Shop made lapping plates

[EclecticNeophyte]

I saw youtube where the person lapped an iron flat against surface stone, using diamond grit powder

did you use any grit?

Sounds to me like the method used to flatten a granite surface plate, but yes I did (more than one actually). You can use common valve grinding compound to start, and then move to finer grits once the plates show good flatness. I think I started with Timesaver #111 (green can), then moved to finer grits from there. Tom Lipton has a good set of videos on YouTube. He's also the one who encouraged me to make a set. The idea of using a sliding miter saw to cut the grooves was my small contribution to the effort...

Hope this helps.

-EN