How sharp is "sharp enough"?

[Freaver]

In a minor effort to help Grant and the forum reach a million posts, I thought it was time I made a thread about sharpness...
Not too long ago, I saw a thread on how people sharpen their knives and multitools, so I thought a good follow-up, would be this: How do you test the sharpness of your blade and how sharp do you make it?

Personally, I cut either receipt paper or notepad-paper, depending on what I have, when sharpening my blades. As I mostly use my blades for opening cardboard-boxes and blister-packages, that's sharp enough. If it gets any sharper, I have a tendency to "let the blade wander off", and end up cutting way more, than just the tape that holds the box together.

So... Let's hear it; how sharp is "sharp enough" for you?

[dks]

It should be able to shave the hair off the private parts of a fly, whilst not afecting its reproductive ability...
 

[AimlessWanderer]

Hard to say really. I just sharpen it till I'm happy with it, then don't sharpen it again till I'm unhappy with it 

I don't tend to do test cuts or shave bits of my anatomy with it, just look for obvious glints of light, and lightly scrape my thumb across the blade. If I'm unsure, I might run it lightly on a thumbnail to see if it slides or catches

[cbl51]

I'm pretty much where 50ft is. I don't get overly hyped on sharpening, and when it comes to knife nuts, more blades are worn out by over sharpening than use.  Living in the 21st century, I don't now how many of us are making a living skinning buffalo or big game, or doing sculpture with an Opinel like Pablo Picaso did.

I'll take it to the stone when it doesn't cut like I like, and after a few moments it's back to where I do like. I may take a little test swipe on some arm hair, then it's back in my pocket. It's a pocket knife, not a surgical tool. As long as it opens UPS boxes and my mail, I'm happy. Cut some twine or rope and it's gravy on the potatoes.

Mostly I use my old boy scout stone I found in the attic. It's good enough.

[kkokkolis]

If it cuts it's OK. I use my Opinel a lot (papers, envelopes, food, parcels, rope, plastics) and sharpen it frequently. If it wears out Ill buy another, they are cheap. I sharpen my Victorinox rarely and never sharpened a Spyderco or Leatherman yet.

[Kin-Luu]

That depends on the intended use of the blade.

My Lionsteel M3 that I use when hiking and camping must be as sharp as possible, it should be able to cut a tomato horizontally - freehanded. The same is true for my kitchen knives.

Everything else is good enough if it cuts cardboard or paper without much effort.

[comis]

Usually just paper cutting sharp or sharp enough I am scared to finger test it, I felt the need to achieve super sharp is just too much effort and the benefit could be just marginal.

[El Rago]

dang, double post. in this thread and in Lynn´s

mono-nuclear edge as I think it is called in SciFi

[Lynn LeFey]

Sorry. I didn't see this thread first.

My answer is, I like my blade sharp enough to cut regular notebook or printer paper. That usually means it's sharp enough to be safe for any task I need.

[Aloha]

While I find it interesting how sharp knife enthusiasts want their knives I have certain knives for certain tasks so......

Work knife needs to be sharp enough to cut rubber and plastic bottles while also being able to cut fabric and thin rope and zip ties.  I tend to go with serrated knives for this type work and thankfully Spyderco makes a helluva serrated knife.  I'll run my knife on ceramic rods when I feel the blade struggle.  I'm no "its gotta be so sharp it cuts on approach"

My food blade is typically a PE and this knife needs to cut a ripe tomato.  I've sharpened a few knives in my time and can "feel" when the blade is good to go.  A quick stopping usually does the trick or ceramic rods then strop.

My MT blades are dirty work blades and need to be ready to cut everything else.  I'll tough up these blades weekly using ceramic rods and on particularly heavy usage I'll strop daily.





On an funny side note, so the last few videos I've watched have been unboxings and the persons knife has struggled to get thru tape  .


 

[sir_mike]

As others have mentioned, I like mine sharp enough to cut computer and phone book paper.  I dont care if it is "super sharp" but as long it cuts paper, the blade will work for me.

[jzmtl]

Slicing newspaper is good enough for me. I used to be obsessed with it, but the more I use knives the less I care (to an extend), ultra sharpness is good for bragging but makes no difference in actual use.

This was something from the height of my obsession, the blue line in background is a line on notebook paper.

[Lynn LeFey]

Okay. Yeah, that's crazy. 

[nate j]

Good old "shaving sharp" is what I target when sharpening, and I do test this on my forearm.

However, I don't use this to gauge when to resharpen.  I just know its time when cuts feel like they are taking more effort.

[Higgins617]

I only really do it freehand, so I just do it as best I can. That sort of depends on the day though.... My knives in 420hc constantly get back to hair popping sharp with little work so they are often at that level. The blade on my Sidekick has to be the easiest to sharpen, maybe the blade design mixed with the softer steel?

[HarleyXJGuy]

AS soon as my Sharpmaker gets here I will let you know. 

[LoveHate]

I like my blades so sharp my hair falls off before the blade even touches my arm 
In all seriousness I do like my knifes shaving sharp and use a lansky and a leather strop. I see sharpening as zen time. But I only re sharpen when the knife will no longer cut cardboard easily. And it's usually a few swipes with the sapphire stone and a strop and it's good to go.

[Kin-Luu]

I like my blades so sharp my hair falls off before the blade even touches my arm 

Works better with the head, than with the arm.

I see sharpening as zen time.

Exactly, it is very relaxing to take a blade to the wetstone, especially after work.

[Crocker]

The sharper the better, though I'm not as fussy as I should be about it. Like lots of folks I learned to sharpen on a stone at my father's side but nowadays a simpler rod style sharpener suffices most of the time. Not letting a blade get too dull is the secret. Already this morning my pocket knife has cut cheese (literally, not figuratively) and cardboard and stirred my coffee, but it has to be able to perform anything from chipping ice off the gate latch to chipping paint out of screw heads to cleaning up mortices. Some things I really ought to use an Olfa knife for but I'm too lazy to search past my pocket for the right tool.

How sharp is sharp enough? How dull is too dull?

[Cupboard]

I aim for shaving sharp when I'm sharpening, and I get that on all my blades apart from my Leatherman Wave that I just cannot get an edge on.

Re-sharpen when I can't do a slash cut through those sausage strings of air pillows you get to pack out boxes. If you've got 20 or so to burst, being able to start at the top and swipe through them ten at a time is a lots quicker than having to do them individually.

The quickest I've ever dulled a blade was cutting through a synthetic lagoon liner. It goes between the waterproof plastic liner that holds the liquid and the ground to stop anything in the ground puncturing the liner. It's pretty thick and designed to be really tough, we were using some of it that we had left over from a job and had some grit in it, after about 2m of cutting it was a struggle to open a box with the blade. That was my C33T.

The white stuff here:

[Philthy]

Knives with 58+ rockwell I sharpen to the point where they can cut a folded over piece of phonebook paper.  I run the edge of the blade against the fold in so it cuts an oval out of the paper.

[AdmSlc]

I usually stop at hair poppin.


-AdmSlc

[jekostas]

You should be able to drape a piece of tissue over the edge and have it split cleanly.

[Grathr]

As long as it can efortlessly clean cut loose (held in one corner) wrapping plastic like on magazines without catching/ripping it, it is usually sharp enough.


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[zoidberg]

I see a lot of sharp talking but only one pic.