How does sharp feel?

G

GarageBoy

Joined
May 23, 2003
Messages
5,952
Is it a biting sensation? My sharp Calypso Jr feels different from an equally sharp Camillus Sizzle
 
How do you know they are equally sharp? I'd say they aren't if they feel different.
 
Having the edge sharp means that the knife is sharp. ;)
However, there is a very different feel of a blade sharpened at 20 degrees per side as opposed to one sharpened at 15 or 12 etc. They can all have perfect edges, but I think the feel depends on the edge bevel angle. The smaller the bevel angle (or thinner blade or back-bevel overall), the sharper the knife will 'feel'.
 
There are different kinds of sharp. If you polish an edge with fine grits, you get a razor sharp that will push cut but may not be as effective on coarse materials. If you stop at a coarser grit, you will get an edge that slices better, since it it acts like it's serrated on a microscopic level.

The razor may feel sharper, and dig into your finger if you touch the edge, but the toothy edge will cut in at least as deep if you run your finger over it.

For real work, a razor edge may act like a wire edge and have a tendency to roll over while a more obtuse and toothy edge will continue cutting even after it dulls somewhat.
 
Garageboy,
In my experience with the blades I own, the 'feel of sharp' varies depending on the abrasive grit size. My chef's knife, EdgePro sharpened on 600 grit feels sharper that a S30V custom blade with a 12,000 grit , .3 micron mirror edge.
 
It may be related to grit size as well, but I have two blades, exactly the same, and sharpened the same way, but one is 40 sharpmaker and the other is 30 sharpmaker. Same level of finish on the UF 204 stones, but the 30 definitely has more 'bite' to the feel.

It could be that at a thinner edge, the same microserrations are more effective and give more bite. So maybe it's both. :o
 
I'd say sharp feels kind of rough, but smooth at the same time. It's a hard question.
 
Tap it against your leg or arm very lightly... sharp feels like stinging and a tiny cut.
 
i think you'd have to define "sharp" before you can decide how it feels. to me, a number of things can be sharp, and they all feel different. serrations, polish, etc. will all affect how something "feels" but don't necessarily determine it's sharpness.

abe m.
 
It's really hard to feel how sharp something is. One thing you can do is hold the blade so the edge is facing upwards and run the barrel of a plastic pen down the edge. If the blade is sharp and free of nicks the plastic should glide along freely. If it drags or feels gritty, then something isn't right.

With straight razors they say to moisten your thumb and lightly press the pad of your thumb against the razor's edge and slide it just a bit to feel if the razor bites or not. This is just something that takes practice and experience. Chefs who cook steaks can press on the steak to determine if it's well done, rare, etc.

For me I just see if it shaves my arm hair well. If you're going for extreme sharpness you can see if it will catch and cut your arm hair above skin level. I can do this easily with my straight razors, but it takes more effort to get a knife to do this.
 
I assume that you are scraping your finger tips across the edges to feel the sharpness. The sharp feel is largely drag as the edge trys to skin off your finger prints. A coarsely sharpened edge will have miniature teeth that will snag on your skin and finger prints and will feel sharp. There is some reality to that feeling since those same teeth will cause the edge to slice well. A smoothly honed edge will not feel as sharp until the apex of the edge is very fine. It will drag as this edge catches a wider bit of skin and tries to slice it off. Assuming that you are careful and holding the blade almost flat against your skin it will not actually dive in and slice off your finger prints. Particularly if the blade is not thin and/or hollow ground like a straight razor the skin will roll off the edge. If you do have a blade that approximates a straight razor it is dangerous to try feeling the edge in this way. The edge and the region behind it are so thin that the skin can catch on the edge and the edge will slice surface skin. If you have the blade spine tipped up too high or if you have a slight bit of crosswise slicing motion the edge will dive into your skin.

The differences in feel relate to these different behaviours. A coarsely ground edge will have sort of a uniform drag that is less sensitive to angle. A very fine edge that is honed at a steep angle will not give as much drag. A very fine edge that is honed at a lower angle will drag with a little bit of slip-and-stick oscillation. If that same edge is stropped to be a little finer it will have a more distinct drag but still feels sort of scratchy as the edge catches and slips. This is a little like you are feeling the edge go over the ridges of your finger prints. If you try feeling the edge of something closer to a razor (a very fine edge and a very low bevel angle) the edge will distinctly catch on your skin. It may shave off a little surface skin. It has a more pronounced catch and slip. It feels a bit more like a scratching process. If you do it wrong you will draw blood.
 
Ok, how does DULL feel then? My definition of sharp is shaves and blasts off hair. My Opinel and Spyderco feel the same, but the Camillus was done on a high grit buff wheel. I can run my fingers safely up and down the edge
 
You describe how they feel and we'll try and guess what you are sensing. Which one feels more like it wants to bite into your skin?
 
GarageBoy said:
Ok, how does DULL feel then? My definition of sharp is shaves and blasts off hair. My Opinel and Spyderco feel the same, but the Camillus was done on a high grit buff wheel. I can run my fingers safely up and down the edge
Click to expand...

Will the Camillus shave hair? Try the toilet paper test on your knives to judge how sharp they are. :)

tp_slice01.jpg


On my scary sharp blades I can run my finger along the edge and it just kinda skates a long. This is probably because the edge is less toothy and is more polished, so there isn't much to snag my skin with. A rougher edge would probably be more apt to bite in.
 
for me, sharp is when you feel the edge 'grab' when you pull a finger across the blade (as opposed to down the blade which could give ya' a nasty cut).
 
The Calypso Jr feels like it's gonna slice my fingers off (Paper Cut feeling) The camillus just feels smooth. I'm going perpendicular into my thumb
 
I would guess that effectively the edges were honed (or at least finished) at different angles. The CJ is a full grind and is easy to hone to a low angle (little material needs to be removed to hone at a low angle and reach the edge). Either you or the factory did a good job of honing this blade to a fine edge at a low angle. The Sizzle is a sabre grind which slightly increases the angle of the primary bevel. My experience with Camillus is that they keep the blade thicker right behind the edge than you would find on a CJ. This pushes you to hone the blade at a higher angle than the CJ. The buffing process will give you a bit of convexing which will further increase the bevel angle right at the edge. I would guess that your hair is a bit easier to shave than some of us old timers. By my way of thinking the CJ is just plain sharper than the Sizzle.
 
You must log in or register to reply here.
Back
Top