ceramics

Pressure = Force/Area. Well, for lapping 2 or 8 or 12 sq inches of area, you would need a lot of force. Whereas sharpening contact area usually less than 0.5sq inch.

I think most of the damage done to the diamond plate by fine-ceramic slurry, which dislodge diamonds from the nickel plate.
 
bluntcut said:
Pressure = Force/Area. Well, for lapping 2 or 8 or 12 sq inches of area, you would need a lot of force. Whereas sharpening contact area usually less than 0.5sq inch.

I think most of the damage done to the diamond plate by fine-ceramic slurry, which dislodge diamonds from the nickel plate.
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I noticed, when lapping my small ceramics on diamond hones, it's pretty easy to 'magnify' the contact pressure at the edges/corners of a dished ceramic hone, when they're face-down against the diamond hone. The central, dished portion of the ceramic won't even make contact on the flat diamond plate, so all the pressure is around the edges. The increased 'grinding' pressure can be felt by the fingers/hands at the beginning of the stroke, or when changing directions. The pressure would obviously get a lot more uniform as the dished surface becomes more flat, and therefore more evenly distributes the contact pressure.


David
 
Obsessed with Edges said:
I noticed, when lapping my small ceramics on diamond hones, it's pretty easy to 'magnify' the contact pressure at the edges/corners of a dished ceramic hone, when they're face-down against the diamond hone. The central, dished portion of the ceramic won't even make contact on the flat diamond plate, so all the pressure is around the edges. The increased 'grinding' pressure can be felt by the fingers/hands at the beginning of the stroke, or when changing directions. The pressure would obviously get a lot more uniform as the dished surface becomes more flat, and therefore more evenly distributes the contact pressure.


David
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Good points David!

However one could grow old trying flatten a 8x2 or 8x3 (306UF) using light pressure. But hey a traded time with a couple ruined 8x3 diamond plates flatten M,F&UF stones.
 
Quick question:

What about a belt sander? Granted it would be difficult to make sure it was completely flat unless the platen is 3" by 8", but if it were flat to begin with, you'd just be refining the surface. And no, I'm not talking about regular belts or even diamond belts, but rather something like a felt or linen belt loaded with diamond paste. You can't ruin the belt, and all you'd need to do is reapply the paste.

I also don't think there's really a need to "flatten" the stones, as I understand it would take a few years for it to become anything other than perfectly flat. If the goal is only to refinish the surface of the stones, wouldn't you only need 10 minutes of light scrubbing anyway?
 
I flattened my two Lansky ceramics because they were warped (lengthwise), which impacted how consistently they maintained a sharpening angle on the guided system. I also flattened both sides of a Spyderco DoubleStuff hone, because each side was 'dished' enough that the edges were getting an inordinate amount of contact with blade edges I sharpened on it. Could see the extra wear on the hone as a 'shinier' surface around the edges of the hone. That was impacting the quality of the finished edges, due to the extreme pressure exerted by the very narrow edge of the hone. The narrow width (1") of the DoubleStuff played into it a bit; a wider hone of maybe 2" or more width might not've been so much a problem. With narrow hones, a relatively straight blade laid across it while sharpening often only makes contact on the outer edges of the hone (at the same time), if the blade is very long at all.

Having said that, I also have medium and fine Spyderco 8" bench hones. Both of those are very nearly flat (from the factory), but still show a little daylight underneath a straight-edge laid across them. Edges are slightly raised. That's why I was earlier emphasizing how, if the hone isn't already perfectly flat, only the edges of the ceramic hone will initially be making contact on a dead-flat diamond plate; hence the extra pressure around the edges, and extra wear on the diamond plate.

I don't know how effective a belt sander with diamond paste might be, on a ceramic hone. I'd assume at least, the result may be a somewhat higher polish on the hone's surface. If that's the goal, then it might work somewhat. If one is shooting for flattening, and then finishing at (hopefully) the same effective 'grit' as the factory finish (or coarser), it might be tricky. Pressure exerted by the lapping substrate (affected by softness or flex, or lack of same) will also play into how deep, and therefore how coarse or fine, the resulting 'scratches' in the surface of the ceramic will be. Also how uniform the distribution of the lapping will be across the entire surface. I'm assuming most factory-lapping of such stones is likely done on very hard and dead-flat working surfaces, and under tightly-regulated pressure, in order to ensure the true flatness and consistency of the finished results.


David
 
The machine used to hand sharpen ceramic blades uses diamond powder.

The diamond plate will become ruined because the ceramic is nearly as hard so its causing a significant amount of wear to the diamonds in a short period of time.
 
Anyone have a guess as to what bead blasting a Lansky ceramic might have?

I guess a lot of the results would have to do with which media exactly is used...

I'll try to find that out because I'm going to take my ceramic in to work with me tomorrow morning to blast it just for kicks. Glazed, I have absolutely no idea what grit it might be, but I do know that it would (incredibly slowly) put a very highly polished mirror edge on Spyderco s30v.

I'll do half the length of the stone then take pics.
 
Please do! This has been where my train of thought has been going. I want to see how the roughened surface would effect some of my other experiments. I would highly appreciate seeing those pics and the experience you have sharpening with it.
 
Seeing these posts about the Lansky ceramics reminds me that I need to lap all of my Lansky ceramics. Someone, I have forgotten who, recommended 180 (IIRC) sand blasting media for this task. But, so far, I have been unable to find a store that sells sandblasting media.
 
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fervens said:
Please do! This has been where my train of thought has been going. I want to see how the roughened surface would effect some of my other experiments. I would highly appreciate seeing those pics and the experience you have sharpening with it.
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Okay I just got done media blasting my Lansky ceramic. I took a quick before shot but I'm having trouble uploading to PB right now.

Before blasting the surface was super smooth. Running my finger nails across the surface (very scientific, I know) it almost felt like a very smooth chalk board. That's the best description I could think of.

Now... Well, the blaster here at work uses glass media. Pretty safe stuff. I've blasted several knives and came away with a nice satin finish. The ceramic now feels very aggressive. I'm actually surprised at how aggressive it feels. I have a pic that I'll upload in a bit. Can't wait to try it on a blade to see how it cuts.

I'm wondering what the binder is in these. Almost feels plastic-y?

Pics in a bit.
 
If it's the same as the Lansky ceramic I had years ago, there is no binder when it's finished. The Aluminum Oxide (Alumina) particles are sintered and bonded together that way, like CPM steels, but with more temperature and time.
 
Before

IMAG1616_zps3f05f7e7.jpg


After

IMAG1620_zpsdeed48e7.jpg
 
Thanks for those pics! I have some spyderco pocket stone i'm going to be getting in hopefully and will have to find someone to do that for me. What grit glass did you use? If it's rated that way. Never used glass before. And as far as i can tell, me2 is right. "Ceramics" don't use a binder. Similar to ceramic knives, too. I think ceramic stones have a lot of untapped potential.
 
Duh on the binders! I must have been really tired. ;)

So I ran an old S&W over the ceramic. It's just as aggressive as it looks. I thought that it might immediately level off, but it cuts the steel just fine.

Here's a pic of the edge. I had my usual trouble of getting a decent shot. One of these days I'll pick up the expensive dslr that I bought months ago and put down the phone! :D

IMAG1623_zps85fb6bf7.jpg


I'd say it cuts about the same as a coarse Norton SiC. Maybe even more aggressive actually raising a very quick burr.
 
Keep in mind, that stone would put a very polished edge on a blade before blasting. More so than my 1500 white ceramic. It was rated at 600 grit, but it never cut anything like that.

It's an entirely different stone now!
 
That's a pretty cool experiment, Strig. Interesting how aggressive it became.

Regarding ceramics, I think some ceramic 'stones' use alumina ceramic media (the grit itself) with binders/carriers, and some don't (I'd assume those are the sintered ones). Sal Glesser has hinted at this, in describing Spyderco's stones. He specifically points out the medium (brown) stones as using different 'carriers' than the white stones, which accounts for part of the differences between them (including firing & heat treat recipes and surface finish). Makes more sense to me, as the 'brown' ceramics seem to wear more easily than the others, which I'd assume has something to do with the carriers used (I'd assume this accounts for color difference, as well). In the case of Spyderco's hones, they all use the same exact ceramic media (including the particle size) as the grit.


David
 
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