What is the test of scary sharpness?

D

Don Mega

Joined
Jan 17, 2002
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28
I know you can tell if a knife is dull, medium, or sharp just by running your finger across the edge, but what is the test of an edge being :eek: SCARY:eek: sharp??? I have a blade that I want to keep on me for "just in case" and use my other EDC for utility purposes. I want the "just in case" knife to be as sharp as I can make it, but I don't know how to test how sharp it really is. So I give it to all of you:

1) What is your test of how sharp a knife is?

2) Do you prefer having a blade more smooth by using a fine hone or with larger micro-serrations using a coarse stone for self defense purposes?
 
Try extending your left arm, and with your right hand hold the blade and make a downward slash at half speed against your left forearm. If you have a light cut then you need to resharpen. If you have a deep cut that needs stitches, then your knife is at scary sharp!:D :rolleyes: ;)

Seriously, I always try and shave my arm. If it takes very little pressure then its sharp enough. If I have to apply harder pressure then I know it needs a better edge!:)
 
If you are carrying it for a Self defense "just-in-case" scenario, then you need to factor in possibly several layers of clothing. I have recently sharpened my Mini Commander to a point that it will cut a free hanging hair easily. It pops hair off my arm with no effort at all. However, I have decided to "rough" the edge a bit because if I run the edge along fabric or a towel, it doesn't do a good job of cutting that. In order for a knife to slice real well, especially through clothing, you need to have at least some micro-serrations on your edge. This may mean that the knife doesn't shave hair real well, but it will eat through the layers of clothing to get to the object you are trying to cut. A hair poppin' edge is limited IMO for self defense applications. I'm sure many people will disagree with me, but this is what I have found. You can test it for yourself by sharpening an edge like mad, and stropping it to a point the hair trembles in fear. Then, try to slash through a rolled towel to see how many layers it opens up. You might be surprised (or shocked/disappointed) at the results. YMMV

Mike
 
I'm re-evaluating this, myself.

When I first got my Edgepro I was in my 'tanto phase.' I had quite a few Microtech USSOCOM's, in both lengths, and I polished each edge to a mirror finish. You could cut yourself without feeling it. One Sabbath afternoon two of my friends came over for lunch and I sharpened several knives. We then noticed blood droplets on my white marble kitchen floor. No one felt anything, we had to follow the blood trail!

I use clip points now, and after reading articles by Ross Siefried and reading a few things by Mick Strider, I now sharpen to a toothy edge. It cuts just as well, and the toothy edge grabs slippery or wet items. I'm more apt to put that mirror edge on a knife that's "carried a lot and used a little," like a fancy Microtech LCC.

Oh, and when you do something stupid with a toothy edge, you can feel it. You're still cut really bad, however.
 
First, if you can actually SEE the edge, then it's not sharp enough. After that, I like an edge that, when run across my thumbnail, actually grabs and digs into my thumbnail without any downward pressure. A lot is made of arm hair cutting, but I rarely find it necessary for a blade to be sharper than this.
 
I had a particle beam accellerator installed in my garage. Yes, it cost a lot of money to have the 150KV electrical transmission line brought in, but it's worth it. Now, I mount the knife in the target and send a stream of subatomic particles at the speed of light toward it. If my knife is able to cut the subatomic particles, then it's sharp enough. And, as a bonus, the upcoming issue of Physics Today will feature my article documenting three new sub-subatomic particles that I've discovered within the cut pieces.

:D
 
Gollnick-- the fact that you have to accelerate those subatomic particles to get your knife to cut them makes me suspect that your blades aren't as sharp as you think. ;)
--Josh
 
I would consider this way:
  • It the blade shaves the hair on the forearm with minimal pressure against the skin – it is really sharp
  • If the blade grabs the hair without touching the skin – it is scary sharp
 
Relying only on hair shaving isn't a good thing. You tend to run out of hair after a heavy sharpening session. :D

To test sharpness, I use a combination of:
  • Hair shaving
  • Fingernail gripping
  • Running finger down blade to test "grippiness"
  • Slicing paper
  • Slicing cardboard
  • Slicing into a piece of wood

Of course, something that can push cut well might not excel at slicing. I try to keep my knife just polished enough to shave with some scraping but also slightly grippy so that it can cut into slick things without slipping.
 
Originally posted by Gollnick
And, as a bonus, the upcoming issue of Physics Today will feature my article documenting three new sub-subatomic particles that I've discovered within the cut pieces.
Click to expand...
What are you going to name them? Chuckon? Bladeon? Knifon? :)
 
While I admit to hair shaving, it can be problematic.

I have a Buck 112 that was recently refitted with a BG42 blade, and was hair popping sharp when I got it back. Recently I was teaching knives and knife safety to a group of cub scout leaders. First someone asked about stropping, and I picked up this knife and demonstrated that. Then someone asked about testing for sharpness and shaving, and I tried to do that with the same knife. Unfortunately, it was now SO sharp that it went through the hairs and into the skin of my forearm without even noticing.

Then I got to demonstrate why you have a first-aid kit around while working with knives and foolish kids...
 
Yeah, a few months ago my left arm started looking like a scrawny mutt's leg from all the shaving. So I stopped shaving the arms, but went to the legs. Much better, nobody ever sees, and they sure feel silky smooth! J/K about the smoothness. :) Really.
 
Gollnick,

Join the 21st century. I converted to the Klingon disrupters. True, they're not as ergonomic, nor do they cut as finely; but, they have their own portable power source, and you can get spare parts at any Harley-Davidson shop (that carries panhead vintage parts, of course) or you can cannabalize Massey-Ferguson magnetos.

I'm getting good. I slap some raw munster cheese between two slices of white bread. I hold it in my right hand, drop the sandwich, draw with the same hand and get a grilled cheese before it hits the floor.

Try that with your particle beam thingie!
 
Originally posted by AlphalphaPB
Yeah, a few months ago my left arm started looking like a scrawny mutt's leg from all the shaving. So I stopped shaving the arms, but went to the legs. Much better, nobody ever sees, and they sure feel silky smooth! J/K about the smoothness. :) Really.
Click to expand...

I tried that. The fur on my legs is so long, it takes a while for the patches to grow back in and match.

Not a problem, until my girlfriend noticed. :(

She thinks its funny to say, hey, do you know what Rob does? Look at this! Hahahahah! It gets annoying after a while.

I went back to my arm. Harder to notice, especially if you do it selectively.

I use cardboard a lot. And paper. If you fold a paper towel up enough, its an excellent measure of slicing ability. At least, slicing paper towels. :)

-- Rob
 
If it shaves arm hair, it's sharp
if it shaves arm hair without grabbing skin cells, it's really sharp
if it shaves arm hair without touching the skin, it's scary sharp
if it shaves my face smoothly, it's sharp enough. Edging onto DAMN sharp.
 
-1 finger on the left hand,:D just kidding, when the hair leaps off before the blade gets there.
 
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