How do you test sharpness

C

culter

Joined
Apr 22, 2001
Messages
121
I'm looking for an objective test of blade sharpness. Any suggestions?

I often shave hairs off my arm as a test. But I feel that depends on the angle etc so I'm not sure that it is really objective.
Also my arms are going bald
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Seek simplicity, and distrust it.
Whitehead, Alfred North (1861 - 1947)

[This message has been edited by culter (edited 05-09-2001).]
 
I usually run my thumb down the edge of a knife, to see if it will grab. Of course, you have to be very very careful or you will cut yourself. Cutting rope is also a good test, however a polished that is razor sharp may just glide over a tough rope, so I guess it depends on how you sharpen the knife for your personal use.

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"A sharp mind is just as important as a sharp knife."
 
i do the same as fish.i have had people wince as if i were going to cut myself, even learned knife folks
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. i feel this is the best test for me. i have a fine touch, and when the blade cuts the outer layer of skin, i grin
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. i have yet to draw blood in all these years with this method.I also sharpen my own blades on stones. 'guess i'm just old school.

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russ aka BladeZealot{former screen name: russ, 850 posts-DEC."99}
a cat almost always blinks when hit in the head with a ball-peen hammer.

to all you cat lovers...does the tail get in the way?
 
Don't know how effect this is in reality, but its served me well. I have a long candle, and when I think the blade is sharp i just lay the edge at an angle against the candle, and push forward very lightly as if carving a stick. If it grabs wax or starts to make a cut then its sharp, if not then I go back to the rods and make is sharper.

After I am satisfied with the wax test I finish off with the old favorite "will it shave my arm hair test", not my personal favorite, but effective
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Dark Nemesis

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Crimson Horizon
Nothing but edge baby...
dark.nemesis@home.com
 
A test that I just recently witnessed was to put the blade at angle on your thumb nail. If it slips right off it is not sharp if if catches and holds then it has a good edge.

This test has proven true so far but I have not tested it on many knives. I have also found that it doesn't work very well on serrated knives.

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Jason Cadden
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Webmaster
Smoky Mountain Knife Works, Inc.
 
this is something I've been interested in for some time now. When I was a kid I just felt the edge like fish. However about two years ago I started shaving my arm/leg. After awhile of doing this I realized that allthough shaving is a good test it's not a good one for the slicing cuts I usually do. So for now I've started feeling the edge again until something better comes around. I also have an edge tester from Razor edge but haven't used it much.
 
I like to dangle a single human hair from a beam and then split it on an upstroke. If the thing doesn't split even all the way then its back to the stones.
Bob
 
They're everywhere-styrofoam coffee cups.
A good, even edge will cleanly slice it, and a really sharp edge will pushcut it. Any rough or uneven spots will cause it to fray or make tiny tears.
Naturally, I shave arm hair (and leg hair when that runs out-just call me "Patches"), pushcut paper, and stuff like that. Fileting notebook paper is a neat trick, too.
 
Here are some objections:
I've heard that going over the edge with your finger is very subjective since a rougher edge might feel sharper than a polished one.

I also use the fingernail test, you can also use any plastic pen, candle etc. That seems rather objective. But I have knives that easily pass that test but wont shave. If it doesn't pass that test I don't even bother trying to shave with it.

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Seek simplicity, and distrust it.
Whitehead, Alfred North (1861 - 1947)
 
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