Degrees of sharpness

[JTR357]

Is there a scale or chart describing the degree of sharpness of a blade?

Something like a 1 thru 10.1 being a toothy edge capable of cutting paper & whittling soft wood,5 being able to shave with,& 10 being the most highly polished,sharpest edge possible(tree-topping hair,etc).

Is there a scale or chart for this?Do you think there should be?

opinions welcome


Thanks

 

[jayinhk]

Sounds like a good idea--will it (1) catch your nail, (2) shave arm hair, (3) shave facial hair, (4) tree top, (5) whittle hair.

 

[C.S. Graves]

9 should be sharp enough to perform surgery on individual cells, and 10 should be reserved for atom-splitting.

 

[JTR357]

Good Points jayinhk & C.S. Graves:thumbup:

My first suggestion was a rough example.

 

[neeman]

Start with different bluntness, then a working edge, then off to the esoteric sharpness

 

[FlaMtnBkr]

I think it might be hard to define because some cutting tests I think require technique. Plus blade geometry plays a big role.

I can tree top hair and even cut curls off a hair, but none of my knives can comfortably shave facial hair.

I guess you could label a knife a certain sharpness and compare them to your other knives, but I think another person would probably end up classifying them differently.

 

[Jason B.]

Its too hard to rank, with each grit their are many levels of sharpness and depending on how many grits you use sharpness can vary greatly. One persons sharp is anothers dull.

 

[chococrazy]

Is there a scale or chart describing the degree of sharpness of a blade?

Something like a 1 thru 10.1 being a toothy edge capable of cutting paper & whittling soft wood,5 being able to shave with,& 10 being the most highly polished,sharpest edge possible(tree-topping hair,etc).

Is there a scale or chart for this?Do you think there should be?

opinions welcome


Thanks

This is what I would say.
But as Knifenut said it's not going to be to accurate.
1. Butter knife dull can't cut paper or anything.
2. Tears paper
3. Slices paper
4. Toothy edge capable of catching hairs above the skin, but instead of cutting them it "rips" them out of your skin (these edges are ideal for rope cutting and such, but dull quick).
5. Slightly less toothy edges, no longer rips hair out, but won't catch above skin, but will shave when touching skin.
6.This is to the point where it begins to take out large chunks of hair, and begin to eat through stuff like a champ!
7. This is prolly where stropping comes into play. You have very little micro serrations, and it slices and dices through anything like butter. Shaves well, begins to catch above skin, but won't cut (you can test this by running an edge on top of your hair)
8. Shaves without trouble at all.
9. Smooth edge capable of tree topping (kind of)
10. Hair whittling, tree topping, slicing, micro serrationless edge.
11. Chuck Norris.

 

[Obsessed with Edges]

I like the idea of a scale or chart for sharpness. But, as others have said, there are many more degrees of sharpness. Cutting paper depends on what kind of paper (printer, newsprint, phone book, cigarette paper, toilet paper, etc.), and even the type of cut (push, draw/slice, straight-line, U or S-curved cuts). Shaving hair can be broken down by type & location of hair (I've noticed that my leg hair pops off more readily than from my forearm, and face-shaving is a challenge to do comfortably, even with my razor).

I suppose only the extremes at either end might be the only straightforward part (0 = DULL = can't be batoned through a stick of warm butter, 100 = TRUE SHARP = splitting atoms ).

 

[tnt-user]

1- Double Spine.

2-It almosts cuts butter.

3-Roughens paper.

4-Tears paper

5-Slices paper

6-Shaves

7-Facial shave

8-Hair splitting

9-Fission

10-Not reached by mankind.

 

[Broos]

I would clearly distinguish between sharpness and cutting ability - sharpness to me is best defined by the diameter of the edge. To make a decent measurement of this you would need to have a finely finished edge - the measurement would not be very consistent on a coarse finished edge.

Sharp is cool, but for cutting with a knife I'll take the best cutting knife over the sharpest knife - I think of cutting ability as force (or work or impulse) required to cut. Not nearly as simple for slicing though, where the velocity of the slice and the finish of the edge is critical to a cut (in addition to downwards force).

Conventional cutting ability (as opposed to cutting using nonconventional means like laser or etc.) will reach its zenith when we can make an extremely strong, wear resistant, and rigid 0.5 micron diameter knife blade - that would be a dangerous knife, nearly invisible and no geometry to get in the way!