I think I am going to flatten my Spyderco ceramics.

I'm sure it can lap ceramics but my point being that there are not any abrasives used in the making of the medium or fine ceramics so lapping them changes them from the original design and construction.

More accurately, we are texturing the surface of the ceramics to alter the their polishing abilities. I did this with my spyderco ceramics a few years ago too.
 
Yes that's true. It doesn't mean we can't do better than they did though for our purposes. Surfaced with a coarse 60 or 80 grit loose grit SiC lap for instance, the medium stones would probably cut a heck of a lot faster than factory. As I previously noted, the finish level and hence speed of the stone is something that each individual needs to decide to suit their own need and preference.
 
On ceramics the grit rating is determined by the surface finish on the stone. I am currently transforming my fine to ultrafine. It would have been nice if those came flat out of the factory so people would not have to deal with lapping ceramics...takes too long.
 
That's right. It's pretty much true of almost all very hard stones. As an example, my Washita will cut like an S.O.B. with a 120 grit loose grit SiC lapping, but lapped to 1200 diamond plate or 1500 loose grit it will barely cut and almost becomes a burnisher. As far as taking awhile, ain't that the truth. The little ones aren't bad, but the bench stones take a bit of time. Mine wasn't too far out of flat, but it had a twist which is no good, and I wanted it smoother.
 
eKretz said:
That's right. It's pretty much true of almost all very hard stones. As an example, my Washita will cut like an S.O.B. with a 120 grit loose grit SiC lapping, but lapped to 1200 diamond plate or 1500 loose grit it will barely cut and almost becomes a burnisher. As far as taking awhile, ain't that the truth. The little ones aren't bad, but the bench stones take a bit of time. Mine wasn't too far out of flat, but it had a twist which is no good, and I wanted it smoother.
Click to expand...

My medium is the worst offender. One side has a plateau running down the side and other side has twist. Two of the opposing corners are higher than the rest of the stone.


Hey, Jason, what grits of Shaptons would you recommend for me?

This has been a fun thread, thanks!
 
My stone was the 2X8" fine and one side was good. So, on that I did nothing. The other side was unlevel or had a slight twist. I leveled it with a older coarse diamond and got it very close. Then finished it off with a fine diamond continuous. The dia coarse was shot but my ceramic stone was level and it still cuts.
So, not glazed. They are difficult to level but not so complicated. DM
 
Just a couple more additions to give guys an idea of the difference between a loose grit lapping and a diamond plate lapping. You can easily see in the scope photos how much more sharp and open the surface of the stone is. The shots are lit with raking lighting from the side at an oblique angle to give a bit better idea of the stone texture. This is a Washita stone lapped with 120 loose SiC grit and with a 140 grit Atoma diamond plate.

Here are the stone surface scope photos.

Atoma 140 grit diamond plate lapped (smooth rounded peaks, very flat so swarf will constantly be in contact with the steel etc.):

WashitaAtoma140Lap.jpg~original


120 grit loose SiC lapped (sharp, jagged edges, open and gives swarf some room to get away from the steel):

Washita120SiCLooseGritLap.jpg~original


And the stone surface photos with my phone's cam just to give an idea of the closed/open condition of the surface by reflectivity:

Atoma 140 lapped (Note how shiny this is compared to the SiC lapped surface):

IMG_20150128_033010.jpg~original


120 grit loose SiC lapped (Note how much more matte this surface is):

IMG_20150128_033116.jpg~original


The loose grit lapped surface cuts like a BMF, while the Atoma lapped surface cuts meh.
 
The diamond plate conditioned image shows what I would call "glazing" - has been surfaced down to a finish that is finer then the abrasive structure. The second is more open due to the loose grit rolling around. Another consideration for those lapping with SiC is that when ground between two hard surfaces it will fracture down in fairly short order into much smaller pieces. If you want the more aggressive surface you will need to add fresh grit and pay attention to the slurry.

Also to consider is the differences in various stone compositions and how that affects what kind of surface you end up with. On my ceramic, the SiC could flatten the surface but could not really generate aggressive surface features, at least not in the order of what the diamond plate can do. The fine ceramic is by construction no more than a really hard material with surface texture added. A Wahita stone or vitreous stones have an open abrasive structure that breaks down somewhat in use and tends toward an equilibrium between abrasive potential and wear rate.
 
When I lapped and flattened my ceramic stone. I did my Washita stone as well, both in the same day. I noticed the Arkansas was cut and leveled Much easier than the ceramic using a coarse dia diamond stone. I'm certain one could level a Arkansas on a flat area of concrete but this would have little affect on the ceramic stone. Secondly, I've been paying attention to my ceramic stone in how it cuts during use and have noticed it cuts slower on the ultra fine side than the fine side. Still, this was to be expected after refining it's surface. Just a common out come. DM
 
Heavy, that shiny, slow-cutting, dull surface is exactly the surface you will get on your ceramic if you surface/flatten it with a diamond plate - unless you do all the flattening then switch to a brand new diamond plate for just a few seconds. As far as the SiC breakdown, I already noted exactly that, as well as stressed the importance of recharging the lapping plate in an earlier post. If you don't refresh/recharge the lapping plate, of COURSE you won't get any aggressive surface characteristics. You are effectively lapping with a much finer grit than you started with. You must recharge MUCH more often when lapping the ceramic because the SiC breaks down rapidly.

I also already covered the differing cutting speed due to varying lapping fineness. You guys are repeating what I've already said now. In your defense, I may have edited that earlier post after you initially read it.
 
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