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Old 06-22-2008, 08:00 PM   #1 (permalink)
Bart
 
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Default Scratch pattern pictures

I'd like to share a few pictures of the scratch pattern that different hones leave on a metal surface.

I produced the pictures in such manner to maximize comparability.
I have often witnessed that with the slightest variation in lighting direction, a surface can go from seemingly scratch-less to a miniature image of the Grand Canyon.
It really is important that the light source remains at a constant inclination and angle, in relation to the magnified bevel. The striations have to run in exactly the same direction for each mounted specimen. And the photographed surfaces need to be in the same horizontal plane.

After thinking a bit about it, I took an aluminium T-bar, and cut off some pieces of about 1 inch. I placed them on the hones resting stable on two points of contact. I honed each one of them 20 laps on a different hone. I used almost no pressure. Because of the aluminium being so soft, on the two points of contact a bevel developed very quickly. I devised a method to place them under the scope in such manner that one bevel ended up perfectly horizontal, which allows for a clean focus at 40X magnification. (see attached picture)

The tested hones were: A DMT-E (1200 grit), a Belgian Blue Whetstone, a pinkish coticule, a yellowish coticule, a cyanish coticule, and a vintage coticule. I don't reveal which picture corresponds to which hone yet, to allow you gentlemen to make some educated guesses

Bart.
Attached Images
 
Attached Images
File Type: pdf 6_scratch-patterns.pdf (461.6 KB, 439 views)
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Last edited by Bart; 06-22-2008 at 11:48 PM.
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