What's your telltale way of knowing sharp?

Not my only way but I do enjoy watching shrink wrap "melt" away from the blade. It seems to part with fear at the approach of a sharp blade - not unlike Matt's spring loaded paracord.
 
I let the knife, lightly held in by forefinger and thumb, and blade 90deg to horizontal, rest on a finger nail that's at a 45-60deg angle.
I test the edge along a few spots that I know might be iffy.
If it 'sticks' without slipping, it's sharp.
If it slips, then I inspect for any flat spots before rectifying it.
Arm hair does get used for purile entertainment as well.
 
I am certainly not a "sophisticate" as to how sharp the edge is. As long as it cuts, I'm happy. I generally just rest the sharpened edge on my thumb nail (at a 45 degree angle) and check all along the edge to see if it slips off. If it doesn't, then it's sharp enough for me. If not, I keep sharpening until it "sticks" to the nail.
 
Some great tips guys and it’s nice to see that you can use simple quick ways of checking your edge

@DaveMartell did a lecture at Ashokan one year on sharpening and I noticed him pressing the edge against the edge of a piece of paper as a quick on the spot check to see if the edge would push cut into the paper not slicing which indicates that the edge is at the apex, I do the same using receipt paper
G2
 
Cross-grain receipt paper. Needs to be smooth and swirl cut.

It can be a misleading method as a really sharp burr will pass this test and then dull on harder mediums but I also feel the edge and inspect it and during sharpening I'll often check to see how it's catching on my thumb nail. The trick is to come back to the receipt paper after some use and see how it is holding up.

For my kitchen knives I often use paper towels. Not always but it does make me smile sometimes. :)
 
Gary W. Graley said:
Not to crack open that complete can of worms, as there are tons of threads about how to sharpen a blade along with how to test for sharpness. But one thing that I seem to always fall back on is a quick and simple check to see if I have the edge fully to an apex shape and that's how well it press cuts down on paracord.

If it is sharp, it parts the paracord easily without any extra effort on the spine of the blade, IF the edge is not sharp, even if it slices paper cleanly or shaves hair, the very edge can still not part the paracord cleanly without some extra effort.

My friend Matthew Gregory Matthew Gregory has a video showing some paracord FLYING apart as it is being cut with a freshly sharpened blade, I still think he some how inserted small springs inside the paracord as I have yet to duplicate such a feat ;)

But, if an edge has the tiniest bit of roundness at the apex area, it will just dent the paracord, so for me, this has lately been my 'test' to see if I have the blade done.

I don't have a video of my doing that, but I did have this video showing opening a folder one handed and then slicing cleanly down through some paper, it's a Boker folder and lemme tell ya, it is one sharp cookie!!!


So, what are your benchmark ways of knowing you are done with sharpening a blade??
G2
Click to expand...



Had to dig around a bit to find that one! Hoping this link to Instagram works, because I must have deleted the original from my phone, and can't upload it to YT...



https://www.instagram.com/p/B4pYBOIDndi/?utm_source=ig_web_copy_link
 
For those who shave their arms. You could be opening yourself up for a nasty infection like MSRA. I don’t even shave my face anymore.

Somewhere I read a bulletin sent out to fire stations telling the chiefs to tell the guys to stop shaving their arms. I guess that’s a thing now? Among the younger body builder types and it was causing a spike in those type of infections.
 
Thumb or fingernail "test".
With just the "weight of the blade", while holding the blade vertical, if I can angle the thumb or fingernail to 60° ~ 70° or more before the blade slides off, I consider it "Sharp enough".
(I hold the knife fairly loosely by the rear bolster or pommel when "testing")
 
I like the 3 finger sticky test that many knife makers use.

I can have hair whittling, receipt paper shaving/push cutting sharp edges that don't quite have that bite when moving three fingers horizontally with the edge. Very lightly. With some shaving sharp, polished edges, I can use a bit of pressure and the edge won't bite into the fingers. When I go back and get a real clean apex, the edge wants to cut the fingers with no pressure/movements. It literally feels sticky to the fingers. Many edges that feel very sharp when you run your thumb 90 degrees to the edge, won't bite when actually moving in the direction you would slice with.

Jason Knight has a good video showing this test.

Always, always, shave the hair on the back of my hand in both directions. If it won't effortless, with no pressure, jump those hairs off, it needs more work.

idPnMam.jpg


Whittling free hanging hair is another fun test.

UFyb4Ha.jpg


If it only does it on one side of the edge, you need to get rid of a wire edge.

For phone book paper, recept paper etc push cut curves, and I also like to roll, or bend the paper and see if it will push cut and slice into the roll/bend.
 
Last edited:
afishhunter said:
Thumb or fingernail "test".
With just the "weight of the blade", while holding the blade vertical, if I can angle the thumb or fingernail to 60° ~ 70° or more before the blade slides off, I consider it "Sharp enough".
(I hold the knife fairly loosely by the rear bolster or pommel when "testing")
Click to expand...

That's it for me, also.
 
The 3 finger test isn’t for everyone as there is some inherent risk involved:), but it does provide feedback about the type of edge you have
Jason Knight‘s video refers to the test that Murray Carter describes here




G2
 
Last edited:
After the stones but before the strop, a notebook paper cut test to make sure I've apexed. After stropping, slicing receipt paper with little conscious effort, then seeing how much irritation I feel from shaving leg hair.
 
Aside the paper tests I see a lot of similar approaches here.

Staring at a cutting board for 30+ years taught me this: If a blade bites or slices into a tomato or bell pepper by sliding it across the skin with only the weight of the blade, then it's a working edge for me. Same for a 10-inch Chef's knife or a 4-inch parer.
 
You must log in or register to reply here.
Back
Top