Thread: Suehiro Gokumyo 20K

400 atoma, when new, will take care of the Suehiro, easy.

Originally Posted by bobski

Only one thing. If you purchased your Gokumyo 20k from Tools of Japan (Stuart Tierney). he says emphatically that using a 1200 Atoma to lap it will void the warranty of the stone, due to particles of diamond breaking free of the plate and lodging in the hone. He recommends the Atoma 400 which I have used for nearly 2 years with great results. E mail him not me.

Why the 400 and not the 1200? I thought they both had the same construction. Tc

It's all about the size of the particles that are embedded/attached to the Atoma or any diamond stone like the DMT. The small 1200 "grit" size is roughly 3x smaller than the 400/325 "grit". Imagine stepping on a golf ball laying on your lawn after a medium rain. The golf ball will be pushed into the lawn, where if you step on a softball it may make an indention in the lawn, but you will not embed it into the lawn. Same works for stones.

My thanks to everyone who replied...

Atoma 400 it is!

Originally Posted by mainaman

400 atoma, when new, will take care of the Suehiro, easy.

The one I received was shaped like a banana so I started with 80 grit SiC on float glass. Then progressed thru 140, 400, 1200 Atoma.

I lapped the concave side as the 2 ends gave me starting points. The convex side would have been impossible

The key with not embedding particles into a stone is just use the weight of the stone when lapping.

Soft stones like Nortons are more prone to getting grit stuck to them. The 20k is so hard it would take some ham fisted pressure to embed anything into it.

Originally Posted by onimaru55

The one I received was shaped like a banana so I started with 80 grit SiC on float glass. Then progressed thru 140, 400, 1200 Atoma.

I lapped the concave side as the 2 ends gave me starting points. The convex side would have been impossible

The key with not embedding particles into a stone is just use the weight of the stone when lapping.

Soft stones like Nortons are more prone to getting grit stuck to them. The 20k is so hard it would take some ham fisted pressure to embed anything into it.

Mine was within visual tolerance. it laps very easy with my new Atoma 400, it was hard to do much with my well worn DMT 320, or my old Atoma 140.

Originally Posted by mainaman

Mine was within visual tolerance. it laps very easy with my new Atoma 400, it was hard to do much with my well worn DMT 320, or my old Atoma 140.

Yes, a new plate cuts quickly.

Originally Posted by bobski

Only one thing. If you purchased your Gokumyo 20k from Tools of Japan (Stuart Tierney). he says emphatically that using a 1200 Atoma to lap it will void the warranty of the stone, due to particles of diamond breaking free of the plate and lodging in the hone. He recommends the Atoma 400 which I have used for nearly 2 years with great results. E mail him not me.

Is this just for the 20k, or for other stones as well ?

Originally Posted by onimaru55

People must have a lot of time on their hands to try lapping a new 20k with a 1200 Atoma.

On the contrary, the Atoma 1200 goes through any stone like a hot knife through butter IME. I may have gotten lucky because I always started lapping any stone with the DMT 325, or the Shapton GDLP and get two thirds of the way and finsih with the Atoma 1200. Examining the plate and the stone under 40x magnification so far I'm all right.

I love my Atoma 1200. I seem to have the same experience as you Jimmy.

Originally Posted by coachmike

I love my Atoma 1200. I seem to have the same experience as you Jimmy.

I should have specified "my 20k". It was truly a nightmare & I would have destroyed my 1200 Atoma lapping it, not to mention the time wasted.