Ways to test sharpness?

CrimsonTideShooter

CrimsonTideShooter

Joined
Oct 23, 2010
Messages
3,196
Do you guys have any tests that you've come across that you use to see how sharp your knife is? I use the shaving/paper slicing method - but a knife doesn't have to be all that sharp to do that and I think mine are sharper than that. So what can I do to really test it out?
 
If its thicker paper like printer paper you could try filleting it, I usually try to use thinner lighter paper like receipt paper, newspaper, phonebook paper, tissue paper, etc the thinner/softer it is the sharper it has to be to do this. Also if it can shave hair, next step would be splitting/whittling hair.
 
TP is the test, if it can cut it clean it will be more than sharp enough to whittle hair.
 
Try cutting a soft paper like toilet paper. You'll be amazed at just how difficult that is to do. Requires a really, really sharp knife.

ETA: I see Ankerson weighed in just before I hit the send button. I couldn't remember where I learned about TP: it was Ankerson.
 
dawsonbob said:
Try cutting a soft paper like toilet paper. You'll be amazed at just how difficult that is to do. Requires a really, really sharp knife.

ETA: I see Ankerson weighed in just before I hit the send button. I couldn't remember where I learned about TP: it was Ankerson.
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Thanks. :D

Yeah it will tear it to hell if it's not sharp enough and or there are any burs on the edge at all.
 
Ankerson said:
Thanks. :D

Yeah it will tear it to hell if it's not sharp enough and or there are any burs on the edge at all.
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Yeah, I tore some at first. Took me awhile to get an edge that would cut TP reliably. I think you've created either a new standard here or a monster here, brother; not sure which.:D
 
Ankerson said:
Thanks. :D

Yeah it will tear it to hell if it's not sharp enough and or there are any burs on the edge at all.
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Haha I saw your video of you cutting the TP. I just tried it and my leek started to cut it, then bogged down and ripped the paper about 1/4 of the way down.


That's good enough for me. If I ever want my edges to be your kind of sharp I'll PM you and give you some legal tender to do it for me. Haha :D
 
CrimsonTideShooter said:
Haha I saw your video of you cutting the TP. I just tried it and my leek started to cut it, then bogged down and ripped the paper about 1/4 of the way down.


That's good enough for me. If I ever want my edges to be your kind of sharp I'll PM you and give you some legal tender to do it for me. Haha :D
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Yes, it's not as easy as it looks is it? :D

Let me know. :thumbup:
 
dawsonbob said:
Yeah, I tore some at first. Took me awhile to get an edge that would cut TP reliably. I think you've created either a new standard here or a monster here, brother; not sure which.:D
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Not sure which either, all I know is it takes an extremely sharp edge to do it, far beyond hair whittling sharp. :)
 
I don't think my edges are sharp enough for the newspaper (I'll keep trying) but they are often sharper than just shaving hair sharp and slicing printer paper is too easy. I'll often test on newspaper - not just to see if it can cut it but to see how easily and smoothly it cuts it. I can tell the difference in sharpness by HOW it cuts the newspaper rather than just whether it cuts it.
 
Ankerson said:
Not sure which either, all I know is it takes an extremely sharp edge to do it, far beyond hair whittling sharp. :)
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I've been sharpening for well over fifty years, and thought my blades were pretty sharp . . . till I saw your video; then, of course, I had to try it. None of my blades would cut TP like in your video.

Hmmmm . . . can't let this happen, says I, so I went to work on a 8CR14MOV blade, just to see if the steel would do it: it did. It took me most of an evening of fooling around to get it that sharp, and I know it won't hold it, but it was amusing.

I really don't need a blade quite that sharp, but it was fun to do.
 
dawsonbob said:
I've been sharpening for well over fifty years, and thought my blades were pretty sharp . . . till I saw your video; then, of course, I had to try it. None of my blades would cut TP like in your video.

Hmmmm . . . can't let this happen, says I, so I went to work on a 8CR14MOV blade, just to see if the steel would do it: it did. It took me most of an evening of fooling around to get it that sharp, and I know it won't hold it, but it was amusing.

I really don't need a blade quite that sharp, but it was fun to do.
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I'm right there with you, Bob (only 30 years for me, though). And I agree -- I don't need a blade that sharp, but it's fun to do. Most of my EDC's only ever see down to a 600 grit at best. That leaves them plenty sharp for normal everyday tasks.
 
If it easily and safely accomplishes tasks that are required of the blade. That simple. When my potato slicer starts showing resistance when I'm cutting, I'll take it to the stones. Goes for anything.
 
PayetteRucker said:
If it easily and safely accomplishes tasks that are required of the blade. That simple. When my potato slicer starts showing resistance when I'm cutting, I'll take it to the stones. Goes for anything.
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One thing I don't like is a knife that does a poor job, like you say if it easily and safely accomplishes tasks required of it then it is good. :thumbup:

Last Christmas I took my DMT Aligner with me to my mothers place - her knives are blunt junk! I just finished sharpening one when she got another out of the drawer to cut some potatoes, I said "I'll swap you" and gave her the one that I'd just sharpened while taking the other one to get that sharp. My favourite comment was when she first slice a potato with the knife I'd sharpened, she said "Oooooh" - that gave me a big smile! :)

There must be a lot of people like my mother - they buy a knife and use it, when it's new it cuts well then after a while it doesn't. It doesn't occur to them to sharpen it. Then you get us obsessive people that can shave hair and slice newspaper and then wonder if we can get the knife sharper. It's quite a contrast. When I walk into my mothers house the sharpest knives there would be on my SAK & LM Wave, when I leave the average knife sharpness in the house drops considerably! :D
 
dawsonbob said:
I've been sharpening for well over fifty years, and thought my blades were pretty sharp . . . till I saw your video; then, of course, I had to try it. None of my blades would cut TP like in your video.

Hmmmm . . . can't let this happen, says I, so I went to work on a 8CR14MOV blade, just to see if the steel would do it: it did. It took me most of an evening of fooling around to get it that sharp, and I know it won't hold it, but it was amusing.

I really don't need a blade quite that sharp, but it was fun to do.
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It's just another level of sharpness past Hair Whittling. :)

The biggest things are it has to be extremely sharp and with no bur left on the edge at all.

When the edge is really good it won't have any TP on it after cutting through it. That means it's equally sharp down the whole edge, duller spots will have TP on them after the cut. Just another way to tell how good the edge really is.
 
All of my kitchen knives are dull also. I just don't have any quality knives that would hold an edge so I don't even bother sharpening them.
 
Can you guys make all steel do this, even the super steels? I find it hard to get S30V or D2 this kind of sharp. I can give them a mirror polish better then a mirror and they will whittle hair, but toilet paper is tough, no can do. Though I can make infi steel and 1095 do this.
 
Incahiker said:
Can you guys make all steel do this, even the super steels? I find it hard to get S30V or D2 this kind of sharp. I can give them a mirror polish better then a mirror and they will whittle hair, but toilet paper is tough, no can do. Though I can make infi steel and 1095 do this.
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M390, ZDP-189, CPM-154 and the list goes on.
 
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