Wire Edges
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I put a blade I’d previously sharpened under the scope yesterday and got a big surprise. There was an enormous wire edge that had started to peel away from the rest of the material. This was a blade I’d imaged many times and had never detected the wire edge. I believe that why it suddenly showed up is that I had been trying to image straight down onto the edge and the various objective lenses I was using brushed back and forth across the edge as I was trying to find it in the scope. They must have pushed over the edge, which clearly turns out to have been very fragile. Check it out:
A couple of notes:
- The wire edge pieces that are tearing loose measure around 6µ.
- The images are stacked for greater depth of field. It seems to be working pretty well lately.
- At 200x, the wire edge just looks like some debris:
The chips missing from the edge in the 200x image are from where I knocked them loose to give myself a reference point to be able to find the same spot in the scope.
-Clay
This image shows another section that hasn’t peeled away but appears flattened to the side of the blade:
-Clay
Here are a couple more that show where the edge is folding over. There are cracks where I’ve placed the arrows. They’re hard to distinguish in the photos because they look like shadows, creating the illusion that there is a mass of metal that is built up, but it’s very clear in the scope that they are cracks.
-Clay
Quite daunting this. Any idea how this came about? It is my experience that if, with the finder grits, I finish an edge with soft sweeps alternately on both sides I hardly/do not get a wire edge.
Molecule Polishing: my blog about sharpening with the Wicked Edge
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Quite daunting this. Any idea how this came about? It is my experience that if, with the finder grits, I finish an edge with soft sweeps alternately on both sides I hardly/do not get a wire edge.
I think, based on the images of stropped edges at Todd Simpson’s blog, I’d drawn up a very thin edge, stretching the metal until the last 10µ-15µ of the bevel were at an angle that was much lower than what I was actually sharpening at. I really want to study it in cross section to see if I can verify that hypothesis. I’ll mill some sample blades to expose the cross section and then strop them a lot. Then I’ll get them under the scope and see how they measure.
-Clay
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Here are some images from Todd’s blog (https://scienceofsharp.wordpress.com/2015/01/13/what-is-a-burr-part-2/comment-page-1/#comment-559):
“Straight razor edge view after Shapton Glass 8k. Prior to stropping; the razor is not sufficiently keen to shave; however, there is no burr.”
“Edge view of the Shapton 8k edge following 10 stropping laps on a hanging latigo leather strop loaded with 0.25 micron mono-diamond spray.”
“Cross-section view of the Shapton 8k edge following 10 stropping laps on a latigo leather strop loaded with 0.25 micron mono-diamond spray. The foil-like burr is approximately 100nm thick and 3 microns long.”
“Cross-section of the edge after an additional 90 laps (total 100) on 0.25 micron mono-diamond on a hanging Latigo leather strop. The foil-like burr is approximately 20nm thick and 500nm long.”
I think that this is essentially what happened with my blade and when I ran it back and forth and it hit the lenses, the foil collapsed and folded over.
-Clay
Very cool. Just out of curiosity, do you have to manually add the magnification level? For example, in your first post, the 1st image says 2000x, then all the others say 200x, even though they don’t appear to be (and clearly not the same as the one that is 200x). Just wondered. Cool photos though!
Yes, thanks for mentioning it. I have to put input the magnification into the software when I snap the photo and sometimes I forget to change it back, which is the case on these photos. They were all, except the one, done at 2000x.
-Clay
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