I have a 8" x 3" 3/8" thick steel diamond hone.
#300 on one side, and #1000 on the other side. Lacking the Renzetti resource to surface grind two flat stones, I simply rubbed the medium India stone ex-woodwork chisel sharpener on #300 side. It gets so flat that it skids on other flat stuff without cutting. Rubbing two stones together that have each seen the diamond might be a partial version of the 3-plate method, but anyway, one slides over the other almost like on an air layer.
Basically, there are only two surfaces that can slide over each other. They are both on a single shared plane, or they are each on a piece of the same sphere. If one is loaded with diamonds, it will be the winner, Rubbing two stones treated this way, they skid over each other without cutting. I tried it on a new 123-block, and all it did was start mirror polishing to reveal the real accuracy of the surface grinding underneath.
With a stone like this, known to be flat enough, and used right, you cannot hurt a lathe way, except for knocking down dings. If there are remaining oil-retention scrape flaking marks, it just makes them look beautiful! Do it à recette
@pontiac428. Even a small wedge-type slip stone, made and kept really flat, and used in the proper way, will do nicely. After all, a stone is the final thing used on a precision beautiful scraped surface. Don't be afraid of it!
DO NOT harsh grind lathe ways with stones! That is
not the same thing as "stoning".
I guess
@Janderso may not approve the cheapskate approach, and we would not dare darken Robin's door with this stuff!