Viewing Knife Edges Under Magnification

V

Vivi

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What do you use to view knife edges up close to inspect for edge damage, burrs, finish consistency etc?
 
I use a 3x when I look for edge damage after manila rope cutting tests.
http://www.bladeforums.com/forums/showpost.php?p=5431117&postcount=2

I find that if I use higher magnifications I can only see little sections of the blade at a time.

With a 3X, what I look for is shiny spots. A well sharpened edge will not have any shiny spots under 3X mag. Shine indicates edge damage. If you want to look at a single shiny spot and determine what kind of edge damage is occuring, then it is worthwhile going to a 20x.
 
Since scrounging up an old student microscope, I've found it very useful to be able to examine edges at 300x or so. Most of the time, however, 40x is adequate. The stability of a 'scope with a table, as opposed to a small handheld, makes things a lot easier.
 
I have x400 and unfortunately it is not enough to see edge being rolled out or dulled. Until it is severe damage. It is only thread cutting test can really tell state of the edge. At least this is what I found.

Thanks, Vassili.
 
I use a 25x Micro Mike Handheld Microscope. It's the size of a pen, and has a pocket clip. I bought mine years ago through Brownells, but they don't sell it any more.
 
I have been using a cheap handheld 40x microscope from Radio Shack, but would like something easier to use. I think using magnification can be very helpful to the sharpening process. Not absolutely necessary, but it is nice to be able to see the results of my process rather than just assuming that it is working correctly.

I'd like to get something locally, but have not found a good source for loupes. There is one at my local REI pictured below. Anyone know if this would serve well? It is a Bausch & Lomb 5-10-15-20x loupe and rather large for a loupe. $24.

469328.jpg
 
Radioshack 60x-100x illuminated scope at the sharpening station.

It shows the images inverted, so it's a bit annoying, but an inverted edge laden with burrs is good enough get me back to the hones.
 
It lets you see where the scratches have or haven't gone all of the way to the edge and it lets you see where bits of steel and abrasive are hanging out on the very edge and keeping you from enjoying long lasting sharpness. Beyond that, edges just look cool under magnification at every level of finish and sharpness.
 
Thanks. I look at mine under 10x just to see that the primary bevel doesn't need to be set back yet and I agree, it does look cool. I was hoping that I wasn't missing something important.
 
thombrogan said:
Radioshack 60x-100x illuminated scope at the sharpening station.

It shows the images inverted, so it's a bit annoying, but an inverted edge laden with burrs is good enough get me back to the hones.
Click to expand...

I've tried a couple of those, but at that level of magnification any little bump or shake (or adjustment of the focus knob) moved you well off of what you were looking at. I'm sure something that wasn't handheld would provide a more stable view. Plus, the inverted image wasn't ideal.

Does anyone know what this thing is that Alton Brown used in his "American Slicer" episode? I'm guessing it's a USB connected digital microscope, but I haven't come across one like that. What does something like that cost?



P.S. He's viewing a low-budget "ginsu" knife, that's able to cut through a work boot!! :p
 
I would guess it is a web cam for macro use (for insects, flowers, stamps, coins, etc.). It appears to have a built-in light. It does not look like high magnification based on the number of serrations visible (but I don't know how small the serrations are so maybe it is higher than I think).
 
Lurker said:
I would guess it is a web cam for macro use (for insects, flowers, stamps, coins, etc.). It appears to have a built-in light. It does not look like high magnification based on the number of serrations visible (but I don't know how small the serrations are so maybe it is higher than I think).
Click to expand...

A little later in the show (on a plain edge) he zooms the view in significantly, which I'm thinking was controlled by the computer (not manually).



 
kelbro said:
Excuse my ignorance but what does the enhanced view do for you?
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You can even see the micro teeth that are left in the edge sharpened up to about 500 grit. You can even see how they slowly disappear when stropping such an edge. It gives you a visual idea how such an edge might perform.

The other points Thom brough already up.
 
Here's a couple of closeups at a bit higher magnification than what you're seeing of an edge I did on my sharpening device. It's only 8000 grit, done with a triple bevel at 7, 11, and 12.5 degrees per side on a nakiri I redid. Those big dots are lint not burr, before you ask. If you compare it to the the micrographs of the previous poster, the scratch pattern is at least one order of magtude smaller and you woud be looking at just the edge of the edge of that picture for the lower magnification pic of the two.



ka2.jpg


This last pic is a 'closeup of the closeup' of the edge you can barely see in the previous two pics at the very bottom.

ka5.jpg


They were shot with a digital camera at 4x zoom and cropped and rescaled with a 15x lens attached in macro mode manual focus FWIW. Note the extra smooth scratch pattern and consistency. The final stone used was an 8k GlassStone.

Some digital cameras (as well as video cameras have a video output that lets you use the TV for viewing as Alton has done.

In these pics, moreso in the first you can see the demaration between the core Aogami Super steel and the cladding of the nakiri.

---
Ken
 
ksskss said:
Some digital cameras (as well as video cameras have a video output that lets you use the TV for viewing as Alton has done.
Click to expand...

He's actually got it hooked up to a laptop (note the keyboard), but yes, most digital cameras and video cameras can output to something other than their own screen. So, no one knows for sure what that thing is he's using?
 
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