Ceramic vs diamond stones

jfindon

jfindon

Joined
Dec 12, 2006
Messages
967
Are the grits comparable? If a ceramic stone grit is 140 and the coarse diamond stone is 300 I'm guessing the ceramic will remove more steel? Reason I'm asking is I have a KME sharpener and I'm pretty sure this is what came with it back in the day:

http://kmesharp.com/4sexcomefi.html

Yet the diamond stones package only goes down to 300:

http://kmesharp.com/gose3set.html


I'm confused why the package deal wouldn't be as coarse as the normal ones unless they do in fact remove more steel.
 
A couple of points:

Grits aren't grits. That is, the grit rating of one system or media type may not be equivalent to another system. See the Grand Unified Grit Chart link at the top of this forum for a table comparing many different systems (ANSI, CAMI, FEPA-P, etc). The media itself can also have a large impact because of particle shape. Diamonds are the most pointy, so they dig the deepest when grinding. So diamond media tend to seem more abrasive than their grit rating would indicate. The finish from a "1200 grit" diamond is closer to a 600 to 800 grit in other systems.

The other thing is, "ceramic" has many meanings. The link you provided referred to "Silicon Carbide Ceramic stone". Silicon Carbide is a well known abrasive that cuts really well and it's grit rating is indicative of it's performance. I'm not sure why they are also calling this "ceramic". In the sharpening world, ceramic *normally* means sintered abrasives that are very hard, break when dropped, and do not wear at all. Kind of like a ceramic plate you eat dinner on. Ceramic abrasives of this type include rod sharpeners, Spyderco's stones, and many other examples. These types of ceramic abrasives are hard to rate in "grit" exactly, but we can estimate based on the scratch pattern. Spyderco's medium ceramic, for example, is something like 800 grit give or take a bit.

All that being said, I think the 80 grit SiC stone from the original KME probably cuts faster than any "300 grit" diamond. 140 grit SiC would probably still cut faster in my estimation.

Brian.
 
Thanks for the info. I thought maybe that was the case but then I started thinking I was wrong.

My 140 (EDIT: Apparently it's 80 grit) grit feels smooth now, is it possible I wore it out without sharpening that many knives? My goal is to get a stone that will reprofile quick, right now use a sharpie and trying to do a 20 degree edge is taking forever to wear all the mark off on a steel that isn't even good, so I'm thinking it's worn out. Maybe I should go with extra coarse from their offerings? Would the Gold Series Diamond set from them be much better than these?

http://kmesharp.com/setdmtdi4x1d.html

I really hate that they don't list more details about the stones.
 
Last edited:
jfindon said:
Thanks for the info. I thought maybe that was the case but then I started thinking I was wrong.

My 140 (EDIT: Apparently it's 80 grit) grit feels smooth now, is it possible I wore it out without sharpening that many knives? My goal is to get a stone that will reprofile quick, right now use a sharpie and trying to do a 20 degree edge is taking forever to wear all the mark off on a steel that isn't even good, so I'm thinking it's worn out. Maybe I should go with extra coarse from their offerings? Would the Gold Series Diamond set from them be much better than these?

http://kmesharp.com/setdmtdi4x1d.html

I really hate that they don't list more details about the stones.
Click to expand...
Hi,
yes, it is possible it has "worn", but its not dead yet :) all stones wear,
but its more likely your stone is loaded/dirty,
so you have to unload it, clean the stone,
maybe using a toothbrush and baby oil (or whatever oil you use)
or water and dish soap....

if cleaning doesn't restore adequate speed, , you have to re-condition/re-cut/loosen some grit
which can be as simple as scratch the surface of the stone with a nail, utility blade, pointy rock,
followed by a short 10-20 second scrub on something flat (glass, tile, another oil stone)...
or followed by sharpening /scrubbing with a knife

scratching the stone with a nail is also a pretty quick way to unload a stone, but it uses up more stone

more on unloading/flattening/lapping/conditioning
 
It's not the answer you want but "it depends" for example I find in most systems the diamond grits of the same # leave much more toothy edges and cuts faster than other stones rated at the same "grit". For example when new even a 1000 grit wicked edge diamond stone leaves a pretty coarse edge, much more than a 600 grit ceramic spyderco sharpmaker stone. There's a HUGE difference between the 1000 grit diamond wicked edge stone and the 1200 grit wicked edge ceramic, much much more than the 200 grit difference would lead you to believe. I like diamond stones for cutting fast but I prefer ceramic for the finer grits. Cleaning non-diamond stones can help restore their cutting efficiency, but with diamond stones the issue is over time they loose the diamonds and there's no way to bring back their cutting efficiency they simply need replacing, where other stones can be "conditioned" and "re-flattened" as they wear. In my experience diamond stones also have a shorter lifespan, in that other stones can be conditioned/re-flattened etc. but from day one a diamond stone is loosing it's efficiency/grit and there's no way to rejuvenate it.
 
This ^ has been my experience as well. Thus, SiC, Alum. Oxide ceramic and other types of grit offer better economy. And I've noticed a slight difference in their speed of cutting. The big difference is initial cost and cost over the life of the stone. DM
 
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