/diy/ - Do It Yourself

>>1495532
>>1495648

You need 3 surfaces. A, B, and C. A is your stone, B and C are flattening stones, which can just be big enough bricks, flattish rocks, or one being a different stone. Don't buy a flattening stone for oil stones, they're for waterstones. Rub B and C together until reasonably flat. Rub A and B together until reasonably flat. Rub A and C together until completely flat. You need to have a common plane between 3 surfaces, using only two will make one concave and the other convex. Even sandpaper on glass will wear unevenly and cause issues.

This is how a surface plate is made, by the way. They just do it with granite or cast iron.

If one is seriously dished like the old one in picrelated you will need to grind it down on the sidewalk or something til the points of contact are not so narrow, then you can go as before.

You don't want to do this with belt grinders/sanders btw, since it will kick up a shitload of dust and load the belts real quick.

>>1495643
Flattening stones are for water stones and you need to flatten them for the reason I said before. They're grooved because water stones wear very quickly and the grooves allow the slurry to escape. I am not a fan of water stones because of how quickly they wear down. They do cut pretty fast but that's a minor issue compared to spending so much time flattening them in between.