How Sharp is Sharp Enough?

S

Scott Free

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Sep 15, 1999
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I recently purchased a Diafold Coarse/Fine sharpener and am very happy with it. I am now able to put edges on my Moras in the field that will shave the hair on my forearms. Diafold also sells an Extra Fine/Extra Extra Fine sharpener. I'm tempted to go to the next level, but how practical is it really? I might be able to show off to my friends, but does it really add much to the function of a user woods knife? How sharp is sharp enough? Does an "extra extra fine" edge last? Or will I be back to where I am now after just a few cuts?
 
Depends on what ya needing to cut buddy. A polished edge works better on wood but if say you want a knife for cutting fish then a ' toothy ' edge is better !
 
I find steels like AUS8 and 1075 will get to a shaving sharp edge with much rougher grits than other steels. It really depends on the grind, steel type, heat treat and intended purpose of the blade.
 
I admit there may be a "sharp enough" for some folks.... but NEVER too sharp. A properly done "scarey sharp" edge will outlast a duller toothier one, every time.
 
I have a coars fine diafold I use in the field as well as a strop I usually use the fine than suoer fine than a strop..that keeps'em lazer sharp and they stay that way for a good long while... WHen the edge gets dinged up than I use the coarse and move up..it;s worth the cheddar for the fine ultra fine..or you cold just make some out of wet dry a paint stirrer and a few small c-clamps
 
I get V edges very, very sharp, but I can only get "omgsosharp" sharpness on skandi and convex edges. Is anyone experiencing the same? And yeah, as Rick said, it's never too sharp. Some steels I just can't get to love if sharpening very fine, mostly stainless I have to say. Again, anyone feeling the same way?
 
I'm not into extreme sharpening as a rule but once you've trained for it and can do it habitually everything else is easy. By that I mean I don't go getting stuff from razor supply shops to go pushing the sub-micron, and I'm not into knife stunts like whittling hair. I do refine my edges a lot though because it is easy and I agree with Rick's “A properly done "scarey sharp" edge will outlast a duller toothier one...”.

Just a gist 'cos I don't count slicing paper as a great indicator, and hair shaving sharp is a huge so what; but if I can't pick a random slightly damp from being in with the tobacco medium weight cigarette paper from the packet, hold it twixt thumb and finger at one end and slice it in half something is wrong. They usually come in packets of 50 for a few pence. If you can't get the hang of it by the end of the packet give up and buy some scissors. Toothy edges are for people that like sharpening regularly. Whilst I can find sharpening cathartic when in mah nest it's not something I really want to be doing out in the sticks despite having the tools with me.
 
Scott Free said:
I recently purchased a Diafold Coarse/Fine sharpener and am very happy with it. I am now able to put edges on my Moras in the field that will shave the hair on my forearms. Diafold also sells an Extra Fine/Extra Extra Fine sharpener. I'm tempted to go to the next level, but how practical is it really? I might be able to show off to my friends, but does it really add much to the function of a user woods knife? How sharp is sharp enough? Does an "extra extra fine" edge last? Or will I be back to where I am now after just a few cuts?
Click to expand...

I say stick with the one you have and buy a leather strop to finish off with.
I will polish the edge up scalpel sharp and make it remain sharp for MUCH longer. The sharper an edge is at the end of the sharpening process the slower it dulls... Not just because it's sharper but because there are much smaller micro serrations which take a lot longer to get bent out of alignment. This bending of the "teeth" happens to be what dulls a knife in fact.
 
Stick with what you have for the field sharpening. If you feel the need for a keener edge when you get home buy the fine/ultra fine/strop for there. Out in the field there is no need for shaving print off of newspaper. Razor keen edges have been known to cry when dealing with wild hog hair and other beasties. Superfine edges have their place as well. It just depends what you plan to do with your knife.
 
I use the same blue/red diafold, but I follow that with an extra fine(green) keychain diamond, then with a leather strop.

Once I have my edge, I usually can keep it touched up with the strop and the green diamond for a long time. Once I get to a point that I can't quite get it as sharp as I used to with the strop and green stone, then I'll back up to the course/fine diafold to reset the edge.

So, In my opinion, I would recommend getting the x-fine/xx-fine diafold, and find yourself a thick piece of scrap leather and rub some polishing compound into it. With that set up, you should only need the course/fine diafold every once in a while.

And, yes, in my opinion the keener your edge the longer it will stay usable. Simply because it has farther to go to get dull, if that makes any sense.

P.S. With my method, I can cut a hanging hair if that means anything... I'll have to try the wet cigarette paper sometime.
 
Its a very good choice, it will make your edges much sharp thus making them cut better. Hair splitting sharp is very possible with the EEF hone.

Yes, you will notice improvements in cutting performance, edge retention, and your removing less metal with touch-ups so your blades life will be extended. Sorry, can't really think of any down side to a sharper knife ;)
 
“I'll have to try the wet cigarette paper sometime.”

To clarify what I meant by damp 'cos I may have mislead. They tend to take up a very slight amount of moisture when they are in a packet and left in with the tobacco. Little gits sometimes stick together along the gum edge and come out in one stream like a bog roll because of it. When I said damp that's the kind of damp I was thinking of, hopefully emphasizing that I'd pick one rather whimsically. I only mentioned that because I think the charlatan, illusionist, sensible bloke wanting to win a bet / make a video would bake any damp out the Rizla first to stack the odds. It's easy if you do that. I don't set much store by this it's just that I always have Rizla available and it does tend to disclose mistakes and imperfections quite well.
 
I can only get a knife sharp enough to shave body hair. Thats where I stop.A couple of times I have got it to whittle hair.Any attempts to get it sharper are futile .Id love to be able to get one scary sharp.

Stropping with magazine covers , phone books, cardboard, denim, my belt have all failed. I need to get a real strop and compound.
 
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to me, "sharp enough" means that for the blade in question, and the task at hand, the blade is sharp enough to easily and safely accomplish that task.

Some feel that every blade needs to be able to pop hair off your arm. Sometimes, depending on the steel, the grind and the tasks that knife is to accomplish, that is not correct.
Having a knife that sharp, can compromise durability and the ability to hold an edge.
 
Mannlicher said:
to me, "sharp enough" means that for the blade in question, and the task at hand, the blade is sharp enough to easily and safely accomplish that task.

Some feel that every blade needs to be able to pop hair off your arm. Sometimes, depending on the steel, the grind and the tasks that knife is to accomplish, that is not correct.
Having a knife that sharp, can compromise durability and the ability to hold an edge.
Click to expand...

I agree with this totally. For cutting fairly tough materials at work (plastic skid banding, cardboard, clay-coated papers, etc) I gave up on using a highly polished edge - I was touching it up once or twice a week. Started experimenting using single bevel edges with coarser and coarser grinds all the way down to a 60/80 grit tile setter's stone. While 60 grit makes the knife fairly useless for press-cutting, it'll draw-cut through some very stubborn materials with ease. For cutting sisal or manilla rope it requires less effort than all but the finest honed edge. That knife stays functionally sharp for months on end with no noticeable loss of cutting ability. What I've found with the highly refined edge is that it becomes functionally dull much faster. Once the edge begins to wear it has no tooth with which to keep cutting, and therefore requires a lot more maintenance if it sees a fair amount of use compared to a "toothier" edge.

I do enjoy working an edge to hair whittling sharpness, I have an old Franz Swaty hone that provides the finishing touches after my hard Arkansas stone. I reserve that sort of treatment for my smaller knives and ones that only see the light of day when I'm wearing a suit. For a general purpose knife I don't go any finer than 600 or 700 grit - sharp enough to shave some hair off my arm and stay sharp for long stretches of light, daily use.

This is what I've found, YMMV - use the edge treatment that works best for what you're cutting most often. There are a lot of variables that go into how well a knife performs.
 
For me whittling a free hanging hair is the most consistent and least technique associated way to test for sharpness. I have used it to teach myself to feel the edge for the slightest hint of a burr. If an edge can whittle a hair on one side and not the other, well then you must have a burr. I feel for it with my finger and have learned to detect very subtle differences.

Whittling hair is also one of the least edge thickness dependent tests I know of. A 40 degree inclusive edge will whittle hair just as easily as a 20 degree edge.

At first I was only able to whittle hair with an edge polished on an ultra fine ceramic stone. But with practice I have learned to maximize the polish I can achieve with an extra fine DMT hone (1200 grit) and now can quite consistently whittle hair right off the diamonds on just about every steel type and hardness I own.

To me it is not a stunt at all but I good way to learn to become a better sharpener. And yes, of course, YMMV.
 
Mannlicher said:
Having a knife that sharp, can compromise durability and the ability to hold an edge.
Click to expand...

That is not true at all. Infact it is quite the opposite. If your knife edge becomes weaker with fine polishing, you are not sharpening correctly. Folk's first mistake is thinking they need to alter geometry to get razor sharp. When they work at a hair popping edge, they unknowingly lower the angle or they do not remove the wire edge completely.

You have to understand what is happenning as you sharpen. Things are happening at a scale that the human eye cannot pick up. You have to go by feel and more importantly... know what to feel for.

If you are serious (and perhaps a little obsessed) about sharpening. I recommend getting a jeweler's loupe... Then you'll be able to see what's really going on.

Rick
 
I like the way Magnusson thinks about sharpening. I use a jewelers loupe when honing my straight razors. A well sharpened straight will top hairs without the hair even moving. I have never needed a knife this sharp. Usually only go to a 1200 grit diamond and then strop on the cardboard backing of a legal pad. Gives a great working edge for everyday tasks.
 
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