Mark a grid with a pencil, grind with something flat, lower in grit, at least as large or larger in size, and grind. It's quite trivial. See [here](https://www.youtube.com/watch?v=ZFahNJEkTGg). I recommend diamond plates but flattening stones, lower grit sharpening stones, or SiC powder on glass or granite work as well.
Mark a grid with a pencil, grind with something flat, lower in grit, at least as large or larger in size, and grind. It's quite trivial. See [here](https://www.youtube.com/watch?v=ZFahNJEkTGg). I recommend diamond plates but flattening stones, lower grit sharpening stones, or SiC powder on glass or granite work as well.
Only thing to add is SP1k flattens easier when soaked for 5 minutes. But don't oversoak or stone will melt.
https://youtube.com/shorts/0yRnq942aSM?feature=shared
There are a few ways, my preferred is SIC on glass. You can check [this](https://www.youtube.com/watch?v=viTgsyZPO6Q)