How sharp is sharp enough?

We've had some more recent traffic about knife sharpening, tools for the occasion, and what is possible for the average person.

There've been a few occassions where I've been able to sharpen pocket knives to rival the finest scalpel edge. It takes me a while, maybe even longer than most, and sometimes I need special tools for the job, but I know it can be done with nothing more than a good set of stones, a little spit, and some elbow grease.

From about 9 years old on, I've been able to keep most all my knives sharp enough to cut hair off my arm. Not what I'd call shaving sharp, but always sharp enough for any and every task I've ever needed. I've used stones, spyderco ceramic sticks, Lansky type sharpeners, diamond wheels and belt sanders to get what I consider an acceptable edge. I've also used those carbide and ceramic draw-through sharpeners that everyone seems to consider mostly worthless, and still been able to get a fairly dull blade sharp enough to cut the hair off my arm as well.

I can get a small diamond stone of suitable grit for about $5, and if I work at it for about 5 minutes from butterknife dull, it will do what I need. I can get one of them carbide/ceramic draw through sharpeners for about $3 and get that same butterknife to about the same sharpness in about half the time.

Now my wife can't sharpen a knife using any tool I can put in front of her, except for these draw through types. This leads me to conclude that although they aren't perhaps the most desirable sharpening device for those of us who can get a hair splitting edge with a $2,000 set of Japanese water stones, it is a fairly practical, foolproof device for the average Joe. The Carbide cutters can be a bit hazardous on making a fine edge if you don't know what you are doing, or get a little too zealous. They also don't seem to work quite right with certain types of blades, but for my $40 stainless Ka-Bar folder, they seem to do okay. For getting a dull edge up to angle quickly, the only thing I've seen go quicker is a diamond wheel or a belt sander. Still, for those too averse to use them, you could just use the ceramic stick type draw through and probably achieve decent results without worrying too much about chipping up the edge.

From a survival viewpoint, I like that they are cheap, functional, small, durable, and easy to operate. I wouldn't really want to consider toting around a Spyderco or Lanski in my EDC, though the small diamond stone I have is as portable as the little draw through tool is. I've also got a little pensized diamond stick that is awful handy, but easily misused, as I discovered when my daughter tried to use it to sharpen a fishing knife.

I've never found much practicality in getting most knives sharper than what it takes to cut the hair off my arm. If so, then I go to my xacto or razor blades and use them for the surgical work I am about to undertake.

I agree with you. I know that a lot of people that are experts at sharpening will laugh at the carbide and ceramid draw thru sharpeners, but I have one of those yellow plastic ones (Smiths) that sell at Wallmart for less than $3 and I have fine results. Besides when I go hunting I carry one in my pocket, for a quick touch up if the blade goes dull.

I have a Double Sided Diafold. The coarse side for my hatchet, and the fine side for my knife.

I've never found the need to shave my arms in a survival or normal outdoor activity. There is an apocryphal folkstory about Richard III meeting Saladin. Richard drew his great sword and cut an anvil in half. Saladin tossed a silk cloth in the air and let it float down over his scimitar, cutting in half as it passed. Both blades apparently did adequate work killing people.You can read the fantastic efforts to sharpen blades online and how they actually lose the ability to cut cigarette papers when to sharp, another activity I've never pursued outdoors. I expect someday lasers will replace knives, flashlights, fire starting devises, emergency signals and firearms. I am equally convinced there will be a forum devoted to tweeking them and complaining bitterly about their shortcomings.

I figure if I can push cut newspaper than I am sharp enough for sport knives, for kitchen knives I usually try to get them razor sharp.

www.lasercommunity.com/

But seriously. One of the things I learned this year is that there are different kinds of sharp and not all kinds are good for the same things. My pocket knife is sharp but I wouldn't shave with it...a straight razor is sharp...but if you used it as a box cutter you'd ruin the edge instantly. Knowing all the different types of edges, how to create them, and what works best for what is what separates a professional knife sharpener from a guy like me...I still sharpen my own however even if the results aren't always spectacular.

I like hair shaving sharp, but as long as an edge is sharp enough to allow me to do whatever it is I want to do, I am happy. Don't really care what I used to get it that sharp. Lately I am using the mousepad/wetdry sandpaper thing with great sucess...

My functional requirement is tomatoes. Except for a straight razor, I don't shave with any of my knives, but I do slice tomatoes (and other food). Now it's not really a convenient gauge to carry around with you, so I do have a bald spot on my arm. But if there's one task I can think of that really requires a sharp knife its slicing tomatoes.

Unlike the oft-misused "LOL", that truly had me laughing aloud "LA" !!! I think there'd have been less double-takes if Benjamin had written it correctly as "pen-sized"

((( )))

I too am a wet/dry sandpaper guy, and I like them just as sharp as I can get them....however sharp or dull that is.....

Now where'd be the fun in that?

As I don't often carry ripe tomatoes with me, and I know that what cuts the hair off my arm is sharp enough, I do have need for cutting hair off my arm in a survival situation when it comes to sharpening my knife back up out in the field. Just me.

Good points. I have a couple of Sharpmakers scattered around, and that's what I use ordinarily. I like to keep my knives arm-hair shaving sharp. It's easy to do with that system and that's sharp enough to do whatever I need.

I also have a couple of the little 3" triangle ceramic rod sharpeners I keep in my earthquake bags. They'll do the job in an emergency. Sharp enough to cut what needs cutting is sharp enough.

Kevin B.

I would take it from the other end of the question:
Is it possible for a knife to be too sharp?

My answer is: No.

The practical minimum of sharpness is simple functionalism: Sharp enough to cut what I need to cut without having to spend too much time or effort.

The practical top end is: How much time and effort are you willing to invest into sharpening and/or maintaining an edge on your knives?

That depends. If I sharpened one of my larger fixed blades down to a very acute edge (like a straight razor) it would do fine with shaving, slicing paper, ect. However, the first time I use it to chop/baton or do any other hard use, the edge would become useless. Probably broken, bent, or heavily chipped. How sharp a tool needs to be depends on the application and what the design/materials can take.

"I've never found the need to shave my arms in a survival or normal outdoor activity"

Spotting that someone else has can be useful! In one of Patricia Cornwalls novels her heroine warns a scumbag in a bar that the he'll never make it to his knife, because cops carry guns....

The Sock

I think I've read that scene. Although maybe it was used by another author as well. Just goes to show, if you're a bad guy...wear long sleeve shirts.

When the blade glides through the target like a bird through air, then it is sharp enough.

My favorite test is if I can push it through really thin paper (thin like a cash register receipt) at 90 degrees without slicing and without having to hold both sides of the paper taught. However I only test my pocket and kitchen paring knives this way. My other kitchen knives are designed to slice so I test them by slicing something heavy like several layers of heavy paper.

i wouldn't bet a penny on it me having quoted even the right author. i only read a chapter. but think it was the first of her books about the female pathologist.
The Sock

Most of my field knives are Bark River Knife & Tool semi-custom knives with a convexed edge. I can easily get them sharp enough to shave hair, and they will baton and still be hair shaving sharp.
A leather strop, mouse pad with leather, or some very fine grit sandpaper all that is usually needed to keep the convexed edge as they should be.

I think your confusing sharpness with the angle, and grind profile, which the blade is configured to.

Edges exposed to more impact and used on harder and tougher materials are usually better sharpened at a more obtuse angle and the grind will typically be one which better supports the edge more.

A straight razor is sharpened at a fairly sharp angle and the grind is often 'hollow ground'. The angle means the edge slices the hair with little resistance and the grind keeps the supporting metal behind the edge out of the way of the cut to reduce friction. A hollow ground blade also sharpens more quickly because you have to remove less metal to reform the cutting edge.

The down side of a hollow grind is that the edge is very much sitting out there on its own unsupported and unprotected from lateral forces or impacts when contemplated in cross-section. Straight razors are rather delicate. So much so that simply dropping one in the sink can break off chunks of the edge and require the razor to be reground at the factory. It is hard to find people who know how to regrind and retune straight razors so the cost and shipping can be prohibitive. Dropping or otherwise abusing these units can mean you need to buy a new one. Not very cheap if you buy quality.

A meat cleaver would be ground to much less of a fine angle and usually to an 'axe' grind that effectively surrounds and supports the edge as it absorbs the stress of impact into hard materials.

Neither the angle nor the grind define how sharp a blade is. Sharpness being how mathematically precise and smoothly the angle of the edge is closed.

A knife used to split wood by being hammered on or otherwise being used roughly in tough materials would benefit from a more obtuse edge and a more supportive and impact resistant grind. If your going to use it like a splitting maul it would be best if the grind and sharpening angle more resembled a splitting maul or axe than a straight razor. Once the blade is well configured it would be better if the edge was appropriately sharp. A different issue.

Art, you beat me to it, although I don;t think I would've been able to go into so much detail.

No matter if the knife is hollow-ground, flat-ground, full or partial convexed, or "Scandinavian" ground, and no matter how razor sharp the knife is, edge strength depends on the thickness of steel behind the edge. The actual edge grind is different than the sharpeness of that same edge.

So, if you want a large knife to handle chopping well, you'd probably like to keep the edge grind a little "obtuse", say 20 degrees or more....or less. For a slicing knife, like a dedicated skinner or caper, you might like a nice hollow grind with a 12-1/2 or 15 degree edge...or so. But in either case, for me anyway, I want the edge just as razor sharp as I can get it...and then some. Even on a large knife I might want to use only for chopping.

And one more time another plug for the Bark River and other convex-ground knives. There is plenty of steel behind the edge for any task you assign the knife, they're easy to get *razor sharp*, and, at least with Bark River's A-2 or 12C27 steel, they're quick and easy to bring back the edge after use.

Sorry for stealing your thunder. I have had a good bit more time to play on the computer recently.

I do tend to go into detail. Part of my job is training and I try to assume very little. I never know what people know or don't. So the explanations tend to be longer, fuller and written like a textbook.

I wasn't faulting the detailed post, just commenting that I'm not smart enough to post all the details!