Clay,

I have found that going with higher grit stones (i.e. 10k and up) give a "damped stroke" and produces a keener edge (IMHO). Also, keeping them damp with DI and clean helps tremendously.

mark76 wrote:


I think the difference is in the hardness of the abrasives and how they're bound in the matrix.

Here is the knife sharpened with the 3k Chosera stones and then stropped lightly with the 1um diamond and leather strops:


Zoom

All the chatter has been eliminated and I can run the sharpness tester along the edge and feel no bumps at all. It is scraping reeds exquisitely and although I have no real experience with reed making, I can tell the the control reed makers will have is very fine.

Overall, I think the Rigotti knife I got to play with has some flaws in the heat treatment making it very brittle, especially in a one inch section along the middle of the blade. Using the Chosera stones, I was able to overcome the problem and create a very straight, refined edge.

Actual Reed knife talk!!!

The diamonds cut through the steel MUCH deeper than the Choseras in general, and the Rigotti knives aren't very hard to begin with (they are a standard beginner's knife), so lower grit diamonds plates were pure overkill in this situation.

While it is interesting to see the differences in performance between the diamonds and Choseras, the edge shouldn't chatter based solely on the use of the diamonds or ceramics vs. the Choseras...

In my experience, the chattering is a combination of the thickness of the blade at the edge being too thin (usually a full hollow ground straight razor), and the edge shape and angles being off. Rigottis usually have enough meat, so it must be an angle thing.

I just looked at my Rigotti hollow ground, and the "resting angle" is about 20 degrees per side. I used the angle cube to check what "my" angles would be, and they work out to be about ~23 and ~27. If you wouldn't mind, go back to the diamonds with the right hand paddle at 27 degrees and keep the left hand one at 23 degrees. If you do a bunch of light alternating strokes and end with the right hand, it would be what the edge would look like after using the WEPS.

In retrospect, when at the IDRS show, I suggested 21 and 23 degrees to Robert, and he ran into a similar problem, and the only solutions were the steel was crap, or the angles were too low. We were on opposite ends of the room, and I didn't get enough chance to play with it or focus on it. Thanks for looking into it more, Clay!

I used the 23/21 degree profile and checked the edge with a 60x loupe throughout. It was very easy to see where the metal was coming off in chunks with the diamond and ceramic stones. It was interesting that effect always occurred within the same 1" range of the blade - the blade on either side of that one inch section didn't experience any of the micro-chipping. I could clearly see that I was reaching the edge with each grit and watched hunks of metal continue to peel off. The Choseras cleaned up the chipping right away.