is sub 200 your good to go with most everyone but those who are to full of themselves and their sharpening skills.
 
No matter what edge is delivered, it is up to the user to maintain whatever edge they prefer.

If there is a weakness to our madness it is that we do not do enough to help the end user develop the confidence and competence to sharpen their knives. Tools and techniques have improved during the last decade, but most users will never be able to keep their knives looking factory fresh. While that may be unrealistic, it is also true that sharpening shouldn’t leave your knife looking like it had been dragged across 20 miles of highway. Perhaps one day we will pursue this with the same passion that we currently chase after the latest super steels.


N2s
 
Nate’s Knives said:
I ran out of arm hair on my last few knives and resorted to leg hair. You know it’s sharp when you test it out, go abt the house on that Saturday and 15 or so minutes later you feel a burning sensation. Look down and blood is running down your leg from where you shaved hair and a fine layer of skin off. I was like ok, it’ll do…if the customer wants it sharper, they can take it to someone else 😂
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I haven't had any body hair, within reach😜and reason😉, in decades.......👌👌👌.....
 
I only make kitchen knives, so I can't speak about anything else, and only sparingly for this as well. As many have said, the geometry is doing most of the heavy lifting. In a cooking application, and except for a few specific tasks, like breaking through tomato skin, even a completely dull blade will cut most anything within reason, as long as it's under 0.1-0.15-ish 1mm bte (that'll be 4-6 thou, 40 thou behind the edge in freedom units).
That being said, I found that the more polished the cutting edge is, the longer it will hold up, so I usually take it up to around 8-10k on the stones, and strop it with 1 and then 0.25 micron.
The edge being thin usually means that even if you go through 3-4 stones and 2 strops, it still doesn't take longer than 5-10 minutes starting from a knife with no cutting edge yet established.
 
Yep...geometry cuts! I take the edges on high carbide steels to 600 the strop. A slightly toothy, aggressive edge is what I aim for. On less caelrbide volume steels (aebl for instance) i like to go higher.
 
Nate’s Knives said:
I ran out of arm hair on my last few knives and resorted to leg hair. You know it’s sharp when you test it out, go abt the house on that Saturday and 15 or so minutes later you feel a burning sensation. Look down and blood is running down your leg from where you shaved hair and a fine layer of skin off. I was like ok, it’ll do…if the customer wants it sharper, they can take it to someone else 😂
Click to expand...
Hairless patches on the arm - used to be called knife fighter's mange! o_O
 
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