sharpness test

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nevertakeadayoff

Joined
Dec 10, 2021
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I'm curious how you guys test how sharp your blade is.

I don't do paper because I would require honing again. Need something soft and consistent...

My favorite way is using the inside of my forearm. Should cut me every time after moving only a millimeter. Doesn't affect blade. The only problem is that I look like I have a mental disorder and I'm thinking these might scar. haha
 
Yikes! If you've properly removed the burr then making a few cuts through paper should have almost no impact on sharpness. If you don't want to go there, shaving a few arm hairs would be preferable to cutting your skin! I've got pretty bad sharpness OCD, so I bought a BESS tester. If a blade doesn't come in below 140 grams on the tester it doesn't see my pocket.
 
Crikey, use a tomato, grape, cabanossi - just don't test it on yourself!
Try the finger nail test - rest the blade (just it's own weight, verticallly, loosely hold the handle between forefinger and thumb woth your other hand) vertically on a finger nail that's at 45deg angle. If the knife is sharp it will not slip off.
 
Ruari said:
Crikey, use a tomato, grape, cabanossi - just don't test it on yourself!
Try the finger nail test - rest the blade (just it's own weight, verticallly, loosely hold the handle between forefinger and thumb woth your other hand) vertically on a finger nail that's at 45deg angle. If the knife is sharp it will not slip off.
Click to expand...
I do the nail test all the time. It also helps see if there is a dull spot. I do the paper test too because why have a knife so sharp that you don't want to use it because you're going to have to sharpen it again?
 
nevertakeadayoff said:
I'm curious how you guys test how sharp your blade is.

I don't do paper because I would require honing again. Need something soft and consistent...

My favorite way is using the inside of my forearm. Should cut me every time after moving only a millimeter. Doesn't affect blade. The only problem is that I look like I have a mental disorder and I'm thinking these might scar. haha
Click to expand...
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I use labels from 2L bottles. Once you "calibrate" yourself, you can tell 1) how sharp the edge is, and 2) if there are any irregularities in the apex by how easily and how smoothly it slices the label. You can also tell if you polished too much if it's hard to get the edge to start the cut on the edge of the label.
 
This handy little RazorEdge Edge Tester is safer and more reliable than a finger nail, and only US$10 plus shipping: https://shop.razoredgesystems.com/products/edge-tester

I also use an Edge-On-Up PT50A, which is a very informative device. But it tests only one tiny section of the blade at a time, and different tiny blade sections on a knife can differ greatly in sharpness. For knives out-of-the-box from major companies such as Spyderco and Benchmade, the PT50A measurements (in grams) often vary by 25% or even 50% from the median value of multiple tests. It baffles me that people on Youtube do one test and think that a single number measures the sharpness of the blade.
 
I have a Bess tester, but I don't get it out much. I mainly cut printer and phonebook paper to test edges with. Sometimes I'll use rolling papers for fun.
 
Good suggestions... I'm going with rhino's idea for now.

LOL, yes, I counted 54 cuts on my arm. Looks like a weird rash. But it's simple math:

cutting skin easily = sharp blade
sharp blade = good
pain = good

Who doesn't enjoy some good pain? : )
 
For HD edge testing, I use my 2" HD Poly/Nylon webbing strap tester that I built. I can't imagine a more sickening feeling than someone dying in a burning car because my knife wouldn't cut the seatbelt. I want to make sure that never happens to me.

Strap Holder-8a.jpg
 
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