Thread: Friable grit stones

GREAT picture! Can we all start sending you stuff to capture under that scope????

Here is a set of photos I took last week at 350 power using a EPI lens on my microscope. The photos are in sequence, same stone (green medium hard asagi), same razor (vintage Boker) just going back and forth from stone to microscope. No tricks here and I am always amazed at the cutting abilities of Jnat slurry on fairly hard steel.

Alx

Originally Posted by alx

You can see the false edge (wire burr) folding over this side from the back.

I am curious about what you call a false edge. Although I can't see anything in your image, I know the digital image does not begin to capture what you see looking at the specimen "live" with your eyes. Do you have another image that maybe shows this more clearly?

I would also comment that I have observed that the edge is a magnet for tiny particles of slurry, which you likely cannot distinguish from the steel in an image like this. As an example, I was looking at an edge the other day that had been run under the water tap for about a minute, and then sonicated in solvent and then blown dry with compressed air. Even after that, I could not find a length of clean edge more than a micron or two long without a particle obscuring the edge.

FuzzyChops
Love that screen name by the way.
In the bottom photo at the very edge of the blade it looks slightly blueish and out of focus, this is the false edge or burr that is laying over towards the camera. In the previous photos above this last one, this false edge was laying ever so slightly away from the camera and towards the back, but now since I made some passes on the stone with the the back side of the blade for this photo (taken from the front) the false edge which was before in a neutral position or was laying away from the camera has now shifted over to the front towards the camera and every so slightly out of focus.

Hope this helps, Alx

Originally Posted by fuzzychops

I am curious about what you call a false edge. Although I can't see anything in your image, I know the digital image does not begin to capture what you see looking at the specimen "live" with your eyes. Do you have another image that maybe shows this more clearly?

I would also comment that I have observed that the edge is a magnet for tiny particles of slurry, which you likely cannot distinguish from the steel in an image like this. As an example, I was looking at an edge the other day that had been run under the water tap for about a minute, and then sonicated in solvent and then blown dry with compressed air. Even after that, I could not find a length of clean edge more than a micron or two long without a particle obscuring the edge.

Chops
Can you describe your microscope set up, it sound interesting as well as the sonic bath and forced air to dry.

Alx

Originally Posted by alx

Chops
Can you describe your microscope set up, it sound interesting as well as the sonic bath and forced air to dry.

Alx

Alx,
Here is an example of a wire edge? false edge? that I formed with lapping paper. It is easy to see in the SEM, particularly in cross-section; however, I cannot see it clearly in my optical microscopes. Maybe there is a hint of it when I focus through.

With a coticule edge, I find there are always bits of slurry on the edge that are difficult to discern from the metal in the optical image. I find running water or squirting solvent does not remove them, but sonication does a reasonable job. I do not want to allow the liquid to dry and leave behind whatever was in solution, so I blow it off rather than let it 'air dry' The lapping film leaves a much cleaner edge of course.

FuzzyChops

Really great photos. About the leftover particles, is there a chance that they are magnetized steel filings? Always wondered.

In the above photos I am guessing that the bevel looked shiny. What paper grit did you end with and do you use a progression of paper? Films? Or do you bevel set with a natural like a Coticule and then go to the paper/films?

One more question, have you taken the same type of SEM photos after honing on a Jnat?


Very much admiring your abilities, Alx

Here is about as clear a photo as I have been able to capture of the false edge, an edge that has no strength and just folds over when shaving, or could be stropped off, or gently honed off with ever finer and finer grits. This was created using a faint slurry using a diamond plate on a Nakayama stone.

Originally Posted by alx

FuzzyChops

Really great photos. About the leftover particles, is there a chance that they are magnetized steel filings? Always wondered.

In the above photos I am guessing that the bevel looked shiny. What paper grit did you end with and do you use a progression of paper? Films? Or do you bevel set with a natural like a Coticule and then go to the paper/films?

One more question, have you taken the same type of SEM photos after honing on a Jnat?


Very much admiring your abilities, Alx

On the coticule edge the particles are definitely mica. On the film there are bits of metal stuck to the edge, some diamond and the other dark material is likely resin from the film.

The honing progression was DMT1200, Shapton 2000 , 15 micron film, 3 micron film and then half micron film (all edge leading). The 15 micron didn't do much, as it is slightly courser than the Shapton 2000.
Other than the last 10 microns, the edge was shiny. It seemed that last 5-10 microns of steel bent away from the film and did not polish. The half-micron polished the rest of the bevel, but ruined the edge. This is an image of the edge after the 3 micron film:

I do not have a Jnat.

Thanks, your last image does show the edge more clearly. I will have another look with my optical microscope.