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The three things that matter in photography of edges
#41
Mike,

Here's what I have so far for photography of your rolled-edge samples.

I labelled your samples A, B, and C, with five inspection sites per sample:

[Image: i-wfFDDdK.jpg]

Here are shallow-depth-of-field side views of all sites, with focus on the edge apex. The top row = sample A, middle row = sample B, and bottom row = sample C. In each row, sites 1 to 5 are presented in order, with site 1 at the left and site 5 at the right: 

[Image: i-QQxQVhs-X3.jpg]

I found sample B to be of the most interest, as the rough texture everywhere on samples A and C made edge details less conspicuous. 

For sample B, here are focus-stacked images of the sites seen from the side and seen from above:

Sample B, site 1:

[Image: i-WnvZMdR.jpg]

Sample B, site 2:

[Image: i-HcL6nfv.jpg]

Sample B, site 3:

[Image: i-28cZhqw.jpg]

Sample B, site 4:

[Image: i-pd3dzkT.jpg]

Sample B, site 5:

[Image: i-jbdVGBg.jpg]
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#42
Those are cool Mr. Cyrano. Thanks for posting and the effort. What is the black line running the length of and in the middle of Sample B, Site 5? Is that a very thick roll that is not reflecting light? Some of those are some gnarly rolls.

Mr. EOU, what were the sharpness readings of the sites and how many roll sets for each sits?
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#43
Very interesting Cyrano and thank you! The story behind Sample B is this Grepper. It was a factory edge but we subjected it to further deburring with a Sharp Pad and took 150 points off the edge in the process so that at point "2" the measurement was 238 and at point "4" 235. Then we rolled a 1.5" section centered at point 2 (5) cycles and point 4 (1) cycle. With post roll readings being "2" = 598 and "4" = 487. 

These are the best depictions of rolled edges we've seen and we're going to have to think a bit about what they mean. In some cases they seem to depict what we would expect and in others not. We'd really like to understand better just exactly what we are measuring with these rolled edges and it looks as if this photographic technique will help. These knives cost $4.87 each at Target Cyrano so please don't contemplate returning them to us.
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