There was also some feeling of roughness when I ran the 8k stones over the blade.
OK- if you felt ANY
bumps on the 8K it was contamination for sure. Also, if you use a very coarse lapping medium on the 5K and above, it makes the surface of the stone feel quite rough (but it won't leave scratches like the previous picture). I suggest using your 600 or 1,200 diamonds to lap those stones.
That's more like it!
I've found that even if things look really perfect at the 1K, 1500 and 2K levels, they still mask some of the deepest scratches, which the 5K exposes.
On the 15K. You will see scratches. I've wrestled with those scratches that seem to appear from nowhere for a while and what I have unofficially concluded is that the metal shavings that come off on the stone from the 15K cause them. On straights, you don't see this because there is little to no swarf buildup. So I suggest keeping the 15K as clean as possible and only use light strokes.
All this magnification does bog us down sometimes, but it really helps improve your game. Either way, those beautiful pics of the finished edge speak huge volumes. Excellent work, Clay! (as usual!)
Thanks Tom. I felt pretty certain about the contamination. I should have wiped the plate off before setting them down. I generally lap them together which works really well. If (as was the case today) the coarse stones have a good sized dish in the middle, then I'll use one of the diamonds. The 120# dish really quickly, so to flatten them, I used the 100 Atomas until most of the gap was gone and then lapped them against each other until they were perfectly mated. You can see how I did exactly as you described when I went to the 15000# stones and pressed a little harder than I should have and put some new scratches back in. When I did that, a question came up for me - what is the friability of the Shapton abrasive? What makes me ask is that I'm fairly convinced that the scratching occurred as I let the end of the stone pass over the bevel. Mostly I work in the center of the stone, building up a nice slurry, but I did a few upward strokes in which the last .5" of the stone passed over the bevel and I could feel that it was a little rougher. My theory is that the abrasive in the middle of the stone and slurry is more broken down and when I run off the end of the stone, I'm getting into abrasive in the larger, original grain size. What do you think?
I can't seem to say enough how much I love both the Choseras and the Shaptons. I did not expect to be quite this thrilled!
Edited by clayallison on 08-26-11 05:04.35. Reason for edit: No reason given.