test sharpness

[RescueRiley]

Looking for some new ways to test the sharpnessof my blades after sharpening..I used to do the shaving test but I'm starting to look like an olympic swimmer, and THe Mrs is getting annoyed by the random bald patches.."All or nothing" she says... Lately I've been holding a sheet of paper by the corner and seing if the knife will slice instead of tear..Any other suggestions?

 

[BarberFobic1992]

press it down against several sheets of news print without any slicing motions.

 

[sasha]

I check on the news paper, When i think its sharp enough. I would cut a tomato, you can see if its realy sharp or not every easy.. Im not sure if it would work on thick knifes. As all my knifes are on the thin side..

Sasha

 

[siguy]

a test used by woodcarvers alot is taking a piece of soft pine and making a cut across the end of the grain. if it slices cleanly, it is sharp. if it tears or you can see little lines, that means that the knife is dull or it has nicks in the edge. i do this sometimes.

i would say fuzzies, but i have done a test where i took a knife and dug a hole in the ground, and stabbed it into the sand several times until i could see light along the entire length of the edge. then i made a nice couple of fuzz sticks with it, just because it has thin edge. so that's not really a good test.

i would say the newspaper test is also a good one, it will tell you if you have a sharp edge or not pretty well.

 

[Jeff H]

a test used by woodcarvers alot is taking a piece of soft pine and making a cut across the end of the grain.....

That's a good one, Siguy.

If I get a glass-smooth, glossy surface when cutting cross-grain on softwoods, it's as sharp as I need to get it for just about anything but it's a long way from any form of compromise - it's SHARP. It works on harwoods but it's more difficult to hold the workpiece and tool steady when applying the extra pressure required. Using a properly tuned chisel, with its flat back against the workpiece (for stability) one can shave see-through shavings off the ends of protruding dowels or tenons but, with a knife and its "two-sided" edge, you're best off using softwood becasue the force required allows you to do it "free-hand."

Depending on the edge geometry and the profile of the rest of the blade, starting on a corner, you can slice a 3/4" x 3/4" piece of Pine or Cottonwood in two - on a bias, and get that satiny smooth surface. Paring thin shavings across the grain without the edge chattering or the "chip" crumbling is just fine though and works for thicker blades of various grinds/profiles. Don't let a chip that looks segmented, or jointed, fool you. That comes from the part of the blade AFTER the edge which is bending the chip away so far that it breaks the fibers in the wood. Your knife can still be VERY sharp and not cut thick wood shavings for beans because of an obtuse edge.

 

[ejes]

How about using just one hair and shaving a little piece off? (Yep, that is my cheap CRKT Prowler!)

 

[coote]

Dang!!

 

[theonew]

My Aurora never goes to the woods unless it can do this:

 

[Bushman5]

Bah! i see your sharp knives and raise you a 3120XP husky chainsaw!

i wil admit shaving hair into two or mroe pieces impresses the hell outta me......

 

[nick-nack]

I just use the paper slicing test - but i do it really slow. You see people just whip through them but if a certain part of the edge is dull or nicked and you slice quickly it will just skip over it/ If you do it slowly you can tell exactly on the edge it needs attention.
You could also step it up by using thinner paper - magazines, newspaper, cigarette paper.

 

[baldtaco-II]

I feel for the catch on my thumbnail then move on to cigarette paper held in one hand 'twixt thumb and finger. After that it is on to bacon skin. If it is has enough bite to whip through greasy bacon without dragging yet still cleanly slice Rizla paper held like that I'm happy.

 

[Joel Stave]

Toilet paper (unused). If a knife can cut a single-ply piece of toilet paper, it's pretty sharp.

 

[stephanfowler]

free hanging paracord or thread can be pretty tricky but doesn't test for nicks.

kleenex will drive you absolutely batty unless you get the entire edge bevel to a very high polish.

Leather with a push cut will help you figure out edge geometry

tomatoes can be a lot of fun but fairly subjective.

shaving hair is nearly useless as a standard test but still fun

shaving slices off of copper wire will show you edge durability

 

[Vivi]

Hair whittling and newsprint push cutting are what I do if I'm running out of convenient patches of hair to use

Slicing paper is good for checking sharpness along the entire length but slicing paper in itself doesn't require much sharpness. Even push cutting newsprint can be done with knives not sharp enough to whittle hair.