Thread: how to lap chinese 12k

I have the chinese 12k from woodcraft that I want to start using, but I should probably lap it first. What is the best way to lap the chinese 12k? What have you guys used, what grits, etc.?? How long does it take??

I tried lapping a surgical black arkansas once and gave up after wearing out my arms, and I'm wondering if I'm in for a similar experience again.

The way to eliminate the "probably" is to take a straightedge like a good ruler and put it on edge on the stone (lengthwise) and hold it up to the light. If you can see light between the straightedge and the stone, you need to lap and especially if there's more light in the center of the stone. My guess is a new stone from Woodcraft probably won't need lapping unless something is wrong with the surface. Several folks have gotten Starrett machinist's rulers from me to test flatness this way. These are precision tools that are as flat and straight as ever you need in a ruler.

Question: what are you lapping with? This should not be an arm-busting process with any stone. It should also be fairly quick. I lap about 20 stones a week and have used a DMT 8" continuous diamond Coarse for a couple of years. It makes coticules purr like velvet. If it's a vintage, dished stone I'm lapping, I use a DMT 8" continous diamond Xtra Coarse and that puppy will wear down a stone right quick. Then finish up on the Coarse DMT. Do all this in the kitchen sink with a thin stream of warm water playing over one end of the stone to wash away swarf as it forms. Using a Fine grit stone doesn't work as it loads in seconds and has to be cleaned before you can move on.

I've lapped that same 12K Chinese stone in just a few minutes using 400 grit wet/dry sandpaper. Those stones tend to come with pretty sharp edges, so I would suggest easing the edges all the way around while you're at it. You can put a small radius on the edge in just a swipe or two. No need to overdo it, you just want to make sure there is no chance of catching a small chip in the edge if you happen to raise the heel or toe of the razor slightly while honing.

Cheers,
Ed