Fun with microscope

jzmtl · **on:** September 19, 2012, 02:53:48 AM

Played with microscope for a while today, the things you don't see even with a magnifier are amazing.

Took some photo of knife edge, unfortunately my camera isn't the best so images aren't as clear as they could be.

At 40x, the knife I have in my pocket, it's a Buck with 420HC, there turned out to be a few microchips deep enough that'll take many sharpenings to go away, not sure how they happened, but guess 420HC isn't particularly tough.

Here you can see the factory hollow grind, the 30° edge I put on with belt sander, and 40° microbevel I finished on sharpmaker white stone.

Now let's take a look at what's probably the sharpest production edge there is, a disposable microtome blade, it will slice single ply toilet paper.

You can see the three grinds, quite similar to a knife if you will, the primary, secondary and microbevel.

Now let's take a closer look at the microbevel, it's very high polished, even at 100x I can barely see any scratch marks. To transfer this to knives, what would you do with a push cutter? Get a fine polished edge. And that's what basically what microtome blade does all day, push cutting with zero slicing.

Unfortunately any higher magnification is useless as the "3D-ness" of the edge makes it impossible to focus on the whole thing, only a very specific point (same with surface of printer paper, for perspective, even though it sure feels flat).

More to come when I think of interesting stuff.

cncguy · **Reply #1 on:** September 19, 2012, 03:55:23 AM

Fascinating stuff! Those are fantastic edge photos!

Mike, Lord of the Spammers! · **Reply #2 on:** September 19, 2012, 07:29:51 AM

Amazing pictures there mate

jzmtl · **Reply #3 on:** September 20, 2012, 01:42:12 AM

Surface of G10, specifically the "natural" finish (as oppose to polished and peel-ply) on spyderco caly 3.5. Each lump you see on the surface is actually formed by a bundle of fiber. The yellow/white color is due to the way I rigged up the lights.

More close up, you can already see that the height difference is causing problem with focus, it's either peak or valley.

jzmtl · **Reply #4 on:** September 29, 2012, 11:45:47 PM

Factory edge on a spyderco from their Golden factory. Notice the waviness of the edge, so it gives you a smooth edge but still bites a little like serrated. As far as I know they are sharpened with 120/150ish belts then directly polished with scotchbrite belt, not progressed through the different grits like how we sharpen manually.

A big chip on a D2 blade, large enough to be visible to naked eye, however notice the small microchip to the upper left, there are quite a few of them. You can also see the edge bevel with deep scratches done with diamond stone, and the more refined microbevel with ceramic/strop.