Thread: Lapping a Chinese 12k

I have attempted to lap the Chinese 12 K with a norton lapping stone. The top seems flat after rubbing off all the markings. There is a slurry from the lapping stone and the 12k when it is done. However, the surface seems really rough. Is this what to expect for polishing or should I use something with a higher grit to lap and smooth the surface of the 12K?
When I hone with it, it seems too gritty.
Any advice or suggestions?
Headdoc

Originally Posted by headdoc

I have attempted to lap the Chinese 12 K with a norton lapping stone. The top seems flat after rubbing off all the markings. There is a slurry from the lapping stone and the 12k when it is done. However, the surface seems really rough. Is this what to expect for polishing or should I use something with a higher grit to lap and smooth the surface of the 12K?
When I hone with it, it seems too gritty.
Any advice or suggestions?
Headdoc

I really don't like the surface that the Norton lapping stone leaves on other stones, it is rough like you describe. The DMT-C leaves a MUCH smoother surface and cuts better so that is what I use. If I were you I would try to smooth out the surface with some high quality 1000 grit sandpaper. It will probably improve the surface.

I've enjoyed the benefits of the 12k Chinese for almost a year now, and it truly is an amazing finisher. I noticed you said "seems" flat. The ONLY way to know whether or not it is flat is to lay a quality metal straightedge lengthwise along the stone. If you can't see light between the straightedge and 12k, you've got a flat stone. I've lapped mine with the Norton Flatstone, low grit sandpaper, and now the DMT 8C. They all work. The only difference is each of these flattens a little quicker, with the DMT the fastest and easiest to use. If you decide to stay in this sport, you might as well get one. As for the roughness, don't worry about it. It will smooth over with use, and this will in no way affect the sharpening abilities. Make sure you rinse your stone after flattening to remove any embedded microscopic low grit particles.

Originally Posted by headdoc

When I hone with it, it seems too gritty.

In my experience it shouldn't feel like this AT ALL. But then again, I have only ever lapped one with the D8C, so maybe the Norton lapper just leaves lots of gritty-ness which needs to be washed away.

I've used the Norton flattening stone to lap it
then used the DMT 1200 to give it the
smooth finish you're looking for.

John

Personally, I don't think that it is possible to properly lap a Chinese 12K with a Norton lapping hone. All you will do is wear down your Norton and probably leave it no longer flat itself. I suspect that all you have done is gouged your 12K and trashed your Norton. The 12K is too hard to be lapped with anything but a diamond hone.

Originally Posted by Utopian

Personally, I don't think that it is possible to properly lap a Chinese 12K with a Norton lapping hone. All you will do is wear down your Norton and probably leave it no longer flat itself. I suspect that all you have done is gouged your 12K and trashed your Norton. The 12K is too hard to be lapped with anything but a diamond hone.

Wow, that sounds much harder than my chinese 12k. Then again I dont have the norton lapping stone. My source of comparison is how fast it raises a slurry just from the honing action, which is fast enough that I wouldn't think the norton stone would have too much trouble flattening it.

I've used the Norton flattening stone on my Chinese 12k stone and checked it with the 2000 grit sandpaper on a glass pane and it was completely flat.
Maybe I just got a softer stone than most people (or maybe I just got lucky) but the Norton really flattened it out in a jiffy.

Whoops! I forgot to mention that I soaked mine for an entire day.

Originally Posted by Russel Baldridge

Wow, that sounds much harder than my chinese 12k. Then again I dont have the norton lapping stone. My source of comparison is how fast it raises a slurry just from the honing action, which is fast enough that I wouldn't think the norton stone would have too much trouble flattening it.

Originally Posted by Howard Newell

I've used the Norton flattening stone on my Chinese 12k stone and checked it with the 2000 grit sandpaper on a glass pane and it was completely flat.
Maybe I just got a softer stone than most people (or maybe I just got lucky) but the Norton really flattened it out in a jiffy.

I think both of you DO have softer Chinese 12ks that I certainly do. Mine is a very hard stone and took about an hour to properly lap it flat using a DMT D8C. Very hard stone.

Chris L

Was it saturated with water? Though, soaking shouldn't make that much of a difference.

Maybe your stone was more uneven on the surface you lapped. Because the time it took to lap it could mean either it is very hard, or that it was really uneven.

How much slurry was produced?