Got myself a 36" lapping plate

[mikepancake]

Bought this used 36in lap, fixed it up a bit and added a 3-phase motor with a VFD. I've heard you can use loose grit like silicon carbide or aluminum oxide instead, just wondering which types and sizes people usually use, how to apply it to the plate so it stays put, and what RPMs work best. Planning to use it mainly for polishing large geodes, quartz crystals and flat sided stone pieces. Thanks

 

[CityDweller]

@mikepancake for those geodes and crystals, usually using Silicon Carbide (SiC) grit for all the grinding and shaping stages. Start with coarser stuff like 220 or 400, then move up through finer grits (600, 1000, 1200).
For the final polish, switch to a dedicated polishing compound like Cerium Oxide or Aluminum Oxide for that mirror finish

 

[mikepancake]

@mikepancake for those geodes and crystals, usually using Silicon Carbide (SiC) grit for all the grinding and shaping stages. Start with coarser stuff like 220 or 400, then move up through finer grits (600, 1000, 1200).
For the final polish, switch to a dedicated polishing compound like Cerium Oxide or Aluminum Oxide for that mirror finish

Thanks, is it better to use a machine too? Or by hand is okay?