Forever SC-16WB ceramic knife

I'm not jealous because I don't own a ceramic knife; just of Kwackster's sharpening ability... :foot::thumbup::thumbup::thumbup:]

Wish I had those skills. :(

Great write up and vids. :thumbup::cool:
 
Great job Rob! Love how you have taken the paper wheels to another level :D
 
The knife is still being used in our kitchen in exactly the same way as described in my previous post, and the edge is still able to whittle little curls from one of my chest hairs towards the hair root.
(click 2 x for more detail)





Through my Victorinox loupe i can now spot 3 micro-chips, which can be felt on my nail as well.
However these are not visible with my naked eyes.
 
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After all this testing would you say benefits of ceramic outweigh the attention required, compared to steel?
 
At this moment i wouldn't say that, as i think ceramic knives in general haven't developed as far as steel knives yet.
Most of them are still too brittle and cannot be resharpened by the end user as easily as most steel types.

This particular knife however has proven itself to me already as an advancement over many other ceramic knives, as the ceramic material certainly has a much higher grindability (fact) and also seemingly a higher toughness (assumption).
While that toughness still isn't in the realm of most steel types i do notice a difference in use by much less edge chipping overall, and the chips that i see are also noticeably smaller (i need my Victorinox loupe to spot them).

What is however even more important in my view is that the ceramic material in this knife has a grindability that is more or less comparable to S90V steel, something i discovered when resharpening the edge on my Tormek T7, which is fitted with a silicon carbide stone.
In only a few slow passes i had a completely new edge.
(as a comparison: S90V steel sharpens like annealed 420J2 when compared to a white Kyocera ceramic knife on the same stone)

Now from experience with other ceramic knives i've learned that the resulting edge needs refinement before being used (toothy edges are a no no on most ceramic knives), so that is what i did with the edge on this knife as well (with various diamond compounds), but in a later stage i plan to experiment with less refined edge types a bit to see how these hold up.

All in all more testing is needed to get a better understanding of how the current generation of ceramics in knives perform to have some benchmarks, as i think we will see much more improved types of ceramic in knives (and other articles) in the near future.
 
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The knife is still being used in our kitchen in exactly the same way as described earlier, but the edge has now lost it's ability to whittle one of my chest hairs towards the root.
I tried it multiple times on 3 different hairs, but the edge did not catch any of them even once.

The edge can however still shave the hair on both the back of my hand as well as on my leg on skinlevel, but i have to press the edge on my skin a bit or it will slide over the hairs without cutting them.
If i do that it will shave a patch clean.
It will also slice a piece of copy paper to confetti easily, so most non-knife people would still consider the edge to be very sharp.

Through my Victorinox loupe i can now spot 5 micro-chips, which can be felt on my nail as well.
However these are not visible with my naked eyes.

Will continue to use the knife to see how things develop and report back again later.
 
The edge can now no longer cleanly cut the skin of most tomatoes, and on some types even downright sawing motions don't work anymore.
On onions i can feel that initial resistance cutting through the top layers, but on most other foods the knife continues to work well.
It also still scrape-shaves armhair and slices copy paper just fine, so most non-knife people would still call it quite sharp.

Although focussing with my new USB-microscope is still quite the challenge i did manage to take some shots of the current edge from tip to heel, to show the edge damage in the form of microchips as well as the sharpening scratches in the bevels.
My Victorinox magnifying glass had already showed me the larger microchips, but the smaller ones and the scratches which can now be seen clearly had always remained invisible to me.
It looks like i have jumped the other diamond wheels a bit to soon before finishing with the 1 micron diamond wheel, so apparently there is some room for improvement.













 
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Nice pics and good write-up.

One thing you might try is backlighting the edge for the pics. On a metallurgical microscope I find it adds some depth to the apex, gives a hint as to how crisp it might/mightn't be esp if comparing before and after.
 
That sounds like a good idea, will see if i can tinker something that works with my USB-camera.
It's a nice tool to have, but very finicky in actual use.
 
I've got two ceramic knives, a small pocket knife that I carry occasionally, it's nice because it's very light but I'd never want to really count on it. I have a kitchen knife that's been lightly used and I've already notice small nicks on the edge. I have the capability to sharpen it but have decided not to bother, I won't be buying any more ceramic knives.
 
For USB scope work, I like to set the bevel parallel to the scope lens and use a collimated light source from off to the side to bounce light off the apex for the best view of what's happening there. This results in a darkfield image with only the apex lit up. Here's what it looks like, this is an edge from M2 HSS finished on CBN and diamond abrasives at about 250x - the actual size of the frame portrayed is about 1mm left to right:

 
Here's a link to some edge wear microographs I did a few years ago.

http://www.bladeforums.com/forums/showthread.php/1203862-Edge-wear-micrographs

Wasn't easy, I had to shape a dam for the immersion oil around the edge using plumber's putty to get the 45° images at 1000x.

800_42hc_400x_PP_Scaled_zps994593d4.jpg


800_42hc_1000x_PP_45_Scaled_zpsb3cb0620.jpg
 
Nice HH. I find that if they are lit correctly, shots of the bevel can still be useful, but they need to be lit in such a way that good contrast is maintained or increased. Here are a few examples.

Edge finished on a Japanese Natural water stone:



HSS edge - attempted finish on slurried coticule - extreme carbide tear-out evident:



Another HSS edge finished on Suehiro Gokumyo 20k, again massive carbide exposure due to the abrasive being unable to cut the carbides - perfect demonstration of why HSS should really be sharpened with diamond or CBN:

 
Currently busy removing the microchips from the apex with a Paper Wheel coated with 15 micron diamond compound.
The idea is to finish the new apex with only this compound and then find out how the knife will do with the resulting rather coarse edge (for a ceramic knife)

Although it remains quite difficult to capture the scratch pattern in pictures, the USB-microscope proves to be very useful in showing a sharpening fault (picture 1) and an extremely small chip remnant (picture 2).
Picture 5 also shows that the apex is already becoming translucent with this finish at 25 degrees inclusive.






 
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Before i completely finished the edge to 15 micron i decided to use it just once, cutting up a box of mushrooms, some bell peppers, and some onions on my end grain wooden cutting board.
The 3 pics below show the result: not only microchips, but larger sections of the apex measuring several millimeters have completely broken off.
I think it's safe to say that a 15 micron edge finish is a bit too coarse for this ceramic material.



 
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Bump

This thread really needs to be a sticky in the maintenance forum.
I am begining to look at paper wheels and diamond for sharpening (polishing ) ceramic blades.
Thanks to whom ever it was who showed me his highly polished black ceramic blade he had polished on paper wheels a year ago give or take.
The info stuck with me. I wish I could remember your name to say thanks. If you read this please say hi.
 
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First resharpened the old edge with a Paper Wheel coated with 15 micron diamond compound to get rid of the damaged sections in the apex, then refined it just one step with a second Paper Wheel coated with 6 micron diamond compound.
The new apex can whittle a chest hair towards the hair root (this is noticeably easier than towards the point of the hair), and it also has a little more bite.
Will see how this edge finish holds up in our kitchen, as the knife is already in use again:

 
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kwackster,

Reprofiling the edge on the Tormek silicon carbide stone turned out to be rather easy

Afterwards i did a first refining step with 15 micron diamond compound on a Paper Wheel,

6 micron diamond compound (with a paper wheel)

One of the coming days i'm going to find out if a Paper Wheel with 1 micron diamond compound can improve the edge further.

I have two questions :
First and more importantly are you using a different paper wheel for each diamond grit size ?
Shall I get more than one paper wheel to "strop" my ZirconiaOxide (black Boker ceramic pocket knife)? At this point it is near hair whittling and brand new. I took it from almost shave sharp to shave sharp on wet / dry paper on my Edge Pro. If I get significant dulling or a chip I am in trouble without a power driven wheel.

In the future I may need / want to abrade more aggressively so shall I get the Razor Edge brand set with the Silicon Carbide coated wheel or skip that and get more paper buffing wheels and just put diamond paste on them ?

Is there another brand or paper wheel from Razors Edge that I should be considering ? I have a full speed (~3000 rpm) 8 inch bench grinder (I have more than one actually).

Second question : However I don't have a Tormec. They always seemed to turn too slow for my tastes.
Any reason to go with the Silicon Carbide rather than just larger diamond grit ? The only thing I will use these wheels on is ceramic blades and maybe, that's a big maybe, a S110V and or S90V blade or two.

Thanks
(about to press the buy button on a single paper wheel but will get the two wheel set with SiC if you say that is the way to go).
 
Yes, i do use a different Paper Wheel for each diamond compound (15, 6, 3, 1, and 0.25 micron)

For just your ceramic knives i would first suggest to buy 2 naked & unslotted Paper Wheels, then coat one with 15 micron diamond compound and the other with 6 micron diamond compound.
Use the 15 micron Wheel for ceramic knives that are just plain blunt or have only minor chipping, then clean the blade thoroughly with WD40, then proceed to refine the edge further with the 6 micron Wheel for a very good & usable sharpness (use a loupe)
To finish clean the edge first with WD40 and second under a running tap with some diluted detergent & a soft old toothbrush to remove all traces of the last diamond compound.
In my experience and depending on the quality of the ceramic in your blades (as there are many different qualities) you will be able to reach at least around armhair shaving/treetopping sharpness.
Resist the urge to use your ceramic blades with just the 15 micron edge finish: your fingers may tell you that the edge now has a nice toothy feel to it, but the apex will most likely receive immediate damage upon contact with anything substantial - it still needs refining with at least 6 micron diamond compound to be usable.
Further refining with 3 and 1 micron on Paper Wheels will lead to a even sharper edge that is stronger & lasts longer, but it will also take more time to get there.
Imo the 6 micron finish is a good compromise between usable sharpness & time spent behind the Wheels, and i use it for the majority of ceramic kitchen knives brought in for sharpening.

In your situation and for more serious reprofiling work on ceramic i would suggest that you buy just another Paper Wheel and coat that with +/- 230 grit diamond grit & wax.
By varying the amount of wax on the surface (add some by holding the wax block to the running Wheel or remove some with a steel wire brush) you can adjust how agressive the diamond grit will cut.
I use this exact same grit on a soft Rubber Wheel and it works just fine (on both ceramic & steel), but a Paper Wheel with the same diamond grit would be more agressive (due to the cardboard being harder than the rubber) and faster while still having some degree of "give", something i think is important in sharpening ceramic knives.
I intend to make one or a few of these in a later stadium myself.
 
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