ceramics

Thanks for the research fervens, That is a very interesting article and answers some questions I have had about ceramic stones. Always wondered about grinding the stones an winding up with a smoother stone than you started out with. My take from what I read just now is that if you grind with a coarse stone, you wind up with a coarser ceramic, and vice versa. Is that the way you interpret it? Of course it is late and past my bedtime.:o

Blessings,

Omar
 
That's pretty much what i see. But i also look at it as if it were a metal file. With spyderco's specifically. You can see the circular saw marks left behind from cutting the stone off of the larger block, and when in use, you see that the metal shavings always collect there. If you milled it like Heavyhanded's WB, you may be able to theoretically make a coarser grit. Literally make the peaks into whichever micron sized peak you want. One of my ideas is to sandblast a ceramic stone to see what kinda of texture/grit rating that would give.
 
Sounds very interesting, keep us posted with whatever your findings are.

Blessings,

Omar
 
Doubt there will be any "findings" anytime soon. Bought a car so the test stones, bead blast chamber and any milling equipment is out of the question. Sticking with theory and research for now.
 
The "saw marks" on a spyderco ceramic are from them lapping the stone. The fine stone is lapped to a UF stone.
 
That was cool!
I have been thinking about getting a set of the Spyderco (M, F, UF) ceramic benchstones. If I did, would I need to work them like the guy on that blog?
 
Squashfan said:
That was cool!
I have been thinking about getting a set of the Spyderco (M, F, UF) ceramic benchstones. If I did, would I need to work them like the guy on that blog?
Click to expand...

Why would you want to mess up a perfectly fine stone?

Besides that you would need a set of diamond stones that would get ruined in the process. I've messed around with lapping spyderco ceramics and the result is never as good as the new stone.
 
I was reading the article in a hurry before I left for work and I thought the author was implying that the stones needed to be lapped before use.

Off topic: Knifenut, do you recommend the Spyderco ceramic bench stones that come in blue boxes?
 
Squashfan said:
I was reading the article in a hurry before I left for work and I thought the author was implying that the stones needed to be lapped before use.

Off topic: Knifenut, do you recommend the Spyderco ceramic bench stones that come in blue boxes?
Click to expand...

If you can freehand sharpen, I think the bench spyderco bench stones are wonderful. I know one particular knife maker, known for his perfect edges, who finishes his knives with the spyderco UF stones.
 
knifenut1013 said:
The "saw marks" on a spyderco ceramic are from them lapping the stone. The fine stone is lapped to a UF stone.
Click to expand...

Do you know how they lap the stones? Those are pretty uniform swirls that look very much like the saw marks when i cut stone. Maybe an orbital type sander. Or one of those cup wheels like for concrete. And i already knew how they got the UF. That's not what i'm trying to figure out, but thanks.

Squashfan,

Spyderco ceramics are great stones to have. All three of them. I have read of some people buying the fine (blue) and lapping one side to a UF finish. which might safe you $40 until you have to replace the diamond stones you used to do the lapping. You can use SiC sand paper, but you will need a lot of free time.

To everyone else,

Does anyone know of another brand of ceramic stones that would be cheaper to play around with than the spyderco's? Thanks!
 
I've seen a picture of the machine, it looks like a oversized floor buffer with several grinding heads that spin on a larger spinning plate. Think industrial size equipment.

It would not be efficient for them to cut stones from a large block, the ceramic would be hell on the cutting bit. I'm pretty sure spyderco fully admits to simply lapping the fine ceramic to make a UF ceramic.

Also, sandpaper will be completely ineffective.
 
I'm making an assumption based on some work I did years ago (15-18). The ceramic stones of various kinds are just ceramic, no binder, no vitrified or resin bond, just ceramic fired in a kiln for hours. The ceramics are usually pressed in a mold to extremely high pressures, and may (and probably do) contain a binder in the ceramic powder to allow the molded piece to be handled and removed from the mold without undue risk of breaking. However, these types of binders, unlike those in water stones or vitrified bond stones, burns away during the firing process, the proper name of which is sintering. During sintering, the powder particles bond to each other, in the same way that powder metal particles bond together. Once they're bonded, and especially if they are 100% dense, the size of the particles isn't really as influential in how they sharpen as it is in resin and vitrified bond stones. This is part of the reason why it's difficult to give them a grit rating, especially based off of the original powder particle sizes.

Now, I don't think sharpening stones are 100% dense, as this takes a lot of time at very high temperatures, perhaps involving hot isostatic pressing (HIP) or other similar processes. The down side of all this is the bonds in the ceramic stones are very strong (again, think of how hard it is to pull the bonds apart in a CPM steel) and the particles are pretty much there to stay unless you lap them with something harder, like diamond. As was discussed above, this has its own issues, and doesn't really expose fresh abrasives as it does recondition the surface of the existing abrasive.

For all the reasons listed, I view ceramics as finishing stones only. They are not suitable for quick removal of metal for resharpening. However, I have had a hard time finding finishing stones that can easily match what I can do with my medium and fine Spyderco ceramics. I do need to try the UF stones. Also, keep in mind I've been using the Sharpmaker as a finishing tool for final edges for nearly 13 years and am only just getting the hang of my finer water stones (4k currently).
 
knifenut1013 said:
I've seen a picture of the machine, it looks like a oversized floor buffer with several grinding heads that spin on a larger spinning plate. Think industrial size equipment.

It would not be efficient for them to cut stones from a large block, the ceramic would be hell on the cutting bit. I'm pretty sure spyderco fully admits to simply lapping the fine ceramic to make a UF ceramic.

Also, sandpaper will be completely ineffective.
Click to expand...

^^That. I briefly tried SiC sandpaper (over a granite reference plate) on one of my Spyderco hones a while back. It was like rubbing two pieces of smooth glass together, with no evidence of abrasion on either surface. No dust, no swarf, nothing.


David
 
knifenut1013 said:
Why would you want to mess up a perfectly fine stone?

Besides that you would need a set of diamond stones that would get ruined in the process. I've messed around with lapping spyderco ceramics and the result is never as good as the new stone.
Click to expand...
Can't you just scrub the thing with diamond paste?
I'd be interested in finding out if you could get an UF stone to sub-micron fineness like 0.25 micron. And I'm rather curious about why the ceramics would ruin a diamond stone if the diamonds can typically handle ceramic knives with no problem and are in fact designed for exactly that.
 
knifenut1013 said:
I've seen a picture of the machine, it looks like a oversized floor buffer with several grinding heads that spin on a larger spinning plate. Think industrial size equipment.

It would not be efficient for them to cut stones from a large block, the ceramic would be hell on the cutting bit. I'm pretty sure spyderco fully admits to simply lapping the fine ceramic to make a UF ceramic.

Also, sandpaper will be completely ineffective.
Click to expand...

You are correct. Sal has mentioned it in a thread, about lapping them with a diamond hone, but he also states, as you have, that the diamond hone would get trashed and be useless afterwards.
 
Noctis3880 said:
Can't you just scrub the thing with diamond paste?
I'd be interested in finding out if you could get an UF stone to sub-micron fineness like 0.25 micron. And I'm rather curious about why the ceramics would ruin a diamond stone if the diamonds can typically handle ceramic knives with no problem and are in fact designed for exactly that.
Click to expand...

I think it's more about the sheer surface area (& depth) of ceramic to be abraded, and therefore the volume of it that needs to be removed. As compared to a narrow and very thin strip of ceramic from the edge of a blade. One bench-sized ceramic hone getting lapped with a diamond plate would likely give up enough ceramic for the equivalent of hundreds of ceramic blades being honed. It's not that the diamond plate won't handle it, but it's useful service life would be pretty dramatically shortened in the process.

I scrubbed quite a lot of diamond off of a DMT Dia-Fold just flattening two ceramic Lansky hones (1/2" x 4"). That's four square inches of ceramic (total), and I left some visibly bare, or nearly bare, spots on the surface of the diamond hone. That's a hone that was in essentially unused, new condition prior to starting. Compare that to trying the same with an 8" x 2" ceramic bench hone, at four times the surface area.


David
 
Noctis3880 said:
Can't you just scrub the thing with diamond paste?
I'd be interested in finding out if you could get an UF stone to sub-micron fineness like 0.25 micron. And I'm rather curious about why the ceramics would ruin a diamond stone if the diamonds can typically handle ceramic knives with no problem and are in fact designed for exactly that.
Click to expand...



That is my question as well. Ceramic knife blades are normally sharpened with diamond.

I would tend to believe that the diamond would only be ruined if pressure was applied thereby fracturing the diamond particles.
 
Not so much an issue of fracturing the diamond particles, but more due to them being knocked/ripped/pulled from the nickel substrate on the plate. I agree, light pressure makes a difference. But it's very hard to maintain that discipline over the course of the several hours' time it usually takes to completely lap & flatten a large ceramic hone, especially if done by hand.


David
 
Last edited:
You must log in or register to reply here.
Back
Top