Lapping coarse stones?

I am starting to find time again to do woodworking now that my son is 1 and a half. In my free time I've started to get my tools set up and ready so I can start making things but I've dished out my stones, I have Shapton Kuromaku series stones an need to replace my lapping stone(Atoma 400) since its been misplaced. I over looked the grit of my coarsest stone when I bought my original lapping stone, what can I use that is capable of handling a 320 Shapton and the rest of my stones?

Thank you in advanced!

There are two (3 if we count making a slurry, but I won't for this purpose) reasons for lapping a stone:
#1. Making it flat.
#2. Conditioning the surface (usually to roughen it up and make it cut quickly).

For flattening, any diamond plate will work. The coarser, the quicker. The finer, the slower. But this depends on the friability of your stone.

For conditioning, you want a stone slightly coarser than the grit you want to end at. But if your stone is very friable and exposes new grit quickly, you won't even notice. This is mainly important for hard natural stones and natural and synthetic oilstones.

I like a very coarse (#150-300) grit diamond plate for flattening and conditioning my coarse stones, and a finer (#1000 grit) stone for conditioning my finer stones. You may be able to find a 300/1000 grit combo stone which is a great all around stone to have. The super coarse (80-200) grit stones are great for flattening the backs of new chisels or grinding new bevels.

In the meantime, you can just flatten with some sand paper and some float glass, a flat tile, or even a flat wooden board or table.

It depends on how badly dished they are.

David Weaver posted a video online showing how he flattened severely dished stones on an old belt sander.
If they are really bad - that would be a good Step 1 to get them into the ballpark. Then you can move on to diamond stones or some other manual method to true them up after the bulk material removal is done......

I invested in a DiaFlat plate a few years ago and it has really reduced the time and hassle of flattening my Shapton ceramic stones. The DiaFlat is big enough to handle almost any stone at 10"x4", is extremely flat (to 0.0005"), comes in at 90 grit, and is *incredibly* durable. I even use it for hand grinding chisels and plane blades (I don't have a power grinder). It works very fast and very efficiently. Expensive, but highly recommended.

DMT DiaFlat Lapping Plate

TedP

Whatever you end up using, just be sure to check your lapping plate / diamond plate / etc is flat because i've seen plenty that are not flat. No point starting with something that isn't flat to try and 'flatten' your sharpening stones.

Thats for all the help guys much appreciate it!