Quote Originally Posted by bluesman7 View Post
Lynn has good things to say about the economical series 1k. Why not use the 1k to lap the 3k, or the wet/dry to lap the both of them. My impression is that the stones are pretty soft and the fineness of the lapped surface will be immaterial.
You might be thinking of the Traditional series, which Lynn also carries in his store. The economical series are a slightly different thing.

If you already have diamond plates and SIC powder, why try to brute force a 120 grit hone into serving as a lapping plate? The only reason we can use diamond hones for lapping is A: they're (generally) very flat, and B: also a LOT harder than the hones/stones they're flattening. Since it's a hone, it will need flattening itself before it could be pressed into service as a lapping plate. And if it isn't (significantly) harder than the 1K or 4K then it will end up out of flat in short order.

If it's just to have an 'in house' lapping stone, Naniwa makes one that will probably serve the purpose better.