Thread: How do you test sharpness?

Thumb nail and experience.

The first shaving or paring will tell you if it is sharp

After 30 or so yrs I have changed to water stones with a veratis guide and leather strop as the best and quickest way to sharpen.

Don't laugh, but I use tissue paper.
I do all my sharpening free-hand on water stones, and after going through the various grits, I use tissue paper to wipe off the water before giving the blade/chisel a coat of oil. I then bunch the tissue paper into a ball, and lightly swipe the cutting edge across the top of the tissue ball. How deep it cuts in very quickly tells me whether it's sharp, or I've got more work to do. Even dull blades will cut, but the ease and depth of cut into the damp bunched tissue paper is a good indication. Bit gay I know, but it works for me.

Des

The several sheets of newspaper folded several times to make a decent solid rounded edge. If it slices nicely, it is pretty good. If it tears a bit it needs more work.

I sharpen so the edge shaves hairs off my arm like a razor. Then chop into some redgum using a mallet.

If after doing that and the edges still shaves hairs.....then its sharp for me.

Yup but if it wont shave hair, it's not sharp enough. At least if it does that, you know you have crossed the threshold into really sharp territory.

According to Leonard Lee's Guide To Sharpening.

"Quote"
In the last 2000 years, western civilization has used at least three standard references for sharpness. For the first 1,500 yrs, the standard was a serpent's tooth. As serpents went out of vogue, the expression became "sharp as a tack," a modern equivalent of the serpent's tooth. For the last 100 yrs or more, both "sharp as a tack" and "sharp as a razor blade" have served as standards in every day speech. Since there is little call for tools that just puncture wood, both the serpents tooth and the tack can be set aside as standards in woodworking. The razor blade makes a more useful reference standard.

And then he goes on to show some electron micrographs of razor blades that look anything but sharp...

I just pare along the grain of some clear grade pine, the amount of force will tell you how sharp... the easier the sharper.

I just look at it end-on... any "gleam" on the edge and it ain't sharp enough.

I've given up trying to get an edge that'll split an atom or even only circumcise a low-flying gnat, the slight gain that I get from it just isn't worth the time it takes me to get it there... I much prefer to spend more time using a tool than sharpening it.

Oh Shivers! Lets see how hot this one gets!

I test plane and chisel blades the same way I test Knives.
Take a piece of paper, I use printer paper, run the blade along the top edge of the paper while holding it in the air, if the blade is sharp it will slice off a piece of paper approx 10mm wide with little effort. If you want to compare it to something to get an idea of sharpness, take a new stanley knife blade and slice off a few strips of paper, if your plane iron can slice paper like a stanley knife or razor blade you know it is as sharp as it needs to be.

I'm with Skew, and over sharpening (if that's possible) is probably simply loosing metal.

soth

Hone to a fine edge on an 8000 grit waterstone.

Then hammer into concrete with a sledge hammer.

Then if it will still shave hair off the back of your cat's neck it's prob sharp.

GW

I recon all the various methods of determining sharpness have their own inherant validity.
But, It's the observation and the subjective feel that will tell you what you want to know.
How easily or cleanly it does waht ever it does what ever you do to test your edge.

What is missing is some for of reference sharpness.
The utility kife blade has been mentioned, but they vary from brand to brand.
I would argue that the WISS brand blades are sharper than the stanley branded blades.

Then you will get the 2 billion gritt sharpening looonies who will point out that a utility knife blade isn't all that sharp at all.

cheers