This was a really fun study to do on the Wicked Edge knife sharpener - I started by sharpening a blade to a near perfect finish using kangaroo strops and .25 micron diamond spray. Here is the edge just after the strops:
There are a few small scratches but the bevel is very smooth overall.
Then I created a micro-bevel 5 degrees wider with a set of .6 micron Micro-Fine ceramic stones that I had not previously lapped. Here is the image:
It’s easy to see the micro-bevel and the way the metal has been grooved.
Next I used a set of .6 micron ceramic stones that I had lapped to create another micro-bevel at 4 degrees lower, so just in between the stropped edge and the unlapped micro-bevel. Here is that picture:
You can see the smooth section where the blade had been stropped, then 1 degree wider there is a small band where the lapped .6 micron ceramic stones were used and then a wider band where the unlapped .6 micron ceramics stones were used. Clearly, lapping the stones will yield a more refined edge. I’ll try another experiment soon where I use each stone on the very edge. I find the ridge of metal being pushed toward the stropped portion interesting. I was using edge leading strokes, pushing into the blade and clearly pushing metal back up the bevel toward the stropped area.
You can check out the zoomed images on my here on my blog.
Next, I smoothed out the bevels again in one long gentle arc from 22 degrees out to 30 degrees using the kangaroo strops and .25 micron diamond spray. Here is the progression up the bevel as I increased the angle:
After progressing up the angles again over the 8 degrees in 2 degree increments, I had a nice smooth bevel:
Since I had a nice smooth curve, I figured I could do a few light strokes with the .6 micron Micro-Fine ceramic stones right in the middle of the curvature and get a great contrast between the scratches and the smooth surface:
This is just 5 very gentle edge-leading strokes. Again, it’s easy to see the metal being pushed toward the shoulder of the bevel down in the bottom of the image.
Again, please see my blog for zoomed images. Once there, click on any image to see it in its original resolution.
Very cool Clay - :woohoo:
Did you lap the ceramic with the 1000 grit diamond?
Interesting to see the metal being pushed - now that I’ve seen it I guess I should have thought it would do that since we can push up a burr…
I lapped them with all stones 100#-1000# and the with a 3um bench stone I have though I doubt is was necessary to go that far.
[quote quote=“BobNash” post=4655]Very cool Clay - :woohoo:
Did you lap the ceramic with the 1000 grit diamond?
Interesting to see the metal being pushed - now that I’ve seen it I guess I should have thought it would do that since we can push up a burr…[/quote]
I also learned something about the kangaroo strops in this series (besides the fact that they ROCK!) which is that they work best when they’re slightly damp. I had loaded them heavily a few blades back and they were long since dry. Powder was coming off so I decided to moisten them to make the most of the diamonds still on the leather. I used rubbing alcohol since that’s what I had on my desk. The difference was dramatic; they worked much better after I sprayed them. Later, I sprayed them with some more .25um spray which worked just as well. In the past, I had thought that I needed to recharge them almost every time - I realize now that the benefit I was getting from the recharges was mostly from the moisture.
Wow, these are incredible pictures! Your new microscope is definitely paying off . And that convex edge looks terrific. It must be unearthly sharp. I will nominate the third-last picture for the best edge ever to be put on a photograph.
In the second-last picture, where you applied the .6 micron stones to the smooth edge, did you use the lapped ones or the unlapped ones? On the picture their coarseness seems to be a bit in the middle, compared to the lapped and the unlapped ones before. (The scratches left by the lapped stone in the third picture seem very tiny.)
And have you ever compared the kangaroo strops to the nanocloth strops? The kangaroo strops leave a very smooth edge, but the nanocloth strops should not be abrasive by themselves either. And they have the advantage that they do not (should not) round the edge.
Thanks Mark! I used the lapped stone in the 2nd to last and last images. I’m not sure why it looks a little coarser there, maybe because it’s biting into the curvature instead of a flat bevel…
I will be doing a lot of studies with the nano-cloth thanks to a generous contribution by Ken Schwartz. He sent me a bunch of pieces for testing. Right now I’m preparing the samples to get them super smooth so each grit I test will start on a clean slate. It should be a very exciting study!
[quote quote=“mark76” post=4661]Wow, these are incredible pictures! Your new microscope is definitely paying off . And that convex edge looks terrific. It must be unearthly sharp. I will nominate the third-last picture for the best edge ever to be put on a photograph.
In the second-last picture, where you applied the .6 micron stones to the smooth edge, did you use the lapped ones or the unlapped ones? On the picture their coarseness seems to be a bit in the middle, compared to the lapped and the unlapped ones before. (The scratches left by the lapped stone in the third picture seem very tiny.)
And have you ever compared the kangaroo strops to the nanocloth strops? The kangaroo strops leave a very smooth edge, but the nanocloth strops should not be abrasive by themselves either. And they have the advantage that they do not (should not) round the edge.[/quote]
[quote quote=“wickededge” post=4662]
I will be doing a lot of studies with the nano-cloth thanks to a generous contribution by Ken Schwartz. He sent me a bunch of pieces for testing. Right now I’m preparing the samples to get them super smooth so each grit I test will start on a clean slate. It should be a very exciting study![/quote]
It definitely should be. My experience thus far is that the nanocloth strops indeed do not have any abrasive powers by their own. (That probably also means they don’t really help much in smoothing out existing scratches, but I wonder how important that is for edge sharpness - smoothing out these scratches looks great, though, of course.)
The main question I have is how to use the nanocloth optimally effect for material removal. Even if I spray them literally with diamond spray, they seem to remove relatively little material and not have a great impact on edge sharpness. Maybe I’m doing something wrong (like not making them wet - I too noticed some dust) or maybe I use too little pressure.
Hey Mark.
I think the whole point of the nanocloth is that it brings nothing to the party on its own. If we have a substrate that does nothing, then the results that we get are entirely due to the abrasive that is applied. I have a set of paddles with nanocloth mounted on them. I use them with 0.05 and 0.025 CBN. They definitely remove metal. I can see the metal grey ultrafine particles left on the cloth when I use them. I don’t use them any differently than any of the other strops that I have, but they definitely are abrading and removing metal, though at these grits it is a lot like sub-micron polishing rather than sharpening in the normal sense.
The concept of using them wet had not occured to me. I have always applied the sprays and let them dry completely before using them. I will have to give the wet strop idea a try.
I will definitely try. The problem with the nanocloth strops I have experienced is not that they don’t work at all (they get slightly black-ish with metal filings), but that they work so little.
Agreed. That’s why I wondered how they compare to the kangaroo strops, which bring nothing to the party on their own either. (That may not be entirely true; they will probably burnish somewhat, but not abrade.)
Sorry, one of the noobs here joining in the discussion with noob qeustions…
Are you telling me that you took the 100 grit diamond stones and rubbed them together with the microfine ceramics (thereby abrading away ceramic material and roughening the surface) and then progressed up to the 1000 grit doing the same? This seems scary as $h1t to me! LOL I thought the benefit of the ceramics was their super smooth surface? Could you please elaborate on this process or even do a video of this?
It’s pretty common to lap ceramic and waterstones to flatten them out and knock off the high points. I started with the 100# stones in order to efficiently flatten the ceramics and then progressed up through the grits to smooth the surface, ending with a 3 micron bench stone that yields a very smooth surface. I could take it a step further and use some sub-micron diamond spray on top of polished granite but it doesn’t seem necessary - I’m really liking the results I’m getting.
Sorry, one of the noobs here joining in the discussion with noob qeustions…
Are you telling me that you took the 100 grit diamond stones and rubbed them together with the microfine ceramics (thereby abrading away ceramic material and roughening the surface) and then progressed up to the 1000 grit doing the same? This seems scary as $h1t to me! LOL I thought the benefit of the ceramics was their super smooth surface? Could you please elaborate on this process or even do a video of this?
Clay, I suspect many of us can go to 1000 grit diamonds for lapping. Would it be of any use to lap the micro fine ceramics against other ceramic stones for further refinement? Or would this have hardly any effect, since the lapping material is exactly as hard as the stone you want to lap?
Clay, I suspect many of us can go to 1000 grit diamonds for lapping. Would it be of any use to lap the micro fine ceramics against other ceramic stones for further refinement? Or would this have hardly any effect, since the lapping material is exactly as hard as the stone you want to lap?[/quote]
I think the surface finish you’ll get with the 1000# diamonds is probably more than sufficient. Rubbing the stones together afterward should work well to give a final smoothing to the surface.
[EDIT (8/25/2012): Clay says he may have used the wrong length-scale for this image. See Clay’s update post(s) and my follow-up after this post (in this thread) for the corrected image(s) and number(s).]
Thanks Clay! Very interesting.
By my measurements, that 100 micron line is 476 pixels wide and 186 pixels tall.
Using the Pythagorean Theorem, I get that the line is about 511 pixels long.
So there are about 5 pixels per micron.
The wavelength of visible light is 0.38 to 0.74 microns.
So the wavelength of light is around 2 to 4 pixels!
Sincerely,
–Lagrangian
P.S. Theoretically, the best possible resolution for an optical microscopes is around half a wavelength, which is approximately 0.2 microns. See Nikon’s microscopy website for details. http://www.microscopyu.com/articles/optics/index.html
P.P.S. Clay, if your camera can take pictures which are uncompressed (such as RAW, TIFF, or PNG), then I would be quite curious to examine one or two uncompressed images.
Uncompressed ImageI think I did the last scale incorrectly. Here is another, uncompressed TIFF with the scale added using a much simpler and more accurate method: It’s still been shrunken by Blogger. If you send me your email address, I can send you the full image via dropbox or something similar - it’s over 28 MB in size.
